Biological roles of carboxymethyl-chitin associated for the growth factor production

Many techniques to restore cartilage defection have been tried. However, the development is still under way because of problems, including loosening of artificial joint, degenerative change of compensated tissue, risk of viral transmission via allograft/autograft, and cost of therapeutic materials for repair. In the previous research, we found that complementing cartilage defective part with carboxymethyl-chitin (CM-chitin)/beta-tricalcium phosphate composite induced regeneration of cartilage in rabbits in vivo, and it is presumable that CM-chitin plays a key role in chondrogenesis causing the regeneration of cartilage. However, the induction mechanism of chondrogenesis with CM-chitin is still unclear. In this study, we investigated the cell responses to CM-chitin by using peritoneal exudate cell (PEC) in mice and found that CM-chitin induced the expression of inflammatory cytokines and growth factors, both of which are both considered to correlate with chondrogenesis. After intraperitoneal injection CM-chitin showed enhanced expressions of mRNA of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), keratinocyte-derived chemokine, tumor necrosis factor-alpha, and transforming growth factor-beta1 (TGF-beta1) in PEC as observed by reverse transcriptase polymerase chain reaction. Productions of TGF-beta1 protein were confirmed by enzyme linked immunosorbant assay. It was also shown that mononuclear cells in PEC were responsible for the TGF-beta1 production. These results suggest that CM-chitin is an inductor of inflammatory cytokines and growth factors and may contribute to regeneration of cartilage.