Abstract: PURPOSE: A mouse osteoblast cell line, MC3T3-E1, was cultivated in the medium that contained chitosan, type Ⅰcollagen and recombinant human bone morphogenetic protein-2 in vitro to evaluate the effect of chitosan and its composites on proliferation and differentiation of mouse osteoblasts. METHODS: This study was categorized into 4 groups based on the medium used. Group A: α-MEM medium; group B: CS, type Ⅰcollagen and α-MEM medium; group C: CS, type Ⅰcollagen, rhBMP-2 and α-MEM medium. α-MEM medium containing 1%FBS was used in the control group. Cells of each group were cultivated for 1,3,5 and 7 days. The optical density (OD) value at each time point was evaluated with MTT assay and growth curve was drawn to observe the proliferation of osteoblasts. Differentiation of osteoblasts was determined with alkaline phosphatase (ALP) activity assay, alkaline phosphatase staining and alizarin red staining. Alkaline phosphatase activity of each group was measured at day 1, 3, 5 and 7 days. After 7 days of culture, the cells were stained with alkaline phosphatase, and at day 14, the mineralized nodules were stained with alizarin red. Statistical analysis was performed using SPSS13.0 software package. RESULTS: The MTT assay results showed that the OD value was maximal when osteoblasts were cultured in group C. The difference were statistically significant between group C and others (P<0.05). The ALP activity showed that the result of group C was significantly higher than other groups. The increase of ALP activity was significant between group C and control group (P<0.05). However, no significant difference was found between group C and group B (P>0.05). Compared with the control group, group C had more calcium nodules and blue particles than others. CONCLUSIONS: The incorporation of type Ⅰ collagen and bone morphogenetic protein-2 into chitosan can promote MC3T3-E1 cell proliferation and differentiation better.

Key words: Osteoblasts, Chitosan, TypeⅠcollagen;Recombinant human bone morphogenetic protein-2