Carboxymethyl-chitosan protects rabbit chondrocytes from interleukin-1β-induced apoptosis

Chondrocyte apoptosis is important in pathogenesis of osteoarthritis. Chitosan is a non-toxic, biodegradable and biocompatible glycosaminoglycan. In this study, the effects of carboxymethyl-chitosan (CM-chitosan), a soluble derivative of chitosan, on chondrocyte apoptosis were investigated. Primary rabbit chondrocytes were cultured and induced to apoptosis by 10 ng/ml interleukin-1β (IL-1β). After treatment with various concentrations of CM-chitosan (50, 100, 200 μg/ml), the apoptotic rate, mitochondrial function, nitric oxide production, and the levels of inducible nitric oxide synthase (iNOS) mRNA and reactive oxygen species in IL-1β-induced chondrocytes were examined. The results showed that CM-chitosan could inhibit chondrocyte apoptosis in a dose-dependent manner. Furthermore, it could partly restore the levels of mitochondrial membrane potential and ATP, decrease nitric oxide production by down-regulation of iNOS mRNA expression, and scavenge reactive oxygen species in chondrocytes induced by IL-1β. The results suggested that the inhibitory effects of CM-chitosan on IL-1β-induced chondrocyte apoptosis were possibly due to the protection of mitochondrial function, the decline in the levels of nitric oxide and reactive oxygen species.