Adhesion characteristics of chondrocytes cultured separately and in co-cultures with synovial fibroblasts.

The present study was designed to investigate the adherence mechanism(s) and behaviour of cultured chondrocytes under various culturing conditions, co-culturing with fibroblasts, or growth in the presence of conditioned medium either of fibroblasts or chondrocytes. The findings obtained indicate that chondrocyte time-adhesion curves and the final percentiles of attached cells to a plastic substrate are much slower and lower respectively than those of anchorage dependent cell types. The poorest adhesion occurs employing chondrocytes originated from suspension cultures, as compared to chondrocytes grown in monolayers. No interference with chondrocyte adhesion was found by inhibiting the production of proteoglycan (PG). Puromycin and to a lesser degree actinomycin but not cytosine arabinoside interfered with chondrocyte adhesion, suggesting the importance of protein synthesis in this process. The nature of proadhesion modifying molecules in synoviocytes conditioned media and antiadhesive agents in chondrocyte conditioned media suggests that both substances are heat labile, non-dialyzable, protein containing factors.