Hedgehog信号对骨髓间充质干细胞（MSCs）多向分化起重要调控作用，但生理状态下Hedgehog对MSCs成软骨分化的调控机制尚未阐明。我们预实验结果提示模拟微重力环境促进MSCs成软骨分化；经Hedgehog修饰的MSCs软骨特征性蛋白表达增强。因此我们提出假说：生理环境下Hedeghog可能与多种信号通路串话协调完成MSCs的成软骨分化。本课题我们将于模拟微重力环境采用转基因、siRNA干扰、FISH、Realtime-PCR、Luciferase、Multiplex Westernblot等对Ihh、Shh在MSCs软骨分化中的调控及与Wnt、TGF-β/BMP、FGF、IGF的信号串话机制开展深入研究，后采用动物软骨缺损修复模型，研究Hedgehog在体内局部的作用。本课题将为研究Hedgehog对MSCs成软骨分化的调控机理奠定基础，为软骨组织工程基础研究提供新的思路。

Mesenchymal stem cell (MSCs) is the most promising seed cell in cartilage tissue engineering, however until now its clinical application is still challenging and many technological problems are unsolved. The Hedgehog signal pathway has been reported playing an important role in regulation of multiple differentiation from MSCs, though its regulation mechanisms of chondrogenesis differentiation from MSCs in physiological behavior are not interpreted.Our previous research works found microgravity rotating culture system was more effective for the construction of tissue engineering cartilage in vitro, and the chondrogenic feature proteins expression were obviously up-regulated in MSCs modified with Hedgehog gene.Thus we make the hypothesis that Hedgehog's crosstalking with other signal pathways may happen and promote the process of chondrogenesis from MSCs under physiological conditions. This project basing on the MSCs' cultivating mode of the mimic microgravity three dimensions environment, will carry out profound studies, which utilize the techniques of transgene, siRNA, Realtime-PCR,FISH，Luciferase analysis and Multiplex western blot, on the signal transduction of Ihh and Shh during chondrocyte differentiation from MSCs，and on the mechanisms of Hedgehog's crosstalking with other signal passways of Wnt, TGF-β/BMP,FGF and IGF. Then the chondrocyte modified with Ihh/Shh or Ihh/Shh siRNA,and combined with chitosan will be transplanted to repair the cartilage defect of New Zealand rabbit. The effects of signal pathway of Hedgehog on chondrogenesis in vivo will be explored. The project may establish a foundation exploring the effects of Hedgehog signal pathway on the chondrogenesis from MSCs，and will provide a new view angle for research of cartilage tissue enineering.