以低剂量BMP快速开启并维持高强度成骨信号通路从而高效诱导成骨、降低副作用是修复大体积骨缺损的主要研究趋势之一。本课题组前期体外、体内研究发现：与BMP同二聚体相比，BMP 异二聚体在体外诱导成骨具有起效早、剂量低，作用快等优点，并能够促进骨微结构的改建和成熟。有最新的研究表明：在Wnt和FGF可以协同增强并延长更低剂量TGF-β/BMP所诱导的细胞内信号转导。我们提出假设：Wnt和FGF通过调节Smad4表达水平显著增强和延长更低剂量BMP2/7所诱导的成骨信号通路，从而显著加快和提高成骨效率。本项目拟先以高通量检测筛选Wnt、FGF促进BMP2/7诱导成骨的最适浓度范围，明确其诱导人成骨细胞成骨的剂效特征，利用microarray、RNA干扰、信号通路抑制剂等分子生物学初步揭示其内在机制，并在体内验证其效果。

Using a very low amount of BMP to rapidly activate, enhance and prolong its-induced osteogenic signaling has become an main research trend in the field of large-volum bone defects repairing. In our previous in-vitro studies, we found that heterodimeric BMP could induce in-vitro osteoblastogenesis more rapidly with a lower concentration threshold and significantly higher dose-efficiency in comparison with homodimeric BMP. Our in-vivo experiment also corroborated that the low-dose heterodimeric BMP2/7 facilitated more rapid bone regeneration and more mature microstructure in peri-implant bone defects than the homodimeric BMPs. A recent study has indicated that Wnt and FGF could cooperatively enhance and prolong the low-concentration TGF-β/BMP signaling. Basing on these data, we put forward the hypothesis: Wnt and FGF can cooperatively enhance and prolong the very low-concentration BMP2/7-induced signaling transduction so as to accelerate and enhance osteogenesis through regulating the Smad4 level. In this study, we will first High throughput screen the suitable concentration for Wnt, FGF and BMP2/7 by checking differentiation markers. We will then identify the time-course and dose-dependent characteristics of their-induced osteogenesis of human osteoblasts. Thereafter, we will identify the intracellular signaling mechanisms of the combination using microarray, RNA silencing, and inhibitors, etc. Finally, we will test the osteoinductive efficacy of the combined Wnt, FGF and BMP2/7 in an in-vivo model.