Year 2017

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Moulin-Frier, C., Fischer, T., Petit, M., Pointeau, G., Puigbo, J., Pattacini, U., Low, S. C., Camilleri, D., Nguyen, P., Hoffmann, M., Chang, H. J., Zambelli, M., Mealier, A., Damianou, A., Metta, G., Prescott, T. J., Demiris, Y., Dominey, P. F., Verschure, P. F. M. J., (2018). DAC-h3: A proactive robot cognitive architecture to acquire and express knowledge about the world and the self IEEE Transactions on Cognitive and Developmental Systems in press

This paper introduces a cognitive architecture for a humanoid robot to engage in a proactive, mixed-initiative exploration and manipulation of its environment, where the initiative can originate from both the human and the robot. The framework, based on a biologically-grounded theory of the brain and mind, integrates a reactive interaction engine, a number of state-of-the art perceptual and motor learning algorithms, as well as planning abilities and an autobiographical memory. The architecture as a whole drives the robot behavior to solve the symbol grounding problem, acquire language capabilities, execute goal-oriented behavior, and express a verbal narrative of its own experience in the world. We validate our approach in human-robot interaction experiments with the iCub humanoid robot, showing that the proposed cognitive architecture can be applied in real time within a realistic scenario and that it can be used with naive users.

Keywords: Autobiographical Memory., Biology, Cognition, Cognitive Robotics, Computer architecture, Distributed Adaptive Control, Grounding, Human-Robot Interaction, Humanoid robots, Robot sensing systems, Symbol Grounding

Hortigüela, Verónica, Larrañaga, Enara, Cutrale, Francesco, Seriola, Anna, García-Díaz, María, Lagunas, Anna, Andilla, Jordi, Loza-Alvarez, Pablo, Samitier, Josep, Ojosnegros, Samuel, Martinez, Elena, (2018). Nanopatterns of surface-bound ephrinB1 produce multivalent ligand-receptor interactions that tune EphB2 receptor clustering Nano Letters 18, (1), 629-637

Here we present a nanostructured surface able to produce multivalent interactions between surface-bound ephrinB1 ligands and membrane EphB2 receptors. We created ephrinB1 nanopatterns of regular size (<30 nm in diameter) by using self-assembled diblock copolymers. Next, we used a statistically enhanced version of the Number and Brightness technique, which can discriminate - with molecular sensitivity - the oligomeric states of diffusive species to quantitatively track the EphB2 receptor oligomerization process in real time. The results indicate that a stimulation using randomly distributed surface-bound ligands was not sufficient to fully induce receptor aggregation. Conversely, when nanopatterned onto our substrates, the ligands effectively induced a strong receptor oligomerization. This presentation of ligands improved the clustering efficiency of conventional ligand delivery systems, as it required a 9-fold lower ligand surface coverage and included faster receptor clustering kinetics compared to traditional crosslinked ligands. In conclusion, nanostructured diblock copolymers constitute a novel strategy to induce multivalent ligand-receptor interactions leading to a stronger, faster, and more efficient receptor activation, thus providing a useful strategy to precisely tune and potentiate receptor responses. The efficiency of these materials at inducing cell responses can benefit applications such as the design of new bioactive materials and drug-delivery systems.

Diez-Escudero, A., Espanol, M., Bonany, M., Lu, X., Persson, C., Ginebra, M. P., (2018). Heparinization of Beta Tricalcium Phosphate: Osteo-immunomodulatory Effects Advanced Healthcare Materials Early View (Online Version of Record published before inclusion in an issue)

Immune cells play a vital role in regulating bone dynamics. This has boosted the interest in developing biomaterials that can modulate both the immune and skeletal systems. In this study, calcium phosphates discs (i.e., beta-tricalcium phosphate, β-TCP) are functionalized with heparin to investigate the effects on immune and stem cell responses. The results show that the functionalized surfaces downregulate the release of hydrogen peroxide and proinflammatory cytokines (tumor necrosis factor alpha and interleukin 1 beta) from human monocytes and neutrophils, compared to nonfunctionalized discs. The macrophages show both elongated and round shapes on the two ceramic substrates, but the morphology of cells on heparinized β-TCP tends toward a higher elongation after 72 h. The heparinized substrates support rat mesenchymal stem cell (MSC) adhesion and proliferation, and anticipate the differentiation toward the osteoblastic lineage as compared to β-TCP and control. The coupling between the inflammatory response and osteogenesis is assessed by culturing MSCs with the macrophage supernatants. The downregulation of inflammation in contact with the heparinized substrates induces higher expression of bone-related markers by MSCs.

Keywords: Calcium phosphates, Heparinization, Inflammation, Osteogenesis

Basas, Jana, Palau, Marta, Ratia, Carlos, Luis Del Pozo, José, Martín-Gómez, María Teresa, Gomis, Xavier, Torrents, Eduard, Almirante, Benito, Gavaldà , Joan, (2018). High-dose daptomycin is effective as an antibiotic-lock therapy in a rabbit model of Staphylococcus epidermidis catheter-related infection Antimicrobial Agents and Chemotherapy 62, (2), e01777

Long-term catheter-related bloodstream infections (CRBSI) involving coagulase-negative Staphylococci are associated with poor patient outcomes, increased hospitalization and high treatment costs. The use of vancomycin-lock therapy has been an important step forward to treat these biofilms although failures appear in 20% of patients. In this study, we report that a high dose of daptomycin-lock therapy may offer a therapeutic advantage for these CRBSI in just 24 h of treatment.

Pacheco, D., Verschure, P. F. M. J., (2018). Long-term spatial clustering in free recall Memory Article in press

We explored the influence of space on the organisation of items in long-term memory. In two experiments, we asked our participants to explore a virtual environment and memorise discrete items presented at specific locations. Memory for those items was later on tested in immediate (T1) and 24 hours delayed (T2) free recall tests, in which subjects were asked to recall as many items as possible in any order. In experiment 2, we further examined the contribution of active and passive navigation in recollection dynamics. Results across experiments revealed a significant tendency for participants to consecutively recall items that were encountered in proximate locations during learning. Moreover, the degree of spatial organisation and the total number of items recalled were positively correlated in the immediate and the delayed tests. Results from experiment 2 indicated that the spatial clustering of items was independent of navigation types. Our results highlight the long-term stability of spatial clustering effects and their correlation with recall performance, complementing previous results collected in immediate or briefly delayed tests.

Keywords: Free recall, Spatial clustering, Spatial memory, Spatial navigation, Virtual reality

Hristova-Panusheva, K., Keremidarska-Markova, M., Altankov, G., Krasteva, N., (2017). Age-related changes in adhesive phenotype of bone marrow-derived mesenchymal stem cells on extracellular matrix proteins Journal of New Results in Science 6, (1), 11-19

Mesenchymal stem cells (MSCs) are a promising cell source for cell-based therapies because of their self-renewal and multi-lineage differentiation potential. Unlike embryonic stem cells adult stem cells are subject of aging processes and the concomitant decline in their function. Age-related changes in MSCs have to be well understood in order to develop clinical techniques and therapeutics based on these cells. In this work we have studied the effect of aging on adhesive behaviour of bone marrow-derived MSC and MG- 63 osteoblastic cells onto three extracellular matrix proteins: fibronectin (FN), vitronectin (VN) and collagen I (Coll I). The results revealed substantial differences in adhesive behaviour of both cell types during 21 days in culture. Bone-marrow derived MSCs decreased significantly their adhesive affinity to all studied proteins after 7th day in culture with further incubation. In contrast, MG-63 cells, demonstrated a stable cell adhesive phenotype with high affinity to FN and Coll I and low affinity to vitronectin over the whole culture period. These data suggest that adhesive behaviour of MSCs to matrix proteins is affected by aging processes unlike MG-63 cells and the age-related changes have to be considered when expanding adult stem cells for clinical applications.

Keywords: Cell morphology, Cell attachment and spreading, Fibronectin, Vitronectin, Collagen I

Barbeck, Mike, Serra, Tiziano, Booms, Patrick, Stojanovic, Sanja, Najman, Stevo, Engel, Elisabeth, Sader, Robert, Kirkpatrick, Charles James, Navarro, Melba, Ghanaati, Shahram, (2017). Analysis of the in vitro degradation and the in vivo tissue response to bi-layered 3D-printed scaffolds combining PLA and biphasic PLA/bioglass components – Guidance of the inflammatory response as basis for osteochondral regeneration Bioactive Materials 2, (4), 208-223

Abstract The aim of the present study was the in vitro and in vivo analysis of a bi-layered 3D-printed scaffold combining a PLA layer and a biphasic PLA/bioglass G5 layer for regeneration of osteochondral defects in vivo Focus of the in vitro analysis was on the (molecular) weight loss and the morphological and mechanical variations after immersion in SBF. The in vivo study focused on analysis of the tissue reactions and differences in the implant bed vascularization using an established subcutaneous implantation model in CD-1 mice and established histological and histomorphometrical methods. Both scaffold parts kept their structural integrity, while changes in morphology were observed, especially for the PLA/G5 scaffold. Mechanical properties decreased with progressive degradation, while the PLA/G5 scaffolds presented higher compressive modulus than PLA scaffolds. The tissue reaction to PLA included low numbers of BMGCs and minimal vascularization of its implant beds, while the addition of G5 lead to higher numbers of BMGCs and a higher implant bed vascularization. Analysis revealed that the use of a bi-layered scaffold shows the ability to observe distinct in vivo response despite the physical proximity of PLA and PLA/G5 layers. Altogether, the results showed that the addition of G5 enables to reduce scaffold weight loss and to increase mechanical strength. Furthermore, the addition of G5 lead to a higher vascularization of the implant bed required as basis for bone tissue regeneration mediated by higher numbers of BMGCs, while within the PLA parts a significantly lower vascularization was found optimally for chondral regeneration. Thus, this data show that the analyzed bi-layered scaffold may serve as an ideal basis for the regeneration of osteochondral tissue defects. Additionally, the results show that it might be able to reduce the number of experimental animals required as it may be possible to analyze the tissue response to more than one implant in one experimental animal.

Keywords: Bioactive glass, Polylactic acid (PLA), Bi-layer scaffold, Multinucleated giant cells, Bone substitute, Vascularization, Calcium phosphate glass

Ballester, Rubio Belén, Nirme, Jens, Camacho, Irene, Duarte, Esther, Rodríguez, Susana, Cuxart, Ampar, Duff, Armin, Verschure, F. M. J. Paul, (2017). Domiciliary VR-based therapy for functional recovery and cortical reorganization: Randomized controlled trial in participants at the chronic stage post stroke JMIR Serious Games 5, (3), e15

Background: Most stroke survivors continue to experience motor impairments even after hospital discharge. Virtual reality-based techniques have shown potential for rehabilitative training of these motor impairments. Here we assess the impact of at-home VR-based motor training on functional motor recovery, corticospinal excitability and cortical reorganization. Objective: The aim of this study was to identify the effects of home-based VR-based motor rehabilitation on (1) cortical reorganization, (2) corticospinal tract, and (3) functional recovery after stroke in comparison to home-based occupational therapy. Methods: We conducted a parallel-group, controlled trial to compare the effectiveness of domiciliary VR-based therapy with occupational therapy in inducing motor recovery of the upper extremities. A total of 35 participants with chronic stroke underwent 3 weeks of home-based treatment. A group of subjects was trained using a VR-based system for motor rehabilitation, while the control group followed a conventional therapy. Motor function was evaluated at baseline, after the intervention, and at 12-weeks follow-up. In a subgroup of subjects, we used Navigated Brain Stimulation (NBS) procedures to measure the effect of the interventions on corticospinal excitability and cortical reorganization. Results: Results from the system?s recordings and clinical evaluation showed significantly greater functional recovery for the experimental group when compared with the control group (1.53, SD 2.4 in Chedoke Arm and Hand Activity Inventory). However, functional improvements did not reach clinical significance. After the therapy, physiological measures obtained from a subgroup of subjects revealed an increased corticospinal excitability for distal muscles driven by the pathological hemisphere, that is, abductor pollicis brevis. We also observed a displacement of the centroid of the cortical map for each tested muscle in the damaged hemisphere, which strongly correlated with improvements in clinical scales. Conclusions: These findings suggest that, in chronic stages, remote delivery of customized VR-based motor training promotes functional gains that are accompanied by neuroplastic changes. Trial Registration: International Standard Randomized Controlled Trial Number NCT02699398 (Archived by at

Keywords: Stroke, Movement disorder, Recovery of function, neuroplasticity, Transcranial magnetic stimulation, Physical therapy, Hemiparesis, Computer applications software

Venkova, Tatiana, Juárez, Antonio, Espinosa, Manuel, (2017). Editorial: Modulating prokaryotic lifestyle by DNA-binding proteins: Learning from (apparently) simple systems Frontiers in Molecular Biosciences 3, Article 86

Within the research in Molecular Biology, one important field along the years has been the analyses on how prokaryotes regulate the expression of their genes and what the consequences of these activities are. Prokaryotes have attracted the interests of researchers not only because the processes taking place in their world are important to cells, but also because many of the effects often can be readily measured, both at the single cell level and in large populations. Contributing to the interest of the present topic is the fact that modulation of gene activity involves the sensing of intra- and inter-cellular conditions, DNA binding and DNA dynamics, and interaction with the replication/transcription machinery of the cell. All of these processes are fundamental to the operation of a biological entity and they condition its lifestyle. Further, the discoveries achieved in the bacterial world have been of ample use in eukaryotes. In addition to the fundamental interest of understanding modulation of prokaryotic lifestyle by DNA-binding proteins, there is an added interest from the healthcare point of view. As it is well-known the antibiotic-resistance strains of pathogenic bacteria are a major world problem, so that there is an urgent need of innovative approaches to tackle it. Human and animal infectious diseases impose staggering costs worldwide in terms of loss of human life and livestock, diminished productivity, and the heavy economic burden of disease. The global dimension of international trade, personal travel, and population migration expands at an ever-accelerating rate. This increasing mobility results in broader and quicker dissemination of bacterial pathogens and in rapid spread of antibiotic resistance. The majority of the newly acquired resistances are horizontally spread among bacteria of the same or different species by processes of lateral (horizontal) gene transfer, so that discovery of new antibiotics is not the definitive solution to fighting infectious diseases. There is an absolute need of finding novel alternatives to the “classical” approach to treat infections by bacterial pathogens, and these new ways must include the exploration and introduction of novel antibacterials, the development of alternative strategies, and the finding of novel bacterial targets. However, all these approaches will result in a stalemate if we, researchers, are not able to achieve a better understanding of the mechanistic processes underlying bacterial gene expression. It is, then, imperative to continue gaining insight into the basic mechanisms by which bacterial cells regulate the expression of their genes. That is why our Research Topic hosted by Frontiers in Molecular Biosciences was timely, and the output of it offers novel and up-to-date points of view to the “simple” bacterial world.

Keywords: DNA-protein interactions, Gene regulation in Prokaryotes, Replication control, Regulation of Bacterial Gene Expression, Global Regulatory Networks

Calvé, Pablo, Gorostiza, Pau, (2017). Estrategias optogenéticas y fotofarmacológicas para restablecer la visión Visión 51, 6-13

La mayoría de los casos de ceguera están causados por defectos en el ojo. Generalmente, estas alteraciones se producen por daños en las vías ópticas que conducen a la retina y son necesarias para el enfoque de las imágenes. A día de hoy, es posible tratar y curar estos impedimentos ópticos. Por ejemplo, la cirugía de cataratas para extraer una lente opaca y reemplazarla con una lente artificial se lleva a cabo rutinariamente en muchas partes del mundo y los trasplantes de córnea con córneas naturales o artificiales comúnmente tienen éxito. Sin embargo, existen casos de ceguera que afectan a un porcentaje considerable de la población y no disponen de tratamiento. La mayor parte de las cegueras incurables son debidas a las enfermedades neurodegenerativas de la retina, que se caracterizan, la mayoría de las veces, por pérdida de las células fotorreceptoras. En estas enfermedades, los fotorreceptores se dañan y mueren en un proceso de apoptosis que eventualmente provoca la ceguera. Sin embargo, las neuronas situadas en las capas internas de la retina permanecen intactas durante un periodo de tiempo prolongado, antes de que la retina sufra procesos de remodelización en las etapas finales de la enfermedad. Entre las enfermedades neurodegenerativas de la retina, la retinosis pigmentaria y la degeneración macular asociada a la edad son las más comunes. De este modo, debido a que las neurodegeneraciones retinianas provocan afectaciones en la visión y pueden inducir ceguera completa en los casos más graves, es necesario buscar y estudiar nuevos tratamientos terapéuticos. Hoy en día, muchos laboratorios de investigación están desarrollando terapias para este tipo de enfermedades, dirigidas a restaurar la función de las células fotorreceptoras en el ojo ciego o bien a sustituir la pérdida de la función fotorreceptora, pretendiendo que las neuronas retinianas restantes sean directamente sensibles a la luz. Estas aproximaciones terapéuticas engloban desde prótesis electrónicas hasta células madre y terapia génica.

Parmar, J., Villa, K., Vilela, D., Sánchez, S., (2017). Platinum-free cobalt ferrite based micromotors for antibiotic removal Applied Materials Today 9, 605-611

Self-propelled micromotors have previously shown to enhance pollutant removal compared to non-motile nano-micro particles. However, these systems are expensive, difficult to scale-up and require surfactant for efficient work. Efficient and inexpensive micromotors are desirable for their practical applications in water treatment technologies. We describe cobalt-ferrite based micromotors (CFO micromotors) fabricated by a facile and scalable synthesis, that produce hydroxyl radicals via Fenton-like reaction and take advantage of oxygen gas generated during this reaction for self-propulsion. Once the reaction is complete, the CFO micromotors can be easily separated and collected due to their magnetic nature. The CFO micromotors are demonstrated for highly efficient advanced oxidative removal of tetracycline antibiotic from the water. Furthermore, the effects of different concentrations of micromotors and hydrogen peroxide on the antibiotic degradation were studied, as well as the generation of the highly reactive hydroxyl radicals responsible for the oxidation reaction.

Keywords: Degradation, Fenton reaction, Microbots, Nanomotors, Self-propelled Micromotors, Water treatment

Oria, Roger, Wiegand, Tina, Escribano, Jorge, Elosegui-Artola, Alberto, Uriarte, Juan Jose, Moreno-Pulido, Cristian, Platzman, Ilia, Delcanale, Pietro, Albertazzi, Lorenzo, Navajas, Daniel, Trepat, Xavier, García-Aznar, José Manuel, Cavalcanti-Adam, Elisabetta Ada, Roca-Cusachs, Pere, (2017). Force loading explains spatial sensing of ligands by cells Nature 552, 219-224

Cells can sense the density and distribution of extracellular matrix (ECM) molecules by means of individual integrin proteins and larger, integrin-containing adhesion complexes within the cell membrane. This spatial sensing drives cellular activity in a variety of normal and pathological contexts1,2. Previous studies of cells on rigid glass surfaces have shown that spatial sensing of ECM ligands takes place at the nanometre scale, with integrin clustering and subsequent formation of focal adhesions impaired when single integrin–ligand bonds are separated by more than a few tens of nanometres3,4,5,6. It has thus been suggested that a crosslinking ‘adaptor’ protein of this size might connect integrins to the actin cytoskeleton, acting as a molecular ruler that senses ligand spacing directly3,7,8,9. Here, we develop gels whose rigidity and nanometre-scale distribution of ECM ligands can be controlled and altered. We find that increasing the spacing between ligands promotes the growth of focal adhesions on low-rigidity substrates, but leads to adhesion collapse on more-rigid substrates. Furthermore, disordering the ligand distribution drastically increases adhesion growth, but reduces the rigidity threshold for adhesion collapse. The growth and collapse of focal adhesions are mirrored by, respectively, the nuclear or cytosolic localization of the transcriptional regulator protein YAP. We explain these findings not through direct sensing of ligand spacing, but by using an expanded computational molecular-clutch model10,11, in which individual integrin–ECM bonds—the molecular clutches—respond to force loading by recruiting extra integrins, up to a maximum value. This generates more clutches, redistributing the overall force among them, and reducing the force loading per clutch. At high rigidity and high ligand spacing, maximum recruitment is reached, preventing further force redistribution and leading to adhesion collapse. Measurements of cellular traction forces and actin flow speeds support our model. Our results provide a general framework for how cells sense spatial and physical information at the nanoscale, precisely tuning the range of conditions at which they form adhesions and activate transcriptional regulation.

Malinverno, C., Corallino, S., Giavazzi, F., Bergert, M., Li, Q., Leoni, M., Disanza, A., Frittoli, E., Oldani, A., Martini, E., Lendenmann, T., Deflorian, G., Beznoussenko, G. V., Poulikakos, D., Ong, K. H., Uroz, M., Trepat, X., Parazzoli, D., Maiuri, P., Yu, W., Ferrari, A., Cerbino, R., Scita, G., (2017). Endocytic reawakening of motility in jammed epithelia Nature Materials 16, 587–596

Dynamics of epithelial monolayers has recently been interpreted in terms of a jamming or rigidity transition. How cells control such phase transitions is, however, unknown. Here we show that RAB5A, a key endocytic protein, is sufficient to induce large-scale, coordinated motility over tens of cells, and ballistic motion in otherwise kinetically arrested monolayers. This is linked to increased traction forces and to the extension of cell protrusions, which align with local velocity. Molecularly, impairing endocytosis, macropinocytosis or increasing fluid efflux abrogates RAB5A-induced collective motility. A simple model based on mechanical junctional tension and an active cell reorientation mechanism for the velocity of self-propelled cells identifies regimes of monolayer dynamics that explain endocytic reawakening of locomotion in terms of a combination of large-scale directed migration and local unjamming. These changes in multicellular dynamics enable collectives to migrate under physical constraints and may be exploited by tumours for interstitial dissemination.

Rodriguez-Franco, P., Brugués, A., Marin-Llaurado, A., Conte, V., Solanas, G., Batlle, E., Fredberg, J. J., Roca-Cusachs, P., Sunyer, R., Trepat, X., (2017). Long-lived force patterns and deformation waves at repulsive epithelial boundaries Nature Materials 16, (10), 1029-1036

For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell-matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary.

Keywords: Biological physics, Cellular motility

Elosegui-Artola, A., Andreu, I., Beedle, A. E. M., Lezamiz, A., Uroz, M., Kosmalska, A. J., Oria, R., Kechagia, J. Z., Rico-Lastres, P., Le Roux, A. L., Shanahan, C. M., Trepat, X., Navajas, D., Garcia-Manyes, S., Roca-Cusachs, P., (2017). Force triggers YAP nuclear entry by regulating transport across nuclear pores Cell 171, (6), 1397-1410

YAP is a mechanosensitive transcriptional activator with a critical role in cancer, regeneration, and organ size control. Here, we show that force applied to the nucleus directly drives YAP nuclear translocation by decreasing the mechanical restriction of nuclear pores to molecular transport. Exposure to a stiff environment leads cells to establish a mechanical connection between the nucleus and the cytoskeleton, allowing forces exerted through focal adhesions to reach the nucleus. Force transmission then leads to nuclear flattening, which stretches nuclear pores, reduces their mechanical resistance to molecular transport, and increases YAP nuclear import. The restriction to transport is further regulated by the mechanical stability of the transported protein, which determines both active nuclear transport of YAP and passive transport of small proteins. Our results unveil a mechanosensing mechanism mediated directly by nuclear pores, demonstrated for YAP but with potential general applicability in transcriptional regulation. Force-dependent changes in nuclear pores control protein access to the nucleus.

Keywords: Atomic force microscopy, Hippo pathway, Mechanosensing, Mechanotransduction, Molecular mechanical stability, Nuclear mechanics, Nuclear pores, Nuclear transport, Rigidity sensing, Transcription regulation

Garreta, Elena, Oria, Roger, Tarantino, Carolina, Pla-Roca, Mateu, Prado, Patricia, Fernández-Avilés, Francisco, Campistol, Josep Maria, Samitier, Josep, Montserrat, Nuria, (2017). Tissue engineering by decellularization and 3D bioprinting Materials Today 20, (4), 166-178

Discarded human donor organs have been shown to provide decellularized extracellular matrix (dECM) scaffolds suitable for organ engineering. The quest for appropriate cell sources to satisfy the need of multiple cells types in order to fully repopulate human organ-derived dECM scaffolds has opened new venues for the use of human pluripotent stem cells (hPSCs) for recellularization. In addition, three-dimensional (3D) bioprinting techniques are advancing towards the fabrication of biomimetic cell-laden biomaterial constructs. Here, we review recent progress in decellularization/recellularization and 3D bioprinting technologies, aiming to fabricate autologous tissue grafts and organs with an impact in regenerative medicine.

Katuri, Jaideep, Ma, Xing, Stanton, Morgan M., Sánchez, Samuel, (2017). Designing micro- and nanoswimmers for specific applications Accounts of Chemical Research 50, (1), 2-11

Conspectus: Self-propelled colloids have emerged as a new class of active matter over the past decade. These are micrometer sized colloidal objects that transduce free energy from their surroundings and convert it to directed motion. The self-propelled colloids are in many ways, the synthetic analogues of biological self-propelled units such as algae or bacteria. Although they are propelled by very different mechanisms, biological swimmers are typically powered by flagellar motion and synthetic swimmers are driven by local chemical reactions, they share a number of common features with respect to swimming behavior. They exhibit run-and-tumble like behavior, are responsive to environmental stimuli, and can even chemically interact with nearby swimmers. An understanding of self-propelled colloids could help us in understanding the complex behaviors that emerge in populations of natural microswimmers. Self-propelled colloids also offer some advantages over natural microswimmers, since the surface properties, propulsion mechanisms, and particle geometry can all be easily modified to meet specific needs.From a more practical perspective, a number of applications, ranging from environmental remediation to targeted drug delivery, have been envisioned for these systems. These applications rely on the basic functionalities of self-propelled colloids: directional motion, sensing of the local environment, and the ability to respond to external signals. Owing to the vastly different nature of each of these applications, it becomes necessary to optimize the design choices in these colloids. There has been a significant effort to develop a range of synthetic self-propelled colloids to meet the specific conditions required for different processes. Tubular self-propelled colloids, for example, are ideal for decontamination processes, owing to their bubble propulsion mechanism, which enhances mixing in systems, but are incompatible with biological systems due to the toxic propulsion fuel and the generation of oxygen bubbles. Spherical swimmers serve as model systems to understand the fundamental aspects of the propulsion mechanism, collective behavior, response to external stimuli, etc. They are also typically the choice of shape at the nanoscale due to their ease of fabrication. More recently biohybrid swimmers have also been developed which attempt to retain the advantages of synthetic colloids while deriving their propulsion from biological swimmers such as sperm and bacteria, offering the means for biocompatible swimming. In this Account, we will summarize our effort and those of other groups, in the design and development of self-propelled colloids of different structural properties and powered by different propulsion mechanisms. We will also briefly address the applications that have been proposed and, to some extent, demonstrated for these swimmer designs.

Labernadie, A., Kato, T., Brugués, A., Serra-Picamal, X., Derzsi, S., Arwert, E., Weston, A., González-Tarragó, V., Elosegui-Artola, A., Albertazzi, L., Alcaraz, J., Roca-Cusachs, P., Sahai, E., Trepat, X., (2017). A mechanically active heterotypic E-cadherin/N-cadherin adhesion enables fibroblasts to drive cancer cell invasion Nature Cell Biology 19, (3), 224-237

Cancer-associated fibroblasts (CAFs) promote tumour invasion and metastasis. We show that CAFs exert a physical force on cancer cells that enables their collective invasion. Force transmission is mediated by a heterophilic adhesion involving N-cadherin at the CAF membrane and E-cadherin at the cancer cell membrane. This adhesion is mechanically active; when subjected to force it triggers β-catenin recruitment and adhesion reinforcement dependent on α-catenin/vinculin interaction. Impairment of E-cadherin/N-cadherin adhesion abrogates the ability of CAFs to guide collective cell migration and blocks cancer cell invasion. N-cadherin also mediates repolarization of the CAFs away from the cancer cells. In parallel, nectins and afadin are recruited to the cancer cell/CAF interface and CAF repolarization is afadin dependent. Heterotypic junctions between CAFs and cancer cells are observed in patient-derived material. Together, our findings show that a mechanically active heterophilic adhesion between CAFs and cancer cells enables cooperative tumour invasion.

Roca-Cusachs, Pere, Conte, Vito, Trepat, Xavier, (2017). Quantifying forces in cell biology Nature Cell Biology 19, (7), 742-751

Cells exert, sense, and respond to physical forces through an astounding diversity of mechanisms. Here we review recently developed tools to quantify the forces generated by cells. We first review technologies based on sensors of known or assumed mechanical properties, and discuss their applicability and limitations. We then proceed to draw an analogy between these human-made sensors and force sensing in the cell. As mechanics is increasingly revealed to play a fundamental role in cell function we envisage that tools to quantify physical forces may soon become widely applied in life-sciences laboratories.

Duro-Castano, Aroa, Nebot, Vicent J., Niño-Pariente, Amaya, Armiñán, Ana, Arroyo-Crespo, Juan J., Paul, Alison, Feiner-Gracia, Natalia, Albertazzi, Lorenzo, Vicent, María J., (2017). Capturing “extraordinary” soft-assembled charge-like polypeptides as a strategy for nanocarrier design Advanced Materials 29, (39), 1702888

The rational design of nanomedicines is a challenging task given the complex architectures required for the construction of nanosized carriers with embedded therapeutic properties and the complex interface of these materials with the biological environment. Herein, an unexpected charge-like attraction mechanism of self-assembly for star-shaped polyglutamates in nonsalty aqueous solutions is identified, which matches the ubiquitous “ordinary–extraordinary” phenomenon previously described by physicists. For the first time, a bottom-up methodology for the stabilization of these nanosized soft-assembled star-shaped polyglutamates is also described, enabling the translation of theoretical research into nanomaterials with applicability within the drug-delivery field. Covalent capture of these labile assemblies provides access to unprecedented architectures to be used as nanocarriers. The enhanced in vitro and in vivo properties of these novel nanoconstructs as drug-delivery systems highlight the potential of this approach for tumor-localized as well as lymphotropic delivery.

Keywords: Charge-like, Drug delivery, Polymer therapeutics, Polypeptides, Self-assembly

Gállego, Isaac, Manning, Brendan, Prades, Joan Daniel, Mir, Mònica, Samitier, Josep, Eritja, Ramon, (2017). DNA-origami-driven lithography for patterning on gold surfaces with sub-10 nm resolution Advanced Materials 29, 1603233

Stanton, Morgan M., Park, Byung-Wook, Vilela, Diana, Bente, Klaas, Faivre, Damien, Sitti, Metin, Sanchez, Samuel, (2017). Magnetotactic bacteria powered biohybrids target E. coli biofilms ACS Nano 11, (10), 9968-9978

Biofilm colonies are typically resistant to general antibiotic treatment and require targeted methods for their removal. One of these methods include the use of nanoparticles as carriers for antibiotic delivery, where they randomly circulate in fluid until they make contact with the infected areas. However, the required proximity of the particles to the biofilm results in only moderate efficacy. We demonstrate here that the non-pathogenic magnetotactic bacteria, Magnetosopirrillum gryphiswalense (MSR-1), can be integrated with drug-loaded mesoporous silica microtubes (MSMs) to build controllable microswimmers (biohybrids) capable of antibiotic delivery to target an infectious biofilm. Applying external magnetic guidance capability and swimming power of the MSR-1 cells, the biohybrids are directed to and forcefully pushed into matured Escherichia coli (E. coli) biofilms. Release of the antibiotic, ciprofloxacin (CFX), is triggered by the acidic microenvironment of the biofilm ensuring an efficient drug delivery system. The results reveal the capabilities of a non-pathogenic bacteria species to target and dismantle harmful biofilms, indicating biohybrid systems have great potential for anti-biofilm applications.

Ruiz, Marta P., Aragones, Albert C., Camarero, Nuria, Vilhena, J. G., Ortega, Maria, Zotti, Linda Angela, Perez, Ruben, Cuevas, Juan Carlos, Gorostiza, Pau, Díez-Pérez, Ismael, (2017). Bioengineering a single-protein junction Journal of the American Chemical Society 139, (43), 15337–15346

Bioelectronics moves towards designing nanoscale electronic platforms that allow in vivo determinations. Such devices require interfacing complex biomolecular moieties as the sensing units to an electronic platform for signal transduction. Inevitably, a systematic design goes through a bottom-up understanding of the structurally related electrical signatures of the biomolecular circuit, which will ultimately lead us to tailor its electrical properties. Toward this aim, we show here the first example of bioengineered charge transport in a single-protein electrical contact. The results reveal that a single point-site mutation at the docking hydrophobic patch of a Cu-Azurin causes minor structural distortion of the protein blue Cu site and a dramatic change in the charge transport regime of the single-protein contact, which goes from the classical Cu-mediated 2-step transport in this system to a direct coherent tunneling. Our extensive spectroscopic studies and molecular-dynamics simulations show that the proteins’ folding structures are preserved in the single-protein junction. The DFT-computed frontier orbital of the relevant protein segments suggests that the Cu center participation in each protein variant accounts for the different observed charge transport behavior. This work is a direct evidence of charge transport control in a protein backbone through external mutagenesis and a unique nanoscale platform to study structurally related biological electron transfer.

Aragonès, A. C., Aravena, D., Valverde-Muñoz, F. J., Real, J. A., Sanz, F., Díez-Pérez, I., Ruiz, E., (2017). Metal-controlled magnetoresistance at room temperature in single-molecule devices Journal of the American Chemical Society 139, (16), 5768-5778

The appropriate choice of the transition metal complex and metal surface electronic structure opens the possibility to control the spin of the charge carriers through the resulting hybrid molecule/metal spinterface in a single-molecule electrical contact at room temperature. The single-molecule conductance of a Au/molecule/Ni junction can be switched by flipping the magnetization direction of the ferromagnetic electrode. The requirements of the molecule include not just the presence of unpaired electrons: the electronic configuration of the metal center has to provide occupied or empty orbitals that strongly interact with the junction metal electrodes and that are close in energy to their Fermi levels for one of the electronic spins only. The key ingredient for the metal surface is to provide an efficient spin texture induced by the spin-orbit coupling in the topological surface states that results in an efficient spin-dependent interaction with the orbitals of the molecule. The strong magnetoresistance effect found in this kind of single-molecule wire opens a new approach for the design of room-temperature nanoscale devices based on spin-polarized currents controlled at molecular level.

Feiner-Gracia, Natalia, Buzhor, Marina, Fuentes, Edgar, Pujals, S., Amir, Roey J., Albertazzi, Lorenzo, (2017). Micellar stability in biological media dictates internalization in living cells Journal of the American Chemical Society 139, (46), 16677-16687

The dynamic nature of polymeric assemblies makes their stability in biological media a crucial parameter for their potential use as drug delivery systems in vivo. Therefore, it is essential to study and understand the behavior of self-assembled nanocarriers under conditions that will be encountered in vivo such as extreme dilutions and interactions with blood proteins and cells. Herein, using a combination of fluorescence spectroscopy and microscopy, we studied four amphiphilic PEG–dendron hybrids and their self-assembled micelles in order to determine their structure–stability relations. The high molecular precision of the dendritic block enabled us to systematically tune the hydrophobicity and stability of the assembled micelles. Using micelles that change their fluorescent properties upon disassembly, we observed that serum proteins bind to and interact with the polymeric amphiphiles in both their assembled and monomeric states. These interactions strongly affected the stability and enzymatic degradation of the micelles. Finally, using spectrally resolved confocal imaging, we determined the relations between the stability of the polymeric assemblies in biological media and their cell entry. Our results highlight the important interplay between molecular structure, micellar stability, and cell internalization pathways, pinpointing the high sensitivity of stability–activity relations to minor structural changes and the crucial role that these relations play in designing effective polymeric nanostructures for biomedical applications.

Trebicka, J., Gluud, L. L., (2017). Reply to: “Adding embolization to TIPS implantation: A better therapy to control bleeding from ectopic varices?” Journal of Hepatology 67, (1), 202-203

We would like to thank the Perricone and colleagues for their letter and for the interest in the article “Emergency TIPS in a Child-Pugh B patient: When does the window of opportunity open and close?”.1 The letter raises an important question, namely the management of bleeding from ectopic varices. Bleeding from ectopic varices other than fundic varices represents a rare and challenging complication. Guidance for clinical practice is needed.

Carini, M., Ruiz, M. P., Usabiaga, I., Fernández, J. A., Cocinero, E. J., Melle-Franco, M., Diez-Perez, I., Mateo-Alonso, A., (2017). High conductance values in π-folded molecular junctions Nature Communications 8, 15195

Folding processes play a crucial role in the development of function in biomacromolecules. Recreating this feature on synthetic systems would not only allow understanding and reproducing biological functions but also developing new functions. This has inspired the development of conformationally ordered synthetic oligomers known as foldamers. Herein, a new family of foldamers, consisting of an increasing number of anthracene units that adopt a folded sigmoidal conformation by a combination of intramolecular hydrogen bonds and aromatic interactions, is reported. Such folding process opens up an efficient through-space charge transport channel across the interacting anthracene moieties. In fact, single-molecule conductance measurements carried out on this series of foldamers, using the scanning tunnelling microscopy-based break-junction technique, reveal exceptionally high conductance values in the order of 10-1 G0 and a low length decay constant of 0.02 Ã…-1 that exceed the values observed in molecular junctions that make use of through-space charge transport pathways.

Agusil, Juan Pablo, Torras, Núria, Duch, Marta, Esteve, Jaume, Pérez-García, Lluïsa, Samitier, Josep, Plaza, José A., (2017). Highly anisotropic suspended planar-array chips with multidimensional sub-micrometric biomolecular patterns Advanced Functional Materials 27, 1605912

Suspended planar-array (SPA) chips embody millions of individual miniaturized arrays to work in extremely small volumes. Here, the basis of a robust methodology for the fabrication of SPA silicon chips with on-demand physical and chemical anisotropies is demonstrated. Specifically, physical traits are defined during the fabrication process with special focus on the aspect ratio, branching, faceting, and size gradient of the final chips. Additionally, the chemical attributes augment the functionality of the chips with the inclusion of complete coverage or patterns of selected biomolecules on the surface of the chips with contact printing techniques, offering an extremely high versatility, not only with the choice of the pattern shape and distribution but also in the choice of biomolecular inks to pattern. This approach increases the miniaturization of printed arrays in 3D structures by two orders of magnitude compared to those previously demonstrated. Finally, functional micrometric and sub-micrometric patterned features are demonstrated with an antibody binding assay with the recognition of the printed spots with labeled antibodies from solution. The selective addition of physical and chemical attributes on the suspended chips represents the basis for future biomedical assays performed within extremely small volumes.

Keywords: Microcontact printing, Microparticles, Molecular multiplexing, Polymer pen lithography, Silicon chip technology

Caballero, D., Palacios, L., Freitas, P. P., Samitier, J., (2017). An interplay between matrix anisotropy and actomyosin contractility regulates 3D-directed cell migration Advanced Functional Materials 27, (35), 1702322

Directed cell migration is essential for many biological processes, such as embryonic development or cancer progression. Cell contractility and adhesion to the extracellular matrix are known to regulate cell locomotion machinery. However, the cross-talk between extrinsic and intrinsic factors at the molecular level on the biophysical mechanism of three dimensional (3D)-directed cell migration is still unclear. In this work, a novel physiologically relevant in vitro model of the extracellular microenvironment is used to reveal how the topological anisotropy of the extracellular matrix synergizes with actomyosin contractility to modulate directional cell migration morphodynamics. This study shows that cells seeded on polarized 3D matrices display asymmetric protrusion morphodynamics and in-vivo-like phenotypes. It is found that matrix anisotropy significantly enhances cell directionality, but strikingly, not the invasion distance of cells. In Rho-inhibited cells, matrix anisotropy counteracts the lack of actomyosin-driven forces to stabilize cell directionality suggesting a myosin-II-independent mechanism for cell guidance. Finally, this study shows that on isotropic 3D environments, cell directionality is independent of actomyosin contractility. Altogether, this study provides novel quantitative data on the biomechanical regulation of directional cell motion and shows the important regulatory role of matrix anisotropy and actomyosin forces to guide cell migration in 3D microenvironments.

Keywords: Anisotropy, Directed cell migration, Extracellular matrices, Migration modes, Three dimensional microenvironments

Valon, L., Marín-Llauradó, A., Wyatt, T., Charras, G., Trepat, X., (2017). Optogenetic control of cellular forces and mechanotransduction Nature Communications 8, 14396

Contractile forces are the end effectors of cell migration, division, morphogenesis, wound healing and cancer invasion. Here we report optogenetic tools to upregulate and downregulate such forces with high spatiotemporal accuracy. The technology relies on controlling the subcellular activation of RhoA using the CRY2/CIBN light-gated dimerizer system. We fused the catalytic domain (DHPH domain) of the RhoA activator ARHGEF11 to CRY2-mCherry (optoGEF-RhoA) and engineered its binding partner CIBN to bind either to the plasma membrane or to the mitochondrial membrane. Translocation of optoGEF-RhoA to the plasma membrane causes a rapid and local increase in cellular traction, intercellular tension and tissue compaction. By contrast, translocation of optoGEF-RhoA to mitochondria results in opposite changes in these physical properties. Cellular changes in contractility are paralleled by modifications in the nuclear localization of the transcriptional regulator YAP, thus showing the ability of our approach to control mechanotransductory signalling pathways in time and space.

Aragonès, A. C., Darwish, N., Ciampi, S., Sanz, F., Gooding, J. J., Díez-Pérez, I., (2017). Single-molecule electrical contacts on silicon electrodes under ambient conditions Nature Communications 8, 15056

The ultimate goal in molecular electronics is to use individual molecules as the active electronic component of a real-world sturdy device. For this concept to become reality, it will require the field of single-molecule electronics to shift towards the semiconducting platform of the current microelectronics industry. Here, we report silicon-based single-molecule contacts that are mechanically and electrically stable under ambient conditions. The single-molecule contacts are prepared on silicon electrodes using the scanning tunnelling microscopy break-junction approach using a top metallic probe. The molecular wires show remarkable current-voltage reproducibility, as compared to an open silicon/nano-gap/metal junction, with current rectification ratios exceeding 4,000 when a low-doped silicon is used. The extension of the single-molecule junction approach to a silicon substrate contributes to the next level of miniaturization of electronic components and it is anticipated it will pave the way to a new class of robust single-molecule circuits.

Perez-Mockus, Gantas, Mazouni, Khalil, Roca, Vanessa, Corradi, Giulia, Conte, Vito, Schweisguth, François, (2017). Spatial regulation of contractility by Neuralized and Bearded during furrow invagination in Drosophila Nature Communications 8, (1), 1594

Embryo-scale morphogenesis arises from patterned mechanical forces. During Drosophila gastrulation, actomyosin contractility drives apical constriction in ventral cells, leading to furrow formation and mesoderm invagination. It remains unclear whether and how mechanical properties of the ectoderm influence this process. Here, we show that Neuralized (Neur), an E3 ubiquitin ligase active in the mesoderm, regulates collective apical constriction and furrow formation. Conversely, the Bearded (Brd) proteins antagonize maternal Neur and lower medial–apical contractility in the ectoderm: in Brd-mutant embryos, the ventral furrow invaginates properly but rapidly unfolds as medial MyoII levels increase in the ectoderm. Increasing contractility in the ectoderm via activated Rho similarly triggers furrow unfolding whereas decreasing contractility restores furrow invagination in Brd-mutant embryos. Thus, the inhibition of Neur by Brd in the ectoderm differentiates the mechanics of the ectoderm from that of the mesoderm and patterns the activity of MyoII along the dorsal–ventral axis.

Keywords: Drosophila, Gastrulation, Morphogenesis

Stanton, Morgan M., Sánchez, Samuel, (2017). Pushing bacterial biohybrids to in vivo applications Trends in Biotechnology 35, (10), 910-913

Bacterial biohybrids use the energy of bacteria to manipulate synthetic materials with the goal of solving biomedical problems at the micro- and nanoscale. We explore current in vitro studies of bacterial biohybrids, the first attempts at in vivo biohybrid research, and problems to be addressed for the future.

Keywords: Bacteria, Biohybrid, Microswimmers, Micromotors, Drug delivery

Arroyo, M., Trepat, X., (2017). Hydraulic fracturing in cells and tissues: fracking meets cell biology Current Opinion in Cell Biology 44, 1-6

The animal body is largely made of water. A small fraction of body water is freely flowing in blood and lymph, but most of it is trapped in hydrogels such as the extracellular matrix (ECM), the cytoskeleton, and chromatin. Besides providing a medium for biological molecules to diffuse, water trapped in hydrogels plays a fundamental mechanical role. This role is well captured by the theory of poroelasticity, which explains how any deformation applied to a hydrogel causes pressure gradients and water flows, much like compressing a sponge squeezes water out of it. Here we review recent evidence that poroelastic pressures and flows can fracture essential biological barriers such as the nuclear envelope, the cellular cortex, and epithelial layers. This type of fracture is known in engineering literature as hydraulic fracturing or ‘fracking’.

Hernández-Vega, Amayra, Marsal, María, Pouille, Philippe-Alexandre, Tosi, Sébastien, Colombelli, Julien, Luque, Tomás, Navajas, Daniel, Pagonabarraga, Ignacio, Martín-Blanco, Enrique, (2017). Polarized cortical tension drives zebrafish epiboly movements EMBO Journal 36, (1), 25-41

The principles underlying the biomechanics of morphogenesis are largely unknown. Epiboly is an essential embryonic event in which three tissues coordinate to direct the expansion of the blastoderm. How and where forces are generated during epiboly, and how these are globally coupled remains elusive. Here we developed a method, hydrodynamic regression (HR), to infer 3D pressure fields, mechanical power, and cortical surface tension profiles. HR is based on velocity measurements retrieved from 2D+T microscopy and their hydrodynamic modeling. We applied HR to identify biomechanically active structures and changes in cortex local tension during epiboly in zebrafish. Based on our results, we propose a novel physical description for epiboly, where tissue movements are directed by a polarized gradient of cortical tension. We found that this gradient relies on local contractile forces at the cortex, differences in elastic properties between cortex components and the passive transmission of forces within the yolk cell. All in all, our work identifies a novel way to physically regulate concerted cellular movements that might be instrumental for the mechanical control of many morphogenetic processes.

Keywords: Epiboly, Hydrodynamics, Mechanics, Morphogenesis, Zebrafish

Ojosnegros, Samuel, Cutrale, Francesco, Rodríguez, Daniel, Otterstrom, Jason J., Chiu, Chi Li, Hortigüela, Verónica, Tarantino, Carolina, Seriola, Anna, Mieruszynski, Stephen, Martínez, Elena, Lakadamyali, Melike, Raya, Angel, Fraser, Scott E., (2017). Eph-ephrin signaling modulated by polymerization and condensation of receptors Proceedings of the National Academy of Sciences 114, (50), 13188-13193

Eph receptor signaling plays key roles in vertebrate tissue boundary formation, axonal pathfinding, and stem cell regeneration by steering cells to positions defined by its ligand ephrin. Some of the key events in Eph-ephrin signaling are understood: ephrin binding triggers the clustering of the Eph receptor, fostering transphosphorylation and signal transduction into the cell. However, a quantitative and mechanistic understanding of how the signal is processed by the recipient cell into precise and proportional responses is largely lacking. Studying Eph activation kinetics requires spatiotemporal data on the number and distribution of receptor oligomers, which is beyond the quantitative power offered by prevalent imaging methods. Here we describe an enhanced fluorescence fluctuation imaging analysis, which employs statistical resampling to measure the Eph receptor aggregation distribution within each pixel of an image. By performing this analysis over time courses extending tens of minutes, the information-rich 4D space (x, y, oligomerization, time) results were coupled to straightforward biophysical models of protein aggregation. This analysis reveals that Eph clustering can be explained by the combined contribution of polymerization of receptors into clusters, followed by their condensation into far larger aggregates. The modeling reveals that these two competing oligomerization mechanisms play distinct roles: polymerization mediates the activation of the receptor by assembling monomers into 6- to 8-mer oligomers; condensation of the preassembled oligomers into large clusters containing hundreds of monomers dampens the signaling. We propose that the polymerization–condensation dynamics creates mechanistic explanation for how cells properly respond to variable ligand concentrations and gradients.

Keywords: Eph, Ephrin, Receptor tyrosine kinase, Gradients, Cell communication

Stanton, M. M., Park, B. W., Miguel-López, A., Ma, X., Sitti, M., Sánchez, S., (2017). Biohybrid microtube swimmers driven by single captured bacteria Small 13, (19), 1603679

Bacteria biohybrids employ the motility and power of swimming bacteria to carry and maneuver microscale particles. They have the potential to perform microdrug and cargo delivery in vivo, but have been limited by poor design, reduced swimming capabilities, and impeded functionality. To address these challenge, motile Escherichia coli are captured inside electropolymerized microtubes, exhibiting the first report of a bacteria microswimmer that does not utilize a spherical particle chassis. Single bacterium becomes partially trapped within the tube and becomes a bioengine to push the microtube though biological media. Microtubes are modified with "smart" material properties for motion control, including a bacteria-attractant polydopamine inner layer, addition of magnetic components for external guidance, and a biochemical kill trigger to cease bacterium swimming on demand. Swimming dynamics of the bacteria biohybrid are quantified by comparing "length of protrusion" of bacteria from the microtubes with respect to changes in angular autocorrelation and swimmer mean squared displacement. The multifunctional microtubular swimmers present a new generation of biocompatible micromotors toward future microbiorobots and minimally invasive medical applications.

Keywords: Biohybrids, E. coli, Micromotors, Microswimmers, Polydopamine

López-Martínez, Montserrat, Artés, Juan Manuel, Sarasso, Veronica, Carminati, Marco, Díez-Pérez, Ismael, Sanz, Fausto, Gorostiza, Pau, (2017). Differential electrochemical conductance imaging at the nanoscale Small 13, (36), 1700958

Electron transfer in proteins is essential in crucial biological processes. Although the fundamental aspects of biological electron transfer are well characterized, currently there are no experimental tools to determine the atomic-scale electronic pathways in redox proteins, and thus to fully understand their outstanding efficiency and environmental adaptability. This knowledge is also required to design and optimize biomolecular electronic devices. In order to measure the local conductance of an electrode surface immersed in an electrolyte, this study builds upon the current–potential spectroscopic capacity of electrochemical scanning tunneling microscopy, by adding an alternating current modulation technique. With this setup, spatially resolved, differential electrochemical conductance images under bipotentiostatic control are recorded. Differential electrochemical conductance imaging allows visualizing the reversible oxidation of an iron electrode in borate buffer and individual azurin proteins immobilized on atomically flat gold surfaces. In particular, this method reveals submolecular regions with high conductance within the protein. The direct observation of nanoscale conduction pathways in redox proteins and complexes enables important advances in biochemistry and bionanotechnology.

Keywords: Differential electrochemical conductance, ECSTM, Electron transport pathway, Iron passivation, Redox metalloproteins

Aragonès, Albert C., Medina, Ernesto, Ferrer-Huerta, Miriam, Gimeno, Nuria, Teixidó, Meritxell, Palma, Julio L., Tao, Nongjian, Ugalde, Jesus M., Giralt, Ernest, Díez-Pérez, Ismael, Mujica, Vladimiro, (2017). Measuring the spin-polarization power of a single chiral molecule Small 13, (2), 1602519

The electronic spin filtering capability of a single chiral helical peptide is measured. A ferromagnetic electrode source is employed to inject spin-polarized electrons in an asymmetric single-molecule junction bridging an α-helical peptide sequence of known chirality. The conductance comparison between both isomers allows the direct determination of the polarization power of an individual chiral molecule.

Keywords: Alpha-helical peptides, Chiral transport, Single-molecule wires, Spin-polarization power, Spin-polarized transmission

Feiner-Gracia, Natalia, Beck, Michaela, Pujals, Sílvia, Tosi, Sébastien, Mandal, Tamoghna, Buske, Christian, Linden, Mika, Albertazzi, Lorenzo, (2017). Super-resolution microscopy unveils dynamic heterogeneities in nanoparticle protein corona Small 13, (41), 1701631

The adsorption of serum proteins, leading to the formation of a biomolecular corona, is a key determinant of the biological identity of nanoparticles in vivo. Therefore, gaining knowledge on the formation, composition, and temporal evolution of the corona is of utmost importance for the development of nanoparticle-based therapies. Here, it is shown that the use of super-resolution optical microscopy enables the imaging of the protein corona on mesoporous silica nanoparticles with single protein sensitivity. Particle-by-particle quantification reveals a significant heterogeneity in protein absorption under native conditions. Moreover, the diversity of the corona evolves over time depending on the surface chemistry and degradability of the particles. This paper investigates the consequences of protein adsorption for specific cell targeting by antibody-functionalized nanoparticles providing a detailed understanding of corona-activity relations. The methodology is widely applicable to a variety of nanostructures and complements the existing ensemble approaches for protein corona study.

Keywords: Heterogeneity, Mesoporous silica nanoparticles, Protein corona, Super-resolution imaging, Targeting

Moles, E., Galiano, S., Gomes, A., Quiliano, M., Teixeira, C., Aldana, I., Gomes, P., Fernàndez-Busquets, X., (2017). ImmunoPEGliposomes for the targeted delivery of novel lipophilic drugs to red blood cells in a falciparum malaria murine model Biomaterials 145, 178-191

Most drugs currently entering the clinical pipeline for severe malaria therapeutics are of lipophilic nature, with a relatively poor solubility in plasma and large biodistribution volumes. Low amounts of these compounds do consequently accumulate in circulating Plasmodium-infected red blood cells, exhibiting limited antiparasitic activity. These drawbacks can in principle be satisfactorily dealt with by stably encapsulating drugs in targeted nanocarriers. Here this approach has been adapted for its use in immunocompetent mice infected by the Plasmodium yoelii 17XL lethal strain, selected as a model for human blood infections by Plasmodium falciparum. Using immunoliposomes targeted against a surface protein characteristic of the murine erythroid lineage, the protocol has been applied to two novel antimalarial lipophilic drug candidates, an aminoquinoline and an aminoalcohol. Large encapsulation yields of >90% were obtained using a citrate-buffered pH gradient method and the resulting immunoliposomes reached in vivo erythrocyte targeting and retention efficacies of >80%. In P. yoelii-infected mice, the immunoliposomized aminoquinoline succeeded in decreasing blood parasitemia from severe to uncomplicated malaria parasite densities (i.e. from ≥25% to ca. 5%), whereas the same amount of drug encapsulated in non-targeted liposomes had no significant effect on parasite growth. Pharmacokinetic analysis indicated that this good performance was obtained with a rapid clearance of immunoliposomes from the circulation (blood half-life of ca. 2 h), suggesting a potential for improvement of the proposed model.

Keywords: Immunoliposomes, Malaria, Nanomedicine, Plasmodium falciparum, Plasmodium yoelii 17XL, Targeted drug delivery

Matalonga, J., Glaria, E., Bresque, M., Escande, C., Carbó, J. M., Kiefer, K., Vicente, R., León, T. E., Beceiro, S., Pascual-García, M., Serret, J., Sanjurjo, L., Morón-Ros, S., Riera, A., Paytubi, S., Juarez, A., Sotillo, F., Lindbom, L., Caelles, C., Sarrias, M. R., Sancho, J., Castrillo, A., Chini, E. N., Valledor, A. F., (2017). The nuclear receptor LXR limits bacterial infection of host macrophages through a mechanism that impacts cellular NAD metabolism Cell Reports 18, (5), 1241-1255

Macrophages exert potent effector functions against invading microorganisms but constitute, paradoxically, a preferential niche for many bacterial strains to replicate. Using a model of infection by Salmonella Typhimurium, we have identified a molecular mechanism regulated by the nuclear receptor LXR that limits infection of host macrophages through transcriptional activation of the multifunctional enzyme CD38. LXR agonists reduced the intracellular levels of NAD+ in a CD38-dependent manner, counteracting pathogen-induced changes in macrophage morphology and the distribution of the F-actin cytoskeleton and reducing the capability of non-opsonized Salmonella to infect macrophages. Remarkably, pharmacological treatment with an LXR agonist ameliorated clinical signs associated with Salmonella infection in vivo, and these effects were dependent on CD38 expression in bone-marrow-derived cells. Altogether, this work reveals an unappreciated role for CD38 in bacterial-host cell interaction that can be pharmacologically exploited by activation of the LXR pathway.

Keywords: Bacterial infection, CD38, Cytoskeleton, LXR, Macrophage, NAD, Nuclear receptor

Pontes, B., Monzo, P., Gole, L., Le Roux, A. L., Kosmalska, A. J., Tam, Z. Y., Luo, W., Kan, S., Viasnoff, V., Roca-Cusachs, P., Tucker-Kellogg, L., Gauthier, N. C., (2017). Membrane tension controls adhesion positioning at the leading edge of cells Journal of Cell Biology 216, (9), 2959-2977

Cell migration is dependent on adhesion dynamics and actin cytoskeleton remodeling at the leading edge. These events may be physically constrained by the plasma membrane. Here, we show that the mechanical signal produced by an increase in plasma membrane tension triggers the positioning of new rows of adhesions at the leading edge. During protrusion, as membrane tension increases, velocity slows, and the lamellipodium buckles upward in a myosin II-independent manner. The buckling occurs between the front of the lamellipodium, where nascent adhesions are positioned in rows, and the base of the lamellipodium, where a vinculin-dependent clutch couples actin to previously positioned adhesions. As membrane tension decreases, protrusion resumes and buckling disappears, until the next cycle. We propose that the mechanical signal of membrane tension exerts upstream control in mechanotransduction by periodically compressing and relaxing the lamellipodium, leading to the positioning of adhesions at the leading edge of cells.

Gómez-Santacana, Xavier, Pittolo, Silvia, Rovira, Xavier, Lopez, Marc, Zussy, Charleine, Dalton, James A. R., Faucherre, Adèle, Jopling, Chris, Pin, Jean-Philippe, Ciruela, Francisco, Goudet, Cyril, Giraldo, Jesús, Gorostiza, Pau, Llebaria, Amadeu, (2017). Illuminating phenylazopyridines to photoswitch metabotropic glutamate receptors: From the flask to the animals ACS Central Science 3, (1), 81-91

Phenylazopyridines are photoisomerizable compounds with high potential to control biological functions with light. We have obtained a series of phenylazopyridines with light dependent activity as negative allosteric modulators (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5). Here we describe the factors needed to achieve an operational molecular photoisomerization and its effective translation into in vitro and in vivo receptor photoswitching, which includes zebrafish larva motility and the regulation of the antinociceptive effects in mice. The combination of light and some specific phenylazopyridine ligands displays atypical pharmacological profiles, including light-dependent receptor overactivation, which can be observed both in vitro and in vivo. Remarkably, the localized administration of light and a photoswitchable compound in the peripheral tissues of rodents or in the brain amygdalae results in an illumination-dependent analgesic effect. The results reveal a robust translation of the phenylazopyridine photoisomerization to a precise photoregulation of biological activity.

Vilela, D., Stanton, M. M., Parmar, J., Sánchez, S., (2017). Microbots decorated with silver nanoparticles kill bacteria in aqueous media ACS Applied Materials and Interfaces 9, (27), 22093-22100

Water contamination is one of the most persistent problems of public health. Resistance of some pathogens to conventional disinfectants can require the combination of multiple disinfectants or increased disinfectant doses, which may produce harmful byproducts. Here, we describe an efficient method for disinfecting Escherichia coli and removing the bacteria from contaminated water using water self-propelled Janus microbots decorated with silver nanoparticles (AgNPs). The structure of a spherical Janus microbot consists of a magnesium (Mg) microparticle as a template that also functions as propulsion source by producing hydrogen bubbles when in contact with water, an inner iron (Fe) magnetic layer for their remote guidance and collection, and an outer AgNP-coated gold (Au) layer for bacterial adhesion and improving bactericidal properties. The active motion of microbots increases the chances of the contact of AgNPs on the microbot surface with bacteria, which provokes the selective Ag+ release in their cytoplasm, and the microbot self-propulsion increases the diffusion of the released Ag+ ions. In addition, the AgNP-coated Au cap of the microbots has a dual capability of capturing bacteria and then killing them. Thus, we have demonstrated that AgNP-coated Janus microbots are capable of efficiently killing more than 80% of E. coli compared with colloidal AgNPs that killed only less than 35% of E. coli in contaminated water solutions in 15 min. After capture and extermination of bacteria, magnetic properties of the cap allow collection of microbots from water along with the captured dead bacteria, leaving water with no biological contaminants. The presented biocompatible Janus microbots offer an encouraging method for rapid disinfection of water.

Keywords: Bactericidal, Magnetic control, Micromotors, Microswimmers, Self-propulsion, Silver nanoparticles

Barba, A., Diez-Escudero, A., Maazouz, Y., Rappe, K., Espanol, M., Montufar, E. B., Bonany, M., Sadowska, J. M., Guillem-Marti, J., Öhman-Mägi, C., Persson, C., Manzanares, M. C., Franch, J., Ginebra, M. P., (2017). Osteoinduction by Foamed and 3D-Printed Calcium Phosphate Scaffolds: Effect of Nanostructure and Pore Architecture ACS Applied Materials and Interfaces 9, (48), 41722-41736

Some biomaterials are osteoinductive, that is, they are able to trigger the osteogenic process by inducing the differentiation of mesenchymal stem cells to the osteogenic lineage. Although the underlying mechanism is still unclear, microporosity and specific surface area (SSA) have been identified as critical factors in material-associated osteoinduction. However, only sintered ceramics, which have a limited range of porosities and SSA, have been analyzed so far. In this work, we were able to extend these ranges to the nanoscale, through the foaming and 3D-printing of biomimetic calcium phosphates, thereby obtaining scaffolds with controlled micro- and nanoporosity and with tailored macropore architectures. Calcium-deficient hydroxyapatite (CDHA) scaffolds were evaluated after 6 and 12 weeks in an ectopic-implantation canine model and compared with two sintered ceramics, biphasic calcium phosphate and β-tricalcium phosphate. Only foams with spherical, concave macropores and not 3D-printed scaffolds with convex, prismatic macropores induced significant ectopic bone formation. Among them, biomimetic nanostructured CDHA produced the highest incidence of ectopic bone and accelerated bone formation when compared with conventional microstructured sintered calcium phosphates with the same macropore architecture. Moreover, they exhibited different bone formation patterns; in CDHA foams, the new ectopic bone progressively replaced the scaffold, whereas in sintered biphasic calcium phosphate scaffolds, bone was deposited on the surface of the material, progressively filling the pore space. In conclusion, this study demonstrates that the high reactivity of nanostructured biomimetic CDHA combined with a spherical, concave macroporosity allows the pushing of the osteoinduction potential beyond the limits of microstructured calcium phosphate ceramics.

Keywords: 3D-printing, calcium phosphate, foaming, nanostructure, osteoinduction

Hoyos-Nogués, M., Velasco, F., Ginebra, M. P., Manero, J. M., Gil, F. J., Mas-Moruno, C., (2017). Regenerating bone via multifunctional coatings: The blending of cell integration and bacterial inhibition properties on the surface of biomaterials ACS Applied Materials and Interfaces 9, (26), 21618-21630

In dentistry and orthopedics, it is well accepted that implant fixation is a major goal. However, an emerging concern is bacterial infection. Infection of metallic implants can be catastrophic and significantly reduce patient quality of life. Accordingly, in this work, we focus on multifunctional coatings to simultaneously address and mitigate both these problems. We have developed a tailor-made peptide-based chemical platform that integrates the well-known RGD cell adhesive sequence and the lactoferrin-derived LF1-11 antimicrobial peptide. The platform was covalently grafted on titanium via silanization and the functionalization process characterized by contact angle, XPS, and QCM-D. The presence of the platform statistically improved the adhesion, proliferation and mineralization of osteoblast-like cells compared to control surfaces. At the same time, colonization by representative bacterial strains was significantly reduced on the surfaces. Furthermore, the biological potency of the multifunctional platform was verified in a co-culture in vitro model. Our findings demonstrate that this multifunctional approach can be useful to functionalize biomaterials to both improve cell integration and reduce the risk of bacterial infection.

Keywords: Antimicrobial peptides, Cell adhesive peptides, Multifunctionality, Osseointegration, Surface functionalization

Caballero, D., Samitier, J., (2017). Topological control of extracellular matrix growth: A native-like model for cell morphodynamics studies ACS Applied Materials and Interfaces 9, (4), 4159-4170

The interaction of cells with their natural environment influences a large variety of cellular phenomena, including cell adhesion, proliferation, and migration. The complex extracellular matrix network has challenged the attempts to replicate in vitro the heterogeneity of the cell environment and has threatened, in general, the relevance of in vitro studies. In this work, we describe a new and extremely versatile approach to generate native-like extracellular matrices with controlled morphologies for the in vitro study of cellular processes. This general approach combines the confluent culture of fibroblasts with microfabricated guiding templates to direct the three-dimensional growth of well-defined extracellular networks which recapitulate the structural and biomolecular complexity of features typically found in vivo. To evaluate its performance, we studied fundamental cellular processes, including cell cytoskeleton organization, cell-matrix adhesion, proliferation, and protrusions morphodynamics. In all cases, we found striking differences depending on matrix architecture and, in particular, when compared to standard two-dimensional environments. We also assessed whether the engineered matrix networks influenced cell migration dynamics and locomotion strategy, finding enhanced migration efficiency for cells seeded on aligned matrices. Altogether, our methodology paves the way to the development of high-performance models of the extracellular matrix for potential applications in tissue engineering, diagnosis, or stem-cell biology.

Keywords: Biomimetics, Cell migration, Engineered cell-derived matrices, Extracellular matrix, In vitro model

Vilela, D., Hortelao, A. C., Balderas-Xicohtencatl, R., Hirscher, M., Hahn, K., Ma, X., Sanchez, S., (2017). Facile fabrication of mesoporous silica micro-jets with multi-functionalities Nanoscale 9, 13990

Self-propelled micro/nano-devices have been proved as powerful tools in various applications given their capability of both autonomous motion and on-demand task fulfilment. Tubular micro-jets stand out as an important member in the family of self-propelled micro/nano-devices and are widely explored with respect to their fabrication and functionalization. A few methods are currently available for the fabrication of tubular micro-jets, nevertheless there is still a demand to explore the fabrication of tubular micro-jets made of versatile materials and with the capability of multi-functionalization. Here, we present a facile strategy for the fabrication of mesoporous silica micro-jets (MSMJs) for tubular micromotors which can carry out multiple tasks depending on their functionalities. The synthesis of MSMJs does not require the use of any equipment, making it facile and cost-effective for future practical use. The MSMJs can be modified inside, outside or both with different kinds of metal nanoparticles, which provide these micromotors with a possibility of additional properties, such as the anti-bacterial effect by silver nanoparticles, or biochemical sensing based on surface enhanced Raman scattering (SERS) by gold nanoparticles. Because of the high porosity, high surface area and also the easy surface chemistry process, the MSMJs can be employed for the efficient removal of heavy metals in contaminated water, as well as for the controlled and active drug delivery, as two proof-of-concept examples of environmental and biomedical applications, respectively. Therefore, taking into account the new, simple and cheap method of fabrication, highly porous structure, and multiple functionalities, the mesoporous silica based micro-jets can serve as efficient tools for desired applications.

Lagunas, Anna, Tsintzou, Iro, Vida, Yolanda, Collado, Daniel, Pérez-Inestrosa, Ezequiel, Pereira, Cristina Rodríguez, Magalhaes, Joana, Andrades, José A., Samitier, Josep, (2017). Tailoring RGD local surface density at the nanoscale toward adult stem cell chondrogenic commitment Nano Research 10, (6), 1959-1971

Arginine-glycine-aspartic acid (RGD) dendrimer-based nanopatterns on poly(L-lactic acid) were used as bioactive substrates to evaluate the impact of the RGD local surface density on the chondrogenic induction of adult human mesenchymal stem cells. During chondrogenic commitment, active extracellular matrix (ECM) remodeling takes place, playing an instructive role in the differentiation process. Although three-dimensional environments such as pellet or micromass cultures are commonly used for in vitro chondrogenic differentiation, these cultures are rather limited with respect to their ability to interrogate cells in cell–ECM interactions. In the present study, the nanopatterns of the tunable RGD surface density were obtained as a function of the initial dendrimer concentration. The local RGD surface density was quantified through probability contour plots for the minimum interparticle distance, constructed from the corresponding atomic force microscopy images, and correlated with the cell adhesion and differentiation response. The results revealed that the local RGD surface density at the nanoscale acts as a regulator of chondrogenic commitment, and that intermediate adhesiveness of cells to the substrates favors mesenchymal cell condensation and early chondrogenic differentiation.

O'Neill, R., McCarthy, H. O., Montufar, E. B., Ginebra, M. P., Wilson, D. I., Lennon, A., Dunne, N., (2017). Critical review: Injectability of calcium phosphate pastes and cements Acta Biomaterialia 50, 1-19

Calcium phosphate cements (CPC) have seen clinical success in many dental and orthopaedic applications in recent years. The properties of CPC essential for clinical success are reviewed in this article, which includes properties of the set cement (e.g. bioresorbability, biocompatibility, porosity and mechanical properties) and unset cement (e.g. setting time, cohesion, flow properties and ease of delivery to the surgical site). Emphasis is on the delivery of calcium phosphate (CaP) pastes and CPC, in particular the occurrence of separation of the liquid and solid components of the pastes and cements during injection; and established methods to reduce this phase separation. In addition a review of phase separation mechanisms observed during the extrusion of other biphasic paste systems and the theoretical models used to describe these mechanisms are discussed. Statement of Significance Occurrence of phase separation of calcium phosphate pastes and cements during injection limits their full exploitation as a bone substitute in minimally invasive surgical applications. Due to lack of theoretical understanding of the phase separation mechanism(s), optimisation of an injectable CPC that satisfies clinical requirements has proven difficult. However, phase separation of pastes during delivery has been the focus across several research fields. Therefore in addition to a review of methods to reduce phase separation of CPC and the associated constraints, a review of phase separation mechanisms observed during extrusion of other pastes and the theoretical models used to describe these mechanisms is presented. It is anticipated this review will benefit future attempts to develop injectable calcium phosphate based systems.

Keywords: Bone cements, Calcium phosphates, Injectability, Material properties, Phase separation

Van Onzen, A. H. A. M., Albertazzi, L., Schenning, A. P. H. J., Milroy, L. G., Brunsveld, L., (2017). Hydrophobicity determines the fate of self-assembled fluorescent nanoparticles in cells Chemical Communications 53, (10), 1626-1629

The fate of small molecule nanoparticles (SMNPs) composed of self-assembling intrinsically fluorescent π-conjugated oligomers was studied in cells as a function of side-chain hydrophobicity. While the hydrophobic SMNPs remained intact upon cellular uptake, the more hydrophilic SMNPs disassembled and dispersed throughout the cytosol.

Diez-Escudero, A., Espanol, M., Beats, S., Ginebra, M. P., (2017). In vitro degradation of calcium phosphates: Effect of multiscale porosity, textural properties and composition Acta Biomaterialia 60, 81-92

The capacity of calcium phosphates to be replaced by bone is tightly linked to their resorbability. However, the relative importance of some textural parameters on their degradation behavior is still unclear. The present study aims to quantify the effect of composition, specific surface area (SSA), and porosity at various length scales (nano-, micro- and macroporosity) on the in vitro degradation of different calcium phosphates. Degradation studies were performed in an acidic medium to mimic the osteoclastic environment. Small degradations were found in samples with interconnected nano- and micropores with sizes below 3 µm although they were highly porous (35–65%), with maximum weight loss of 8 wt%. Biomimetic calcium deficient hydroxyapatite, with high SSA and low crystallinity, presented the highest degradation rates exceeding even the more soluble β-TCP. A dependence of degradation on SSA was indisputable when porosity and pore sizes were increased. The introduction of additional macroporosity with pore interconnections above 20 µm significantly impacted degradation, more markedly in the substrates with high SSA (>15 m2/g), whereas in sintered substrates with low SSA (<1 m2/g) it resulted just in a linear increase of degradation. Up to 30 % of degradation was registered in biomimetic substrates, compared to 15 % in β-TCP or 8 % in sintered hydroxyapatite. The incorporation of carbonate in calcium deficient hydroxyapatite did not increase its degradation rate. Overall, the study highlights the importance of textural properties, which can modulate or even outweigh the effect of other features such as the solubility of the compounds. Statement of Significance The physicochemical features of calcium phosphates are crucial to tune biological events like resorption during bone remodeling. Understanding in vitro resorption can help to predict the in vivo behavior. Besides chemical composition, other parameters such as porosity and specific surface area have a strong influence on resorption. The complexity of isolating the contribution of each parameter lies in the close interrelation between them. In this work, a multiscale study was proposed to discern the extent to which each parameter influences degradation in a variety of calcium phosphates, using an acidic medium to resemble the osteoclastic environment. The results emphasize the importance of textural properties, which can modulate or even outweigh the effect of the intrinsic solubility of the compounds.

Keywords: Calcium phosphates, Degradation, Porosity, Textural properties

Ciapetti, G., Di Pompo, G., Avnet, S., Martini, D., Diez-Escudero, A., Montufar, E. B., Ginebra, M. P., Baldini, N., (2017). Osteoclast differentiation from human blood precursors on biomimetic calcium-phosphate substrates Acta Biomaterialia 50, 102-113

The design of synthetic bone grafts to foster bone formation is a challenge in regenerative medicine. Understanding the interaction of bone substitutes with osteoclasts is essential, since osteoclasts not only drive a timely resorption of the biomaterial, but also trigger osteoblast activity. In this study, the adhesion and differentiation of human blood-derived osteoclast precursors (OCP) on two different micro-nanostructured biomimetic hydroxyapatite materials consisting in coarse (HA-C) and fine HA (HA-F) crystals, in comparison with sintered stoichiometric HA (sin-HA, reference material), were investigated. Osteoclasts were induced to differentiate by RANKL-containing supernatant using cell/substrate direct and indirect contact systems, and calcium (Ca++) and phosphorus (P5+) in culture medium were measured. We observed that OCP adhered to the experimental surfaces, and that osteoclast-like cells formed at a rate influenced by the micro- and nano-structure of HA, which also modulate extracellular Ca++. Qualitative differences were found between OCP on biomimetic HA-C and HA-F and their counterparts on plastic and sin-HA. On HA-C and HA-F cells shared typical features of mature osteoclasts, i.e. podosomes, multinuclearity, tartrate acid phosphatase (TRAP)-positive staining, and TRAP5b-enzyme release. However, cells were less in number compared to those on plastic or on sin-HA, and they did not express some specific osteoclast markers. In conclusion, blood-derived OCP are able to attach to biomimetic and sintered HA substrates, but their subsequent fusion and resorptive activity are hampered by surface micro-nano-structure. Indirect cultures suggest that fusion of OCP is sensitive to topography and to extracellular calcium. Statement of Significance: The novelty of the paper is the differentiation of human blood-derived osteoclast precursors, instead of mouse-derived macrophages as used in most studies, directly on biomimetic micro-nano structured HA-based surfaces, as triggered by osteoblast-produced factors (RANKL/OPG), and influenced by chemistry and topography of the substrate(s). Biomimetic HA-surfaces, like those obtained in calcium phosphate cements, are very different from the conventional calcium phosphate ceramics, both in terms of topography and ion exchange. The role of these factors in modulating precursors’ differentiation and activity is analysed. The system is closely reproducing the physiological process of attachment of host cells and further maturation to osteoclasts toward resorption of the substrate, which occurs in vivo after filling bone defects with the calcium phosphate grafts.

Keywords: Bone resorption, Differentiation, Hydroxyapatite, Ionic exchange, Osteoclasts, Topography

Oliveira, H., Catros, S., Castano, O., Rey, Sylvie, Siadous, R., Clift, D., Marti-Munoz, J., Batista, M., Bareille, R., Planell, J., Engel, E., Amédée, J., (2017). The proangiogenic potential of a novel calcium releasing composite biomaterial: Orthotopic in vivo evaluation Acta Biomaterialia 54, 377-385

Insufficient angiogenesis remains a major hurdle in current bone tissue engineering strategies. An extensive body of work has focused on the use of angiogenic factors or endothelial progenitor cells. However, these approaches are inherently complex, in terms of regulatory and methodologic implementation, and present a high cost. We have recently demonstrate the potential of electrospun poly(lactic acid) (PLA) fiber-based membranes, containing calcium phosphate (CaP) ormoglass particles, to elicit angiogenesis in vivo, in a subcutaneous model in mice. Here we have devised an injectable composite, containing CaP glass-ceramic particles, dispersed within a (Hydroxypropyl)methyl cellulose (HPMC) matrix, with the capacity to release calcium in a more sustained fashion. We show that by tuning the release of calcium in vivo, in a rat bone defect model, we could improve both bone formation and increase angiogenesis. The bone regeneration kinetics was dependent on the Ca2+ release rate, with the faster Ca2+ release composite gel showing improved bone repair at 3 weeks, in relation to control. In the same line, improved angiogenesis could be observed for the same gel formulation at 6 weeks post implantation. This methodology allows to integrate two fundamental processes for bone tissue regeneration while using a simple, cost effective, and safe approach. Statement of Significance In current bone tissue engineering approaches the achievement of sufficient angiogenesis, during tissue regeneration, is a major limitation in order to attain full tissue functionality. Recently, we have shown that calcium ions, released by the degradation of calcium phosphate ormoglasses (CaP), are effective angiogenic promoters, in both in vitro and in a subcutaneous implantation model. Here, we devised an injectable composite, containing CaP glass-ceramic particles, dispersed within a HPMC matrix, enabling the release of calcium in a more sustained fashion. We show that by tuning the release of calcium in vivo, in a rat bone defect model, we could improve both bone formation and increase angiogenesis. This simple and cost effective approach holds great promise to translate to the clinics.

Keywords: Angiogenesis, Bone regeneration, Calcium phosphate ormoglasses

Maazouz, Y., Montufar, E. B., Malbert, J., Espanol, M., Ginebra, M. P., (2017). Self-hardening and thermoresponsive alpha tricalcium phosphate/pluronic pastes Acta Biomaterialia 49, 563-574

Although calcium phosphate cements (CPCs) are used for bone regeneration in a wide range of clinical applications, various physicochemical phenomena are known to hinder their potential use in minimally invasive surgery or in highly vascularized surgical sites, mainly because of their lack of injectability or their low washout resistance. The present work shows that the combination of CPCs with an inverse-thermoresponsive hydrogel is a good strategy for finely tuning the cohesive and rheological properties of CPCs to achieve clinical acceptable injectability to prevent phase separation during implantation and cohesion to avoid washout of the paste. The thermoresponsive CPC developed combines alpha-tricalcium phosphate with an aqueous solution of pluronic F127, which exhibits an inverse thermoresponsive behaviour, with a gelling transformation at around body temperature. These novel CPCs exhibited temperature-dependent properties. Addition of the polymer enhanced the injectability of the paste, even at a low liquid-to-powder ratio, and allowed the rheological properties of the cement to be tuned, with the injection force decreasing with the temperature of the paste. Moreover, the cohesion of the paste was also temperature-dependent and increased as the temperature of the host medium increased due to gelling induced in the paste. The thermoresponsive cement exhibited excellent cohesion and clinically acceptable setting times at 37 °C, irrespective of the initial temperature of the paste. The addition of pluronic F127 slightly delayed the setting reaction in the early stages but did not hinder the full transformation to calcium-deficient hydroxyapatite. Moreover, the frozen storage of premixed thermoresponsive cement pastes was explored, the main physicochemical properties of the cements being maintained upon thawing, even after 18 months of frozen storage. This avoids the need to mix the cement in the operating theatre and allows its use off-the-shelf. The reverse thermoresponsive cements studied herein open up new perspectives in the surgical field, where the sequential gelling/hardening of these novel cements could allow for a better and safer clinical application. Statement of Significance: Calcium phosphate cements are attractive bone substitutes due to their similarity to the bone mineral phase. Although they can be injectable, cohesion and stability of the paste are crucial in terms of performance and safety. A common strategy is the combination with hydrogels. However, this often results in a decrease of viscosity with increasing temperature, which can lead to extravasation and particle leakage from the bone defect. The preferred evolution would be the opposite: a low viscosity would enhance mixing and injection, and an instantaneous increase of viscosity after injection would ensure washout resistance to the blood flow. Here we develop for the first time a calcium phosphate cement exhibiting reverse thermoresponsive properties using a poloxamer featuring inverse thermal gelling.

Keywords: Calcium phosphate cement, Cohesion, Hydroxyapatite, Injectability, Pluronic, Thermoresponsive

Pujals, S., Tao, K., Terradellas, A., Gazit, E., Albertazzi, L., (2017). Studying structure and dynamics of self-Assembled peptide nanostructures using fluorescence and super resolution microscopy Chemical Communications 53, (53), 7294-7297

Understanding the formation and properties of self-Assembled peptide nanostructures is the basis for the design of new architectures for various applications. Here we show the potential of fluorescence and super resolution imaging to unveil the structural and dynamic features of peptide nanofibers with high spatiotemporal resolution.

Grice, L. F., Gauthier, M. E. A., Roper, K. E., Fernàndez-Busquets, X., Degnan, S. M., Degnan, B. M., (2017). Origin and evolution of the sponge aggregation factor gene family Molecular Biology and Evolution 34, (5), 1083-1099

Although discriminating self from nonself is a cardinal animal trait, metazoan allorecognition genes do not appear to be homologous. Here, we characterize the Aggregation Factor (AF) gene family, which encodes putative allorecognition factors in the demosponge Amphimedon queenslandica, and trace its evolution across 24 sponge (Porifera) species. The AF locus in Amphimedon is comprised of a cluster of five similar genes that encode Calx-beta and Von Willebrand domains and a newly defined Wreath domain, and are highly polymorphic. Further AF variance appears to be generated through individualistic patterns of RNA editing. The AF gene family varies between poriferans, with protein sequences and domains diagnostic of the AF family being present in Amphimedon and other demosponges, but absent from other sponge classes. Within the demosponges, AFs vary widely with no two species having the same AF repertoire or domain organization. The evolution of AFs suggests that their diversification occurs via high allelism, and the continual and rapid gain, loss and shuffling of domains over evolutionary time. Given the marked differences in metazoan allorecognition genes, we propose the rapid evolution of AFs in sponges provides a model for understanding the extensive diversification of self-nonself recognition systems in the animal kingdom.

Keywords: Aggregation factor, Allorecognition, Intron phase, Polymorphism, Porifera, RNA editing

Mata, Agata, Urrea, Laura, Vilches, Silvia, Llorens, Franc, Thüne, Katrin, Espinosa, Juan-Carlos, Andréoletti, Olivier, Sevillano, Alejandro M., Torres, Juan María, Requena, Jesús Rodríguez, Zerr, Inga, Ferrer, Isidro, Gavín, Rosalina, del Río, José Antonio, (2017). Reelin expression in Creutzfeldt-Jakob disease and experimental models of transmissible spongiform encephalopathies Molecular Neurobiology 54, (8), 6412-6425

Reelin is an extracellular glycoprotein involved in key cellular processes in developing and adult nervous system, including regulation of neuronal migration, synapse formation, and plasticity. Most of these roles are mediated by the intracellular phosphorylation of disabled-1 (Dab1), an intracellular adaptor molecule, in turn mediated by binding Reelin to its receptors. Altered expression and glycosylation patterns of Reelin in cerebrospinal and cortical extracts have been reported in Alzheimer’s disease. However, putative changes in Reelin are not described in natural prionopathies or experimental models of prion infection or toxicity. With this is mind, in the present study, we determined that Reelin protein and mRNA levels increased in CJD human samples and in mouse models of human prion disease in contrast to murine models of prion infection. However, changes in Reelin expression appeared only at late terminal stages of the disease, which prevent their use as an efficient diagnostic biomarker. In addition, increased Reelin in CJD and in in vitro models does not correlate with Dab1 phosphorylation, indicating failure in its intracellular signaling. Overall, these findings widen our understanding of the putative changes of Reelin in neurodegeneration.

Keywords: Reelin, Creutzfeldt-Jakob disease, Dab-1, Cellular prion protein

Gutiérrez-Franco, Ana, Eixarch, Herena, Costa, Carme, Gil, Vanessa, Castillo, Mireia, Calvo-Barreiro, Laura, Montalban, Xavier, Del Río, José A., Espejo, Carmen, (2017). Semaphorin 7A as a potential therapeutic target for multiple sclerosis Molecular Neurobiology 54, (6), 4820-4831

Semaphorin 7A (sema7A) is classified as an immune semaphorin with dual functions in the immune system and in the central nervous system (CNS). These molecules are of interest due to their potential role in multiple sclerosis (MS), which is a chronic demyelinating and neurodegenerative disease of autoimmune origin. In this study, we elucidated the role of sema7A in neuroinflammation using both in vitro and in vivo experimental models. In an in vitro model of neuroinflammation, using cerebellar organotypic slice cultures, we observed that challenge with lipopolysaccharide (LPS) endotoxin did not affect demyelination or cell death in sema7A-deficient cultures compared to wild-type cultures. Moreover, the in vivo outcome of experimental autoimmune encephalomyelitis (EAE) in sema7A-deficient mice was altered in an antigen- and adjuvant-dose-dependent manner, while no differences were observed in the wild-type counterparts. Altogether, these results indicate that sema7A is involved in peripheral immunity and CNS inflammation in MS pathogenesis. Indeed, these data suggest that sema7A might be a potential therapeutic target to treat MS and autoimmune conditions.

Caballero, David, Blackburn, Sophie M., de Pablo, Mar, Samitier, Josep, Albertazzi, Lorenzo, (2017). Tumour-vessel-on-a-chip models for drug delivery Lab on a Chip 17, 3760-3771

Nanocarriers for drug delivery have great potential to revolutionize cancer treatment, due to their enhanced selectivity and efficacy. Despite this great promise, researchers have had limited success in the clinical translation of this approach. One of the main causes of these difficulties is that standard in vitro models, typically used to understand nanocarriers' behaviour and screen their efficiency, do not provide the complexity typically encountered in living systems. In contrast, in vivo models, despite being highly physiological, display serious bottlenecks which threaten the relevancy of the obtained data. Microfluidics and nanofabrication can dramatically contribute to solving this issue, providing 3D high-throughput models with improved resemblance to in vivo systems. In particular, microfluidic models of tumour blood vessels can be used to better elucidate how new nanocarriers behave in the microcirculation of healthy and cancerous tissues. Several key steps of the drug delivery process such as extravasation, immune response and endothelial targeting happen under flow in capillaries and can be accurately modelled using microfluidics. In this review, we will present how tumour-vessel-on-a-chip systems can be used to investigate targeted drug delivery and which key factors need to be considered for the rational design of these materials. Future applications of this approach and its role in driving forward the next generation of targeted drug delivery methods will be discussed.

Marques, J., Valle-Delgado, J. J., Urbán, P., Baró, E., Prohens, R., Mayor, A., Cisteró, P., Delves, M., Sinden, R. E., Grandfils, C., de Paz, J. L., García-Salcedo, J. A., Fernàndez-Busquets, X., (2017). Adaptation of targeted nanocarriers to changing requirements in antimalarial drug delivery Nanomedicine: Nanotechnology, Biology, and Medicine 13, (2), 515-525

The adaptation of existing antimalarial nanocarriers to new Plasmodium stages, drugs, targeting molecules, or encapsulating structures is a strategy that can provide new nanotechnology-based, cost-efficient therapies against malaria. We have explored the modification of different liposome prototypes that had been developed in our group for the targeted delivery of antimalarial drugs to Plasmodium-infected red blood cells (pRBCs). These new models include: (i) immunoliposome-mediated release of new lipid-based antimalarials; (ii) liposomes targeted to pRBCs with covalently linked heparin to reduce anticoagulation risks; (iii) adaptation of heparin to pRBC targeting of chitosan nanoparticles; (iv) use of heparin for the targeting of Plasmodium stages in the mosquito vector; and (v) use of the non-anticoagulant glycosaminoglycan chondroitin 4-sulfate as a heparin surrogate for pRBC targeting. The results presented indicate that the tuning of existing nanovessels to new malaria-related targets is a valid low-cost alternative to the de novo development of targeted nanosystems.

Keywords: Glycosaminoglycans, Malaria, Nanomedicine, Plasmodium, Targeted drug delivery

Caddeo, C., Manca, M. L., Matos, M., Gutierrez, G., Díez-Sales, O., Peris, J. E., Usach, I., Fernàndez-Busquets, X., Fadda, A. M., Manconi, M., (2017). Functional response of novel bioprotective poloxamer-structured vesicles on inflamed skin Nanomedicine: Nanotechnology, Biology, and Medicine 13, (3), 1127-1136

Resveratrol and gallic acid, a lipophilic and a hydrophilic phenol, were co-loaded in innovative, biocompatible nanovesicles conceived for ensuring the protection of the skin from oxidative- and inflammatory-related affections. The basic vesicles, liposomes and glycerosomes, were produced by a simple, one-step method involving the dispersion of phospholipid and phenols in water or water/glycerol blend, respectively. Liposomes and glycerosomes were modified by the addition of poloxamer, a stabilizer and viscosity enhancer, thus obtaining viscous or semisolid dispersions of structured vesicles. The vesicles were spherical, unilamellar and small in size (~70 nm in diameter). The superior ability of the poloxamer-structured vesicles to promote the accumulation of both phenols in the skin was demonstrated, as well as their low toxicity and great ability to protect fibroblasts from chemically-induced oxidative damage. The in vivo administration of the vesicular phenols on TPA (phorbol ester)-exposed skin led to a significant reduction of oedema and leukocyte infiltration.

Keywords: Fibroblasts, Mice, Phenol, Phospholipid vesicle, Poloxamer, Skin inflammation

Canal, C., Fontelo, R., Hamouda, I., Guillem-Marti, J., Cvelbar, U., Ginebra, M. P., (2017). Plasma-induced selectivity in bone cancer cells death Free Radical Biology and Medicine 110, 72-80

Background: Current therapies for bone cancers - either primary or metastatic – are difficult to implement and unfortunately not completely effective. An alternative therapy could be found in cold plasmas generated at atmospheric pressure which have already demonstrated selective anti-tumor action in a number of carcinomas and in more relatively rare brain tumors. However, its effects on bone cancer are still unknown. Methods: Herein, we employed an atmospheric pressure plasma jet (APPJ) to validate its selectivity towards osteosarcoma cell line vs. osteoblasts & human mesenchymal stem cells. Results: Cytotoxicity following direct interaction of APPJ with cells is comparable to indirect interaction when only liquid medium is treated and subsequently added to the cells, especially on the long-term (72 h of cell culture). Moreover, following contact of the APPJ treated medium with cells, delayed effects are observed which lead to 100% bone cancer cell death through apoptosis (decreased cell viability with incubation time in contact with APPJ treated medium from 24 h to 72 h), while healthy cells remain fully viable and unaffected by the treatment. Conclusions: The high efficiency of the indirect treatment indicates that an important role is played by the reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the gaseous plasma stage and then transmitted to the liquid phase, which overall lead to lethal and selective action towards osteosarcoma cells. These findings open new pathways for treatment of metastatic bone disease with a minimally invasive approach.

Keywords: Atmospheric pressure plasma jet, Bone cancer, hMSC, HOb, Liquids, Osteoblasts, Osteosarcoma, SaOS-2

Bregestovski, Piotr, Maleeva, Galyna, Gorostiza, Pau, (2017). Light-induced regulation of ligand-gated channel activity British Journal of Pharmacology Early View (Online Version of Record published before inclusion in an issue),

The control of ligand-gated receptors with light using photochromic compounds has evolved from the first handcrafted examples to accurate, engineered receptors, whose development is supported by rational design, high-resolution protein structures, comparative pharmacology and molecular biology manipulations. Photoswitchable regulators have been designed and characterized for a large number of ligand-gated receptors in the mammalian nervous system, including nicotinic acetylcholine, glutamate and GABA receptors. They provide a well-equipped toolbox to investigate synaptic and neuronal circuits in all-optical experiments. This focused review discusses the design and properties of these photoswitches, their applications and shortcomings and future perspectives in the field.

Frau-Méndez, Margalida A., Fernández-Vega, Iván, Ansoleaga, Belén, Blanco, Rosa, Carmona, Margarita, Antonio del Rio, Jose, Zerr, Inga, Llorens, Franc, Zarranz, Juan José, Ferrer, Isidro, (2017). Fatal familial insomnia: Mitochondrial and protein synthesis machinery decline in the mediodorsal thalamus Brain Pathology 27, (1), 95-106

The expression of subunits of mitochondrial respiratory complexes and components of the protein synthesis machinery from the nucleolus to the ribosome was analyzed in the mediodorsal thalamus in seven cases of Fatal Familial Insomnia (FFI) compared with age-matched controls. NDUFB8 (complex I subunit), SDHB (complex II subunit), UQCRC2 (complex III subunit), COX2 (complex IV subunit) and ATP50 (complex V subunit) expression levels, as revealed by western blotting, were reduced in FFI. Voltage-dependent anion channel (VDAC) and ATP5H were also reduced due to the marked depopulation of neurons. In contrast, a marked increase in superoxide dismutase 2 (SOD2) was found in reactive astrocytes thus suggesting that astrocytes are key factors in oxidative stress responses. The histone-binding chaperones nucleolin and nucleoplasmin 3, and histone H3 di-methylated K9 were markedly reduced together with a decrease in the expression of protein transcription elongation factor eEF1A. These findings show severe impairment in the expression of crucial components of mitochondrial function and protein synthesis in parallel with neuron loss in mediodorsal thalamus at terminal stages of FFI. Therapeutic measures must be taken long before the appearance of clinical symptoms to prevent the devastating effects of FFI.

Keywords: Fatal familial insomnia, Mitochondria, Protein synthesis, Mitochondrial respiratory chain, Nucleolus, Ribosome

Valls-Comamala, V., Guivernau, B., Bonet, J., Puig, M., Perálvarez-Marín, A., Palomer, E., Fernàndez-Busquets, X., Altafaj, X., Tajes, M., Puig-Pijoan, A., Vicente, R., Oliva, B., Muñoz, F. J., (2017). The antigen-binding fragment of human gamma immunoglobulin prevents amyloid β-peptide folding into β-sheet to form oligomers Oncotarget 8, (25), 41154-41165

The amyloid beta-peptide (Aβ) plays a leading role in Alzheimer’s disease (AD) physiopathology. Even though monomeric forms of Aβ are harmless to cells, Aβ can aggregate into β-sheet oligomers and fibrils, which are both neurotoxic. Therefore, one of the main therapeutic approaches to cure or delay AD onset and progression is targeting Aβ aggregation. In the present study, we show that a pool of human gamma immunoglobulins (IgG) protected cortical neurons from the challenge with Aβ oligomers, as assayed by MTT reduction, caspase-3 activation and cytoskeleton integrity. In addition, we report the inhibitory effect of IgG on Aβ aggregation, as shown by Thioflavin T assay, size exclusion chromatography and atomic force microscopy. Similar results were obtained with Palivizumab, a human anti-sincitial virus antibody. In order to dissect the important domains, we cleaved the pool of human IgG with papain to obtain Fab and Fc fragments. Using these cleaved fragments, we functionally identified Fab as the immunoglobulin fragment inhibiting Aβ aggregation, a result that was further confirmed by an in silico structural model. Interestingly, bioinformatic tools show a highly conserved structure able to bind amyloid in the Fab region. Overall, our data strongly support the inhibitory effect of human IgG on Aβ aggregation and its neuroprotective role.

Keywords: Alzheimer’s disease, Amyloid, Immunoglobulin, Fab, Oligomers

Neri, L., Lasa, M., Elosegui-Artola, A., D'Avola, D., Carte, B., Gazquez, C., Alve, S., Roca-Cusachs, P., Iñarrairaegui, M., Herrero, J., Prieto, J., Sangro, B., Aldabe, R., (2017). NatB-mediated protein N-α-terminal acetylation is a potential therapeutic target in hepatocellular carcinoma Oncotarget 8, (25), 40967-40981

The identification of new targets for systemic therapy of hepatocellular carcinoma (HCC) is an urgent medical need. Recently, we showed that hNatB catalyzes the N-α-terminal acetylation of 15% of the human proteome and that this action is necessary for proper actin cytoskeleton structure and function. In tumors, cytoskeletal changes influence motility, invasion, survival, cell growth and tumor progression, making the cytoskeleton a very attractive antitumor target. Here, we show that hNatB subunits are upregulated in in over 59% HCC tumors compared to non-tumor tissue and that this upregulation is associated with microscopic vascular invasion. We found that hNatB silencing blocks proliferation and tumor formation in HCC cell lines in association with hampered DNA synthesis and impaired progression through the S and the G2/M phases. Growth inhibition is mediated by the degradation of two hNatB substrates, tropomyosin and CDK2, which occurs when these proteins lack N-α-terminal acetylation. In addition, hNatB inhibition disrupts the actin cytoskeleton, focal adhesions and tight/adherens junctions, abrogating two proliferative signaling pathways, Hippo/YAP and ERK1/2. Therefore, inhibition of NatB activity represents an interesting new approach to treating HCC by blocking cell proliferation and disrupting actin cytoskeleton function.

Keywords: CDK2, Cell cycle arrest, Cell-cell junctions, Focal adhesions, Tropomyosin

Schieber, R., Lasserre, F., Hans, M., Fernández-Yagüe, M., Díaz-Ricart, M., Escolar, G., Ginebra, M. P., Mücklich, F., Pegueroles, M., (2017). Direct laser interference patterning of CoCr alloy surfaces to control endothelial cell and platelet response for cardiovascular applications Advanced Healthcare Materials 6, (19), 1700327

The main drawbacks of cardiovascular bare-metal stents (BMS) are in-stent restenosis and stent thrombosis as a result of an incomplete endothelialization after stent implantation. Nano- and microscale modification of implant surfaces is a strategy to recover the functionality of the artery by stimulating and guiding molecular and biological processes at the implant/tissue interface. In this study, cobalt-chromium (CoCr) alloy surfaces are modified via direct laser interference patterning (DLIP) in order to create linear patterning onto CoCr surfaces with different periodicities (≈3, 10, 20, and 32 μm) and depths (≈20 and 800 nm). Changes in surface topography, chemistry, and wettability are thoroughly characterized before and after modification. Human umbilical vein endothelial cells' adhesion and spreading are similar for all patterned and plain CoCr surfaces. Moreover, high-depth series induce cell elongation, alignment, and migration along the patterned lines. Platelet adhesion and aggregation decrease in all patterned surfaces compared to CoCr control, which is associated with changes in wettability and oxide layer characteristics. Cellular studies provide evidence of the potential of DLIP topographies to foster endothelialization without enhancement of platelet adhesion, which will be of high importance when designing new BMS in the future.

Keywords: CoCr, Direct laser interference patterning, Endothelial cells, Linear surface pattern, Platelets

Maffei, Giovanni, Herreros, Ivan, Sanchez-Fibla, Marti, Friston, Karl J., Verschure, Paul F. M. J., (2017). The perceptual shaping of anticipatory actions Proceedings of the Royal Society B 284, (1869)

Humans display anticipatory motor responses to minimize the adverse effects of predictable perturbations. A widely accepted explanation for this behavior relies on the notion of an inverse model that, learning from motor errors, anticipates corrective responses. Here, we propose and validate the alternative hypothesis that anticipatory control can be realized through a cascade of purely sensory predictions that drive the motor system, reflecting the causal sequence of the perceptual events preceding the error. We compare both hypotheses in a simulated anticipatory postural adjustment task. We observe that adaptation in the sensory domain, but not in the motor one, supports the robust and generalizable anticipatory control characteristic of biological systems. Our proposal unites the neurobiology of the cerebellum with the theory of active inference and provides a concrete implementation of its core tenets with great relevance both to our understanding of biological control systems and, possibly, to their emulation in complex artefacts.

Keywords: Active inference, Cerebellum, Computational model, Motor control, Perceptual learning

Caddeo, C., Pons, R., Carbone, C., Fernàndez-Busquets, X., Cardia, M. C., Maccioni, A. M., Fadda, A. M., Manconi, M., (2017). Physico-chemical characterization of succinyl chitosan-stabilized liposomes for the oral co-delivery of quercetin and resveratrol Carbohydrate Polymers 157, 1853-1861

In the present work, quercetin and resveratrol, natural polyphenols with strong antioxidant and anti-inflammatory properties, were co-loaded in polymer-associated liposomes conceived for oral delivery, by exploiting the potential of pH-sensitive succinyl-chitosan. Chitosan was succinylated, characterized by Nuclear Magnetic Resonance spectroscopy and Gel Permeation Chromatography, and used to form a protective shell on the surface of liposomes. The physico-chemical properties of the succinyl-chitosan liposomes were assessed by light scattering, zeta potential, cryogenic transmission electron microscopy, and small angle X-ray scattering. Small, spherical, uni- and bilamellar vesicles were produced. The succinyl-chitosan shell increased not only the physical stability of the vesicular system, as demonstrated by accelerated stability tests, but also the release of the polyphenols to a greater extent at pH 7.0, mimicking the intestinal environment. The proposed approach based on polyphenol vesicular formulations may be of value in the treatment of pre-cancerous/cancerous intestinal conditions associated with inflammation and oxidative stress.

Keywords: Antioxidant, Liposome, Oral delivery, Quercetin, Resveratrol, Succinyl-chitosan

Santander-Nelli, M., Silva, C. P., Espinoza-Vergara, J., Silva, J. F., Olguín, C. F., Cortés-Arriagada, D., Zagal, J. H., Mendizabal, F., Díez-Pérez, I., Pavez, J., (2017). Tailoring electroactive surfaces by non-template molecular assembly. Towards electrooxidation of L-cysteine Electrochimica Acta 254, 201-213

We have prepared a nanoelectrode ensemble containing vertically aligned single walled carbon nanotubes (SWCNTs) using a non-template molecular self-assembling strategy. We used a bottom-up construction approach to assemble amino functionalized SWCNTs (af-SWCNTs) in a well-defined architecture. These af-SWCNTs were linked and vertically aligned to pre-formed self-assembled monolayers of 4-MBA. A Cobalt(II) tetracarboxyphthalocyanine (Co(COOH)4Pc) complex was covalently bonded to external portion of af-SWCNTs to complete the final nanoelectrode ensemble. X-ray photoelectron spectroscopy (XPS) and Atomic Force Microcopy (AFM) confirmed the effectiveness of the assembling steps on the gold surface starting from the Au/MBA SAMs. The system Au/4-MBA/af-SWCNTs shows an interface with large ordered array, which exhibits a high activity for the electrooxidation of L-cysteine (L-cys). Theoretical calculations suggest that the incorporation of the af-SWCNTs increased the activity of the assembly to electronic transfer and it was observed that the electrooxidation reaction is energetically favorable.

Keywords: Bottom-up construction, DFT, Modified electrode, Molecular assembly, SAMs, Single walled carbon nanotube

Aláez-Versón, C. R., Lantero, E., Fernàndez-Busquets, X., (2017). Heparin: New life for an old drug Nanomedicine 12, (14), 1727-1744

Heparin is one of the oldest drugs, which nevertheless remains in widespread clinical use as an inhibitor of blood coagulation. The history of its identification a century ago unfolded amid one of the most fascinating scientific controversies turning around the distribution of credit for its discovery. The composition, purification and structure-function relationship of this naturally occurring glycosaminoglycan regarding its classical role as anticoagulant will be dealt with before proceeding to discuss its therapeutic potential in, among other, inflammatory and infectious disease, cancer treatment, cystic fibrosis and Alzheimer's disease. The first bibliographic reference hit using the words 'nanomedicine' and 'heparin' is as recent as 2008. Since then, nanomedical applications of heparin have experienced an exponential growth that will be discussed in detail, with particular emphasis on its antimalarial activity. Some of the most intriguing potential applications of heparin nanomedicines will be exposed, such as those contemplating the delivery of drugs to the mosquito stages of malaria parasites.

Keywords: Anopheles, Antimalarial drugs, Heparin, Malaria, Mosquitoes, Nanomedicine, Nanotechnology, Plasmodium, Targeted drug delivery

Ma, Xing, Sánchez, Samuel, (2017). Self-propelling micro-nanorobots: challenges and future perspectives in nanomedicine Nanomedicine 12, (12), 1363-1367

Wang, Y., van Merwyk, L., Tönsing, K., Walhorn, V., Anselmetti, D., Fernàndez-Busquets, X., (2017). Biophysical characterization of the association of histones with single-stranded DNA Biochimica et Biophysica Acta (BBA) - General Subjects 1861, (11), 2739-2749

Background: Despite the profound current knowledge of the architecture and dynamics of nucleosomes, little is known about the structures generated by the interaction of histones with single-stranded DNA (ssDNA), which is widely present during replication and transcription. Methods: Non-denaturing gel electrophoresis, transmission electron microscopy, atomic force microscopy, magnetic tweezers. Results: Histones have a high affinity for ssDNA in 0.15 M NaCl ionic strength, with an apparent binding constant similar to that calculated for their association with double-stranded DNA (dsDNA). The length of DNA (number of nucleotides in ssDNA or base pairs in dsDNA) associated with a fixed core histone mass is the same for both ssDNA and dsDNA. Although histone-ssDNA complexes show a high tendency to aggregate, nucleosome-like structures are formed at physiological salt concentrations. Core histones are able to protect ssDNA from digestion by micrococcal nuclease, and a shortening of ssDNA occurs upon its interaction with histones. The purified (+) strand of a cloned DNA fragment of nucleosomal origin has a higher affinity for histones than the purified complementary (−) strand. Conclusions: At physiological ionic strength histones have high affinity for ssDNA, possibly associating with it into nucleosome-like structures. General significance: In the cell nucleus histones may spontaneously interact with ssDNA to facilitate their participation in the replication and transcription of chromatin.

Keywords: Electrophoresis, Force spectroscopy, Histones, Magnetic tweezers, Nucleosome, Single-stranded DNA

Gómez-Santacana, Xavier, Dalton, James A. R., Rovira, Xavier, Pin, Jean Philippe, Goudet, Cyril, Gorostiza, Pau, Giraldo, Jesús, Llebaria, Amadeu, (2017). Positional isomers of bispyridine benzene derivatives induce efficacy changes on mGlu5 negative allosteric modulation European Journal of Medicinal Chemistry 127, 567-576

Modulation of metabotropic glutamate receptor 5 (mGlu5) with partial allosteric antagonists has received increased interest due to their favourable in vivo activity profiles compared to the unfavourable side-effects of full inverse agonists. Here we report on a series of bispyridine benzene derivatives with a functional molecular switch affecting antagonistic efficacy, shifting from inverse agonism to partial antagonism with only a single change in the substitution pattern of the benzene ring. These efficacy changes are explained through computational docking, revealing two different receptor conformations of different energetic stability and different positional isomer binding preferences.

Keywords: mGlu5, Isomers, Partial efficacy, NAM, Antagonist, Inverse agonist

Sachot, N., Roguska, A., Planell, J. P., Lewandowska, M., Engel, E., Castaño, O., (2017). Fast-degrading PLA/ORMOGLASS fibrous composite scaffold leads to a calcium-rich angiogenic environment International Journal of Nanomedicine 12, 4901-4919

The success of scaffold implantation in acellular tissue engineering approaches relies on the ability of the material to interact properly with the biological environment. This behavior mainly depends on the design of the graft surface and, more precisely, on its capacity to biodegrade in a well-defined manner (nature of ions released, surface-to-volume ratio, dissolution profile of this release, rate of material resorption, and preservation of mechanical properties). The assessment of the biological behavior of temporary templates is therefore very important in tissue engineering, especially for composites, which usually exhibit complicated degradation behavior. Here, blended polylactic acid (PLA) calcium phosphate ORMOGLASS (organically modified glass) nanofibrous mats have been incubated up to 4 weeks in physiological simulated conditions, and their morphological, topographical, and chemical changes have been investigated. The results showed that a significant loss of inorganic phase occurred at the beginning of the immersion and the ORMOGLASS maintained a stable composition afterward throughout the degradation period. As a whole, the nanostructured scaffolds underwent fast and heterogeneous degradation. This study reveals that an angiogenic calcium-rich environment can be achieved through fast-degrading ORMOGLASS/PLA blended fibers, which seems to be an excellent alternative for guided bone regeneration.

Keywords: Angiogenesis, Calcium release, Electrospinning, Fast degradation, Nanofibers, ORMOGLASSES

Wu, Bi-Yi, Sheng, Xin-Qing, Fabregas, Rene, Hao, Yang, (2017). Full-wave modeling of broadband near field scanning microwave microscopy Scientific Reports 7, (1), 16064

A three-dimensional finite element numerical modeling for the scanning microwave microscopy (SMM) setup is applied to study the full-wave quantification of the local material properties of samples. The modeling takes into account the radiation and scattering losses of the nano-sized probe neglected in previous models based on low-frequency assumptions. The scanning techniques of approach curves and constant height are implemented. In addition, we conclude that the SMM has the potential for use as a broadband dielectric spectroscopy operating at higher frequencies up to THz. The results demonstrate the accuracy of previous models. We draw conclusions in light of the experimental results.

Sanmartí-Espinal, Marta, Iavicoli, Patrizia, Calò, Annalisa, Taulés, Marta, Galve, Roger, Marco, M. Pilar, Samitier, Josep, (2017). Quantification of interacting cognate odorants with olfactory receptors in nanovesicles Scientific Reports 7, (1), 17483

This study aims to improve our understanding of the interaction between olfactory receptors and odorants to develop highly selective biosensing devices. Natural nanovesicles (NVs) from Saccharomyces cerevisiae, ~100 nm in diameter, carrying either the human OR17-40 or the chimpanzee OR7D4 olfactory receptor (OR) tagged with the c-myc epitope at their N-terminus, are presented as model systems to quantify the interaction between odorant and olfactory receptors. The level of expression of olfactory receptors was determined at individual NVs using a novel competitive ELISA immunoassay comparing the values obtained against those from techniques involving the solubilization of cell membrane proteins and the identification of c-myc-carrying receptors. Surface Plasmon Resonance (SPR) measurements on L1 Biacore chips indicate that cognate odorants bind to their Ors, thereby quantifying the approximate number of odorants that interact with a given olfactory receptor. The selectivity of OR17-40-carrying NVs towards helional and OR7D4-carrying NVs towards androstenone has been proven in cross-check experiments with non-specific odorant molecules (heptanal and pentadecalactone, respectively) and in control receptors.

Crespo, Anna, Pedraz, Lucas, Van Der Hofstadt, Marc, Gomila, Gabriel, Torrents, Eduard, (2017). Regulation of ribonucleotide synthesis by the Pseudomonas aeruginosa two-component system AlgR in response to oxidative stress Scientific Reports 7, (1), 17892

Ribonucleotide reductases (RNR) catalyze the last step of deoxyribonucleotide synthesis, and are therefore essential to DNA-based life. Three forms of RNR exist: classes I, II, and III. While eukaryotic cells use only class Ia RNR, bacteria can harbor any combination of classes, granting them adaptability. The opportunistic pathogen Pseudomonas aeruginosa surprisingly encodes all three classes, allowing it to thrive in different environments. Here we study an aspect of the complex RNR regulation whose molecular mechanism has never been elucidated, the well-described induction through oxidative stress, and link it to the AlgZR two-component system, the primary regulator of the mucoid phenotype. Through bioinformatics, we identify AlgR binding locations in RNR promoters, which we characterize functionally through EMSA and physically through AFM imaging. Gene reporter assays in different growth models are used to study the AlgZR-mediated control on the RNR network under various environmental conditions and physiological states. Thereby, we show that the two-component system AlgZR, which is crucial for bacterial conversion to the mucoid phenotype associated with chronic disease, controls the RNR network and directs how the DNA synthesis pathway is modulated in mucoid and non-mucoid biofilms, allowing it to respond to oxidative stress.

Keywords: Bacterial genes, Bacteriology, Pathogens

Campillo, N., Torres, M., Vilaseca, A., Nonaka, P. N., Gozal, D., Roca-Ferrer, J., Picado, C., Montserrat, J. M., Farré, R., Navajas, D., Almendros, I., (2017). Role of cyclooxygenase-2 on intermittent hypoxia-induced lung tumor malignancy in a mouse model of sleep apnea Scientific Reports 7, 44693

An adverse role for obstructive sleep apnea (OSA) in cancer epidemiology and outcomes has recently emerged from clinical and animal studies. In animals, intermittent hypoxia (IH) mimicking OSA promotes tumor malignancy both directly and via host immune alterations. We hypothesized that IH could potentiate cancer aggressiveness through activation of the cyclooxygenase-2 (COX-2) pathway and the concomitant increases in prostaglandin E2 (PGE2). The contribution of the COX-2 in IH-induced enhanced tumor malignancy was assessed using celecoxib as a COX-2 specific inhibitor in a murine model of OSA bearing Lewis lung carcinoma (LLC1) tumors. Exposures to IH accelerated tumor progression with a tumor associated macrophages (TAMs) shift towards a pro-tumoral M2 phenotype. Treatment with celecoxib prevented IH-induced adverse tumor outcomes by inhibiting IH-induced M2 polarization of TAMs. Furthermore, TAMs isolated from IH-exposed mice treated with celecoxib reduced the proliferation of LLC1 naïve cells, while the opposite occurred with placebo-treated IH-exposed mice. Finally, in vitro IH exposures of murine macrophages and LLC1 cells showed that both cell types increased PGE2 release in response to IH. These results suggest a crucial role for the COX-2 signaling pathway in the IH-exacerbated malignant processes, and designate macrophages and lung adenocarcinoma cells, as potential sources of PGE2.

Crespo, A., Gavaldà, J., Julián, E., Torrents, E., (2017). A single point mutation in class III ribonucleotide reductase promoter renders Pseudomonas aeruginosa PAO1 inefficient for anaerobic growth and infection Scientific Reports 7, (1), 13350

Pseudomonas aeruginosa strain PAO1 has become the reference strain in many laboratories. One enzyme that is essential for its cell division is the ribonucleotide reductase (RNR) enzyme that supplies the deoxynucleotides required for DNA synthesis and repair. P. aeruginosa is one of the few microorganisms that encodes three different RNR classes (Ia, II and III) in its genome, enabling it to grow and adapt to diverse environmental conditions, including during infection. In this work, we demonstrate that a lack of RNR activity induces cell elongation in P. aeruginosa PAO1. Moreover, RNR gene expression during anaerobiosis differs among P. aeruginosa strains, with class III highly expressed in P. aeruginosa clinical isolates relative to the laboratory P. aeruginosa PAO1 strain. A single point mutation was identified in the P. aeruginosa PAO1 strain class III RNR promoter region that disrupts its anaerobic transcription by the Dnr regulator. An engineered strain that induces the class III RNR expression allows P. aeruginosa PAO1 anaerobic growth and increases its virulence to resemble that of clinical strains. Our results demonstrate that P. aeruginosa PAO1 is adapted to laboratory conditions and is not the best reference strain for anaerobic or infection studies.

Keywords: Bacterial genes, Cellular microbiology, Pathogens

Schillers, H., Rianna, C., Schäpe, J., Luque, T., Doschke, H., Wälte, M., Uriarte, J. J., Campillo, N., Michanetzis, G. P. A., Bobrowska, J., Dumitru, A., Herruzo, E. T., Bovio, S., Parot, P., Galluzzi, M., Podestà, A., Puricelli, L., Scheuring, S., Missirlis, Y., Garcia, R., Odorico, M., Teulon, J. M., Lafont, F., Lekka, M., Rico, F., Rigato, A., Pellequer, J. L., Oberleithner, H., Navajas, D., Radmacher, M., (2017). Standardized nanomechanical atomic force microscopy procedure (SNAP) for measuring soft and biological samples Scientific Reports 7, (1), 5117

We present a procedure that allows a reliable determination of the elastic (Young's) modulus of soft samples, including living cells, by atomic force microscopy (AFM). The standardized nanomechanical AFM procedure (SNAP) ensures the precise adjustment of the AFM optical lever system, a prerequisite for all kinds of force spectroscopy methods, to obtain reliable values independent of the instrument, laboratory and operator. Measurements of soft hydrogel samples with a well-defined elastic modulus using different AFMs revealed that the uncertainties in the determination of the deflection sensitivity and subsequently cantilever's spring constant were the main sources of error. SNAP eliminates those errors by calculating the correct deflection sensitivity based on spring constants determined with a vibrometer. The procedure was validated within a large network of European laboratories by measuring the elastic properties of gels and living cells, showing that its application reduces the variability in elastic moduli of hydrogels down to 1%, and increased the consistency of living cells elasticity measurements by a factor of two. The high reproducibility of elasticity measurements provided by SNAP could improve significantly the applicability of cell mechanics as a quantitative marker to discriminate between cell types and conditions.

Nedjari, Salima, Awaja, Firas, Altankov, George, (2017). Three dimensional honeycomb patterned fibrinogen based nanofibers induce substantial osteogenic response of mesenchymal stem cells Scientific Reports 7, (1), 15947

Stem cells therapy offers a viable alternative for treatment of bone disorders to the conventional bone grafting. However clinical therapies are still hindered by the insufficient knowledge on the conditions that maximize stem cells differentiation. Hereby, we introduce a novel 3D honeycomb architecture scaffold that strongly support osteogenic differentiation of human adipose derived mesenchymal stem cells (ADMSCs). The scaffold is based on electrospun hybrid nanofibers consisting of poly (L-lactide ε-caprolactone) and fibrinogen (PLCL/FBG). Classical fibers orientations, random or aligned were also produced and studied for comparison. The overall morphology of ADMSC’s generally followed the nanofibers orientation and dimensionality developing regular focal adhesions and direction-dependent actin cytoskeleton bundles. However, there was an initial tendency for cells rounding on honeycomb scaffolds before ADMSCs formed a distinct bridging network. This specific cells organization appeared to have significant impact on the differentiation potential of ADMSCs towards osteogenic lineage, as indicated by the alkaline phosphatase production, calcium deposition and specific genes expression. Collectively, it was observed synergistic effect of nanofibers with honeycomb architecture on the behavior of ADMSCs entering osteogenic path of differentiation which outlines the potential benefits from insertion of such bioinspired geometrical cues within scaffolds for bone tissue engineering.

Fraioli, R., Tsimbouri, P. M., Fisher, L. E., Nobbs, A. H., Su, B., Neubauer, S., Rechenmacher, F., Kessler, H., Ginebra, M. P., Dalby, M. J., Manero, J. M., Mas-Moruno, C., (2017). Towards the cell-instructive bactericidal substrate: Exploring the combination of nanotopographical features and integrin selective synthetic ligands Scientific Reports 7, (1), 16363

Engineering the interface between biomaterials and tissues is important to increase implant lifetime and avoid failures and revision surgeries. Permanent devices should enhance attachment and differentiation of stem cells, responsible for injured tissue repair, and simultaneously discourage bacterial colonization; this represents a major challenge. To take first steps towards such a multifunctional surface we propose merging topographical and biochemical cues on the surface of a clinically relevant material such as titanium. In detail, our strategy combines antibacterial nanotopographical features with integrin selective synthetic ligands that can rescue the adhesive capacity of the surfaces and instruct mesenchymal stem cell (MSC) response. To this end, a smooth substrate and two different high aspect ratio topographies have been produced and coated either with an αvβ3-selective peptidomimetic, an α5β1-selective peptidomimetic, or an RGD/PHSRN peptidic molecule. Results showed that antibacterial effects of the substrates could be maintained when tested on pathogenic Pseudomonas aeruginosa. Further, functionalization increased MSC adhesion to the surfaces and the αvβ3-selective peptidomimetic-coated nanotopographies promoted osteogenesis. Such a dual physicochemical approach to achieve multifunctional surfaces represents a first step in the design of novel cell-instructive biomaterial surfaces.

Keywords: Bioinspired materials, Biomaterials – cells

Bianchi, M. V., Awaja, F., Altankov, G., (2017). Dynamic adhesive environment alters the differentiation potential of young and ageing mesenchymal stem cells Materials Science and Engineering C 78, 467-474

Engineering dynamic stem cell niche-like environment offers opportunity to obtain better control of the fate of stem cells. We identified, for the first time, that periodic changes in the adhesive environment of human adipose derived mesenchymal stem cells (ADSCs) alters dramatically their asymmetric division but not their ability for symmetric renewal. Hereby, we used smart thermo-responsive polymer (PNIPAM) to create a dynamic adhesive environment for ADSCs by applying periodic temperature cycles to perturb adsorbed adhesive proteins to substratum interaction. Cumulative population doubling time (CPDT) curves showed insignificant decline in the symmetric cell growth studied for up to 13th passages accompanied with small changes in the overall cell morphology and moderately declined fibronectin (FN) matrix deposition probably as a functional consequence of ADSCs ageing. However, a substantial alteration in the differentiation potential of ADSCs from both early and late passages (3rd and 14th, respectively) was found when the cells were switched to osteogenic differentiation conditions. This behavior was evidenced by the significantly altered alkaline phosphatase activity and Ca deposition (Alizarin red) assayed at 3, 14 and 21 day in comparison to the control samples of regular TC polystyrene processed under same temperature settings.

Keywords: Cell ageing, Dynamic adhesive environment, Extracellular matrix, Mesenchymal stem cells, PNIPAM, Stem cell niche, Symmetric and asymmetric cell growth, Thermo-cycling, Thermo-responsive polymer

Moles, E., Marcos, J., Imperial, S., Pozo, O. J., Fernàndez-Busquets, X., (2017). 2-picolylamine derivatization for high sensitivity detection of abscisic acid in apicomplexan blood-infecting parasites Talanta 168, 130-135

We have developed a new liquid chromatography-electrospray ionization tandem mass spectrometry methodology based on 2-picolylamine derivatization and positive ion mode detection for abscisic acid (ABA) identification. The selected reaction leads to the formation of an amide derivative which contains a highly active pyridyl group. The enhanced ionization allows for a 700-fold increase over commonly monitored unmodified ABA, which in turn leads to excellent limits of detection and quantification values of 0.03 and 0.15 ng mL-1, respectively. This method has been validated in the highly complex matrix of a red blood cell extract. In spite of the high sensitivity achieved, ABA could not be detected in Plasmodium falciparum-infected red blood cells, suggesting that, if present, it will be found either in ultratrace amounts or as brief bursts at defined time points within the intraerythrocytic cycle and/or in the form of a biosynthetic analogue.

Keywords: Abscisic acid, Apicomplexa, Liquid chromatography-electrospray ionization tandem mass spectrometry, Malaria, Picolylamine, Plasmodium falciparum

Vitonyte, J., Manca, M. L., Caddeo, C., Valenti, D., Peris, J. E., Usach, I., Nacher, A., Matos, M., Gutiérrez, G., Orrù, G., Fernàndez-Busquets, X., Fadda, A. M., Manconi, M., (2017). Bifunctional viscous nanovesicles co-loaded with resveratrol and gallic acid for skin protection against microbial and oxidative injuries European Journal of Pharmaceutics and Biopharmaceutics 114, 278-287

Resveratrol and gallic acid were co-loaded in phospholipid vesicles aiming at protecting the skin from external injuries, such as oxidative stress and microbial infections. Liposomes were prepared using biocompatible phospholipids dispersed in water. To improve vesicle stability and applicability, the phospholipids and the phenols were dispersed in water/propylene glycol or water/glycerol, thus obtaining PEVs and glycerosomes, respectively. The vesicles were characterized by size, morphology, physical stability, and their therapeutic efficacy was investigated in vitro. The vesicles were spherical, unilamellar and small in size: liposomes and glycerosomes were around 70 nm in diameter, while PEVs were larger (∼170 nm). The presence of propylene glycol or glycerol increased the viscosity of the vesicle systems, positively affecting their stability. The ability of the vesicles to promote the accumulation of the phenols (especially gallic acid) in the skin was demonstrated, as well as their low toxicity and great ability to protect keratinocytes and fibroblasts from oxidative damage. Additionally, an improvement of the antimicrobial activity of the phenols was shown against different skin pathogens. The co-loading of resveratrol and gallic acid in modified phospholipid vesicles represents an innovative, bifunctional tool for preventing and treating skin affections.

Keywords: Fibroblasts, Keratinocytes, Phenol, Phospholipid vesicle, Skin pathogens

Biagi, Maria Chiara, Badino, Giorgio, Fabregas, Rene, Gramse, Georg, Fumagalli, Laura, Gomila, Gabriel, (2017). Direct mapping of the electric permittivity of heterogeneous non-planar thin films at gigahertz frequencies by scanning microwave microscopy Physical Chemistry Chemical Physics 19, (5), 3884-3893

We obtained maps of the electric permittivity at ~19 GHz frequencies on non-planar thin film heterogeneous samples by means of combined atomic force-scanning microwave microscopy (AFM-SMM). We show that the electric permittivity maps can be obtained directly from the capacitance images acquired in contact mode, after removing the topographic cross-talk effects. This result demonstrates the possibility to identify the electric permittivity of different materials in a thin film sample irrespectively of their thickness by just direct imaging and processing. We show, in addition, that quantitative maps of the electric permittivity can be obtained with no need of any theoretical calculation or complex quantification procedure when the electric permittivity of one of the materials is known. To achieve these results the use of contact mode imaging is a key factor. For non-contact imaging modes the effects of the local sample thickness and of the imaging distance makes the interpretation of the capacitance images in terms of the electric permittivity properties of the materials much more complex. Present results represent a substantial contribution to the field of nanoscale microwave dielectric characterization of thin film materials with important implications for the characterization of novel 3D electronic devices and 3D nanomaterials.

Jansen, C., Thiele, M., Verlinden, W., Krag, A., Francque, S., Trebicka, J., (2017). Prediction of presence of oesophageal varices just by shear-wave elastography of the liver and spleen Liver International 37, (9), 1406-1407

Jorba, I., Uriarte, J. J., Campillo, N., Farré, R., Navajas, D., (2017). Probing micromechanical properties of the extracellular matrix of soft tissues by atomic force microscopy Journal of Cellular Physiology 232, (1), 19-26

The extracellular matrix (ECM) determines 3D tissue architecture and provides structural support and chemical and mechanical cues to the cells. Atomic force microscopy (AFM) has unique capabilities to measure ECM mechanics at the scale at which cells probe the mechanical features of their microenvironment. Moreover, AFM measurements can be readily combined with bright field and fluorescence microscopy. Performing reliable mechanical measurements with AFM requires accurate calibration of the device and correct computation of the mechanical parameters. A suitable approach to isolate ECM mechanics from cell contribution is removing the cells by means of an effective decellularization process that preserves the composition, structure and mechanical properties of the ECM. AFM measurement of ECM micromechanics provides important insights into organ biofabrication, cell-matrix mechanical crosstalk and disease-induced tissue stiffness alterations.

Gugutkov, D., Gustavsson, J., Cantini, M., Salmeron-Sánchez, M., Altankov, G., (2017). Electrospun fibrinogen-PLA nanofibres for vascular tissue engineering Journal of Tissue Engineering and Regenerative Medicine 11, (10), 2774-2784

Here we report on the development of a new type of hybrid fibrinogen-polylactic acid (FBG-PLA) nanofibres (NFs) with improved stiffness, combining the good mechanical properties of PLA with the excellent cell recognition properties of native FBG. We were particularly interested in the dorsal and ventral cell response to the nanofibres' organization (random or aligned), using human umbilical endothelial cells (HUVECs) as a model system. Upon ventral contact with random NFs, the cells developed a stellate-like morphology with multiple projections. The well-developed focal adhesion complexes suggested a successful cellular interaction. However, time-lapse analysis shows significantly lowered cell movements, resulting in the cells traversing a relatively short distance in multiple directions. Conversely, an elongated cell shape and significantly increased cell mobility were observed in aligned NFs. To follow the dorsal cell response, artificial wounds were created on confluent cell layers previously grown on glass slides and covered with either random or aligned NFs. Time-lapse analysis showed significantly faster wound coverage (within 12 h) of HUVECs on aligned samples vs. almost absent directional migration on random ones. However, nitric oxide (NO) release shows that endothelial cells possess lowered functionality on aligned NFs compared to random ones, where significantly higher NO production was found. Collectively, our studies show that randomly organized NFs could support the endothelization of implants while aligned NFs would rather direct cell locomotion for guided neovascularization.

Keywords: Electrospun nanofibers, Endothelial cells, Fibrinogen, Guided cellular behavior, Polylactic acid, Vascular tissue engineering

Reiberger, T., Trebicka, J., (2017). New liver – Fresh microbiome: Implications on brain function Liver Transplantation 23, (7), 873-874

Blanch-Mercader, C., Vincent, R., Bazellières, E., Serra-Picamal, X., Trepat, X., Casademunt, J., (2017). Effective viscosity and dynamics of spreading epithelia: a solvable model Soft Matter 13, (6), 1235-1243

Collective cell migration in spreading epithelia in controlled environments has become a landmark in our current understanding of fundamental biophysical processes in development, regeneration, wound healing or cancer. Epithelial monolayers are treated as thin layers of a viscous fluid that exert active traction forces on the substrate. The model is exactly solvable and shows a broad range of applicabilities for the quantitative analysis and interpretation of force microscopy data of monolayers from a variety of experiments and cell lines. In addition, the proposed model provides physical insights into how the biological regulation of the tissue is encoded in a reduced set of time-dependent physical parameters. In particular the temporal evolution of the effective viscosity entails a mechanosensitive regulation of adhesion. Besides, the observation of an effective elastic tensile modulus can be interpreted as an emergent phenomenon in an active fluid.

Mattotti, M., Alvarez, Z., Delgado, L., Mateos-Timoneda, M. A., Aparicio, C., Planell, J. A., Alcántara, S., Engel, E., (2017). Differential neuronal and glial behavior on flat and micro patterned chitosan films Colloids and Surfaces B: Biointerfaces 158, 569-577

Chitosan is a biodegradable natural polysaccharide that has been widely studied for regenerative purposes in the central nervous system. In this study we assessed the in vitro glial and neuronal cells response to chitosan either flat or patterned with grooves in the micrometric range. Chitosan demonstrated to be a good substrate for the attachment and growth of both neurons and glial cells. Chitosan micropatterns promoted glial cell maturation, suggesting astroglial activation. Nevertheless, those mature/reactive glial cells were permissive for axonal growth. Axons aligned and organized along the patterned grooves and the size of the linear topographic patterns is also affecting neurite and cell response. Patterns with 10 μm width induced fasciculation of axons, which can be useful for CNS tissue engineering substrates when precise orientation of the axonal outgrowth is desired.

Keywords: Brain, Chitosan, Glia, Micropattern, Neuron

González-Tarragó, V., Elosegui-Artola, A., Bazellières, E., Oria, R., Pérez-González, C., Roca-Cusachs, P., (2017). Binding of ZO-1 to α5β1 integrins regulates the mechanical properties of α5β1–fibronectin links Molecular Biology of the Cell 28, (14), 1847-1852

Fundamental processes in cell adhesion, motility, and rigidity adaptation are regulated by integrin-mediated adhesion to the extracellular matrix (ECM). The link between the ECM component fibronectin (fn) and integrin α5β1 forms a complex with ZO-1 in cells at the edge of migrating monolayers, regulating cell migration. However, how this complex affects the α5β1-fn link is unknown. Here we show that the α5β1/ZO-1 complex decreases the resistance to force of α5β1-fn adhesions located at the edge of migrating cell monolayers while also increasing α5β1 recruitment. Consistently with a molecular clutch model of adhesion, this effect of ZO-1 leads to a decrease in the density and intensity of adhesions in cells at the edge of migrating monolayers. Taken together, our results unveil a new mode of integrin regulation through modification of the mechanical properties of integrin-ECM links, which may be harnessed by cells to control adhesion and migration.

Punet, X., Levato, R., Bataille, I., Letourneur, D., Engel, E., Mateos-Timoneda, M. A., (2017). Polylactic acid organogel as versatile scaffolding technique Polymer 113, 81-91

Tissue engineering requires scaffolding techniques based on non-toxic processes that permits the fabrication of constructs with tailored properties. Here, a two-step methodology based on the gelation and precipitation of the poly(lactic) acid/ethyl lactate organogel system is presented. With this technique nanofibrous matrices that resemble natural extracellular matrix can be easily obtained, while allowing control over the mechanical properties of the device. Gelation temperature and the dynamics of the gelation of the organogel system are characterized, and the final mechanical and viscoelastic properties, as well as porosity, as function of the initial polymer concentration are described. We show that gelation temperature of the system is concentration independent and below 44.5 °C, which permits gelation at room temperature. Furthermore, mechanical properties are found in the range of the soft organic tissues, and the obtained micro-network architecture gives place to a flexible structure. Such structure presents tuneable elastic modulus and viscoelastic properties as function of nanofibers density. Moreover, centimetre-long tubular scaffolds with the diameter of medium-caliber blood vessels were produced. The fibrous nano-architecture mimics the native extracellular matrix fibres diameter and morphology was proven to be suitable to support endothelialization of the lumen of the tube. Thus, this strategy, based on biocompatible green compound might be promising for the fabrication of large 3D scaffolds for tissue engineering applications.

Keywords: Gel, Gelation, Nanofibrous, Organogel, PLA, Poly(lactic) acid, Scaffold

Juarez, A., Villa, J. A., Lanza, V. F., Lázaro, B., Cruz, F., Alvarez, H. M., Moncalián, G., (2017). Nutrient starvation leading to triglyceride accumulation activates the Entner Doudoroff pathway in Rhodococcus jostii RHA1 Microbial Cell Factories 16, 35

Background: Rhodococcus jostii RHA1 and other actinobacteria accumulate triglycerides (TAG) under nutrient starvation. This property has an important biotechnological potential in the production of sustainable oils. Results: To gain insight into the metabolic pathways involved in TAG accumulation, we analysed the transcriptome of R jostii RHA1 under nutrient-limiting conditions. We correlate these physiological conditions with significant changes in cell physiology. The main consequence was a global switch from catabolic to anabolic pathways. Interestingly, the Entner-Doudoroff (ED) pathway was upregulated in detriment of the glycolysis or pentose phosphate pathways. ED induction was independent of the carbon source (either gluconate or glucose). Some of the diacylglycerol acyltransferase genes involved in the last step of the Kennedy pathway were also upregulated. A common feature of the promoter region of most upregulated genes was the presence of a consensus binding sequence for the cAMP-dependent CRP regulator. Conclusion: This is the first experimental observation of an ED shift under nutrient starvation conditions. Knowledge of this switch could help in the design of metabolomic approaches to optimize carbon derivation for single cell oil production.

Keywords: CRP, Entner-Doudoroff pathway, Nutrient starvation, Rhodococcus, RNA-Seq, Triacylglycerol

Elosegui-Artola, A., Roca-Cusachs, P., (2017). Amoebae as mechanosensitive tanks Biophysical Journal 112, (12), 2457-2458

Whether employed to search for nutrients or to rearrange tissues, cell migration is essential to the function of uni- and multicellular systems, both in healthy conditions and in disease. Among the several described modes of migration, amoeboid migration is particularly intriguing due to its apparent simplicity. Indeed, it requires only low levels of cell-substrate adhesion, which does not even have to be mediated by specific molecular bonds. This type of migration can be observed across a broad range of cell types including neutrophils, lymphocytes, and tumor cells, although the best-studied case is that of the amoeba of the lower eukaryote Dictyostelium discoideum.

Garcia-Esparcia, Paula, López-González, Irene, Grau-Rivera, Oriol, García-Garrido, María Francisca, Konetti, Anusha, Llorens, Franc, Zafar, Saima, Carmona, Margarita, del Rio, José Antonio, Zerr, Inga, Gelpi, Ellen, Ferrer, Isidro, (2017). Dementia with Lewy Bodies: Molecular pathology in the frontal cortex in typical and rapidly progressive forms Frontiers in Neurology 8, Article 89

Objectives: The goal of this study was to assess mitochondrial function, energy, and purine metabolism, protein synthesis machinery from the nucleolus to the ribosome, inflammation, and expression of newly identified ectopic olfactory receptors (ORs) and taste receptors (TASRs) in the frontal cortex of typical cases of dementia with Lewy bodies (DLB) and cases with rapid clinical course (rpDLB: 2 years or less) compared with middle-aged non-affected individuals, in order to learn about the biochemical abnormalities underlying Lewy body pathology. Methods: Real-time quantitative PCR, mitochondrial enzymatic assays, and analysis of β-amyloid, tau, and synuclein species were used. Results: The main alterations in DLB and rpDLB, which are more marked in the rapidly progressive forms, include (i) deregulated expression of several mRNAs and proteins of mitochondrial subunits, and reduced activity of complexes I, II, III, and IV of the mitochondrial respiratory chain; (ii) reduced expression of selected molecules involved in energy metabolism and increased expression of enzymes involved in purine metabolism; (iii) abnormal expression of nucleolar proteins, rRNA18S, genes encoding ribosomal proteins, and initiation factors of the transcription at the ribosome; (iv) discrete inflammation; and (v) marked deregulation of brain ORs and TASRs, respectively. Severe mitochondrial dysfunction involving activity of four complexes, minimal inflammatory responses, and dramatic altered expression of ORs and TASRs discriminate DLB from Alzheimer’s disease. Altered solubility and aggregation of α-synuclein, increased β-amyloid bound to membranes, and absence of soluble tau oligomers are common in DLB and rpDLB. Low levels of soluble β-amyloid are found in DLB. However, increased soluble β-amyloid 1–40 and β-amyloid 1–42, and increased TNFα mRNA and protein expression, distinguish rpDLB. Conclusion: Molecular alterations in frontal cortex in DLB involve key biochemical pathways such as mitochondria and energy metabolism, protein synthesis, purine metabolism, among others and are accompanied by discrete innate inflammatory response.

Keywords: Dementia with Lewy bodies, Alzheimer’s disease, α-synuclein, Mitochondria, Protein synthesis, Inflammation, β-amyloid, Olfactory receptors

Sadowska, J. M., Guillem-Marti, J., Montufar, E. B., Espanol, M., Ginebra, M. P., (2017). Biomimetic versus sintered calcium phosphates: The in vitro behavior of osteoblasts and mesenchymal stem cells Tissue Engineering Part A 23, (23-24), 1297-1309

The fabrication of calcium phosphates using biomimetic routes, namely, precipitation processes at body temperature, results in distinct features compared to conventional sintered calcium phosphate ceramics, such as a high specific surface area (SSA) and micro-or nanometric crystal size. The aim of this article is to analyze the effects of these parameters on cell response, focusing on two bone cell types: rat mesenchymal stem cells (rMSCs) and human osteoblastic cells (SaOS-2). Biomimetic calcium-deficient hydroxyapatite (CDHA) was obtained by a low temperature setting reaction, and α-Tricalcium phosphate (α-TCP) and β-Tricalcium phosphate were subsequently obtained by sintering CDHA either at 1400°C or 1100°C. Sintered stoichiometric hydroxyapatite (HA) was also prepared using ceramic routes. The materials were characterized in terms of SSA, skeletal density, porosity, and pore size distribution. SaOS-2 cells and rMSCs were seeded either directly on the surfaces of the materials or on glass coverslips subsequently placed on top of the materials to expose the cells to the CaP-induced ionic changes in the culture medium, while avoiding any topography-related effects. CDHA produced higher ionic fluctuations in both cell culture media than sintered ceramics, with a strong decrease of calcium and a release of phosphate. Indirect contact cell cultures revealed that both cell types were sensitive to these ionic modifications, resulting in a decrease in proliferation rate, more marked for CDHA, this effect being more pronounced for rMSCs. In direct contact cultures, good cell adhesion was found on all materials, but, while cells were able to proliferate on the sintered calcium phosphates, cell number was significantly reduced with time on biomimetic CDHA, which was associated to a higher percentage of apoptotic cells. Direct contact of the cells with biomimetic CDHA resulted also in a higher alkaline phosphatase activity for both cell types compared to sintered CaPs, indicating a promotion of the osteoblastic phenotype.

Keywords: Biomimetic hydroxyapatite, Calcium phosphate, Mesenchymal stem cell, Osteoblast

Diez-Escudero, A., Espanol, M., Montufar, E. B., Di Pompo, G., Ciapetti, G., Baldini, N., Ginebra, M. P., (2017). Focus ion beam/scanning electron microscopy characterization of osteoclastic resorption of calcium phosphate substrates Tissue Engineering Part C: Methods 23, (2), 118-124

This article presents the application of dual focused ion beam/scanning electron microscopy (FIB-SEM) imaging for preclinical testing of calcium phosphates with osteoclast precursor cells and how this high-resolution imaging technique is able to reveal microstructural changes at a level of detail previously not possible. Calcium phosphate substrates, having similar compositions but different microstructures, were produced using low-and high-Temperature processes (biomimetic calcium-deficient hydroxyapatite [CDHA] and stoichiometric sintered hydroxyapatite, respectively). Human osteoclast precursor cells were cultured for 21 days before evaluating their resorptive potential on varying microstructural features. Alternative to classical morphological evaluation of osteoclasts (OC), FIB-SEM was used to observe the subjacent microstructure by transversally sectioning cells and observing both the cells and the substrates. Resorption pits, indicating OC activity, were visible on the smoother surface of high-Temperature sintered hydroxyapatite. FIB-SEM analysis revealed signs of acidic degradation on the grain surface under the cells, as well as intergranular dissolution. No resorption pits were evident on the surface of the rough CDHA substrates. However, whereas no degradation was detected by FIB sections in the material underlying some of the cells, early stages of OC-mediated acidic degradation were observed under cells with more spread morphology. Collectively, these results highlight the potential of FIB to evaluate the resorptive activity of OC, even in rough, irregular, or coarse surfaces where degradation pits are otherwise difficult to visualize.

Keywords: Bone Regeneration, Calcium Phosphate, Focus Ion Beam, Osteoclast, Resorption, Scanning Electron Microscopy

Schierwagen, R., Uschner, F. E., Magdaleno, F., Klein, S., Trebicka, J., (2017). Rationale for the use of statins in liver disease American Journal of Physiology - Gastrointestinal and Liver Physiology 312, (5), G407-G412

The evolution of chronic liver injuries from benign and manageable dysfunction to life threatening end-stage liver disease with severe complications renders chronic liver disease a global health burden. Because of the lack of effective medication, transplantation remains the only and final curative option for end-stage liver disease. Since the demand for organ transplants by far exceeds the supply, other treatment options are urgently required to prevent progression and improve end-stage liver disease. Statins are primarily cholesterol-lowering drugs used for primary or secondary prevention of cardiovascular diseases. In addition to the primary effect, statins act beneficially through different pleiotropic mechanisms on inflammation, fibrosis, endothelial function, thrombosis, and coagulation to improve chronic liver diseases. However, concerns remain about the efficacy and safety of statin treatment because of their potential hepatotoxic risks, and as of now, these risks impede broader use of statins in the treatment of chronic liver diseases. The aim of this review is to comprehensively describe the mechanisms by which statins improve prospects for different chronic liver diseases with special focus on the pathophysiological rationale and the clinical experience of statin use in the treatment of liver diseases.

Estrada, L., Torres, A., Sarlabous, L., Jané, R., (2017). Onset and offset estimation of the neural inspiratory time in surface diaphragm electromyography: A pilot study in healthy subjects IEEE Journal of Biomedical and Health Informatics 22, (1), 67-76

This study evaluates the onset and offset of neural inspiratory time estimated from surface diaphragm electromyographic (EMGdi) recordings. EMGdi and airflow signals were recorded in ten healthy subjects according to two respiratory protocols based on respiratory rate (RR) increments, from 15 to 40 breaths per minute (bpm), and fractional inspiratory time (Ti/Ttot) decrements, from 0.54 to 0.18. The analysis of diaphragm electromyographic (EMGdi) signal amplitude is an alternative approach for the quantification of neural respiratory drive (NRD). The EMGdi amplitude was estimated using the fixed sample entropy computed over a 250 ms moving window of the EMGdi signal (EMGdifse). The neural onset was detected through a dynamic threshold over the EMGdifse using the kernel density estimation method, while neural offset was detected by finding when the EMGdifse had decreased to 70 % of the peak value reached during inspiration. The Bland-Altman analysis between airflow and neural onsets showed a global bias of 46 ms in the RR protocol and 22 ms in the Ti/Ttot protocol. The Bland-Altman analysis between airflow and neural offsets reveals a global bias of 11 ms in the RR protocol and -2 ms in the Ti/Ttot protocol. The relationship between pairs of RR values (Pearson’s correlation coefficient of 0.99, Bland- Altman limits of -2.39 to 2.41 bpm, and mean bias of 0.01 bpm) and between pairs of Ti/Ttot values (Pearson’s correlation coefficient of 0.86, Bland-Altman limits of -0.11 to 0.10, and mean bias of -0.01) showed a good agreement. In conclusion, we propose a method for determining neural onset and neural offset based on non-invasive recordings of the electrical activity of the diaphragm that requires no filtering of cardiac muscle interference.

Keywords: Kernel density estimation (KDE),, Surface diaphragm electromyographic,, (EMGdi) signal,, Inspiratory time,, Neural respiratory drive (NRD),, Neural inspiratory time,, Fixed sample entropy (fSampEn)

Ramos, E., Pardo, W. A., Mir, M., Samitier, J., (2017). Dependence of carbon nanotubes dispersion kinetics on surfactants Nanotechnology 28, (13), 135702

Carbon nanotubes (CNTs) have been the subject of many studies due to their unique structure and desirable properties. However, the ability to solubilize and separate single CNTs from the bundles they form is still a challenge that needs to be overcome in order to extend their applications in the field of Nanotechnology. Covalent interactions are designed to modify CNTs surface and so prevent agglomeration. Though, this method alters the structures and intrinsic properties of CNTs. In the present work, noncovalent approaches to functionalize and solubilize CNTs are studied in detail. A dispersion kinetic study was performed to characterize the ability of different type of surfactants (non-ionic, anionic, cationic and biopolymer) to unzip CNT bundles. The dispersion kinetic study performed depicts the distinct CNTs bundles unzipping behavior of the different type of surfactants and the results elucidate specific wavelengths in relation with the degree of CNT clustering, which provides new tools for a deeper understanding and characterization of CNTs. Small angle x-ray scattering and transmission electron microscopy results are in agreement with UV-vis-NIR observations, revealing perfectly monodispersed CNTs for the biopolymer and cationic surfactant.

Keywords: Dispersion, DNA, Single-walled carbon nanotubes (SWCNTs), Small angle x-ray scattering (SAXS), Sodium dodecyl sulfate (SDS), Surfactant, Triton X-100

Castellanos, M. I., Mas-Moruno, C., Grau, A., Serra-Picamal, X., Trepat, X., Albericio, F., Joner, M., Gil, F. J., Ginebra, M. P., Manero, J. M., Pegueroles, M., (2017). Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation Applied Surface Science 393, 82-92

Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.

Keywords: Cell adhesive peptides, CoCr alloy, Endothelialization, HUVEC proliferation, SMCs adhesion, Surface functionalization

Campillo, N., Falcones, B., Montserrat, J. M., Gozal, D., Obeso, A., Gallego-Martin, T., Navajas, D., Almendros, I., Farré, R., (2017). Frequency and magnitude of intermittent hypoxia modulate endothelial wound healing in a cell culture model of sleep apnea Journal of Applied Physiology 123, (5), 1047-1054

Intermittent hypoxia (IH) has been implicated in the cardiovascular consequences of obstructive sleep apnea (OSA). However, the lack of suitable experimental systems has precluded assessment as to whether IH is detrimental, protective, or both for the endothelium. The aim of the work was to determine the effects of frequency and amplitude of IH oxygenation swings on aortic endothelial wound healing. Monolayers of human primary endothelial cells were wounded and subjected to constant oxygenation (1%, 4%, 13%, or 20% O2) or IH at different frequencies (0.6, 6, or 60 cycles/h) and magnitude ranges (13–4% O2 or 20–1% O2), using a novel well-controlled system, with wound healing being measured after 24 h. Cell monolayer repair was similar at 20% O2 and 13% O2, but was considerably increased (approximately twofold) in constant hypoxia at 4% O2. The magnitude and frequency of IH considerably modulated wound healing. Cycles ranging 13–4% O2 at the lowest frequency (0.6 cycles/h) accelerated endothelial wound healing by 102%. However, for IH exposures consisting of 20% to 1% O2 oscillations, wound closure was reduced compared with oscillation in the 13–4% range (by 74% and 44% at 6 cycles/h and 0.6 cycles/h, respectively). High-frequency IH patterns simulating severe OSA (60 cycles/h) did not significantly modify endothelial wound closure, regardless of the oxygenation cycle amplitude. In conclusion, the frequency and magnitude of hypoxia cycling in IH markedly alter wound healing responses and emerge as key factors determining how cells will respond in OSA. NEW & NOTEWORTHY Intermittent hypoxia (IH) induces cardiovascular consequences in obstructive sleep apnea (OSA) patients. However, the vast array of frequencies and severities of IH previously employed in OSA-related experimental studies has led to controversial results on the effects of IH. By employing an optimized IH experimental system here, we provide evidence that the frequency and magnitude of IH markedly alter human aortic endothelial wound healing, emerging as key factors determining how cells respond in OSA.

Keywords: Sleep apnea, Repair, Endothelium, Hypoxia, Reoxygenation

Terni, Beatrice, Pacciolla, Paolo, Masanas, Helena, Gorostiza, Pau, Llobet, Artur, (2017). Tight temporal coupling between synaptic rewiring of olfactory glomeruli and the emergence of odor-guided behavior in Xenopus tadpoles Journal of Comparative Neurology 525, (17), 3769-3783

Olfactory sensory neurons (OSNs) are chemoreceptors that establish excitatory synapses within glomeruli of the olfactory bulb. OSNs undergo continuous turnover throughout life, causing the constant replacement of their synaptic contacts. Using Xenopus tadpoles as an experimental system to investigate rewiring of glomerular connectivity, we show that novel OSN synapses can transfer information immediately after formation, mediating olfactory-guided behavior. Tadpoles recover the ability to detect amino acids 4 days after bilateral olfactory nerve transection. Restoration of olfactory-guided behavior depends on the efficient reinsertion of OSNs to the olfactory bulb. Presynaptic terminals of incipient synaptic contacts generate calcium transients in response to odors, triggering long lasting depolarization of olfactory glomeruli. The functionality of reconnected terminals relies on well-defined readily releasable and cytoplasmic vesicle pools. The continuous growth of non-compartmentalized axonal processes provides a vesicle reservoir to nascent release sites, which contrasts to the gradual development of cytoplasmic vesicle pools in conventional excitatory synapses. The immediate availability of fully functional synapses upon formation supports an age-independent contribution of OSNs to the generation of odor maps.

Keywords: Olfactory receptor neurons, Olfactory bulb, Presynaptic terminals, RRID:SCR_013731, RRID:SCR_007164, RRID: AB-887824, RRID: AB-221570, Synaptic vesicles

Jorba, I., Menal, M. J., Torres, M., Gozal, D., Piñol-Ripoll, G., Colell, A., Montserrat, J. M., Navajas, D., Farré, R., Almendros, I., (2017). Ageing and chronic intermittent hypoxia mimicking sleep apnea do not modify local brain tissue stiffness in healthy mice Journal of the Mechanical Behavior of Biomedical Materials 71, 106-113

Recent evidence suggests that obstructive sleep apnea (OSA) may increase the risk of Alzheimer´s disease (AD), with the latter promoting alterations in brain tissue stiffness, a feature of ageing. Here, we assessed the effects of age and intermittent hypoxia (IH) on brain tissue stiffness in a mouse model of OSA. Two-month-old and 18-month-old mice (N=10 each) were subjected to IH (20% O2 40 s – 6% O2 20 s) for 8 weeks (6 h/day). Corresponding control groups for each age were kept under normoxic conditions in room air (RA). After sacrifice, the brain was excised and 200-micron coronal slices were cut with a vibratome. Local stiffness of the cortex and hippocampus were assessed in brain slices placed in an Atomic Force Microscope. For both brain regions, the Young's modulus (E) in each animal was computed as the average values from 9 force-indentation curves. Cortex E mean (±SE) values were 442±122 Pa (RA) and 455±120 (IH) for young mice and 433±44 (RA) and 405±101 (IH) for old mice. Hippocampal E values were 376±62 (RA) and 474±94 (IH) for young mice and 486±93 (RA) and 521±210 (IH) for old mice. For both cortex and hippocampus, 2-way ANOVA indicated no statistically significant effects of age or challenge (IH vs. RA) on E values. Thus, neither chronic IH mimicking OSA nor ageing up to late middle age appear to modify local brain tissue stiffness in otherwise healthy mice.

Keywords: Atomic Force Microscopy, Brain mechanics, Cortex stiffness, Hippocampus stiffness, Obstructive sleep apnea, Young's modulus

Echalier, C., Levato, R., Mateos-Timoneda, M. A., Castaño, O., Déjean, S., Garric, X., Pinese, C., Noël, D., Engel, E., Martinez, J., Mehdi, A., Subra, G., (2017). Modular bioink for 3D printing of biocompatible hydrogels: sol-gel polymerization of hybrid peptides and polymers RSC Advances 7, (20), 12231-12235

An unprecedented generic system allowing the 3D printing of peptide-functionalized hydrogels by soft sol-gel inorganic polymerization is presented. Hybrid silylated inorganic/bioorganic blocks are mixed in biological buffer in an appropriate ratio, to yield a multicomponent bioink that can be printed as a hydrogel without using any photochemical or organic reagent. Hydrolysis and condensation of the silylated precursors occur during the printing process and result in a covalent network in which molecules are linked through siloxane bonds. The viscosity of the colloidal solution used as bioink was monitored in order to set up the optimal conditions for extrusion printing. Grid-patterned hydrogel scaffolds containing a hybrid integrin ligand were printed using a pressure-driven rapid prototyping machine. Finally, they were seeded with mesenchymal stem cells, demonstrating their suitability for cell culture. The versatility of the sol-gel process and its biocompatibility makes this approach highly promising for the preparation of tailor-made cell-laden scaffolds.

Pacheco, D., Sánchez-Fibla, M., Duff, A., Verschure, P. F. M. J., (2017). A spatial-context effect in recognition memory Frontiers in Behavioral Neuroscience 11, Article 143

We designed a novel experiment to investigate the modulation of human recognition memory by environmental context. Human participants were asked to navigate through a four-arm Virtual Reality (VR) maze in order to find and memorize discrete items presented at specific locations in the environment. They were later on tested on their ability to recognize items as previously presented or new. By manipulating the spatial position of half of the studied items during the testing phase of our experiment, we could assess differences in performance related to the congruency of environmental information at encoding and retrieval. Our results revealed that spatial context had a significant effect on the quality of memory. In particular, we found that recognition performance was significantly better in trials in which contextual information was congruent as opposed to those in which it was different. Our results are in line with previous studies that have reported spatial-context effects in recognition memory, further characterizing their magnitude under ecologically valid experimental conditions.

Keywords: Context effects, Recognition memory, Spatial behavior, Spatial memory and navigation, Virtual reality

Castellanos, M. I., Guillem-Marti, J., Mas-Moruno, C., Díaz-Ricart, M., Escolar, G., Ginebra, M. P., Gil, F. J., Pegueroles, M., Manero, J. M., (2017). Cell adhesive peptides functionalized on CoCr alloy stimulate endothelialization and prevent thrombogenesis and restenosis Journal of Biomedical Materials Research - Part A 105, (4), 973-983

Immobilization of bioactive peptide sequences on CoCr surfaces is an effective route to improve endothelialization, which is of great interest for cardiovascular stents. In this work, we explored the effect of physical and covalent immoblization of RGDS, YIGSR and their equimolar combination peptides on endothelial cells (EC) and smooth muscle cell (SMC) adhesion and on thrombogenicity. We extensively investigated using RT-qPCR, the expression by ECs cultured on functionalised CoCr surfaces of different genes. Genes relevant for adhesion (ICAM-1 and VCAM-1), vascularization (VEGFA, VEGFR-1 and VEGFR-2) and anti-thrombogenicity (tPA and eNOS) were over-expressed in the ECs grown to covalently functionalized CoCr surfaces compared to physisorbed and control surfaces. Pro-thrombogenic genes expression (PAI-1 and vWF) decreased over time. Cell co-cultures of ECs/SMCs found that functionalization increased the amount of adhered ECs onto modified surfaces compared to plain CoCr, independently of the used peptide and the strategy of immobilization. SMCs adhered less compared to ECs in all surfaces. All studied peptides showed a lower platelet cell adhesion compared to TCPS. Covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represented prevailing strategy to enhance the early stages of ECs adhesion and proliferation, while preventing SMCs and platelet adhesion.

Keywords: Cell coculture, CoCr alloy, Functionalization, Gene expression, Platelet adhesion

Gugutkov, D., Awaja, F., Belemezova, K., Keremidarska, M., Krasteva, N., Kuyrkchiev, S., GallegoFerrer, G., Seker, S., Elcin, A. E., Elcin, Y. M., Altankov, G., (2017). Osteogenic differentiation of mesenchymal stem cells using hybrid nanofibers with different configurations and dimensionality Journal of Biomedical Materials Research - Part A 105, (7), 2065-2074

Novel hybrid, fibrinogen/polylactic acid (FBG/PLA) nanofibers with different configuration (random vs. aligned) and dimensionality (2D vs.3D environment) were used to control the overall behaviour and the osteogenic differentiation of human Adipose Derived Mesenchymal Stem Cells (ADMSCs). Aligned nanofibers in both the 2D and 3D configurations are proved to be favoured for osteo-differentiation. Morphologically we found that on randomly configured nanofibers, the cells developed a stellate-like morphology with multiple projections, however, time-lapse analysis showed significantly diminished cell movements. Conversely, an elongated cell shape with advanced cell spreading and extended actin cytoskeleton accompanied with significantly increased cell mobility were observed when cells attached on aligned nanofibers. Moreover, a clear tendency for higher alkaline phosphatase activity was also found on aligned fibres when ADMSCs were switched to osteogenic induction medium. The strongest accumulation of Alizarin red (AR) and von Kossa stain at 21 day of culture in osteogenic medium were found on 3D aligned constructs while the rest showed lower and rather undistinguishable activity. Quantitative reverse transcription-polymerase chain reaction analysis for Osteopontin (OSP) and RUNX 2 generally confirmed this trend showing favourable expression of osteogenic genes activity in 3D environment particularly in aligned configuration.

Keywords: Mesenchymal stem cells, Nanofibers, Osteogenic, Fibrinogen, Cell movements

Simmchen, Juliane, Baeza, Alejandro, Miguel-Lopez, Albert, Stanton, Morgan M., Vallet-Regi, Maria, Ruiz-Molina, Daniel, Sánchez, Samuel, (2017). Dynamics of novel photoactive AgCl microstars and their environmental applications ChemNanoMat 3, (1), 65-71

In the field of micromotors many efforts are taken to find a substitute for peroxide as fuel. While most approaches turn towards other toxic high energy chemicals such as hydrazine, we introduce an energy source that is widely used in nature: light. Light is an ideal source of energy and some materials, such as AgCl, have the inherent property to transform light energy for chemical processes, which can be used to achieve propulsion. In the case of silver chloride, one observed process after light exposure is surface modification which leads to the release of ions generating chemo-osmotic gradients. Here we present endeavours to use those processes to propel uniquely shaped micro objects of micro star morphology with a high surface to volume ratio, study their dynamics and present approaches to go towards real environmental applications.

Keywords: Self-propellers, Silver chloride, Environmental applications, Photoactive colloids, Anti bacterial

Urbano, Jessica Julioti, da Palma, Renata Kelly, de Lima, Flávia Mafra, Fratini, Paula, Guimaraes, Leticia Lopes, Uriarte, Juan J., Alvarenga, Letícia Heineck, Miglino, Maria Angelica, Vieira, Rodolfo de Paula, Prates, Renato Araujo, Navajas, Daniel, Farré, Ramon, Oliveira, Luis Vicente Franco, (2017). Effects of two different decellularization routes on the mechanical properties of decellularized lungs PLoS ONE 12, (6), e0178696

Considering the limited number of available lung donors, lung bioengineering using whole lung scaffolds has been proposed as an alternative approach to obtain lungs suitable for transplantation. However, some decellularization protocols can cause alterations on the structure, composition, or mechanical properties of the lung extracellular matrix. Therefore, the aim of this study was to compare the acellular lung mechanical properties when using two different routes through the trachea and pulmonary artery for the decellularization process. This study was performed by using the lungs excised from 30 healthy male C57BL/6 mice, which were divided into 3 groups: tracheal decellularization (TDG), perfusion decellularization (PDG), and control groups (CG). Both decellularized groups were subjected to decellularization protocol with a solution of 1% sodium dodecyl sulfate. The behaviour of mechanical properties of the acellular lungs was measured after decellularization process. Static (Est) and dynamic (Edyn) elastances were obtained by the end-inspiratory occlusion method. TDG and PDG showed reduced Est and Edyn elastances after lung decellularization. Scanning electron microscopy showed no structural changes after lung decellularization of the TDG and PDG. In conclusion, was demonstrated that there is no significant difference in the behaviour of mechanical properties and extracellular matrix of the decellularized lungs by using two different routes through the trachea and pulmonary artery.

Sarlabous, Leonardo, Torres, Abel, Fiz, José A., Martínez-Llorens, Juana M., Gea, Joaquim, Jané, Raimon, (2017). Inspiratory muscle activation increases with COPD severity as confirmed by non-invasive mechanomyographic analysis PLoS ONE 12, (5), e0177730

There is a lack of instruments for assessing respiratory muscle activation during the breathing cycle in clinical conditions. The aim of the present study was to evaluate the usefulness of the respiratory muscle mechanomyogram (MMG) for non-invasively assessing the mechanical activation of the inspiratory muscles of the lower chest wall in both patients with chronic obstructive pulmonary disease (COPD) and healthy subjects, and to investigate the relationship between inspiratory muscle activation and pulmonary function parameters. Both inspiratory mouth pressure and respiratory muscle MMG were simultaneously recorded under two different respiratory conditions, quiet breathing and incremental ventilatory effort, in 13 COPD patients and 7 healthy subjects. The mechanical activation of the inspiratory muscles was characterised by the non-linear multistate Lempel–Ziv index (MLZ) calculated over the inspiratory time of the MMG signal. Subsequently, the efficiency of the inspiratory muscle mechanical activation was expressed as the ratio between the peak inspiratory mouth pressure to the amplitude of the mechanical activation. This activation estimated using the MLZ index correlated strongly with peak inspiratory mouth pressure throughout the respiratory protocol in both COPD patients (r = 0.80, p<0.001) and healthy (r = 0.82, p<0.001). Moreover, the greater the COPD severity in patients, the greater the level of muscle activation (r = -0.68, p = 0.001, between muscle activation at incremental ventilator effort and FEV1). Furthermore, the efficiency of the mechanical activation of inspiratory muscle was lower in COPD patients than healthy subjects (7.61±2.06 vs 20.42±10.81, respectively, p = 0.0002), and decreased with increasing COPD severity (r = 0.78, p<0.001, between efficiency of the mechanical activation at incremental ventilatory effort and FEV1). These results suggest that the respiratory muscle mechanomyogram is a good reflection of inspiratory effort and can be used to estimate the efficiency of the mechanical activation of the inspiratory muscles. Both, inspiratory muscle activation and inspiratory muscle mechanical activation efficiency are strongly correlated with the pulmonary function. Therefore, the use of the respiratory muscle mechanomyogram can improve the assessment of inspiratory muscle activation in clinical conditions, contributing to a better understanding of breathing in COPD patients.

Vilaseca, A., Campillo, N., Torres, M., Musquera, M., Gozal, D., Montserrat, J. M., Alcaraz, A., Touijer, K. A., Farré, R., Almendros, I., (2017). Intermittent hypoxia increases kidney tumor vascularization in a murine model of sleep apnea PLoS ONE 12, (6),

We investigate the effects of intermittent hypoxia (IH), a characteristic feature of obstructive sleep apnea (OSA), on renal cancer progression in an animal and cell model. An in vivo mouse model (Balb/c, n = 50) of kidney cancer was used to assess the effect of IH on tumor growth, metastatic capacity, angiogenesis and tumor immune response. An in vitro model tested the effect of IH on RENCA cells, macrophages and endothelial cells. Tumor growth, metastatic capacity, circulating vascular endothelial growth factor (VEGF) and content of endothelial cells, tumor associated macrophages and their phenotype were assessed in the tumor. In vitro, VEGF cell expression was quantified.Although IH did not boost tumor growth, it significantly increased endothelial cells (p = 0.001) and circulating VEGF (p<0.001) in the in vivo model. Macrophages exposed to IH in vitro increased VEGF expression, whereas RENCA cells and endothelial cells did not. These findings are in keeping with previous clinical data suggesting that OSA has no effect on kidney cancer size and that the association observed between OSA and higher Fuhrman grade of renal cell carcinoma may be mediated though a proangiogenic process, with a key role of macrophages.

Hindriks, Rikkert, Schmiedt, Joscha, Arsiwalla, Xerxes D., Peter, Alina, Verschure, Paul F. M. J., Fries, Pascal, Schmid, Michael C., Deco, Gustavo, (2017). Linear distributed source modeling of local field potentials recorded with intra-cortical electrode arrays PLoS ONE 12, (12), e0187490

Planar intra-cortical electrode (Utah) arrays provide a unique window into the spatial organization of cortical activity. Reconstruction of the current source density (CSD) underlying such recordings, however, requires “inverting” Poisson’s equation. For inter-laminar recordings, this is commonly done by the CSD method, which consists in taking the second-order spatial derivative of the recorded local field potentials (LFPs). Although the CSD method has been tremendously successful in mapping the current generators underlying inter-laminar LFPs, its application to planar recordings is more challenging. While for inter-laminar recordings the CSD method seems reasonably robust against violations of its assumptions, is it unclear as to what extent this holds for planar recordings. One of the objectives of this study is to characterize the conditions under which the CSD method can be successfully applied to Utah array data. Using forward modeling, we find that for spatially coherent CSDs, the CSD method yields inaccurate reconstructions due to volume-conducted contamination from currents in deeper cortical layers. An alternative approach is to “invert” a constructed forward model. The advantage of this approach is that any a priori knowledge about the geometrical and electrical properties of the tissue can be taken into account. Although several inverse methods have been proposed for LFP data, the applicability of existing electroencephalographic (EEG) and magnetoencephalographic (MEG) inverse methods to LFP data is largely unexplored. Another objective of our study therefore, is to assess the applicability of the most commonly used EEG/MEG inverse methods to Utah array data. Our main conclusion is that these inverse methods provide more accurate CSD reconstructions than the CSD method. We illustrate the inverse methods using event-related potentials recorded from primary visual cortex of a macaque monkey during a motion discrimination task.

Lozano-Garcia, M., Fiz, J. A., Martínez-Rivera, C., Torrents, A., Ruiz-Manzano, J., Jané, R., (2017). Novel approach to continuous adventitious respiratory sound analysis for the assessment of bronchodilator response PLoS ONE 12, (2), e0171455

Background A thorough analysis of continuous adventitious sounds (CAS) can provide distinct and complementary information about bronchodilator response (BDR), beyond that provided by spirometry. Nevertheless, previous approaches to CAS analysis were limited by certain methodology issues. The aim of this study is to propose a new integrated approach to CAS analysis that contributes to improving the assessment of BDR in clinical practice for asthma patients. Methods Respiratory sounds and flow were recorded in 25 subjects, including 7 asthma patients with positive BDR (BDR+), assessed by spirometry, 13 asthma patients with negative BDR (BDR-), and 5 controls. A total of 5149 acoustic components were characterized using the Hilbert spectrum, and used to train and validate a support vector machine classifier, which distinguished acoustic components corresponding to CAS from those corresponding to other sounds. Once the method was validated, BDR was assessed in all participants by CAS analysis, and compared to BDR assessed by spirometry. Results BDR+ patients had a homogenous high change in the number of CAS after bronchodilation, which agreed with the positive BDR by spirometry, indicating high reversibility of airway obstruction. Nevertheless, we also found an appreciable change in the number of CAS in many BDR- patients, revealing alterations in airway obstruction that were not detected by spirometry. We propose a categorization for the change in the number of CAS, which allowed us to stratify BDR- patients into three consistent groups. From the 13 BDR- patients, 6 had a high response, similar to BDR+ patients, 4 had a noteworthy medium response, and 1 had a low response.Conclusions In this study, a new non-invasive and integrated approach to CAS analysis is proposed as a high-sensitive tool for assessing BDR in terms of acoustic parameters which, together with spirometry parameters, contribute to improving the stratification of BDR levels in patients with obstructive pulmonary diseases.

Zaffino, R. L., Mir, M., Samitier, J., (2017). Oligonucleotide probes functionalization of nanogap electrodes Electrophoresis 38, (21), 2712-2720

Nanogap electrodes have attracted a lot of consideration as promising platform for molecular electronic and biomolecules detection. This is mainly for their higher aspect ratio, and because their electrical properties are easily accessed by current-voltage measurements. Nevertheless, application of standard current-voltages measurements used to characterize nanogap response, and/or to modify specific nanogap electrodes properties, represents an issue. Since the strength of electrical fields in nanoscaled devices can reach high values, even at low voltages. Here, we analyzed the effects induced by different methods of surface modification of nanogap electrodes, in test-voltage application, employed for the electrical detection of a desoxyribonucleic acid (DNA) target. Nanogap electrodes were functionalized with two antisymmetric oligo-probes designed to have 20 terminal bases complementary to the edges of the target, which after hybridization bridges the nanogap, closing the electrical circuit. Two methods of functionalization were studied for this purpose; a random self-assembling of a mixture of the two oligo-probes (OPs) used in the platform, and a selective method that controls the position of each OP at selected side of nanogap electrodes. We used for this aim, the electrophoretic effect induced on negatively charged probes by the application of an external direct current voltage. The results obtained with both functionalization methods where characterized and compared in terms of electrode surface covering, calculated by using voltammetry analysis. Moreover, we contrasted the electrical detection of a DNA target in the nanogap platform either in site-selective and in randomly assembled nanogap. According to our results, a denser, although not selective surface functionalization, is advantageous for such kind of applications.

Keywords: Biosensor bioelectronics, DNA electrophoresis, Nanogap electrodes, Self-assembled monolayers, Site-selective deposition

Aviles, A. I., Widlak, T., Casals, A., Nillesen, M. M., Ammari, H., (2017). Robust cardiac motion estimation using ultrafast ultrasound data: A low-rank topology-preserving approach Physics in Medicine and Biology 62, (12), 4831-4851

Cardiac motion estimation is an important diagnostic tool for detecting heart diseases and it has been explored with modalities such as MRI and conventional ultrasound (US) sequences. US cardiac motion estimation still presents challenges because of complex motion patterns and the presence of noise. In this work, we propose a novel approach to estimate cardiac motion using ultrafast ultrasound data. Our solution is based on a variational formulation characterized by the L 2-regularized class. Displacement is represented by a lattice of b-splines and we ensure robustness, in the sense of eliminating outliers, by applying a maximum likelihood type estimator. While this is an important part of our solution, the main object of this work is to combine low-rank data representation with topology preservation. Low-rank data representation (achieved by finding the k-dominant singular values of a Casorati matrix arranged from the data sequence) speeds up the global solution and achieves noise reduction. On the other hand, topology preservation (achieved by monitoring the Jacobian determinant) allows one to radically rule out distortions while carefully controlling the size of allowed expansions and contractions. Our variational approach is carried out on a realistic dataset as well as on a simulated one. We demonstrate how our proposed variational solution deals with complex deformations through careful numerical experiments. The low-rank constraint speeds up the convergence of the optimization problem while topology preservation ensures a more accurate displacement. Beyond cardiac motion estimation, our approach is promising for the analysis of other organs that exhibit motion.

Keywords: Cardiac analysis, Low-rank representation, Motion estimation, Topology preservation, Ultrafast ultrasound

Obiols-Rabasa, M., Oncins, G., Sanz, F., Tadros, T. F., Solans, C., Levecke, B., Booten, K., Esquena, J., (2017). Investigation of the elastic and adhesion properties of adsorbed hydrophobically modified inulin films on latex particles using Atomic Force Microscopy (AFM) Colloids and Surfaces A: Physicochemical and Engineering Aspects 524, 185-192

Graft polymer surfactants provide very good colloidal stability because of strong steric repulsions between adsorbed surfactant films. The elastic and adhesion properties of adsorbed hydrophobically modified inulin polymer surfactant (INUTEC NRA) have been directly measured using Atomic Force Microscopy (AFM) measurements. For this purpose, poly(methyl methacrylate/butyl acrylate), P(MMA/BuA), latexes prepared in the presence of the hydrophobically modified inulin (INUTEC NRA) were used. These latexes (diameter 118 nm and polydispersity index of 1.05) showed a very high colloidal stability in water and in the presence of electrolyte (up to 0.2 mol dm−3 KBr). The latexes were deposited on mica, which was silanated to enhance the adhesion of the latex particles to the surface. A silicon nitride tip with approximately 10 nm diameter that also contained an adsorbed layer of surfactant was used in the AFM apparatus. The tip was allowed to approach, contact thereafter the particles with an applied force of 12.5 nN, and finally detach from the film. Both elastic (Young’s) modulus of the film and adhesion force were studied. The results showed that the adsorbed surfactant films are highly elastic and their elastic modulus and adhesion force did not change significantly with the presence of Na2SO4 up to 0.05 mol dm−3. The high elastic contribution to the steric interaction ensures strong repulsion between the latex particles both in water and at high electrolyte concentrations. In addition, the lack of dependence of adhesion force on electrolyte concentration ensures uniform deposition of the latex particles on a flat substrate as for example in coating applications. These results show the advantages of using a graft polymer surfactant for enhancing the stability of particle suspensions, as illustrated in previous investigations.

Keywords: AFM, Colloidal stability, Interaction forces, Steric repulsion

Pomareda, V., Magrans, R., Jiménez-Soto, J., Martínez, D., Tresánchez, M., Burgués, J., Palacín, J., Marco, S., (2017). Chemical source localization fusing concentration information in the presence of chemical background noise Sensors 17, (4), 904

We present the estimation of a likelihood map for the location of the source of a chemical plume dispersed under atmospheric turbulence under uniform wind conditions. The main contribution of this work is to extend previous proposals based on Bayesian inference with binary detections to the use of concentration information while at the same time being robust against the presence of background chemical noise. For that, the algorithm builds a background model with robust statistics measurements to assess the posterior probability that a given chemical concentration reading comes from the background or from a source emitting at a distance with a specific release rate. In addition, our algorithm allows multiple mobile gas sensors to be used. Ten realistic simulations and ten real data experiments are used for evaluation purposes. For the simulations, we have supposed that sensors are mounted on cars which do not have among its main tasks navigating toward the source. To collect the real dataset, a special arena with induced wind is built, and an autonomous vehicle equipped with several sensors, including a photo ionization detector (PID) for sensing chemical concentration, is used. Simulation results show that our algorithm, provides a better estimation of the source location even for a low background level that benefits the performance of binary version. The improvement is clear for the synthetic data while for real data the estimation is only slightly better, probably because our exploration arena is not able to provide uniform wind conditions. Finally, an estimation of the computational cost of the algorithmic proposal is presented.

Keywords: Machine olfaction, Odor robots, Chemical sensors, Bayesian inference

Ma, X., Sánchez, S., (2017). Bio-catalytic mesoporous Janus nano-motors powered by catalase enzyme Tetrahedron 73, (33), 4883-4886

Enzyme triggered bio-catalytic reactions convert chemical energy into mechanical force to power micro/nano-machines. Though there have been reports about enzymes powered micro/nano-motors, enzymatic Janus nano-motor smaller than 100 nm has not been reported yet. Here, we prepared an enzyme powered Janus nano-motor by half-capping a thin layer of silicon dioxide (4 nm SiO2) onto a mesoporous silica nanoparticle (MSNP) of 90 nm, enabling asymmetry to the nano-architecture. The nano-motors are chemically powered by the decomposition of H2O2 triggered by the enzyme catalase located at one face of the nanoparticles. The self-propulsion is characterized by dynamic light scattering (DLS) and optical microscopy. The apparent diffusion coefficient was enhanced by 150% compared to their Brownian motion at low H2O2 concentration (i.e. below 3 wt%). Mesoporous nano-motors might serve as active drug delivery nano-systems in future biomedical applications such as intracellular drug delivery.

Keywords: Enzyme catalysis, Janus particles, Mesoporous silica, Nano-motors, Nanomachine, Self-propulsion

Mohammadi, M. H., Obregón, R., Ahadian, S., Ramón-Azcón, J., Radisic, M., (2017). Engineered muscle tissues for disease modeling and drug screening applications Current Pharmaceutical Design 23, (20), 2991-3004

Animal models have been the main resources for drug discovery and prediction of drugs’ pharmacokinetic responses in the body. However, noticeable drawbacks associated with animal models include high cost, low reproducibility, low physiological similarity to humans, and ethical problems. Engineered tissue models have recently emerged as an alternative or substitute for animal models in drug discovery and testing and disease modeling. In this review, we focus on skeletal muscle and cardiac muscle tissues by first describing their characterization and physiology. Major fabrication technologies (i.e., electrospinning, bioprinting, dielectrophoresis, textile technology, and microfluidics) to make functional muscle tissues are then described. Finally, currently used muscle tissue models in drug screening are reviewed and discussed.

Keywords: Cardiac muscle, Drug screening, Engineering muscle, Human pharmacological response, Physiological similarity, Skeletal muscle

Beiert, T., Tiyerili, V., Knappe, V., Effelsberg, V., Linhart, M., Stöckigt, F., Klein, S., Schierwagen, R., Trebicka, J., Nickenig, G., Schrickel, J. W., Andrié, R. P., (2017). Relaxin reduces susceptibility to post-infarct atrial fibrillation in mice due to anti-fibrotic and anti-inflammatory properties Biochemical and Biophysical Research Communications 490, (3), 643-649

Background Relaxin-2 (RLX) is a peptide hormone that exerts beneficial anti-fibrotic and anti-inflammatory effects in diverse models of cardiovascular disease. The goal of this study was to determine the effects of RLX treatment on the susceptibility to atrial fibrillation (AF) after myocardial infarction (MI). Methods Mice with cryoinfarction of the left anterior ventricular wall were treated for two weeks with either RLX (75 μg/kg/d) or vehicle (sodium acetate) delivered via subcutaneously implanted osmotic minipumps. Results RLX treatment significantly attenuated the increase in AF-inducibility following cryoinfarction and reduced the mean duration of AF episodes. Furthermore, epicardial mapping of both atria revealed an increase in conduction velocity. In addition to an attenuation of atrial hypertrophy, chronic application of RLX reduced atrial fibrosis, which was linked to a significant reduction in atrial mRNA expression of connective tissue growth factor. Transcript levels of the pro-inflammatory cytokines interleukin-6 and interleukin-1β were reduced in RLX treated mice, but macrophage infiltration into atrial myocardium was similar in the vehicle and RLX treated groups. Conclusion Treatment with RLX in mice after MI reduces susceptibility to AF due to anti-inflammatory and anti-fibrotic properties. Because to these favorable actions, RLX may become a new therapeutic option in the treatment of AF, even when complicating MI.

Keywords: Atrial fibrillation, Atrial fibrosis, Myocardial infarction, Relaxin-2

Laiou, Petroula, Andrzejak, Ralph G., (2017). Coupling strength versus coupling impact in nonidentical bidirectionally coupled dynamics Physical Review E 95, (1), 012210

The understanding of interacting dynamics is important for the characterization of real-world networks. In general, real-world networks are heterogeneous in the sense that each node of the network is a dynamics with different properties. For coupled nonidentical dynamics symmetric interactions are not straightforwardly defined from the coupling strength values. Thus, a challenging issue is whether we can define a symmetric interaction in this asymmetric setting. To address this problem we introduce the notion of the coupling impact. The coupling impact considers not only the coupling strength but also the energy of the individual dynamics, which is conveyed via the coupling. To illustrate this concept, we follow a data-driven approach by analyzing signals from pairs of coupled model dynamics using two different connectivity measures. We find that the coupling impact, but not the coupling strength, correctly detects a symmetric interaction between pairs of coupled dynamics regardless of their degree of asymmetry. Therefore, this approach allows us to reveal the real impact that one dynamics has on the other and hence to define symmetric interactions in pairs of nonidentical dynamics.

Malvestio, I., Kreuz, T., Andrzejak, R. G., (2017). Robustness and versatility of a nonlinear interdependence method for directional coupling detection from spike trains Physical Review E 96, (2), 022203

The detection of directional couplings between dynamics based on measured spike trains is a crucial problem in the understanding of many different systems. In particular, in neuroscience it is important to assess the connectivity between neurons. One of the approaches that can estimate directional coupling from the analysis of point processes is the nonlinear interdependence measure L. Although its efficacy has already been demonstrated, it still needs to be tested under more challenging and realistic conditions prior to an application to real data. Thus, in this paper we use the Hindmarsh-Rose model system to test the method in the presence of noise and for different spiking regimes. We also examine the influence of different parameters and spike train distances. Our results show that the measure L is versatile and robust to various types of noise, and thus suitable for application to experimental data.

Urrea, Laura, Ferrer, Isidro, Gavín, Rosalina, del Río, José Antonio, (2017). The cellular prion protein (PrPC) as neuronal receptor for α-synuclein Prion 11, (4), 226-233

The term ‘prion-like’ is used to define some misfolded protein species that propagate intercellularly, triggering protein aggregation in recipient cells. For cell binding, both direct plasma membrane interaction and membrane receptors have been described for particular amyloids. In this respect, emerging evidence demonstrates that several β-sheet enriched proteins can bind to the cellular prion protein (PrPC). Among other interactions, the physiological relevance of the binding between β-amyloid and PrPC has been a relevant focus of numerous studies. At the molecular level, published data point to the second charged cluster domain of the PrPC molecule as the relevant binding domain of the β-amyloid/PrPC interaction. In addition to β-amyloid, participation of PrPC in binding α-synuclein, responsible for neurodegenerative synucleopathies, has been reported. Although results indicate relevant participation of PrPC in the spreading of α-synuclein in living mice, the physiological relevance of the interaction remains elusive. In this comment, we focus our attention on summarizing current knowledge of PrPC as a receptor for amyloid proteins and its physiological significance, with particular focus on α-synuclein.

Keywords: α-synuclein, Charged cluster domain, Interneuronal transport, LAG3, Neurodegeneration, PrPC, Parkinson disease

Guduric, V., Metz, C., Siadous, R., Bareille, R., Levato, R., Engel, E., Fricain, J. C., Devillard, R., Luzanin, O., Catros, S., (2017). Layer-by-layer bioassembly of cellularized polylactic acid porous membranes for bone tissue engineering Journal of Materials Science: Materials in Medicine 28, (5), 78

Abstract: The conventional tissue engineering is based on seeding of macroporous scaffold on its surface (“top–down” approach). The main limitation is poor cell viability in the middle of the scaffold due to poor diffusion of oxygen and nutrients and insufficient vascularization. Layer-by-Layer (LBL) bioassembly is based on “bottom–up” approach, which considers assembly of small cellularized blocks. The aim of this work was to evaluate proliferation and differentiation of human bone marrow stromal cells (HBMSCs) and endothelial progenitor cells (EPCs) in two and three dimensions (2D, 3D) using a LBL assembly of polylactic acid (PLA) scaffolds fabricated by 3D printing. 2D experiments have shown maintain of cell viability on PLA, especially when a co-cuture system was used, as well as adequate morphology of seeded cells. Early osteoblastic and endothelial differentiations were observed and cell proliferation was increased after 7 days of culture. In 3D, cell migration was observed between layers of LBL constructs, as well as an osteoblastic differentiation. These results indicate that LBL assembly of PLA layers could be suitable for BTE, in order to promote homogenous cell distribution inside the scaffold and gene expression specific to the cells implanted in the case of co-culture system.

Andrzejak, Ralph G., Ruzzene, G., Malvestio, I., (2017). Generalized synchronization between chimera states Chaos: An Interdisciplinary Journal of Nonlinear Science 27, (5), 053114

Networks of coupled oscillators in chimera states are characterized by an intriguing interplay of synchronous and asynchronous motion. While chimera states were initially discovered in mathematical model systems, there is growing experimental and conceptual evidence that they manifest themselves also in natural and man-made networks. In real-world systems, however, synchronization and desynchronization are not only important within individual networks but also across different interacting networks. It is therefore essential to investigate if chimera states can be synchronized across networks. To address this open problem, we use the classical setting of ring networks of non-locally coupled identical phase oscillators. We apply diffusive drive-response couplings between pairs of such networks that individually show chimera states when there is no coupling between them. The drive and response networks are either identical or they differ by a variable mismatch in their phase lag parameters. In both cases, already for weak couplings, the coherent domain of the response network aligns its position to the one of the driver networks. For identical networks, a sufficiently strong coupling leads to identical synchronization between the drive and response. For non-identical networks, we use the auxiliary system approach to demonstrate that generalized synchronization is established instead. In this case, the response network continues to show a chimera dynamics which however remains distinct from the one of the driver. Hence, segregated synchronized and desynchronized domains in individual networks congregate in generalized synchronization across networks.

Keywords: Oscillators, Synchronisation

Isetta, V., Torres, M., González, K., Ruiz, C., Dalmases, M., Embid, C., Navajas, D., Farré, R., Montserrat, J. M., (2017). A New mHealth application to support treatment of sleep apnoea patients Journal of Telemedicine and Telecare 23, (1), 14-18

Introduction: Continuous positive airway pressure (CPAP) is the first-choice treatment for obstructive sleep apnoea (OSA), but adherence is frequently suboptimal. Innovative, patient-centred interventions are, therefore, needed to enhance compliance. Due to its low cost and ubiquity, mobile health (mHealth) technology seems particularly suited for this purpose. We endeavoured to develop an mHealth application called “APPnea,” aimed at promoting patient self-monitoring of CPAP treatment. We then assessed the feasibility and acceptability of APPnea in a group of OSA patients. Methods: Consecutive OSA patients used APPnea for six weeks. APPnea gave patients daily reminders to answer three questions about their OSA treatment (CPAP use, physical activity, and diet) and prompted them to upload their body weight weekly. Answers were saved to a secure server for further analysis. After completing the study, patients gave their anonymous opinions about APPnea. Results: We enrolled 60 patients with OSA receiving CPAP treatment. The mean age was 56 ± 10 years and the apnoea–hypopnea index was 47 ± 25 events/hour. In total, 63% of participants completed the daily questionnaire for more than 66% of the study period. Objective CPAP compliance was generally high (5.3 ± 1.6 hours/night). In a subset of 38 patients naïve to CPAP, those who used APPnea regularly had significantly higher CPAP compliance. Satisfaction levels were high for the majority of users. Conclusion: This mHealth intervention is not only feasible but also satisfactory to patients. Although larger randomized trials and cost-effectiveness studies should be performed, this study shows that APPnea could promote participation and improve compliance among patients with OSA, thereby improving outcomes.

Keywords: CPAP, MHealth, Sleep apnoea, Smartphone application

Aviles, A. I., Alsaleh, S. M., Hahn, J. K., Casals, A., (2017). Towards retrieving force feedback in robotic-assisted surgery: A supervised neuro-recurrent-vision approach IEEE Transactions on Haptics 10, (3), 431-443

Robotic-assisted minimally invasive surgeries have gained a lot of popularity over conventional procedures as they offer many benefits to both surgeons and patients. Nonetheless, they still suffer from some limitations that affect their outcome. One of them is the lack of force feedback which restricts the surgeon's sense of touch and might reduce precision during a procedure. To overcome this limitation, we propose a novel force estimation approach that combines a vision based solution with supervised learning to estimate the applied force and provide the surgeon with a suitable representation of it. The proposed solution starts with extracting the geometry of motion of the heart's surface by minimizing an energy functional to recover its 3D deformable structure. A deep network, based on a LSTM-RNN architecture, is then used to learn the relationship between the extracted visual-geometric information and the applied force, and to find accurate mapping between the two. Our proposed force estimation solution avoids the drawbacks usually associated with force sensing devices, such as biocompatibility and integration issues. We evaluate our approach on phantom and realistic tissues in which we report an average root-mean square error of 0.02 N.

Keywords: Computer-assisted surgery, Deep networks, Force estimation, Visual deformation

Schwab, S., Lehmann, J., Lutz, P., Jansen, C., Appenrodt, B., Lammert, F., Strassburg, C. P., Spengler, U., Nischalke, H. D., Trebicka, J., (2017). Influence of genetic variations in the SOD1 gene on the development of ascites and spontaneous bacterial peritonitis in decompensated liver cirrhosis European Journal of Gastroenterology and Hepatology 29, (7), 800-804

Background The balance between generation and elimination of reactive oxygen species by superoxide dismutase (SOD) is crucially involved in the pathophysiology of liver cirrhosis. Reactive oxygen species damage cells and induce inflammation/fibrosis, but also play a critical role in immune defense from pathogens. As both processes are involved in the development of liver cirrhosis and its complications, genetic variation of the SOD1 gene was investigated. Patients and methods Two SOD1 single nucleotide polymorphisms (rs1041740 and rs3844942) were analyzed in 49 cirrhotic patients undergoing liver transplantation. In addition, 344 cirrhotic patients with ascites were analyzed in a cohort of 521 individuals in terms of the relationship of these polymorphisms with spontaneous bacterial peritonitis (SBP). Results Although rs3844942 showed no associations with complications of cirrhosis, we observed a significant association between rs1041740 and the presence of ascites and SBP in the discovery cohort of patients with cirrhosis. Importantly, the association with SBP was not confirmed in the validation cohort of patients with ascites. By contrast, a trend toward lower SBP rates was observed in carriers of rs1041740. In this cohort, rs1041740 was not associated with survival. Conclusion These data suggest a complex role of SOD1 in different processes leading to complications of liver cirrhosis. rs1041740 might be associated with the development of ascites and possibly plays a role in SBP once ascites has developed.

Keywords: Ascites, Genetic polymorphism, Liver cirrhosis, Reactive oxygen stress, Spontaneous bacterial peritonitis, Superoxide dismutases

Garde, A., Sörnmo, L., Laguna, P., Jané, R., Benito, S., Bayés-Genís, A., Giraldo, B. F., (2017). Assessment of respiratory flow cycle morphology in patients with chronic heart failure Medical and Biological Engineering and Computing 55, (2), 245-255

Breathing pattern as periodic breathing (PB) in chronic heart failure (CHF) is associated with poor prognosis and high mortality risk. This work investigates the significance of a number of time domain parameters for characterizing respiratory flow cycle morphology in patients with CHF. Thus, our primary goal is to detect PB pattern and identify patients at higher risk. In addition, differences in respiratory flow cycle morphology between CHF patients (with and without PB) and healthy subjects are studied. Differences between these parameters are assessed by investigating the following three classification issues: CHF patients with PB versus with non-periodic breathing (nPB), CHF patients (both PB and nPB) versus healthy subjects, and nPB patients versus healthy subjects. Twenty-six CHF patients (8/18 with PB/nPB) and 35 healthy subjects are studied. The results show that the maximal expiratory flow interval is shorter and with lower dispersion in CHF patients than in healthy subjects. The flow slopes are much steeper in CHF patients, especially for PB. Both inspiration and expiration durations are reduced in CHF patients, mostly for PB. Using the classification and regression tree technique, the most discriminant parameters are selected. For signals shorter than 1 min, the time domain parameters produce better results than the spectral parameters, with accuracies for each classification of 82/78, 89/85, and 91/89 %, respectively. It is concluded that morphologic analysis in the time domain is useful, especially when short signals are analyzed.

Keywords: Chronic heart failure, Ensemble average, Periodic and non-periodic breathing, Respiratory pattern

Leguia, Marc G., Andrzejak, Ralph G., Levnaji, (2017). Evolutionary optimization of network reconstruction from derivative-variable correlations Journal of Physics A: Mathematical and Theoretical 50, (33), 334001

Topologies of real-world complex networks are rarely accessible, but can often be reconstructed from experimentally obtained time series via suitable network reconstruction methods. Extending our earlier work on methods based on statistics of derivative-variable correlations, we here present a new method built on integrating an evolutionary optimization algorithm into the derivative-variable correlation method. Results obtained from our modification of the method in general outperform the original results, demonstrating the suitability of evolutionary optimization logic in network reconstruction problems. We show the method’s usefulness in realistic scenarios where the reconstruction precision can be limited by the nature of the time series. We also discuss important limitations coming from various dynamical regimes that time series can belong to.

Estrada, L., Torres, A., Sarlabous, L., Jané, R., (2017). Influence of parameter selection in fixed sample entropy of surface diaphragm electromyography for estimating respiratory activity Entropy 19, (9), 460

Fixed sample entropy (fSampEn) is a robust technique that allows the evaluation of inspiratory effort in diaphragm electromyography (EMGdi) signals, and has potential utility in sleep studies. To appropriately estimate respiratory effort, fSampEn requires the adjustment of several parameters. The aims of the present study were to evaluate the influence of the embedding dimension m, the tolerance value r, the size of the moving window, and the sampling frequency, and to establish recommendations for estimating the respiratory activity when using the fSampEn on surface EMGdi recorded for different inspiratory efforts. Values of m equal to 1 and r ranging from 0.1 to 0.64, and m equal to 2 and r ranging from 0.13 to 0.45, were found to be suitable for evaluating respiratory activity. fSampEn was less affected by window size than classical amplitude parameters. Finally, variations in sampling frequency could influence fSampEn results. In conclusion, the findings suggest the potential utility of fSampEn for estimating muscle respiratory effort in further sleep studies.

Keywords: Fixed sample entropy (fSampEn), Non-invasive respiratory monitoring, Respiratory activity, Respiratory effort, Surface diaphragm electromyography

Santos-Pata, D., Zucca, R., Low, S. C., Verschure, P. F. M. J., (2017). Size matters: How scaling affects the interaction between grid and border cells Frontiers in Computational Neuroscience 11, Article 65

Many hippocampal cell types are characterized by a progressive increase in scale along the dorsal-to-ventral axis, such as in the cases of head-direction, grid and place cells. Also located in the medial entorhinal cortex (MEC), border cells would be expected to benefit from such scale modulations. However, this phenomenon has not been experimentally observed. Grid cells in the MEC of mammals integrate velocity related signals to map the environment with characteristic hexagonal tessellation patterns. Due to the noisy nature of these input signals, path integration processes tend to accumulate errors as animals explore the environment, leading to a loss of grid-like activity. It has been suggested that border-to-grid cells' associations minimize the accumulated grid cells' error when rodents explore enclosures. Thus, the border-grid interaction for error minimization is a suitable scenario to study the effects of border cell scaling within the context of spatial representation. In this study, we computationally address the question of (i) border cells' scale from the perspective of their role in maintaining the regularity of grid cells' firing fields, as well as (ii) what are the underlying mechanisms of grid-border associations relative to the scales of both grid and border cells. Our results suggest that for optimal contribution to grid cells' error minimization, border cells should express smaller firing fields relative to those of the associated grid cells, which is consistent with the hypothesis of border cells functioning as spatial anchoring signals.

Keywords: Border cells, Error minimization, Grid cells, Navigation, Path integration

Marsal, Maria, Jorba, Ignasi, Rebollo, Elena, Luque, Tomas, Navajas, Daniel, Martín-Blanco, Enrique, (2017). AFM and microrheology in the zebrafish embryo yolk cell Journal of Visualized Experiments Developmental Biology, (129), e56224

Elucidating the factors that direct the spatio-temporal organization of evolving tissues is one of the primary purposes in the study of development. Various propositions claim to have been important contributions to the understanding of the mechanical properties of cells and tissues in their spatiotemporal organization in different developmental and morphogenetic processes. However, due to the lack of reliable and accessible tools to measure material properties and tensional parameters in vivo, validating these hypotheses has been difficult. Here we present methods employing atomic force microscopy (AFM) and particle tracking with the aim of quantifying the mechanical properties of the intact zebrafish embryo yolk cell during epiboly. Epiboly is an early conserved developmental process whose study is facilitated by the transparency of the embryo. These methods are simple to implement, reliable, and widely applicable since they overcome intrusive interventions that could affect tissue mechanics. A simple strategy was applied for the mounting of specimens, AFM recording, and nanoparticle injections and tracking. This approach makes these methods easily adaptable to other developmental times or organisms.

Keywords: Developmental Biology, Zebrafish, Yolk, Atomic Force Microscopy, Cortical Tension, Microrheology, Nanoparticle tracking

Giménez, A., Uriarte, J. J., Vieyra, J., Navajas, D., Alcaraz, J., (2017). Elastic properties of hydrogels and decellularized tissue sections used in mechanobiology studies probed by atomic force microscopy Microscopy Research and Technique 80, (1), 85-96

The increasing recognition that tissue elasticity is an important regulator of cell behavior in normal and pathologic conditions such as fibrosis and cancer has driven the development of cell culture substrata with tunable elasticity. Such development has urged the need to quantify the elastic properties of these cell culture substrata particularly at the nanometer scale, since this is the relevant length scale involved in cell-extracellular matrix (ECM) mechanical interactions. To address this need, we have exploited the versatility of atomic force microscopy to quantify the elastic properties of a variety of cell culture substrata used in mechanobiology studies, including floating collagen gels, ECM-coated polyacrylamide gels, and decellularized tissue sections. In this review we summarize major findings in this field from our group within the context of the state-of-the-art in the field, and provide a critical discussion on the applicability and complementarity of currently available cell culture assays with tunable elasticity. In addition, we briefly describe how the limitations of these assays provide opportunities for future research, which is expected to continue expanding our understanding of the mechanobiological aspects that support both normal and diseased conditions.

Keywords: 3D culture, Atomic force microscopy, Elastic modulus, Extracellular matrix, Polyacrylamide

Tezanos, E., Badiola, M., Samitier, J., (2017). 3D Bioprinted muscle on a chip CASEIB Proceedings XXXV Congreso Anual de la Sociedad Española de Ingeniería Biomédica (CASEIB 2017) , Sociedad Española de Ingeniería Biomédica (Valencia, Spain) , XXXX (falta pdf)

Rodríguez, J. C., Arizmendi, C. J., Forero, C. A., Lopez, S. K., Giraldo, B. F., (2017). Analysis of the respiratory flow signal for the diagnosis of patients with chronic heart failure using artificial intelligence techniques IFMBE Proceedings VII Latin American Congress on Biomedical Engineering (CLAIB 2016) , Springer (Santander, Colombia) 60, 46-49

Patients with Chronic Heart Failure (CHF) often develop oscillatory breathing patterns. This work proposes the characterization of respiratory pattern by Wavelet Transform (WT) technique to identify Periodic Breathing pattern (PB) and Non-Periodic Breathing pattern (nPB) through the respiratory flow signal. A total of 62 subjects were analyzed: 27 CHF patients and 35 healthy subjects. Respiratory time series were extracted, and statistical methods were applied to obtain the most relevant information to classify patients. Support Vector Machine (SVM) were applied using forward selection technique to discriminate patients, considering four kernel functions. Differences between these parameters are assessed by investigating the following four classification issues: healthy subjects versus CHF patients, PB versus nPB patients, PB patients versus healthy subjects, and nPB patients versus healthy subjects. The results are presented in terms of average accuracy for each kernel function, and comparison groups.

Keywords: Chronic heart failure, Forward selection, Non-periodic breathing, Periodic breathing, Support vector machine

Rodriguez, J., Voss, A., Caminal, P., Bayes-Genis, A., Giraldo, B. F., (2017). Characterization and classification of patients with different levels of cardiac death risk by using Poincaré plot analysis Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 1332-1335

Cardiac death risk is still a big problem by an important part of the population, especially in elderly patients. In this study, we propose to characterize and analyze the cardiovascular and cardiorespiratory systems using the Poincaré plot. A total of 46 cardiomyopathy patients and 36 healthy subjets were analyzed. Left ventricular ejection fraction (LVEF) was used to stratify patients with low risk (LR: LVEF > 35%, 16 patients), and high risk (HR: LVEF ≤ 35%, 30 patients) of heart attack. RR, SBP and TTot time series were extracted from the ECG, blood pressure and respiratory flow signals, respectively. Parameters that describe the scatterplott of Poincaré method, related to short- and long-term variabilities, acceleration and deceleration of the dynamic system, and the complex correlation index were extracted. The linear discriminant analysis (LDA) and the support vector machines (SVM) classification methods were used to analyze the results of the extracted parameters. The results showed that cardiac parameters were the best to discriminate between HR and LR groups, especially the complex correlation index (p = 0.009). Analising the interaction, the best result was obtained with the relation between the difference of the standard deviation of the cardiac and respiratory system (p = 0.003). When comparing HR vs LR groups, the best classification was obtained applying SVM method, using an ANOVA kernel, with an accuracy of 98.12%. An accuracy of 97.01% was obtained by comparing patients versus healthy, with a SVM classifier and Laplacian kernel. The morphology of Poincaré plot introduces parameters that allow the characterization of the cardiorespiratory system dynamics.

Keywords: Time series analysis, Electrocardiography, Support vector machines, Kernel, Standards, Correlation, RF signals

Castillo, Y., Camara, M. A., Blanco-Almazan, D., Jane, R., (2017). Characterization of microphones for snoring and breathing events analysis in mHealth Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 1547-1550

Obstructive sleep apnea (OSA) is one of the most common sleep disorders, especially in elderly population. Despite its high prevalence and severe consequences, most patients remain undiagnosed due to serious limitations on the existing equipment. Efforts are being done to find cost-effective alternatives and mHealth solutions could play a key role. One promising approach in this context is the acoustic analysis of snoring. The sensor it requires is a microphone, which is widely available in different models and even integrated in smartphones. The objective of this work is to characterize and compare the responses of two commercial tracheal microphones and a mHealth-based microphone, as a proof-of-concept to evaluate their potential as sensors for OSA detection. To do that, we designed an experimental protocol to study OSA-related events (breaths, snores and apneas) simulated by 4 subjects. Test signals were simultaneously recorded with different microphones and posteriorly processed and analyzed. We accurately characterized the frequency response of the two commercial microphones, finding that one of them was too restrictive (bandwidth 50-250 Hz) and thus not suitable as snoring sensor for high-frequency acoustic analysis. Regarding smartphones, we studied the Samsung Galaxy S5 microphone. We found that, when located over the thorax, it provided quality signals comparable to those of tracheal microphones, with a broader frequency response. Further work is required, but this preliminary study suggests that acoustic analysis of snoring through mHealth solutions can be a feasible alternative to screen and monitor OSA patients at home.

Burgues, J., Fonollosa, J., Marco, S., (2017). Discontinuously operated MOX sensors for low power applications IEEE Conference Publications ISOCS/IEEE International Symposium on Olfaction and Electronic Nose (ISOEN) , IEEE (Montreal, Canada) , 1-3

Metal oxide semiconductor sensors are limited by their low selectivity, high power consumption and temporal drift. This paper proposes a novel discontinuous temperature modulation operation mode characterized by on-demand measurements and periodic warm-up cycles. The performance of two sets of FIS SB-500-12 sensors, one group continuously operated and the other group discontinuously operated, was compared in a scenario of carbon monoxide detection at low concentrations for five consecutive days. Results showed that the discontinuous operating mode moderately increased the prediction error and the limit of detection but was advantageous in terms of energy savings (up to 60% with respect to the continuous temperature modulation mode).

Keywords: Discontinuous operation, Duty-cycling, Low power, MOX sensors, Temperature modulation

Gállego, Isaac, Manning, Brendan, Prades, Joan Daniel, Mir, Mónica, Samitier, Josep, Eritja, Ramon, (2017). DNA-Origami-Aided Lithography for Sub-10 Nanometer Pattern Printing Proceedings Eurosensors 2017 , MDPI (Paris, France) 1, (4), 325

We report the first DNA-based origami technique that can print addressable patterns on surfaces with sub-10 nm resolution. Specifically, we have used a two-dimensional DNA origami as a template (DNA origami stamp) to transfer DNA with pre-programmed patterns (DNA ink) on gold surfaces. The DNA ink is composed of thiol-modified staple strands incorporated at specific positions of the DNA origami stamp to create patterns upon thiol-gold bond formation on the surface (DNA ink). The DNA pattern formed is composed of unique oligonucleotide sequences, each of which is individually addressable. As a proof-of-concept, we created a linear pattern of oligonucleotide-modified gold nanoparticles complementary to the DNA ink pattern. We have developed an in silico model to identify key elements in the formation of our DNA origami-driven lithography and nanoparticle patterning as well as simulate more complex nanoparticle patterns on surfaces.

Keywords: DNA nanotechnology, Lithography, Nanopatterning, Gold nanoparticles, Metasurfaces

Moulin-Frier, C., Puigbò, J.-Y., Arsiwalla, Xerxes D., Martì Sanchez-Fibla, M., Verschure, Paul F. M. J., (2017). Embodied artificial intelligence through distributed adaptive control: An integrated framework 7th Joint IEEE International Conference on Development and Learning and on Epigenetic Robotics (ICDL-Epirob 2017) , IEEE (Lisbon, Portugal) , 1-8

In this paper, we argue that the future of Artificial Intelligence research resides in two keywords: integration and embodiment. We support this claim by analyzing the recent advances of the field. Regarding integration, we note that the most impactful recent contributions have been made possible through the integration of recent Machine Learning methods (based in particular on Deep Learning and Recurrent Neural Networks) with more traditional ones (e.g. Monte-Carlo tree search, goal babbling exploration or addressable memory systems). Regarding embodiment, we note that the traditional benchmark tasks (e.g. visual classification or board games) are becoming obsolete as state-of-the-art learning algorithms approach or even surpass human performance in most of them, having recently encouraged the development of first-person 3D game platforms embedding realistic physics. Building upon this analysis, we first propose an embodied cognitive architecture integrating heterogenous sub-fields of Artificial Intelligence into a unified framework. We demonstrate the utility of our approach by showing how major contributions of the field can be expressed within the proposed framework. We then claim that benchmarking environments need to reproduce ecologically-valid conditions for bootstrapping the acquisition of increasingly complex cognitive skills through the concept of a cognitive arms race between embodied agents.

Keywords: Cognitive Architectures, Embodied Artificial Intelligence, Evolutionary Arms Race, Unified Theories of Cognition

Garcia-Castellote, D., Torres, A., Estrada, L., Sarlabous, L., Jane, R., (2017). Evaluation of indirect measures of neural inspiratory time from invasive and noninvasive recordings of respiratory activity Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 341-344

Measuring diaphragmatic electromyography (EMGdi) provides an indirect quantification of neural respiratory drive and allows the delimitation of diaphragm neural activation and deactivation during inspiration. EMGdi recordings have been incorporated in novel modes of assisted mechanical ventilation, such as neurally adjusted ventilatory assist (NAVA), to trigger and cycle-off the ventilator. The EMGdi signal improves the assistance delivered by more conventional ventilatory modes, in which the ventilator is synchronized with the patient employing a pneumatic triggering. In this work, we evaluate the time delay between the onset and offset of inspiratory activity estimated from EMGdi and three respiratory mechanical signals: the respiratory flow (FL), the transdiaphragmatic pressure (Pdi) and the diaphragm length (Ldi) signals. To this purpose, these signals were acquired in three mongrel dogs surgically instrumented under general anesthesia. Onsets and offsets were estimated manually and by automatic algorithms on these signals. The highest delays were obtained between EMGdi and FL (100 ms) while the lowest delays were obtained between EMGdi and Pdi (8 ms). Moreover, differences between manual and automatic estimations showed a mean absolute error lower than 45 ms. In conclusion, our study points out that both EMGdi and Pdi signals detect the onset and offset of inspiratory activity earlier than the FL signal, and would therefore be better for the improvement of patient-ventilator synchrony.

Keywords: Estimation, Ventilation, Anesthesia, Dogs, Manuals, Power harmonic filters

Solorzano, A., Fonollosa, J., Fernandez, L., Eichmann, J., Marco, S., (2017). Fire detection using a gas sensor array with sensor fusion algorithms IEEE Conference Publications ISOCS/IEEE International Symposium on Olfaction and Electronic Nose (ISOEN) , IEEE (Montreal, Canada) , 1-3

Conventional fire alarms are based on smoke detection. Nevertheless, in some fire scenarios volatiles are released before smoke. Fire detectors based only on chemical sensors have already been proposed as they may provide faster response, but they are still prone to false alarms in the presence of nuisances. These systems rely heavily on pattern recognition techniques to discriminate fires from nuisances. In this context, it is important to test the systems according to international standards for fires and testing the system against a diversity of nuisances. In this work, we investigate the behavior of a gas sensor array coupled to sensor fusion algorithms for fire detection when exposed to standardized fires and several nuisances. Results confirmed the ability to detect fires (97% Sensitivity), although the system still produces a significant rate of false alarms (35%) for nuisances not presented in the training set.

Keywords: Fire alarm, Gas sensor array, Machine Olfaction, Multisensor system, Sensor fusion

Fernandez, L., Martin-Gomez, A., Mar Contreras, M., Padilla, M., Marco, S., Arce, L., (2017). Ham quality evaluation assisted by gas chromatography ion mobility spectrometry IEEE Conference Publications ISOCS/IEEE International Symposium on Olfaction and Electronic Nose (ISOEN) , IEEE (Montreal, Canada) , 1-3

In recent years, Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) has been successfully employed in food science as a control technique for the prevention of fraud according to food and labeling regulations. In this work, we propose the use of GC-IMS technique to assess the quality of Iberian ham with regard to the Iberian Pig's diet (either nourished with feed or with acorns). For this purpose, we have acquired a dataset composed of 53 samples of Iberian ham from different food providers using a commercial GC-IMS (FlavourSpec, from G.A.S. Dortmund, Germany). Intensive signal pre-processing for GC-IMS was applied to the raw data. This dataset was employed to create four Partial Least Squares Discriminant Analysis (PLSDA) models corresponding to different train/test partitions of the dataset. Nearly perfect classification rates (above 91 %) were obtained for each partition of the dataset, denoting the high power of GC-IMS to characterize food samples.

Keywords: Classification, Food Science, GC-IMS, Ham quality, PLSDA

Climent, A. M., Hernandez-Romero, I., Guillem, M. S., Montserrat, N., Fernandez, M. E., Atienza, F., Fernandez-Aviles, F., (2017). High resolution microscopic optical mapping of anatomical and functional reentries in human cardiac cell cultures IEEE Conference Publications Computing in Cardiology Conference (CinC), 2016 , IEEE (Vancouver, Canada) 43, 233-236

Anatomical and/or functional reentries have been proposed as one of the main mechanism of perpetuation of cardiac fibrillation processes. However, technical limitations have difficult the characterization of those reentries and are hampering the development of effective anti-arrhythmic treatments. The goal of this study is to present a novel technology to map with high resolution the center of fibrillation drivers in order to characterize the mechanisms of reentry. Cell cultures of human cardiac-like cells differentiated from pluripotent stem cells were analyzed with a novel microscopic optical mapping system. The pharmacological response to verapamil administration of each type of reentry was analyzed. In all analyzed cell cultures, a reentry was identified as the mechanism of maintenance of the arrhythmia. Interestingly, the administration of verapamil produced opposite effects on activation rate depending on the mechanisms of reentry (i.e. anatomical or functional). Microscopic optical mapping of reentries allows the identification of perpetuation mechanisms which has been demonstrated to be linked with different pharmacological response.

Keywords: Stem cells, Rotors, Microscopy, Optical filters, Calcium, Optical microscopy, Biomedical optical imaging

Badiola, M., Hervera, A., López, J., Segura, Miriam, del Río, J. A., Samitier, J., (2017). In-vitro Peripheral Nervous System on a chip CASEIB Proceedings XXXV Congreso Anual de la Sociedad Española de Ingeniería Biomédica (CASEIB 2017) , Sociedad Española de Ingeniería Biomédica (Valencia, Spain) , XXXX (falta pdf)

Camara, M. A., Castillo, Y., Blanco-Almazan, D., Estrada, L., Jane, R., (2017). MHealth tools for monitoring Obstructive Sleep Apnea patients at home: Proof-of-concept Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 1555-1558

Obstructive Sleep Apnea (OSA) is a sleep disorder that affects mainly the adult and elderly population. Due to the high percentage of patients who remain undiagnosed and untreated because of limitations of current diagnosis methods, the management of OSA is an important social, scientific and economic problem that will be difficult to be assumed by health systems. On the other hand, smartphone platforms (mHealth systems) are being considered as an innovative solution, thanks to the integration of the essential sensors to obtain clinically relevant parameters in the same device or in combination with wireless wearable devices.

Keywords: Sleep apnea, Microphones, Monitoring, Sensors, Accelerometers, Biomedical monitoring, Band-pass filters

Schulz, S., Legorburu Cladera, B., Giraldo, B., Bolz, M., Bar, K. J., Voss, A., (2017). Neuronal desynchronization as marker of an impaired brain network Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 2251-2254

Synchronization is a central key feature of neural information processing and communication between different brain areas. Disturbance of oscillatory brain rhythms and decreased synchronization have been associated with different disorders including schizophrenia. The aim of this study was to investigate whether synchronization (in relaxed conditions with no stimuli) between different brain areas within the delta, theta, alpha (alpha1, alpha2), beta (beta1, beta2), and gamma bands is altered in patients with a neurological disorder in order to generate significant cortical enhancements. To achieve this, we investigated schizophrenic patients (SZO; N=17, 37.5±10.4 years, 15 males) and compared them to healthy subjects (CON; N=21, 36.7±13.4 years, 15 males) applying the phase locking value (PLV). We found significant differences between SZO and CON in different brain areas of the theta, alpha1, beta2 and gamma bands. These areas are related to the central and parietal lobes for the theta band, the parietal lobe for the alpha1, the parietal and frontal for the beta2 and the frontal-central for the gamma band. The gamma band revealed the most significant differences between CON and SZO. PLV were 61.7% higher on average in SZO in most of the clusters when compared to CON. The related brain areas are directly related to cognition skills which are proved to be impaired in SZO. The results of this study suggest that synchronization in SZO is also altered when the patients were not asked to perform a task that requires their cognitive skills (i.e., no stimuli are applied - in contrast to other findings).

Keywords: Synchronization, Electroencephalography, Electrodes, Brain, Time series analysis, Oscillators, Frequency synchronization

Trapero, J. I., Arizmendi, C. J., Gonzalez, H., Forero, C., Giraldo, B. F., (2017). Nonlinear dynamic analysis of the cardiorespiratory system in patients undergoing the weaning process Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 3493-3496

In this work, the cardiorespiratory pattern of patients undergoing extubation process is studied. First, the respiratory and cardiac signals were resampled, next the Symbolic Dynamics (SD) technique was implemented, followed of a dimensionality reduction applying Forward Selection (FS) and Moving Window with Variance Analysis (MWVA) methods. Finally, the Linear Discriminant Analysis (LDA) and Support Vector Machines (SVM) classifiers were used. The study analyzed 153 patients undergoing weaning process, classified into 3 groups: Successful Group (SG: 94 patients), Failed Group (FG: 39 patients), and patients who had been successful during the extubation and had to be reintubated before 48 hours, Reintubated Group (RG: 21 patients). According to the results, the best classification present an accuracy higher than 88.98 ± 0.013% in all proposed combinations.

Keywords: Support vector machines, Standards, Time series analysis, Resonant frequency, Nonlinear dynamical systems, Ventilation

Sola-Soler, J., Giraldo, B. F., Fiz, J. A., Jane, R., (2017). Relationship between heart rate excursion and apnea duration in patients with Obstructive Sleep Apnea Engineering in Medicine and Biology Society (EMBC) 39th Annual International Conference of the IEEE , IEEE (Seogwipo, South Korea) , 1539-1542

Obstructive Sleep Apnea (OSA) is a sleep disorder with a high prevalence in the general population. It is a risk factor for many cardiovascular diseases, and an independent risk factor for cerebrovascular diseases such as stroke. After an apnea episode, both arterial blood pressure and cerebral blood flow velocity change in function of the apnea duration (AD). We hypothesized that the relative excursion in heart rate (AHR), defined as the percentage difference between the maximum and the minimum heart rate values associated to an obstructive apnea event, is also related to AD. In this work we studied the relationship between apnea-related AHR and AD in a population of eight patients with severe OSA. AHR and AD showed a moderate but statistically significant correlation (p <; 0.0001) in a total of 1454 obstructive apneas analyzed. The average heart rate excursion for apneas with AD ≥ 30s (ΔHR = 31.29 ± 6.64%) was significantly greater (p = 0.0002) than for apneas with AD ∈ [10,20)s (ΔHR = 18.14±3.08%). We also observed that patients with similar Apnea-Hypopnea Index (AHI) may exhibit remarkably different distributions of AHR and AD, and that patients with a high AHI need not have a higher average AHR than others with a lower severity index. We conclude that the overall apnea-induced heart rate excursion is partially explained by the duration of apnoeic episodes, and it may be a simple measure of the cardiovascular stress associated with OSA that is not directly reflected in the AHI.

Keywords: Heart rate, Sleep apnea, Correlation, Indexes, Sociology, Blood vessels

Quadri, M., Matera, C., Silnovi, Pismataro, M. C., Horenstein, N. A., Stokes, C., Papke, R. L., Dallanoce, C., (2017). Identification of α7 nicotinic acetylcholine receptor silent agonists based on the spirocyclic quinuclidine-Δ2-isoxazoline scaffold: Synthesis and electrophysiological evaluation ChemMedChem XXIV National Meeting in Medicinal Chemistry (NMMC 2016) , Wiley Online Library (Perugia, Spain) 12, (16), 1335-1348

Compound 11 (3-(benzyloxy)-1′-methyl-1′-azonia-4H-1′-azaspiro[isoxazole-5,3′-bicyclo[2.2.2]octane] iodide) was selected from a previous set of nicotinic ligands as a suitable model compound for the design of new silent agonists of α7 nicotinic acetylcholine receptors (nAChRs). Silent agonists evoke little or no channel activation but can induce the α7 desensitized Ds state, which is sensitive to a type II positive allosteric modulator, such as PNU-120596. Introduction of meta substituents into the benzyloxy moiety of 11 led to two sets of tertiary amines and quaternary ammonium salts based on the spirocyclic quinuclidinyl-Δ2-isoxazoline scaffold. Electrophysiological assays performed on Xenopus laevis oocytes expressing human α7 nAChRs highlighted four compounds that are endowed with a significant silent-agonism profile. Structure–activity relationships of this group of analogues provided evidence of the crucial role of the positive charge at the quaternary quinuclidine nitrogen atom. Moreover, the present study indicates that meta substituents, in particular halogens, on the benzyloxy substructure direct specific interactions that stabilize a desensitized conformational state of the receptor and induce silent activity

Keywords: Agonists, Cycloaddition, Nitrogen heterocycles, Receptors, Spiro compounds

Morer, A., Basas, J., Colominas, S., Ratia, C., Gomis, X., Abellà, J., Torrents, E., Larrosa, N., Almirante, B., Gavaldà, J., (2017). Actividad de la electrólisis con corriente eléctrica directa continua de bajo amperaje en infecciones por biopelículas y por microorganismos XDR Gram-negativos Enfermedades Infecciosas y Microbiología Clínica XXI Congreso de la Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC) , Elsevier (Málaga, Spain) 35, (Espec. Cong. 1), 41

Necesitamos nuevas estrategias para combatir la resistencia a los antibióticos. Las infecciones crónicas asociadas con dispositivos médicos se asocian con una morbimortalidad significativa. Nuestro objetivo fue desarrollar una nueva estrategia frente a infecciones productoras de biopelículas y aquellas producidas por microorganismos gramnegativos XDR mediante el uso de una corriente eléctrica directa continua de bajo amperaje (CD). Esta estrategia se evaluó en presencia de suero fisiológico como electrolito para aproximarse a la situación in vivo.

Basas, J., Morer, A., Ratia, C., Rojo, E., Larrosa, N., Oliver, A., Cantón, R., Ferrer, R., Gomis, X., Grau, S., Vima, J., Torrents, E., Almirante, B., Gavaldà, J., (2017). Eficacia in vitro e in vivo de distintas combinaciones antibióticas para el tratamiento nebulizado de neumonía aguda frente a clones de alto riesgo de Pseudomonas aeruginosa. Enfermedades Infecciosas y Microbiología Clínica Enfermedades Infecciosas y Microbiología Clínica XXI Congreso de la Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC) , Elsevier (Málaga, Spain) 35, (Espec. Cong. 1), 126

El tratamiento de las infecciones respiratorias por cepas extremadamente resistentes (XDR) de P. aeruginosa (sólo sensibles a colistina/amikacina) es complicado, en ocasiones ineficaz y/o nefrotóxico. La nebulización con antibióticos parece una estrategia terapéutica adecuada frente a ese tipo de infecciones.

Castaño, O., Pérez, S., Mateos-Timoneda, M. A., Engel, E., (2017). Cell Interactions with Calcium Phosphate Glasses RSC Smart Materials (ed. Boccaccini, Aldo R., Brauer, Delia S., Hupa, L.), Royal Society of Chemistry (London, UK) Bioactive Glasses: Fundamentals, Technology and Applications, 303-315

This chapter will review the interactions between calcium phosphate (CaP) glasses and different cell types. These glasses are less established in the biomaterials field than silicate-based glasses, but phosphate glasses generate interest owing to their higher solubility. CaP glasses have been less studied than silicate-based glasses, possibly due to the commercialization of Hench's Bioglass that allowed many laboratory groups to use them for different studies, including cell culture studies, without having to prepare them in-house. Studies on CaP glasses focused on compositional modification in order to elicit different properties to enhance biodegradability and bioactivity, two main properties for the application of these glasses. These properties have opened the application of these glasses and have enhanced the effect on cells allowing exploration of the bioactivity of ions released by these exceptionally interesting biomaterials.

Bosch, M., Castro, J., Sur, M., Hayashi, Y., (2017). Photomarking relocalization technique for correlated two-photon and electron microcopy imaging of single stimulated synapses Synapse Development - Methods and Protocols (Methods in Molecular Biology) (ed. Poulopoulos , A.), Humana Press (New York, USA) 1538, 185-214

Synapses learn and remember by persistent modifications of their internal structures and composition but, due to their small size, it is difficult to observe these changes at the ultrastructural level in real time. Two-photon fluorescence microscopy (2PM) allows time-course live imaging of individual synapses but lacks ultrastructural resolution. Electron microscopy (EM) allows the ultrastructural imaging of subcellular components but cannot detect fluorescence and lacks temporal resolution. Here, we describe a combination of procedures designed to achieve the correlated imaging of the same individual synapse under both 2PM and EM. This technique permits the selective stimulation and live imaging of a single dendritic spine and the subsequent localization of the same spine in EM ultrathin serial sections. Landmarks created through a photomarking method based on the 2-photon-induced precipitation of an electrodense compound are used to unequivocally localize the stimulated synapse. This technique was developed to image, for the first time, the ultrastructure of the postsynaptic density in which long-term potentiation was selectively induced just seconds or minutes before, but it can be applied for the study of any biological process that requires the precise relocalization of micron-wide structures for their correlated imaging with 2PM and EM.

Keywords: Correlated imaging, DAB, Dendritic spine, Photobranding, Photoetching, Photomarking, Postsynaptic density, Serial-section transmission electron microscopy, Synapse, Time-lapse live two-photon fluorescence microscopy

Garreta, Elena, Marco, Andrés, Eguizábal, Cristina, Tarantino, Carolina, Samitier, Mireia, Badiola, Maider, Gutiérrez, Joaquín, Samitier, Josep, Montserrat, Nuria, (2017). Pluripotent stem cells and skeletal muscle differentiation: Challenges and immediate applications The Plasticity of Skeletal Muscle: From Molecular Mechanism to Clinical Applications (ed. Sakuma, Kunihiro), Springer Singapore (Singapore, Singapore) online, 1-35

Recent advances in the generation of skeletal muscle derivatives from pluripotent stem cells (PSCs) provide innovative tools for muscle development, disease modeling, and cell replacement therapies. Here, we revise major relevant findings that have contributed to these advances in the field, by the revision of how early findings using mouse embryonic stem cells (ESCs) set the bases for the derivation of skeletal muscle cells from human pluripotent stem cells (hPSCs) and patient-derived human-induced pluripotent stem cells (hiPSCs) to the use of genome editing platforms allowing for disease modeling in the petri dish.

Keywords: Pluripotent stem cells, Differentiation, Genome editing, Disease modeling

Puigbò, Jordi-Ysard, Gonzalez-Ballester, Miguel Ángel, Verschure, Paul F. M. J., (2017). Behavior-state dependent modulation of perception based on a model of conditioning Biomimetic and Biohybrid Systems: Living Machines 2017 (Lecture Notes in Computer Science) (ed. Mangan, M., Cutkosky, M., Mura, A., Verschure, P., Prescott, T., Lepora, N.), Springer, Cham 10384, 387-393

The embodied mammalian brain evolved to adapt to an only partially known and knowable world. The adaptive labeling of the world is critically dependent on the neocortex which in turn is modulated by a range of subcortical systems such as the thalamus, ventral striatum and the amygdala. A particular case in point is the learning paradigm of classical conditioning where acquired representations of states of the world such as sounds and visual features are associated with predefined discrete behavioral responses such as eye blinks and freezing. Learning progresses in a very specific order, where the animal first identifies the features of the task that are predictive of a motivational state and then forms the association of the current sensory state with a particular action and shapes this action to the specific contingency. This adaptive feature selection has both attentional and memory components, i.e. a behaviorally relevant state must be detected while its representation must be stabilized to allow its interfacing to output systems. Here we present a computational model of the neocortical systems that underlie this feature detection process and its state dependent modulation mediated by the amygdala and its downstream target, the nucleus basalis of Meynert. Specifically, we analyze how amygdala driven cholinergic modulation these mechanisms through computational modeling and present a framework for rapid learning of behaviorally relevant perceptual representations.

Planell, J. A., Navarro, M., Engel, E., (2017). Developing targeted biocomposites in tissue engineering and regenerative medicine Biomedical Composites (ed. Ambrosio, L.), Woodhead Publishing (Duxfor, UK) Biomaterials, 569-587

Regenerative medicine is a relatively new field with new requirements for smart materials, where composites will have a strong role to play. The new paradigm of regenerative medicine and tissue engineering requires biomaterials with high specificity, where physical and chemical properties are duly tailored and combined with appropriate mechanical and degradation features in order to trigger specific cell events and functions involved in the regenerative process. In this chapter, the chemical, physical, and biological elements that have to be targeted by biocomposites in regenerative medicine are described.

Keywords: Biocomposite, Regenerative medicine, Tissue engineering, Scaffolds, Cell/material interactions

Xia, Yun, Montserrat, Nuria, Campistol, Josep M., Izpisua Belmonte, Juan Carlos, Remuzzi, Giuseppe, Williams, David F., (2017). Lineage reprogramming toward kidney regeneration Kidney Transplantation, Bioengineering and Regeneration (ed. Orlando, G., Remuzzi, Giuseppe, Williams, David F.), Academic Press (London, UK) , 1167-1175

We have known for decades that it is possible to switch the phenotype of one somatic cell type into another. Such epigenetic rewiring processes can be artificially managed and even reversed by using a defined set of transcription factors. Lineage reprogramming is very often defined as a process of converting one cell type into another without going through a pluripotent state, providing great promise for regenerative medicine. However, the identification of key transcription factors for lineage reprogramming is limited, due to the exhaustive and expensive experimental processes. Accumulating knowledge of genetic and epigenetic regulatory networks that are critical for defining a specific lineage provides unprecedented opportunities to model and predict pioneering factors that may drive directional lineage reprogramming to obtain the desired cell type.

Keywords: Reprogramming, Pluripotency, Differentiation, Lineage specification, Epigenetic regulatory network, Regeneration

Klein, S., Schierwagen, R., Uschner, F. E., Trebicka, J., (2017). Mouse and rat models of induction of hepatic fibrosis and assessment of portal hypertension Fibrosis (Methods in Molecular Biology) (ed. Rittié, L.), Humana Press (New York, USA) 1627, 91-116

Portal hypertension either develops due to progressive liver fibrosis or is the consequence of vascular liver diseases such as portal vein thrombosis or non-cirrhotic portal hypertension. This chapter focuses on different rodent models of liver fibrosis with portal hypertension and also in few non-cirrhotic portal hypertension models. Importantly, after the development of portal hypertension, the proper assessment of drug effects in the portal and systemic circulation should be discussed. The last part of the chapter is dedicated in these techniques to assess the in vivo hemodynamics and the ex vivo techniques of the isolated liver perfusion and vascular contractility.

Keywords: Aortic ring contraction, Bile duct ligation, Carbon tetrachloride, Colored microsphere technique, High-fat diet, Isolated in situ liver perfusion, Methionine-choline-deficient diet, Partial portal vein ligation, Portal hypertension

Obregón, R., Ramón-Azcón, J., Ahadian, S., (2017). Nanofiber composites in blood vessel tissue engineering Nanofiber Composites for Biomedical Applications (ed. Ramalingam, M., Ramakrishna, S.), Elsevier (Duxford, UK) Woodhead Publishing Series in Biomaterials, 483-506

Tissue engineering (TE) aims to restore function or replace damaged tissue through biological principles and engineering. Nanofibers are attractive substrates for tissue regeneration applications because they structurally mimic the native extracellular matrix. Composite nanofibers, which are hybrid nanofibers blended from natural and synthetic polymers, represent a major advancement in TE and regenerative medicine, since they take advantage of the physical properties of the synthetic polymer and the bioactivity of the natural polymer while minimizing the disadvantages of both. Although various nanofibrous matrices have been applied to almost all the areas of TE, in this chapter we will focus on nanofiber composites scaffolds for vascular TE.

Keywords: Blood vessels, Nanofiber composite, Tissue engineering, Vascularized tissue

Espinosa, M., Juarez, A, Venkova, Tatiana, (2017). Modulating prokaryotic lifestyle by DNA-binding proteins Frontiers in Molecular Biosciences , 311

One of the most active areas of research in molecular microbiology has been the study of how bacteria modulate their genetic activity and its consequences. The prokaryotic world has received much interest not only because the resulting phenomena are important to cells, but also because many of the effects often can be readily measured. Contributing to the interest of the present topic is the fact that modulation of gene activity involves the sensing of intra- and inter-cellular conditions, DNA binding and DNA dynamics, and interaction with the replication/transcription machinery of the cell. All of these processes are fundamental to the operation of a genetic entity and condition their lifestyle. Further, the discoveries achieved in the bacterial world have been of ample use in eukaryotes. In addition to the fundamental interest of understanding modulation of prokaryotic lifestyle by DNA-binding proteins, there is an added interest from the healthcare point of view. As it is well known the antibiotic-resistance strains of pathogenic bacteria are a major world problem, so that there is an urgent need of innovative technologies to tackle it. Most of the acquired resistances are spread by processes of horizontal gene transfer mediated by mobile elements in which DNA replication and gene expression are of basic interest. There is an imperative of finding new alternatives to the ‘classical’ way of treatment of bacterial infections and these new alternatives include the discovery of new drugs and of new bacterial targets. Nevertheless, these new alternatives will find a dead-end if we are unable to obtain a better understanding of the basic processes modulating bacterial gene expression. Our goal to achieve with this Topic of Frontiers is to accelerate our understanding of protein-DNA interactions. First, the topic will bring together several very active researchers in the study of gene replication, gene regulation, the strategies applied by the different proteins that participate in these processes, and their consequences. We will also acquire an in-depth knowledge of some of the mechanisms of gene regulation, gene transfer and gene replication. Further, the readers of the papers will realize the importance of the topic and will learn the most recent thinking, results, and approaches in the are.