骨形态蛋白9(BMP9)是诱导间充质干细胞（MSCs）成骨分化能力最强的因子之一，具有很好的临床应用前景。但BMP9诱导的成骨分化仍存在不足，有待进一步提高。课题组前期结果显示，BMP9在MSCs中能抑制PTEN表达，并且抑制PTEN能促进BMP9诱导MSCs成骨分化，过表达PTEN则抑制BMP9的这种作用；同时，BMP9促进Wnt10b表达，抑制PTEN可促进BMP9诱导Wnt10b表达，免疫耗竭Wnt10b明显抑制BMP9诱导MSCs碱性磷酸酶活性增加。因此，课题组推测：Wnt10b对BMP9诱导MSCs成骨分化有促进作用，PTEN可通过调节Wnt10b的表达影响BMP9诱导MSCs成骨分化。本课题拟利用过表达、siRNA干扰和基因敲除等多种技术和方法，阐明Wnt10b对BMP9诱导MSCs成骨分化的影响，以及这种影响与PTEN的关系，并分析PTEN调节Wnt10b表达的可能分子机制。

BMP9 is one of the most potent osteogenic factors to induce osteogenic differentiation in mesenchymal stem cells (MSCs). Hence, BMP9 is a promising factor for bone tissue engineering to treat the bone related disease. However, our previous studies demonstrated that there are still some defects in BMP9 induced bone formation, such as too much adipocytes in BMP9 induced bone mass, the strength is not so strong at the early stage,and too long for the bone mature, which will directly attenuate the clinical usage of BMP9.Therefor, it’s necessary to enhance the quanlity of BMP9 induced bone formation, and shorten the time needed for bone mature. Our previous investigation indicated that BMP9 can down-regulate the expression of PTEN in MSCs, and inhibition of PTEN can promote BMP9 induced osteogenic differentiation, while exogenous expression of PTEN can greatly inhibit BMP9 induced osteogenesis.Further analysis indicated that BMP9 can up-regulate the expression of Wnt10b,and the BMP9 induced expression of Wnt10b can be enhanced if inhibit PTEN at the same time.With immunodepletion analysis, we found that the use of Wnt10b antibody could substantially inhibit the alkaline phosphatase induced by BMP9 in MSCs.Hence, we make a hypothesis that Wnt10b may be very important for BMP9 to induce osteogenic differentiation in MSCs,and PTEN may affect BMP9 induced osteogenic differentiation through regulating the expression of PTEN.In this project, we will introduce adenovirus mediated over-expression or siRNA interference, and knockout technic, as well as a serial of well establised assay methods to demonstrate the effect of Wnt10b on BMP9 induced osteogenic differentiation, clarify the correlation between PTEN and the effect of Wnt10b on BMP9 induced osteogenesis, and decipher the possible mechanism through which PTEN regulate the expression of Wnt10b in MSCs.