The chondroprotective effect of selective COX-2 inhibition in osteoarthritis: ex vivo evaluation of human cartilage tissue after in vivo treatment

Objective: Recent in vitro studies showed that celecoxib, a selective cyclooxygenase (COX)-2 inhibitor, protects human osteoarthritic cartilage tissue from degeneration. The objective was to substantiate these beneficial effects in an in vivo (clinical) study with celecoxib treatment of patients with severe knee osteoarthritis (OA) and subsequent evaluation of cartilage tissue ex vivo. Methods: Patients with knee OA were treated 4 weeks prior to total knee replacement surgery with either celecoxib 200 mg b.d., indomethacin 50 mg b.d., or received no treatment. During surgery cartilage and synovium were collected and analyzed in detail ex vivo. Results: When compared to non-treated patients, patients treated with celecoxib showed significant beneficial effects on proteoglycan synthesis, -release, and -content, confirming the in vitro data. In the indomethacin group, no significant differences were found compared to the control group. On the contrary, a tendency towards a lower content and lower synthesis rate was found. In the treated groups prostaglandin-E2 levels were lower than in the control group, indicating COX-2 inhibition. Ex vivo release of interleukin-1β (IL-1β) and tumour necrosis factor-α by synovial tissue was decreased by treatment with celecoxib, whereas in the indomethacin group only IL-1β release was decreased. Conclusion: Using this novel approach we were able to demonstrate an in vivo generated chondrobeneficial effect of celecoxib in patients with end stage knee OA. © 2008 Osteoarthritis Research Society International.