ASGSB 1998 Annual Meeting Abstracts

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MICROGRAVITY TISSUE ENGINEERING: DEVELOPMENTAL AND FUNCTIONAL STUDIES.   L.E. Freed and G. Vunjak-Novakovic. M.I.T. Division of Health Sciences and Technology, Cambridge, Mass.

A system to cultivate functional tissue equivalents using isolated cells, three dimensional polymer scaffolds, and rotating tissue culture bioreact-ors has been developed. Engineered cell-polymer constructs are cultivated in a state of continual free-fall, which simulates some aspects of micro-g. Our goals are to use this model system for controlled studies of tissue development and function on earth and in space, and ultimately to produce medically useful musculoskeletal and cardiovascular implants.

In engineered cartilage grown at 1g, chondrocytes produced extracellular matrix, polymer scaffolds degraded at a controlled rate, and mechanically functional, differentiated cartilaginous tissue developed. In engineered cardiac muscle grown at 1g, cardiomyocytes formed electrically conductive junctions and contracted spontaneously and synchronously. Engineered tissues grown in rotating bioreactors at 1g were morphologically, compositionally and functionally superior to those grown in conventional in vitro culture systems.

The cartilage tissue engineering system was selected for the first long term study of tissue culture in space. Bovine chondrocytes were grown on polymer scaffolds in rotating vessels, first for 3 months on earth and then for an additional 4 months either on the Mir Space Station or on earth. Final constructs from both groups were 8-10 mm in diameter x 5-8 mm thick, weighed 330-440 mg, and contained viable, metabolically active cells. Mir-grown constructs became more spherical while earth-grown constructs tended to maintain their initial discoid shapes. Constructs grown on Mir were compositionally and mechanically inferior to those grown on earth, which were in turn comparable to natural cartilage.

In summary: 1. ground studies: functional, engineered cartilage and cardiac tissues were grown using cells, polymers, and rotating bioreact-ors, and 2. space studies: engineered cartilage grown for 4 months on Mir was metabolically active, and structurally and functionally different from that grown on earth. We hope to extend the experience gained on Mir to future ISS studies using both the rotating bioreactor system and a new cell culture unit now under development that will be compatible with the space centrifuge, in order to determine the specific effects of gravity on tissue development and function. (Support: NAG9-836, CCU-97001)

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