Sox9对BMP2诱导间充质干细胞成软骨分化的影响及机制研究

Cartilaginous pathologies, from degenerative disorders to traumatic injuries, present a very difficult clinical challenge because of its lack of regenerative capabilities.Since the efficacy of current clinical practices in cartilage repair remains controversial, alternative cartilage tissue engineering is being considered. Our previous results indicate that BMP2 exhibits chondrogenic activity at the early stages of endochondral ossification of MSCs. BMP2-stimulated negative regulatory factors such as Smad6,Smad7 inhibit Smads and MAPKp38 pathways. Meanwhile BMP2-induced Runx2 inhibits chondrogenesis and potentiates osteogenesis.It is conceivable that effective chondrogenesis can be achieved by inhibiting BMP2-induced ossfication through directing BMP2-stimulated MSCs towards chondrocyte lineage with chondrogenic factors,such as Sox9.We have found that exogenous overexpression of Sox9 can potentiate BMP2-induced early chondrogenic marker activity and expression of later markers.In order to further characterize our chondrogenic cell line,Open Cell PolyLactic Acid（OPLA） three-dimensional cell culturing is utilized. Our studies will attempt to more clearly demonstrate the effect of overexpression of Sox9 in BMP2-induced MSCs chondrogenesis both in vitro and in vivo. We will determine an optimal cocktail of growth factors that most effectively stimulates the generation of cartilage.

软骨缺损是临床上的治疗难点，构建成软骨活性的组织工程软骨具有广阔的运用前景。BMP2通过诱导成软骨关键因子Sox9的表达促进间充质干细胞（MSCs）成软骨分化，但BMP2同时激活负性调控因子Smad6、Smad7和成骨关键因子Runx2，从而限制了成软骨分化和软骨细胞表型的维持。课题组前期发现过表达Sox9能有效促进BMP2诱导的MSCs成软骨分化，但其机制尚不明确。因此我们通过重组腺病毒系统,以BMP2诱导间充质干细胞体内外成软骨分化模型为基础，采用多孔聚乳酸（OPLA）三维支架培养体系，研究过表达Sox9对BMP2诱导的间充质干细胞成软骨分化的影响及机制，寻求更佳的成软骨效应和有效维持软骨细胞表型；以期为推动软骨组织工程技术的发展和解决临床难题，提供相关实验基础和理论依据。

软骨缺损是临床上的治疗难点，构建成软骨活性的组织工程软骨具有广阔的运用前景。BMP2通过诱导成软骨关键因子Sox9的表达促进间充质干细胞（MSCs）成软骨分化，但BMP2同时激活负性调控因子Smad6、Smad7和成骨关键因子Runx2，从而限制了成软骨分化和软骨细胞表型的维持。课题组发现过表达Sox9能有效促进BMP2诱导的MSCs成软骨分化，但其机制尚不明确。因此我们通过重组腺病毒系统,以BMP2诱导间充质干细胞体内外成软骨分化模型为基础，三维培养体系，研究过表达Sox9对BMP2诱导的间充质干细胞成软骨分化的影响及机制，发现Sox9可以促进BMP2诱导的成软骨分化，抑制成骨分化和软骨内骨化；而这一效用的实现是通过抑制Runx2的表达实现的；同时相关的分子机制与抑制Smad7介导的MSCs细胞凋亡相关。另外我们还探讨了低氧环境对BMP2诱导MSCs成软骨分化的影响。本研究为推动构建基于BMP2的软骨组织工程技术的发展和解决临床难题，提供了相关实验基础和理论依据。