氧化石墨烯诱导骨髓间充质干细胞成骨分化的机制研究

Osteogenic induction based on biological materials is always the struggling work in orthopedic biomaterial research. Graphene oxide is a potential orthopedic biomaterial due to the osteoinductive character to bone mesenchymal stem cells (BMSCs), but the mechanism of this process is unknown. In our previous study, it’s found that BMSCs seeded on graphene oxide membrane completed osteogenic differentiation under non-osteoinductive culture condition, and the expression of β-catenin reduced, integrin α2β1 and Wnt5a increased, disturbing WNT/Ca2+ signaling pathway can abolish the osteogenic differentiation of BMSCs. Considering the literature reviews and our unpublished results, it’s hypothesized that graphene oxide induced osteogenic differentiation of BMSCs may be triggered by activation of integrin α2β1 and through integrin/FAK/PI3K—Rac/NF-κB—Wnt5a pathway. To test the hypothesis, we focus on function of integrin α2β1 to explore the mechanism of graphene oxide induced BMSCs- osteoblast transition in detail through modulating integrin expression in vitro and in vivo, combined with medication or genetic manipulation of the signaling cascades in this signal pathway. This study is expected to uncover the mechanism of osteogenic differentiation of BMSCs induced by graphene oxide, and to provide new insights into osteoinduction biomaterials and integration of bone¬-implant interface. This study also holds special hope for providing potential excellent orthopedic biomaterials in the future.

我们前期研究发现氧化石墨烯在体外和体内均能够诱导骨髓间充质干细胞成骨分化，进一步研究发现β-catenin表达降低，integrin α2β1和Wnt5a表达升高，干扰WNT/Ca2+信号通路导致成骨分化消失。结合已有研究线索我们认为氧化石墨烯诱导骨髓间充质干细胞成骨分化，很可能是由integrin α2β1激活并通过integrin/FAK/PI3K—Rac/NF-κB—Wnt5a信号通路实现。为验证该假说，本项目以integrin α2β1为切入点，联合体内外实验通过改变integrin α2β1表达，结合干扰integrin/FAK/PI3K—Rac/NF-κB—Wnt5a信号通路上不同位点，研究此过程中信号传导机制。该项目的实施，将揭示氧化石墨烯诱导骨髓间充质干细胞成骨分化的信号传递机制，丰富材料诱导成骨分化及增强假体-骨界面整合的理论基础，为制作优异的骨科生物材料提供新思路。

通过制备还原型氧化石墨烯羟基磷灰石（rGO/HA）复合支架材料，评价其体外生物相容性及对骨髓间充质干细胞（BMSCs）成骨分化的影响，以及体内验证该复合支架修复骨缺损的能力。采用改进的hummers方法及两步氧化法制备了氧化石墨稀（GO）材料，然后将羟基磷灰石（HA）与GO相复合，使用超高温烧结法还原，成功制备了含不同质量分数的还原型氧化石墨烯（rGO）的多孔rGO/HA复合支架材料。研究结果表明rGO/HA复合材料具有良好的生物安全性；0.3% rGO/HA复合材料表现出最佳的生物学活性，能够促进mBMSCs粘附及增殖，并促进其向成骨方向分化；该rGO/HA复合材料在体内具有良好的骨整合、骨传导能力，对节段性骨缺损有一定骨修复作用；rGO是骨组织工程骨修复领域具有良好应用前景的改性材料，值得进一步开发与研究。