Effects of BMP-2 and dexamethasone on proliferation and differentiation of adult osteoblasts in vitro

Objective To investigate the effects of bone morphogenetic protein-2 (BMP-2) and dexamethasone (DEX) on proliferation and differentiation of adult osteoblasts in vitro.Methods Adult osteoblasts were isolated from iliac trabecula and cultured in vitro.The biological characteristics were observed by phase-contrast microscope and investigated by alkaline phosphatase (ALP),osteocalcin (OCN),collagen Ⅰ and Ⅲ staining.The cells were subjected to the treatment with different concentrations of BMP-2 (1,10,100 and 1 000 ng/ml) and DEX (10 -8,10 -7,10 -6 mol/L).The proliferation was measured with methylthiazol tetrazolium (MTT) method.Alkaline phosphatase activity and osteocalcin were measured to evaluate the differentiation of osteoblasts after 48h.Results ALP,OCN and collagen Ⅰ were synthesized by the osteoblasts.but collagen Ⅲ staining was negative.Compared with the control group,the OD value of MTT,ALP activity and OCN level were increased with different concentrations of DEX.However,ALP and OCN were significantly increased in different concentrations of BMP-2,but OD value of MTT did not significantly increase.Conclusions DEX has significant effect on proliferation and differentiation of adult osteoblasts in vitro.After short-term treatment BMP-2 also has differentiating effect on adult osteoblasts,but no significant effect on proliferation.