Effect of Synovial Cell Fractionation on Tenascin-C Expression in Chondrocytes Under Coculture

ObjectiveThis study investigated the effect of synovial cell fractionation on tenascin-C (TNC) expression in chondrocytes by coculturing human chondrocytes with synovial cells derived from osteoarthritis (OA) patients.DesignHuman cartilage and synovium were isolated from patients undergoing total knee arthroplasty. Synovial cells were classified into CD68 positive- and negative groups using western blotting. Cocultures were performed for 7 days using Cell Culture Inserts. The expression of TNC, syndecan-4 (SDC4), and anabolic and catabolic factors was measured by real-time polymerase chain reaction. TNC levels in the medium were compared using enzyme-linked immunosorbent assay. Flow cytometry examined M1 and M2 macrophage proportions in synovial cells immediately after isolation, after 7 days of monoculture, and after coculture.ResultsIn the CD68 positive group, TNC and matrix metalloproteinase (MMP)-3 were significantly upregulated in cocultured chondrocytes, and SDC4 was significantly upregulated in cocultured synovial cells. TNC concentration in the medium was significantly higher in CD68 positive cocultures. M1 proportions were significantly higher in synovial cells immediately after isolation and in cocultured synovial cells than in those cultured alone.ConclusionsSynovial cell fractionation differentially affects TNC and SDC4 expression. Macrophage-like synovial cells (MLS) increase TNC expression in chondrocytes and may contribute to OA pathology.