HEALING OF CHONDRAL AND OSTEOCHONDRAL DEFECTS IN A CANINE MODEL - THEROLE OF CULTURED CHONDROCYTES IN REGENERATION OF ARTICULAR-CARTILAGE

In this study a canine model was developed to investigate the nature o f early healing responses to both chondral and osteochondral defects a nd to evaluate the tissue regenerative capacity of cultured autologous chondrocytes in chondral defects. The healing response to surgically created chondral defects was minor, with little cellular infiltration. In contrast, osteochondral defects exhibited a rapid cellular respons e, resulting ultimately in the formation of fibrous tissue. The lack o f significant cellular activity in chondral defects suggests that an e valuation of the capacity of cultured autologous chondrocytes to regen erate articular cartilage is best studied in chondral defects using th e canine model. When dedifferentiated cultured articular chondrocytes were implanted into chondral defects, islands of type II collagen stai ning were demonstrated in the regenerative tissue within 6 weeks. The relatively early expression of cartilage specific markers by the impla nted chondrocytes, coupled with the inability of untreated chondral de fects to repair or regenerate, demonstrates the utility of the canine model in evaluating novel materials for cartilage repair and regenerat ion.