by Keyword: Bioreactor

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Uriarte, J. J., Nonaka, P. N., Campillo, N., Palma, R. K., Melo, E., de Oliveira, L. V. F., Navajas, D., Farré, R., (2014). Mechanical properties of acellular mouse lungs after sterilization by gamma irradiation Journal of the Mechanical Behavior of Biomedical Materials 40, 168-177

Lung bioengineering using decellularized organ scaffolds is a potential alternative for lung transplantation. Clinical application will require donor scaffold sterilization. As gamma-irradiation is a conventional method for sterilizing tissue preparations for clinical application, the aim of this study was to evaluate the effects of lung scaffold sterilization by gamma irradiation on the mechanical properties of the acellular lung when subjected to the artificial ventilation maneuvers typical within bioreactors. Twenty-six mouse lungs were decellularized by a sodium dodecyl sulfate detergent protocol. Eight lungs were used as controls and 18 of them were submitted to a 31kGy gamma irradiation sterilization process (9 kept frozen in dry ice and 9 at room temperature). Mechanical properties of acellular lungs were measured before and after irradiation. Lung resistance (RL) and elastance (EL) were computed by linear regression fitting of recorded signals during mechanical ventilation (tracheal pressure, flow and volume). Static (Est) and dynamic (Edyn) elastances were obtained by the end-inspiratory occlusion method. After irradiation lungs presented higher values of resistance and elastance than before irradiation: RL increased by 41.1% (room temperature irradiation) and 32.8% (frozen irradiation) and EL increased by 41.8% (room temperature irradiation) and 31.8% (frozen irradiation). Similar increases were induced by irradiation in Est and Edyn. Scanning electron microscopy showed slight structural changes after irradiation, particularly those kept frozen. Sterilization by gamma irradiation at a conventional dose to ensure sterilization modifies acellular lung mechanics, with potential implications for lung bioengineering.

Keywords: Gamma irradiation, Lung bioengineering, Lung decellularization, Organ scaffold, Pulmonary mechanics, Decellularization, Gamma irradiation, Mouse lung, Pulmonary mechanics, dodecyl sulfate sodium, animal tissue, Article, artificial ventilation, bioengineering, bioreactor, compliance (physical), controlled study, freezing, gamma irradiation, lung, lung mechanics, lung resistance, male, mouse, nonhuman, room temperature, scanning electron microscopy, tissue scaffold, trachea pressure

Santoro, R., Olivares, A. L., Brans, G., Wirz, D., Longinotti, C., Lacroix, D., Martin, I., Wendt, D., (2010). Bioreactor based engineering of large-scale human cartilage grafts for joint resurfacing Biomaterials 31, (34), 8946-8952

Apart from partial or total joint replacement, no surgical procedure is currently available to treat large and deep cartilage defects associated with advanced diseases such as osteoarthritis. In this work, we developed a perfusion bioreactor system to engineer human cartilage grafts in a size with clinical relevance for unicompartmental resurfacing of human knee joints (50 mm diameter x 3 mm thick). Computational fluid dynamics models were developed to optimize the flow profile when designing the perfusion chamber. Using the developed system, human chondrocytes could be seeded throughout large 50 mm diameter scaffolds with a uniform distribution. Following two weeks culture, tissues grown in the bioreactor were viable and homogeneously cartilaginous, with biomechanical properties approaching those of native cartilage. In contrast, tissues generated by conventional manual production procedures were highly inhomogeneous and contained large necrotic regions. The unprecedented engineering of human cartilage tissues in this large-scale opens the practical perspective of grafting functional biological substitutes for the clinical treatment for extensive cartilage defects, possibly in combination with surgical or pharmacological therapies to support durability of the implant. Ongoing efforts are aimed at integrating the up-scaled bioreactor based processes within a fully automated and closed manufacturing system for safe, standardized, and GMP compliant production of large-scale cartilage grafts.

Keywords: Bioreactor, Cartilage repair, Computational fluid dynamics, Scale-up, Regenerative medicine, Tissue engineering

Koch, M. A., Vrij, E. J., Engel, E., Planell, J. A., Lacroix, D., (2010). Perfusion cell seeding on large porous PLA/calcium phosphate composite scaffolds in a perfusion bioreactor system under varying perfusion parameters Journal of Biomedical Materials Research - Part A 95A, (4), 1011-1018

A promising approach to bone tissue engineering lies in the use of perfusion bioreactors where cells are seeded and cultured on scaffolds under conditions of enhanced nutrient supply and removal of metabolic products. Fluid flow alterations can stimulate cell activity, making the engineering of tissue more efficient. Most bioreactor systems are used to culture cells on thin scaffold discs. In clinical use, however, bone substitutes of large dimensions are needed. In this study, MG63 osteoblast-like cells were seeded on large porous PLA/glass scaffolds with a custom developed perfusion bioreactor system. Cells were seeded by oscillating perfusion of cell suspension through the scaffolds. Applicable perfusion parameters for successful cell seeding were determined by varying fluid flow velocity and perfusion cycle number. After perfusion, cell seeding, the cell distribution, and cell seeding efficiency were determined. A fluid flow velocity of 5 mm/s had to be exceeded to achieve a uniform cell distribution throughout the scaffold interior. Cell seeding efficiencies of up to 50% were achieved. Results suggested that perfusion cycle number influenced cell seeding efficiency rather than fluid flow velocities. The cell seeding conducted is a promising basis for further long term cell culture studies in large porous scaffolds.

Keywords: Bioreactor, Bone tissue engineering, Scaffolds, In vitro

Koch, M. A., Engel, E., Planell, J. A., Lacroix, D., (2008). Cell seeding and characterisation of PLA/glass composite scaffolds for bone tissue engineering Journal of Biomechanics 16th Congress, European Society of Biomechanics , Elsevier (Lucerne, Switzerland) 41, (Supplement 1), S162

In this study polymer-glass composite scaffolds were characterized by permeability and porosity, two important properties for the use in perfusion bioreactors. These scaffolds were seeded with osteoblast-like cells to assess the efficiency of the used bioreactor. The used PLA/glass composite scaffolds are adequate for the perfusion culture. The high porosity and pore interconnectivity allow an even cell distribution and incorporation of a high cell number. For optimisation of the perfusion bioreactor system, further research has to be dedicated to the cell seeding and culture.

Keywords: Biomedical materials, Bioreactors, Bone, Cellular biophysics, Composite materials, Orthopaedics, Permeability, Polymers, Porosity, Porous materials, Tissue engineering