[Effect of SL-1010 (sodium hyaluronate with high molecular weight) on experimental osteoarthritis induced by intra-articularly applied papain in rabbits].

Sodium hyaluronate (HA) with a molecular weight of approximately 600,000-1,200,000 is reportedly effective against osteoarthritis (OA). However, since HA with higher molecular weight is expected to be more effective against OA, we investigated the effects of HA (SL-1010) newly produced by fermentation with a molecular weight of 1,800,000-2,100,000 on the experimental OA induced by intraarticular injection of papain, into the knee joint of the rabbit, in comparison with those of HA with a molecular weight of about 950,000 (HA-95). When 0.4, 0.8, and 1.6% papain (0.5ml) was injected into the knee joint of the animal twice with a 3-day interval, there were dose-dependent degenerative changes and a decrease in sulfated glycosaminoglycan (S-GAG) in the articular cartilage with slight synovial inflammatory changes 6 weeks after the final injection of papain. In this OA model, intraarticular application of SL-1010 slightly reduced the degeneration of articular cartilage, compared with the injections of HA-95 or saline (control). SL-1010 also caused a significant recovery in the S-GAG level which was decreased in the cartilage of the OA model, compared with the control. In addition, SL-1010 inhibited the release of 35S-GAG from the cartilage obtained from normal and OA model joints. These results suggest that SL-1010 is effective in inhibiting the degeneration of cartilage in the OA model, probably due to the recovery of the S-GAG level by reducing the release of S-GAG from the cartilage.