KINETICS OF CHONDROCYTE GROWTH IN CELL-POLYMER IMPLANTS

In vitro cultivation of cartilage cells (chondrocytes) on biodegradabl e polyglycolic acid (PGA) scaffolds resulted in implants which could p otentially be used to repair damaged joint cartilage or for reconstruc tive surgery. Cell growth kinetics were studied to define conditions u nder which the cellularity of implants made from isolated calf chondro cytes reached that of the parent calf cartilage. In static cultures, c hondrocyte growth rates decreased as either implant thickness or impla nt cell density increased. Over 4 weeks of cultivation, implant permea bility to glucose decreased to 3% that of-the plain polymer scaffold; this effect was attributed to the decrease in effective implant porosi ty associated with cartilage tissue regeneration. In a well-mixed cult ure, implants 1 cm in diameter by 0.3 cm thick maintained high cell gr owth rates over 7 weeks and had normal cell densities. Regenerated car tilage with these dimensions is large enough to resurface small joints such as the trapezium bone at the base of the human thumb. Such impla nts could not be grown statically, since cell growth stopped at 3-4 we eks and cell densities remained below normal. Optimization of the tiss ue culture environment is thus essential in order to cultivate clinica lly useful cartilage implants in vitro. (C) 1994 John Wiley and Sons, Inc.