Study On Effect Of Chitin Derivatives In Bone Defect Healing

Bone defect may be the result of a variety of causes such as trauma, infection, tumor resection and skeletal abnormalities. Presently, most classical techniques are based on the transplantation including the use of autogenerous grafts and flaps, allograft bone, non-degradable bone cement, metals and ceramics and bone tissue engineering productions. Furthermore, physical methods, growth factors, Chinese traditional medicines are applied for it. All of these options have their associated problems. Therefore, the research for medicines to deal with bone defect continues.Chi tin, the second most abundant biopolymer on earth after cellulose, is recognized as a natural, biocompatible, biodegradable, non-toxic, adsorbable and multifunctional resource. Chitin and its derivatives are already widely applied in many fields such as agriculture, light industry, medicine, biomedicial materials, environmental protection. Recently, much attention has been paid to chitin derivatives with low molecular weight because of their more soluble and special bioactive properties.Effect of four kinds of low molecular weight chitin derivatives: glucosamine (GluNH2), N-acetyl-glucosamine (NAG), chito-oligosaccharide (COS) and carboxymethyl-chito-oligosaccharide (CM-COS) on bone defect healing was studied in the present paper.In this essay, NAG, GluNH2, COS and CM-COS were prepared and purified according to the level of cell culture. Their physical properties were studied.Four kinds of chitin derivatives were added into culture medium with some concentrations of 10μ g/mK lOOμg/mK 500μg/mK lOOOμg/mK 2000 g/ml respecitvely and then the abilities to promote the proliferation of osteoblasts MC3T3-E1 in vitro were observed. The results show that NAG at appropriate concentrations can promote the proliferation of osteoblasts and the higher concentrations (1000ng/ml) have stronger effects. The promotion of COS is more obvious, and the most effective concentration is 500 u g/ml. GluNH2 can promote the proliferation of osteoblasts on lower concentrations while higer concentrations indicate inhibiting function. CM-COS can show the function of proliferation but the effect is not prominent.New Zealand rabbits were used to make animal model of segmental defects of 3mm in right raddi, randomly divided into control group, positive drug group and experimental groups and then respectively fed daily. The X-ray films, histological sections, image analysis methods and serum Ca, serum P and ALP were made to evaluate the effect 9, 17, 30 and 42 days after operation. Results demonstrate that the absorption and organization of the hematoma, the appearance of cartilage callus, endochondral ossification and trabecular bone and the phenomenon of the defect heal are significantly earlier than those in control group. The data of serum Ca P ALP demonstrate the results, too.All these results indicate that these four chitin derivatives could improve the progress of bone defect healing and might provide the theory basis for the medicine screening of bone defect healing.