Intra-articular injection of magnesium chloride attenuates osteoarthritis progression in rats

Objective: To explore the effects of Mg2+ on the expression of osteoarthritic markers in human cartilage and synovium tissue explants. To investigate the therapeutic effect of intra-articular injection of Mg2+ in an established rat OA (Osteoarthritis) model of anterior cruciate ligament transection with partial medial meniscectomy (ACLT + PMM). Design: Human cartilage and synovium explants were collected from total knee replacement surgeries and incubated with MgCl2 (20 mmol/L) in vitro. A rat OA model was established by ACLT + PMM surgery in 450-500 g male Sprague Dawley (SD) rats. To select the optimal dose, intra-articular injections of MgCl2 (0.05, 0.5, 5 mol/L) were performed at 4 weeks after the surgery every 3 days for 2 weeks. The effect of optimized MgCl2 was further determined by histology, immunohistochemistry, and quantitative real-time polymerase chain reaction. Results: The expressions of osteoarthritic markers in human cartilage and synovium explants were inhibited by Mg2+ in vitro. Immunohistochemical analysis further suggested the inhibitory effects of Mg2+ on the expression of MMP-13 and IL-6 in the human tissue explants. Cartilage degeneration and synovitis in ACLT + PMM rats were significantly improved by intra-articular injections of Mg2+ (0.5 mol/L). Immunohistochemical analysis also showed the regulatory effects of Mg2+ on osteoarthritic markers in both cartilage and synovium in rats, consistent with in vitro results. Conclusion: Intra-articular injections of Mg2+ at 0.5 mol/L attenuate the progression of OA in the ACLT + PMM rat model. Such effect was at least in part explained by the promotion of cartilage matrix synthesis and the suppression of synovial inflammation. (C) 2019 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.