Interactions between human osteoarthritic chondrocytes and synovial fibroblasts in co-culture

Objective To imitate the in vivo joint situation and to allow cell interactions, a co -culture system of human human osteoarthritic chondrocytes and synovial fib roblasts from a single joint was established and characterized with or with out stimulation by IL-1 beta. Methods Culture settings included chondrocytes in alginate alone, synovial fibrobla sts in monolayer alone and a co-culture of both. Proteoglycan (PG) synthesi s was measured by S-35-incorporation, PG content by a dimethylmethylene blu e assay, DNA content by a fluorometric assay, and prostaglandin-E-2 and IL- 1 beta release by ELISA. Results In co-culture PG synthesis by chondrocytes was significantly reduced in the presence of IL-1 beta (1 ng/ml) compared to controls. PG content of chondr ocyte cultures was reduced for controls and IL-1 beta treated co-cultures. Synovial fibroblasts in co-culture did not show significant change of PG sy nthesis or content when compared to cells in mono-cell culture. PG release into the medium was relatively high in co-cultures. IL-1 beta significantly deer-eased the proliferation rate of chondrocytes in co-cultures and sligh tly increased prostaglandin-E-2 release. Conclusions Co-culturing of osteoarthritic chondrocytes and synovial fibroblasts from a single human joint allows interactions between both entities and may offer a useful tool to study the effects of mediators or new drugs under more in vivo like conditions compared to mono-cell cultures.