Glucosamine sulfate modulates dysregulated activities of human osteoarthritic chondrocytes in vitro

Objective: The efficacy of glucosamine sulfate (GS) in the symptomatic trea tment of patients with osteoarthritis (OA) is suggested to be mediated by s till unknown effects on the altered OA cartilage. Design: Using human OA chondrocytes in culture, the effects of GS on protei n synthesis, caseinase, collagenase, phospholipase A2 (PLA2) and protein ki nase C (PKC) activities as well as production of nitric oxide and cyclic AM P were studied in both cells and culture medium. Results: GS significantly reduced PLA2 activity, and more modestly collagen ase activity, in the OA chondrocytes in a dose-dependent manner. By contras t, PLA2 and collagenase activity of the culture medium was not modified. No effects on caseinase activity was seen. GS significantly and dose-dependen tly increased protein synthesis. GS did not modify nitric oxide and cAMP pr oduction but significantly increased PKC production. Conclusion: GS modified cultured OA chondrocyte metabolism by acting on PKC , cellular PLA2, protein synthesis and possibly collagenase activation. Ext rapolation of the effect to the in-vivo situation remains hypothetical but they might represent some possible mechanisms of action of the drug in huma n. (C) 2000 OsteoArthritis Research Society International.