Publications

Exposure of experimental rodents to controlled cycles of light, food, and temperature is important when investigating alterations in circadian cycles that profoundly influence health and disease. However, applying such stimuli simultaneously is difficult in practice. We aimed to design, build, test, and open-source describe a simple device that subjects a conventional mouse cage to independent cycles of physiologically relevant environmental variables. The device is based on a box enclosing the rodent cage to modify the light, feeding, and temperature environments. The device provides temperature-controlled air conditioning (heating or cooling) by a Peltier module and includes programmable feeding and illumination. All functions are set by a user-friendly front panel for independent cycle programming. Bench testing with a model simulating the CO2 production of mice in the cage showed: a) suitable air renewal (by measuring actual ambient CO2), b) controlled realistic illumination at the mouse enclosure (measured by a photometer), c) stable temperature control, and d) correct cycling of light, feeding, and temperature. The cost of all the supplies (retail purchased by e-commerce) was <300 US$. Detailed technical information is open-source provided, allowing for any user to reliably reproduce or modify the device. This approach can considerably facilitate circadian research since using one of the described low-cost devices for any mouse group with a given light-food-temperature paradigm allows for all the experiments to be performed simultaneously, thereby requiring no changes in the light/temperature of a general-use laboratory. 1 Introduction

JTD Keywords: Animal experiment, Animal model, Animal research, Article, Circadian alteration, Circadian rhythm, Commercial phenomena, Controlled study, Cycling, Energy consumption, Energy-expenditure, Experimental model, Feeding, Food, Food availability, Illumination, Intermittent fasting, Light, Light cycle, Light dark cycle, Mouse, Nonhuman, Open source technology, Open-source hardware, Performance, Photography, Research, Rhythms, Rodent, Temperature, Temperature cycle

Human pluripotent stem cell -derived kidney organoids offer unprecedented opportunities for studying polycystic kidney disease (PKD), which still has no effective cure. Here, we developed both in vitro and in vivo organoid models of PKD that manifested tubular injury and aberrant upregulation of renin-angiotensin aldosterone system. Single -cell analysis revealed that a myriad of metabolic changes occurred during cystogenesis, including defective autophagy. Experimental activation of autophagy via ATG5 overexpression or primary cilia ablation significantly inhibited cystogenesis in PKD kidney organoids. Employing the organoid xenograft model of PKD, which spontaneously developed tubular cysts, we demonstrate that minoxidil, a potent autophagy activator and an FDA -approved drug, effectively attenuated cyst formation in vivo. This in vivo organoid model of PKD will enhance our capability to discover novel disease mechanisms and validate candidate drugs for clinical translation.

JTD Keywords: Adenylate kinase, Adult, Animal cell, Animal experiment, Animal model, Animal tissue, Article, Autophagosome, Autophagy, Autophagy (cellular), Autosomal-dominant, Calcium homeostasis, Cilia, Cilium, Cohort analysis, Controlled study, Cyclic amp, Disease, Dominant polycystic kidney, Enzyme linked immunosorbent assay, Epithelium, Exon, Expression, Female, Food and drug administration, Framework, Generation, Growth, Hepatitis a virus cellular receptor 1, Human, Human cell, Humans, Immunohistochemistry, In vitro study, In vivo study, Kidney, Kidney organoid, Kidney polycystic disease, Male, Minoxidil, Mouse, Mutations, Nonhuman, Organoid, Organoids, Platelet derived growth factor beta receptor, Pluripotent stem-cells, Polycystic kidney diseases, Protein kinase lkb1, Renin, Sequestosome 1, Single cell analysis, Single cell rna seq, Small nuclear rna, Tunel assay, Upregulation, Western blotting, Whole exome sequencing

Lysosomes play a central role in cellular homeostasis and alterations in this compartment associate with many diseases. The most studied example is that of lysosomal storage disorders (LSDs), a group of 60 + maladies due to genetic mutations affecting lysosomal components, mostly enzymes. This leads to aberrant intracellular storage of macromolecules, altering normal cell function and causing multiorgan syndromes, often fatal within the first years of life. Several treatment modalities are available for a dozen LSDs, mostly consisting of enzyme replacement therapy (ERT) strategies. Yet, poor biodistribution to main targets such as the central nervous system, musculoskeletal tissue, and others, as well as generation of blocking antibodies and adverse effects hinder effective LSD treatment. Drug delivery systems are being studied to surmount these obstacles, including polymeric constructs and nanoparticles that consti-tute the focus of this article. We provide an overview of the formulations being tested, the diseases they aim to treat, and the results observed from respective in vitro and in vivo studies. We also discuss the advantages and disadvantages of these strategies, the remaining gaps of knowledge regarding their per-formance, and important items to consider for their clinical translation. Overall, polymeric nanocon-structs hold considerable promise to advance treatment for LSDs.(c) 2023 Elsevier B.V. All rights reserved.

JTD Keywords: cellular and animal models, enzyme replacement therapy, lysosomal storage disorders, nanoemulsions, nanoparticles, Beta-glucuronidase deficiency, Blood-brain-barrier, Cellular and animal models, Central-nervous-system, Enzyme replacement therapy, Feline gm1 gangliosidosis, Human acid sphingomyelinase, Human alpha-galactosidase, Lysosomal storage disorders, Mucopolysaccharidosis type-ii, Nanoemulsions, Nanoparticles, Neuronal ceroid-lipofuscinosis, Niemann-pick-disease, Pluripotent stem-cells, Polymer-based drug delivery systems

Around 30-40% of patients with colorectal cancer (CRC) undergoing curative resection of the primary tumour will develop metastases in the subsequent years1. Therapies to prevent disease relapse remain an unmet medical need. Here we uncover the identity and features of the residual tumour cells responsible for CRC relapse. An analysis of single-cell transcriptomes of samples from patients with CRC revealed that the majority of genes associated with a poor prognosis are expressed by a unique tumour cell population that we named high-relapse cells (HRCs). We established a human-like mouse model of microsatellite-stable CRC that undergoes metastatic relapse after surgical resection of the primary tumour. Residual HRCs occult in mouse livers after primary CRC surgery gave rise to multiple cell types over time, including LGR5+ stem-like tumour cells2-4, and caused overt metastatic disease. Using Emp1 (encoding epithelial membrane protein 1) as a marker gene for HRCs, we tracked and selectively eliminated this cell population. Genetic ablation of EMP1high cells prevented metastatic recurrence and mice remained disease-free after surgery. We also found that HRC-rich micrometastases were infiltrated with T cells, yet became progressively immune-excluded during outgrowth. Treatment with neoadjuvant immunotherapy eliminated residual metastatic cells and prevented mice from relapsing after surgery. Together, our findings reveal the cell-state dynamics of residual disease in CRC and anticipate that therapies targeting HRCs may help to avoid metastatic relapse.© 2022. The Author(s), under exclusive licence to Springer Nature Limited.

JTD Keywords: colonization, defines, human colon, mutations, plasticity, retrieval, stem-cells, subtypes, underlie, Animal, Animal cell, Animal experiment, Animal model, Animal tissue, Animals, Article, Cancer, Cancer growth, Cancer immunotherapy, Cancer inhibition, Cancer recurrence, Cancer staging, Cell, Cell adhesion, Cell migration, Cell population, Cell surface receptor, Cohort analysis, Colorectal cancer, Colorectal neoplasms, Colorectal tumor, Comprehensive molecular characterization, Controlled study, Crispr-cas9 system, Cytoskeleton, Disease exacerbation, Disease progression, Dynamics, Emp1 gene, Epithelial membrane protein-1, Extracellular matrix, Flow cytometry, Fluorescence intensity, Gene expression, Genetics, Human, Human cell, Humans, Immune response, Immunofluorescence, In situ hybridization, Marker gene, Metastasis potential, Mice, Minimal residual disease, Mouse, Neoplasm proteins, Neoplasm recurrence, local, Neoplasm, residual, Nonhuman, Pathology, Phenotype, Prevention and control, Protein, Receptors, cell surface, Single cell rna seq, Tumor, Tumor protein, Tumor recurrence

The mechanical signals sensed by the alveolar cells through the changes in the local matrix stiffness of the extracellular matrix (ECM) are determinant for regulating cellular functions. Therefore, the study of the mechanical response of lung tissue becomes a fundamental aspect in order to further understand the mechanosensing signals perceived by the cells in the alveoli. This study is focused on the development of a finite element (FE) model of a decellularized rat lung tissue strip, which reproduces accurately the mechanical behaviour observed in the experiments by means of a tensile test. For simulating the complex structure of the lung parenchyma, which consists of a heterogeneous and non-uniform network of thin-walled alveoli, a 3D model based on a Voronoi tessellation is developed. This Voronoi-based model is considered very suitable for recreating the geometry of cellular materials with randomly distributed polygons like in the lung tissue. The material model used in the mechanical simulations of the lung tissue was characterized experimentally by means of AFM tests in order to evaluate the lung tissue stiffness on the micro scale. Thus, in this study, the micro (AFM test) and the macro scale (tensile test) mechanical behaviour are linked through the mechanical simulation with the 3D FE model based on Voronoi tessellation. Finally, a micro-mechanical FE-based model is generated from the Voronoi diagram for studying the stiffness sensed by the alveolar cells in function of two independent factors: the stretch level of the lung tissue and the geometrical position of the cells on the extracellular matrix (ECM), distinguishing between pneumocyte type I and type II. We conclude that the position of the cells within the alveolus has a great influence on the local stiffness perceived by the cells. Alveolar cells located at the corners of the alveolus, mainly type II pneumocytes, perceive a much higher stiffness than those located in the flat areas of the alveoli, which correspond to type I pneumocytes. However, the high stiffness, due to the macroscopic lung tissue stretch, affects both cells in a very similar form, thus no significant differences between them have been observed. © 2021 The Authors

JTD Keywords: rat, scaffolds, stiffness, Afm, Animal cell, Animal experiment, Animal model, Animal tissue, Article, Biological organs, Cell function, Cells, Computational geometry, Cytology, Extracellular matrices, Extracellular matrix, Extracellular-matrix, Geometry, High stiffness, Human, Lung alveolus cell type 1, Lung alveolus cell type 2, Lung parenchyma, Lung tissue, Male, Mechanical behavior, Mechanical modeling, Mechanical simulations, Mechanosensing, Model-based opc, Nonhuman, Physical model, Rat, Rigidity, Stiffness, Stiffness matrix, Tensile testing, Thin walled structures, Three dimensional finite element analysis, Tissue, Type ii, Voronoi tessellations

Despite tremendous progress in the understanding of COVID-19, mechanistic insight into immunological, disease-driving factors remains limited. We generated maVie16, a mouse-adapted SARS-CoV-2, by serial passaging of a human isolate. In silico modeling revealed how only three Spike mutations of maVie16 enhanced interaction with murine ACE2. maVie16 induced profound pathology in BALB/c and C57BL/6 mice, and the resulting mouse COVID-19 (mCOVID-19) replicated critical aspects of human disease, including early lymphopenia, pulmonary immune cell infiltration, pneumonia, and specific adaptive immunity. Inhibition of the proinflammatory cyto-kines IFN? and TNF substantially reduced immunopathology. Importantly, genetic ACE2-deficiency completely prevented mCOVID-19 development. Finally, inhalation therapy with recombinant ACE2 fully protected mice from mCOVID-19, revealing a novel and efficient treatment. Thus, we here present maVie16 as a new tool to model COVID-19 for the discovery of new therapies and show that disease severity is determined by cytokine-driven immunopathology and critically dependent on ACE2 in vivo. © Gawish et al.

JTD Keywords: covid-19 mouse model, covid-19 therapy, cytokine storm, immunology, inflammation, mavie16, mouse, mouse-adapted sars-cov-2, program, recombinant soluble ace2, tmprss2, Adaptive immunity, Angiotensin converting enzyme 2, Angiotensin-converting enzyme 2, Animal, Animal cell, Animal experiment, Animal model, Animal tissue, Animals, Apoptosis, Article, Bagg albino mouse, Breathing rate, Bronchoalveolar lavage fluid, C57bl mouse, Cell composition, Cell infiltration, Controlled study, Coronavirus disease 2019, Coronavirus spike glycoprotein, Covid-19, Cytokeratin 18, Cytokine production, Dipeptidyl carboxypeptidase, Disease model, Disease models, animal, Disease severity, Drosophila-melanogaster, Enzyme linked immunosorbent assay, Expression vector, Flow cytometry, Gamma interferon, Gene editing, Gene expression, Gene mutation, Genetic engineering, Genetics, Glycosylation, High mobility group b1 protein, Histology, Histopathology, Immune response, Immunocompetent cell, Immunology, Immunopathology, Interferon-gamma, Interleukin 2, Metabolism, Mice, inbred balb c, Mice, inbred c57bl, Mouse-adapted sars-cov-2, Myeloperoxidase, Neuropilin 1, Nonhuman, Nucleocapsid protein, Pathogenicity, Peptidyl-dipeptidase a, Pyroptosis, Recombinant soluble ace2, Renin angiotensin aldosterone system, Rna extraction, Rna isolation, Sars-cov-2, Severe acute respiratory syndrome coronavirus 2, Spike glycoprotein, coronavirus, T lymphocyte activation, Trabecular meshwork, Tumor necrosis factor, Virology, Virus load, Virus replication, Virus transmission, Virus virulence

Under intrauterine growth restriction (IUGR), abnormal attainment of the nutrients and oxygen by the fetus restricts the normal evolution of the prenatal causing in many cases high morbidity being one of the top-ten causes of neonatal death. The current gold standards in hospitals to detect this relevant problem is the clinical observation by echography, cardiotocography and Doppler. These qualitative techniques are not conclusive and requires risky invasive fetal scalp blood testing and/or amniocentesis. We developed micro-implantable multiparametric electrochemical sensors for measuring ischemia in real time in fetal tissue and vascular. This implantable technology is designed to continuous monitoring for an early detection of ischemia to avoid potential fetal injury. Two miniaturized electrochemical sensors were developed based on oxygen and pH detection. The sensors were optimized in vitro under controlled concentration, to assess the selectivity and sensitivity required. The sensors were then validated in vivo in the ewe fetus model, by means of their insertion in the muscle leg and inside the iliac artery of the fetus. Ischemia was achieved by gradually obstructing the umbilical cord to regulate the amount of blood reaching the fetus. An important challenge in fetal monitoring is the detection of low levels of oxygen and pH changes under ischemic conditions, requiring high sensitivity sensors. Significant differences were observed in both; pH and pO(2) sensors under changes from normoxia to hypoxia states in the fetus tissue and vascular with both sensors. Herein, we demonstrate the feasibility of the developed sensors for future fetal monitoring in medical applications.

JTD Keywords: electrochemical biosensor, implantable sensor, in vivo validation, ischemia detection, tissue and vascular monitoring, Animal experiment, Animal model, Animal tissue, Article, Blood-gases, Brain, Classification, Controlled study, Diagnosis, Doppler, Early diagnosis, Electrochemical analysis, Electrochemical biosensor, Ewe, Feasibility study, Female, Fetus, Fetus disease, Fetus monitoring, Gestational age, Hypoxemia, Iliac artery, Implantable sensor, In vivo validation, Intrauterine growth restriction, Intrauterine growth retardation, Ischemia detection, Leg muscle, Management, Nonhuman, Oxygen consumption, Ph, Ph and oxygen detection, Ph measurement, Process optimization, Sheep, Tissue and vascular monitoring, Umbilical-cord occlusion

Goel and colleagues show that CDK4/6 inhibition induces global chromatin changes mediated by AP-1 factors, which mediate key biological and clinical effects in breast cancer. Pharmacologic inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6) were designed to induce cancer cell cycle arrest. Recent studies have suggested that these agents also exert other effects, influencing cancer cell immunogenicity, apoptotic responses and differentiation. Using cell-based and mouse models of breast cancer together with clinical specimens, we show that CDK4/6 inhibitors induce remodeling of cancer cell chromatin characterized by widespread enhancer activation, and that this explains many of these effects. The newly activated enhancers include classical super-enhancers that drive luminal differentiation and apoptotic evasion, as well as a set of enhancers overlying endogenous retroviral elements that are enriched for proximity to interferon-driven genes. Mechanistically, CDK4/6 inhibition increases the level of several activator protein-1 transcription factor proteins, which are in turn implicated in the activity of many of the new enhancers. Our findings offer insights into CDK4/6 pathway biology and should inform the future development of CDK4/6 inhibitors.

JTD Keywords: Abemaciclib, Androgen receptor, Animal experiment, Animal model, Animal tissue, Apoptosis, Article, Breast cancer, C-jun, Cancer cell, Carcinoembryonic antigen related cell adhesion molecule 1, Caspase 3, Cell cycle arrest, Cells, Chromatin, Chromatin immunoprecipitation, Controlled study, Cyclin dependent kinase 4, Cyclin dependent kinase 6, Dna damage, Epidermal growth factor receptor 2, Estrogen receptor, Female, Flow cytometry, Fulvestrant, Hla drb1 antigen, Human, Human cell, Immunoblotting, Immunogenicity, Immunoprecipitation, Interferon, Luciferase assay, Mcf-7 cell line, Mda-mb-231 cell line, Microarray analysis, Morphogenesis, Mouse, Nonhuman, Palbociclib, Protein, Protein expression, Rb, Resistance, Rna polymerase ii, Rna sequence, Selective-inhibition, Senescence, Short tandem repeat, Signal transduction, Tamoxifen, Transcription elongation, Transcription factor, Transcription factor ap 1, Transcriptome, Tumor biopsy, Tumor differentiation, Tumor spheroid, Tumor xenograft, Vinculin, Whole exome sequencing

Objective: Intermittent hypoxia (IH)—a hallmark of obstructive sleep apnea (OSA)—enhances lung cancer progression in mice via altered host immune responses that are also age and sex-dependent. However, the interactions of menopause with IH on tumor malignant properties remain unexplored. Here, we aimed to investigate lung cancer outcomes in the context of ovariectomy (OVX)-induced menopause in a murine model of OSA. Methods: Thirty-four female mice (C57BL/6, 12-week-old) were subjected to bilateral OVX or to Sham intervention. Six months after surgery, mice were pre-exposed to either IH or room air (RA) for 2 weeks. Then, 105 lung carcinoma (LLC1) cells were injected subcutaneously in the left flank, with IH or RA exposures continued for 4 weeks. Tumor weight, tumor invasion, and spontaneous lung metastases were assessed. Tumor-associated macrophages (TAMs) were isolated and subjected to flow cytometry polarity evaluation along with assessment of TAMs modulation of LLC1 proliferation in vitro. To determine the effect of IH and OVX on each experimental variable, a two-way analysis of variance was performed. Results: IH and OVX promoted a similar increase in tumor growth (2-fold; P = 0.05 and 1.74-fold; P < 0.05, respectively), and OVX-IH further increased it. Regarding lung metastasis, the concurrence of OVX in mice exposed to IH enhanced the number of metastases (23.7 ± 8.0) in comparison to those without OVX (7.9 ± 2.8; P < 0.05). The pro-tumoral phenotype of TAMS, assessed as M2/M1 ratio, was increased in OVX (0.06 ± 0.01; P < 0.01) and IH (0.06 ± 0.01; P < 0.01) compared with sham/RA conditions (0.14 ± 0.03). The co-culture of TAMS with naive LLC1 cells enhanced their proliferation only under IH. Conclusion: In female mice, both the IH that is characteristically present in OSA and OVX as a menopause model emerge as independent contributors that promote lung cancer aggressiveness and seemingly operate through alterations in the host immune response.

JTD Keywords: Animal models, Cancer progression, Intermittent hypoxia, Menopause, Obstructive sleep apnea, Ovariectomy

Adult zebrafish, in contrast to mammals, are able to regenerate their hearts in response to injury or experimental amputation. Our understanding of the cellular and molecular bases that underlie this process, although fragmentary, has increased significantly over the last years. However, the role of the extracellular matrix (ECM) during zebrafish heart regeneration has been comparatively rarely explored. Here, we set out to characterize the ECM protein composition in adult zebrafish hearts, and whether it changed during the regenerative response. For this purpose, we first established a decellularization protocol of adult zebrafish ventricles that significantly enriched the yield of ECM proteins. We then performed proteomic analyses of decellularized control hearts and at different times of regeneration. Our results show a dynamic change in ECM protein composition, most evident at the earliest (7 days post-amputation) time-point analyzed. Regeneration associated with sharp increases in specific ECM proteins, and with an overall decrease in collagens and cytoskeletal proteins. We finally tested by atomic force microscopy that the changes in ECM composition translated to decreased ECM stiffness. Our cumulative results identify changes in the protein composition and mechanical properties of the zebrafish heart ECM during regeneration.

JTD Keywords: Animal models, Atomic force microscopy, Cardiovascular disease, Cardiovascular function or biology, Developmental biology, Extracellular matrix, Heart regeneration, Proteomic analysis

Background: Evidence from patients and animal models suggests that obstructive sleep apnea (OSA) may increase the risk of Alzheimer’s disease (AD) and that AD is associated with reduced brain tissue stiffness. Aim: To investigate whether intermittent hypoxia (IH) alters brain cortex tissue stiffness in AD mutant mice exposed to IH mimicking OSA. Methods: Six-eight month old (B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J) AD mutant mice and wild-type (WT) littermates were subjected to IH (21% O2 40 s to 5% O2 20 s; 6 h/day) or normoxia for 8 weeks. After euthanasia, the stiffness (E) of 200-μm brain cortex slices was measured by atomic force microscopy. Results: Two-way ANOVA indicated significant cortical softening and weight increase in AD mice compared to WT littermates, but no significant effects of IH on cortical stiffness and weight were detected. In addition, reduced myelin was apparent in AD (vs. WT), but no significant differences emerged in the cortex extracellular matrix components laminin and glycosaminoglycans when comparing baseline AD and WT mice. Conclusion: AD mutant mice exhibit reduced brain tissue stiffness following both normoxia and IH mimicking sleep apnea, and such differences are commensurate with increased edema and demyelination in AD.

JTD Keywords: Animal model, Atomic force microscopy, Brain mechanics, Cortex stiffness, Neurodegenerative disease

Background Bacillus Calmette-Guérin (BCG) prevents tumour recurrence and progression in non–muscle-invasive bladder cancer (BC). However, common adverse events occur, including BCG infections. Objective To find a mycobacterium with similar or superior antitumour activity to BCG but with greater safety. Design In vitro, ex vivo, and in vivo comparisons of the antitumour efficacy of nonpathogenic mycobacteria and BCG. Intervention The in vitro antitumour activity of a broad set of mycobacteria was studied in seven different BC cell lines. The most efficacious was selected and its ex vivo capacity to activate immune cells and its in vivo antitumour activity in an orthotopic murine model of BC were investigated. Outcome measurements and statistical analysis Growth inhibition of BC cells was the primary outcome measurement. Parametric and nonparametric tests were use to analyse the in vitro results, and a Kaplan-Meier test was applied to measure survival in mycobacteria-treated tumour-bearing mice. Results and limitations Mycobacterium brumae is superior to BCG in inhibiting low-grade BC cell growth, and has similar effects to BCG against high-grade cells. M. brumae triggers an indirect antitumour response by activating macrophages and the cytotoxic activity of peripheral blood cells against BC cells. Although no significant differences were observed between BCG and M. brumae treatments in mice, M. brumae treatment prolonged survival in comparison to BCG treatment in tumour-bearing mice. In contrast to BCG, M. brumae does not persist intracellularly or in tumour-bearing mice, so the risk of infection is lower. Conclusions Our preclinical data suggest that M. brumae represents a safe and efficacious candidate as a therapeutic agent for non–muscle-invasive BC. Patient summary We investigated the antitumour activity of nonpathogenic mycobacteria in in vitro and in vivo models of non–muscle-invasive bladder cancer. We found that Mycobacterium brumae effectively inhibits bladder cancer growth and helps the host immune system to eradicate cancer cells, and is a promising agent for antitumour immunotherapy.

JTD Keywords: Animal models, Bacillus Calmette-Guérin, Cytokines, Immunomodulation, Immunotherapy, Mycobacteria, Urothelial cell line

Hypoxia can be damaging either because cells are directly sensitive to low oxygen pressure in their local microenvironment and/or because they are exposed to circulating factors systemically secreted in response to hypoxia. The conventional hypoxia model, breathing hypoxic air, does not allow one to distinguish between these local and systemic effects. Here we propose and validate a model for differentially applying local and systemic hypoxic challenges in an animal. We used parabiosis, two mice sharing circulation by surgical union through the skin, and tested the hypothesis that when one of the parabionts breathes room air and the other one is subjected to hypoxic air, both mice share systemic circulation but remain normoxic and hypoxic, respectively. We tested two common hypoxic paradigms in 10 parabiotic pairs: continuous hypoxia (10% O2) mimicking chronic lung diseases, and intermittent hypoxia (40 s, 21% O2; 20 s, 5% O2) simulating sleep apnea. Arterial oxygen saturation and oxygen partial pressure at muscle tissue were measured in both parabionts. Effective cross-circulation was assessed by intraperitoneally injecting a dye in one of the parabionts and measuring blood dye concentration in both animals after 2 h. The results confirmed the hypothesis that tissues of the parabiont under room air were perfused with normally oxygenated blood and, at the same time, were exposed to all of the systemic mediators secreted by the other parabiont actually subjected to hypoxia. In conclusion, combination of parabiosis and hypoxic/normoxic air breathing is a novel approach to investigate the effects of local and systemic hypoxia in respiratory diseases.

JTD Keywords: Animal model, Local hypoxia, Parabiosis, Systemic hypoxia

Study Objectives: To test the hypotheses that brain oxygen partial pressure (PtO2) in response to obstructive apneas changes with age and that it might lead to different levels of cerebral tissue oxidative stress. Design: Prospective controlled animal study. Setting: University laboratory. Participants: Sixty-four male Wistar rats: 32 young (3 mo old) and 32 aged (18 mo). Interventions: Protocol 1: Twenty-four animals were subjected to obstructive apneas (50 apneas/h, lasting 15 sec each) or to sham procedure for 50 min. Protocol 2: Forty rats were subjected to obstructive apneas or sham procedure for 4 h. Measurements and Results: Protocol 1: Real-time PtO2 measurements were performed using a fast-response oxygen microelectrode. During successive apneas cerebral cortex PtO2 presented a different pattern in the two age groups; there was a fast increase in young rats, whereas it remained without significant changes between the beginning and the end of the protocol in the aged group. Protocol 2: Brain oxidative stress assessed by lipid peroxidation increased after apneas in young rats (1.34 ± 0.17 nmol/mg of protein) compared to old ones (0.63 ± 0.03 nmol/mg), where a higher expression of antioxidant enzymes was observed. Conclusions: The results suggest that brain oxidative stress in aged rats is lower than in young rats in response to recurrent apneas, mimicking obstructive sleep apnea. This could be due to the different PtO2 response observed between age groups and the increased antioxidant expression in aged rats.

JTD Keywords: Aging, Animal model, Obstructive apnea, Oxidative stress, Tissue oxygenation, antioxidant, glutathione disulfide, aged, animal experiment, animal model, animal tissue, apnea, arterial oxygen saturation, article, brain cortex, brain oxygen tension, brain tissue, controlled study, groups by age, hypoxia, lipid peroxidation, male, nonhuman, oxidative stress, pressure, priority journal, rat

Lung disease models are useful to study how cell engraftment, proliferation and differentiation are modulated in lung bioengineering. The aim of this work was to characterize the local stiffness of decellularized lungs in aged and fibrotic mice. Mice (2- and 24-month old; 14 of each) with lung fibrosis (N=20) and healthy controls (N=8) were euthanized after 11 days of intratracheal bleomycin (fibrosis) or saline (controls) infusion. The lungs were excised, decellularized by a conventional detergent-based (sodium-dodecyl sulfate) procedure and slices of the acellular lungs were prepared to measure the local stiffness by means of atomic force microscopy. The local stiffness of the different sites in acellular fibrotic lungs was very inhomogeneous within the lung and increased according to the degree of the structural fibrotic lesion. Local stiffness of the acellular lungs did not show statistically significant differences caused by age. The group of mice most affected by fibrosis exhibited local stiffness that were ~2-fold higher than in the control mice: from 27.2±1.64 to 64.8±7.1. kPa in the alveolar septa, from 56.6±4.6 to 99.9±11.7. kPa in the visceral pleura, from 41.1±8.0 to 105.2±13.6. kPa in the tunica adventitia, and from 79.3±7.2 to 146.6±28.8. kPa in the tunica intima. Since acellular lungs from mice with bleomycin-induced fibrosis present considerable micromechanical inhomogeneity, this model can be a useful tool to better investigate how different degrees of extracellular matrix lesion modulate cell fate in the process of organ bioengineering from decellularized lungs.

JTD Keywords: Ageing, Atomic force microscopy, Decellularization, Lung fibrosis, Tissue engineering, Atomic force microscopy, Biological organs, Peptides, Sodium dodecyl sulfate, Sodium sulfate, Tissue engineering, Ageing, Decellularization, Extracellular matrices, Healthy controls, Inhomogeneities, Lung fibrosis, Micro-mechanical, Statistically significant difference, Mammals, bleomycin, adventitia, animal experiment, animal model, article, atomic force microscopy, bleomycin-induced pulmonary fibrosis, cell fate, controlled study, extracellular matrix, female, intima, lung alveolus, lung fibrosis, lung mechanics, mechanical probe, microenvironment, mouse, nonhuman, pleura, priority journal, rigidity, tissue engineering

Background: Intermittent hypoxia and obesity which are two pathological conditions commonly found in patients with obstructive sleep apnea (OSA), potentially enhance cancer progression. Objective: To investigate whether obesity and/or intermittent hypoxia (IH) mimicking OSA affect tumor growth. Methods: A subcutaneous melanoma was induced in 40 mice [22 obese (40-45 g) and 18 lean (20-25 g)] by injecting 10(6) B16F10 cells in the flank. Nineteen mice (10 obese/9 lean) were subjected to IH (6 h/day for 17 days). A group of 21 mice (12 obese/9 lean) were kept under normoxia. At day 17, tumors were excised, weighed and processed to quantify necrosis and endothelial expression of vascular endothelial growth factor (VEGF) and CD-31. VEGF in plasma was also assessed. Results: In lean animals, IH enhanced tumor growth from 0.81 +/- 0.17 to 1.95 +/- 0.32 g. In obese animals, a similar increase in tumor growth (1.94 +/- 0.18 g) was observed under normoxia, while adding IH had no further effect (1.69 +/- 0.23 g). IH only promoted an increase in tumoral necrosis in lean animals. However, obesity under normoxic conditions increased necrosis, VEGF and CD-31 expression in tumoral tissue. Plasma VEGF strongly correlated with tumor weight (rho = 0.76, p < 0.001) in the whole sample; it increased in lean IH-treated animals from 66.40 +/- 3.47 to 108.37 +/- 9.48 pg/mL, p < 0.001), while the high baseline value in obese mice (106.90 +/- 4.32 pg/mL) was unaffected by IH. Conclusions: Obesity and IH increased tumor growth, but did not appear to exert any synergistic effects. Circulating VEGF appeared as a crucial mediator of tumor growth in both situations.

JTD Keywords: Intermittent hypoxia, Obesity, Cancer, Sleep apnea, Animal model

Study Objectives: To test the hypotheses that the dynamic changes in brain oxygen partial pressure (PtO(2)) in response to obstructive apneas or to intermittent hypoxia differ from those in other organs and that the changes in brain PtO(2) in response to obstructive apneas is a source of oxidative stress. Design: Prospective controlled animal study. Setting: University laboratory. Participants: 98 Sprague-Dawley rats. Interventions: Cerebral cortex, skeletal muscle, or visceral fat tissues were exposed in anesthetized animals subjected to either obstructive apneas or intermittent hypoxia (apneic and hypoxic events of 15 s each and 60 events/h) for 1 h. Measurements and Results: Arterial oxygen saturation (spO(2)) presented a stable pattern, with similar desaturations during both stimuli. The PtO(2) was measured by a microelectrode. During obstructive apneas, a fast increase in cerebral PtO(2) was observed (38.2 +/- 3.4 vs. 54.8 +/- 5.9 mm Hg) but not in the rest of tissues. This particular cerebral response was not found during intermittent hypoxia. The cerebral content of reduced glutathione was decreased after obstructive apneas (46.2% +/- 15.2%) compared to controls (100.0% +/- 14.7%), but not after intermittent hypoxia. This antioxidant consumption after obstructive apneas was accompanied by increased cerebral lipid peroxidation under this condition. No changes were observed for these markers in the other tissues. Conclusions: These results suggest the cerebral cortex could be protected in some way from hypoxic periods caused by obstructive apneas. The increased cerebral PtO(2) during obstructive apneas may, however, cause harmful effects (oxidative stress). The obstructive apnea model appears to be more adequate than the intermittent hypoxia model for studying brain changes associated with OSA.

JTD Keywords: Tissue oxygenation, Obstructive apnea, Intermittent hypoxia, Animal model, Oxidative stress

Background: Obstructive sleep apnea (OSA) is associated with cardiovascular disorders, but the different comorbidities in OSA patients make it difficult to know their specific effects on the development of cardiovascular injury. The aim of the present study was to investigate whether recurrent obstructive apneas could lead to myocardial injury. Methods: Thirty-six male Sprague-Dawley rats (300-350. g) were either acutely (3. h) or sustainably (5. h/day, for 10. days) subjected to obstructive apneas with a pattern of 15. s each, 60. apneas/h. Corresponding control groups were formed for the acute and sustained models. To assess the induction of systemic inflammation, IL1-β was measured in plasma. Ventricular tissue injury was evaluated by histological techniques (presence of inflammatory cell infiltration, eosin autofluorescence, and detection of apoptosis). Results: After 3. h of obstructive apneas, a significant increase in IL1-β (64.9. ±. 29.6. ng/μl) were observed with respect to the controls (7.3. ±. 1.0. ng/μl), but no myocardial injury was present. Conversely to the acute model, the systemic inflammation triggered by obstructive apneas for 10. days was reduced. However, the percentage of area with enhanced eosin autofluorescence and of apoptotic cells (1.83. ±. 0.35% and 24.4. ±. 1.5%, respectively) was increased when compared to the control group (0.72. ±. 0.20% and 5.0. ±. 2.8%, respectively). Conclusions: This study suggests that obstructive apneas are a potential source of early systemic and ventricular inflammation and myocardial cell injury after sustained apneas application, which could represent an initial phase in the progression of heart disease associated with OSA.

JTD Keywords: Animal models, Inflammation, Myocardial injury, Obstructive sleep apnea

During alternating ventilation (AV) one lung is inflating while the other is deflating. Considering the possible respiratory and hemodynamic advantages of AV, we investigated its effects during increased intra-abdominal pressure (IAP = 10 mmHg). In Sprague-Dawley rats (n = 6, 270–375 g) the main bronchi were independently cannulated, and respiratory mechanics determined while animals underwent different ventilatory patterns: synchronic ventilation without increased IAP (SV-0), elevated IAP during SV (SV-10), and AV with elevated IAP (AV-10). Thirty-three other animals (SV-0, n = 10; SV-10, n = 11 and AV-10, n = 12) were ventilated during 3 h. Mean arterial pressure (MAP), and lung histology were assessed. Increased IAP resulted in significantly higher elastances (p < 0.001), being AV-10 lower than SV-10 (p < 0.020). SV-10 showed higher central venous pressure (p < 0.003) than S-0; no change was observed in AV-10. Wet/dry lung weight ratio was lower in AV-10 than SV-10 (p = 0.009). Application of AV reduced hemodynamic and lung impairments induced by increased IAP during SV.

JTD Keywords: Alternating ventilation, Respiratory mechanics, Intra-abdominal pressure, Hemodynamic, Mechanical ventilation, Animal model

Obstructive sleep apnea (OSA) is characterized by recurrent upper airway obstructions during sleep. The most common animal model of OSA is based on subjecting rodents to intermittent hypoxic exposures and does not mimic important OSA features, such as recurrent hypercapnia and increased inspiratory efforts. To circumvent some of these issues, a novel murine model involving non-invasive application of recurrent airway obstructions was developed. An electronically controlled airbag system is placed in front of the mouse's snout, whereby inflating the airbag leads to obstructed breathing and spontaneous breathing occurs with the airbag deflated. The device was tested on 29 anesthetized mice by measuring inspiratory effort and arterial oxygen saturation (SaO(2)). Application of recurrent obstructive apneas (6s each, 120/h) for 6h resulted in SaO(2) oscillations to values reaching 84.4 +/- 2.5% nadir, with swings mimicking OSA patients. This novel system, capable of applying controlled recurrent airway obstructions in mice, is an easy-to-use tool for investigating pertinent aspects of OSA.

JTD Keywords: Animal model, Upper airway Obstruction, Mouse model, Non-invasive system, Model sleep apnea, Respiratory disease

The aim was to test the hypothesis that mesenchymal stem cells (MSC) could reduce the inflammation induced by recurrent airway occlusions in an animal model of obstructive sleep apnea (OSA). A nasal mask was applied to 30 anesthetized rats. Twenty rats were subjected to a pattern of recurrent obstructive apneas mimicking OSA (60/h, lasting 15 s each) for 5h. MSC (5x10(6) cells) were intravenously injected into 10 of these rats. Ten rats not subjected to apneas or MSC injection were used as controls. The rat blood serum concentrations of pro-inflammatory cytokine IL-1beta were measured by ELISA. IL-1beta was significantly greater in the rats subjected to recurrent apneas (66.7+/-41.2 pg/mL; m+/-SEM) than in controls (1.9+/-1.0 pg/mL; p<0.05). In the group of apneic rats subjected to MSC injection, IL-1beta was significantly reduced (6.1+/-3.8 pg/mL; p<0.05). In conclusion, MSC triggered an early anti-inflammatory response in rats subjected to recurrent obstructive apneas, suggesting that these stem cells could play a role in the physiological response to counterbalance inflammation in OSA.

JTD Keywords: Obstructive sleep apnea, Animal model, Airway obstruction, Inflammation

PURPOSE OF REVIEW: Obstructive sleep apnea (OSA) is a prevalent disorder with clinically well known mid-term and long-term consequences. It is difficult, however, to investigate the mechanisms causing morbidity in OSA from human studies, owing to confounding factors in patients. Animal research is useful to analyze the various injurious stimuli--intermittent hypoxia/hypercapnia, mechanical stress and sleep disruption--that potentially cause OSA morbidity. This review is focused on the most recent advances in our understanding of the consequences of OSA, achieved as a result of animal models. RECENT FINDINGS: Animal research has improved our knowledge of various aspects of the cardiovascular consequences of OSA: myocardial damage, left ventricular dysfunction, vasoconstriction, hypertension and atherosclerosis. The systemic and metabolic consequences of OSA--inflammation, insulin resistance, alterations in lipid metabolism and hepatic morbidity--have also been investigated with animal models. Our understanding of the mechanisms involved in the neurocognitive consequences of OSA--neuronal and brain alterations and cognitive dysfunctions--has also been improved through animal research. Moreover, animal models have recently been used to investigate the mechanisms of upper airway inflammation and dysfunction. SUMMARY: The simple experimental models used to investigate OSA morbidity are useful for investigating isolated mechanisms. However, more complex and realistic models incorporating the various injurious challenges characterizing OSA are required to more precisely translate the results of animal research to patients and to design potentially preventive and therapeutic strategies.

JTD Keywords: Animal model, Morbidity, Sleep apnea, Translational research

Study Objectives: To implement a chronic rat model of recurrent airway obstructions to study the obstructive sleep apnea (OSA) syndrome. Design: Prospective controlled animal study. Setting: University laboratory. Patients or Participants: 24 male Sprague-Dawley rats (250-300 g). Interventions: The rats were placed in a setup consisting of a body chamber and a head chamber separated by a neck collar specially designed to apply recurrent airway obstructions with OSA patterns. Rats in the Obstruction group (n=8) were subjected to 5-s obstructions at a rate of 60 per hour, 6 h/day during 4 weeks. Sham rats (n=8) were placed in the setup but no obstructions were applied. Naive rats (n=8) were subjected to no intervention. Measurements and Results: Breathing flow, pressure, CO2 air concentration, and SpO(2) showed that the model mimicked OSA respiratory events (obstructive apneas, increased respiratory efforts, and oxygen saturation dips). Animal stress, assessed by body weight and plasma corticosterone, was not significantly different across Obstruction and Sham groups. This supports the concept that this novel model does not introduce a significant burden of stress in the rat after acclimatization to the chamber. Thromboxane-B2/6-keto-Prostaglandin-F1a ratio in plasma, which is an index of vasoconstriction, was significantly increased in the rats subjected to obstructions. Conclusions: The designed animal model of chronic recurrent airway obstructions is feasible and potentially useful to study the mechanisms involved in the cardiovascular consequences of OSA.

JTD Keywords: Obstructive sleep apnea, Animal model, Airway obstruction