TISSUE ENGINEERING OF CARTILAGE IN SPACE

Tissue engineering of cartilage, i.e., the in vitro cultivation of car tilage cells on synthetic polymer scaffolds, was studied on the Mir Sp ace Station and on Earth. Specifically, three-dimensional cell-polymer constructs consisting of bovine articular chondrocytes and polyglycol ic acid scaffolds were grown in rotating bioreactors, first for 3 mont hs on Earth and then for an additional 4 months on either Mir (10(-4) - 10(-6) g) or Earth (1 g). This mission provided a unique opportunity to study the feasibility of long-term cell culture flight experiments and to assess the effects of spaceflight on the growth and function o f a model musculoskeletal tissue. Both environments yielded cartilagin ous constructs, each weighing between 0.3 and 0.4 g and consisting of viable, differentiated cells that synthesized proteoglycan and type II collagen. Compared with the Earth group, Mir-grown constructs were mo re spherical, smaller, and mechanically inferior. The same bioreactor system can be used for a variety of controlled microgravity studies of cartilage and other tissues. These results may have implications for human spaceflight, e.g., a Mars mission, and clinical medicine, e.g., improved understanding of the effects of pseudo-weightlessness in prol onged immobilization, hydrotherapy, and intrauterine development.