Effect of estrogen on proliferation and differentiation of rat bone marrow stromal cells

Objective:To study the effect of estrogen on proliferation and differentiation of rat bone marrow stromal cells and to explore the mechanism of stimulation of bone formation by estrogen. Methods:Bone marrow stromal cells were isolated from four-week-old female Sprague-Dawley rats and cultured in DMEM medium to be induced into osteoblasts. They were cultured in medium with estrogen at different concentrations. The prolifereation, ALP activity and type-I pro-collagen of osteoblasts were examined by MTT, PNPP and assaying the level of hydroxyproline. The capacity of mineralization were measured by counting bone nodules. Results:The cell quantity, the alkaline phosphatase activity and the level of hydroxyproline of osteoblasts were increased , and the number of nodules was significantly higher. The peak value of all these stimulating effects on osteoblasts was in 10-7mol/L group. Conclusion:Estrogen can increase proliferation, differentiation and the capability of mineralization of osteoblast and this may contribute to bone formation.