骨植入材料表面微纳米形貌通过巨噬细胞影响植入体周边成骨微环境的机制研究

To achieve an exact assessment on the biological performance of bone implant, all the aspects of host response to the implant should be considered as far as possible. Currently, the evaluation on the biological performance of bone implant mainly concentrates on the cells involved in osteogenesis while the osteogenic microenvironment around implant is ignored. The inflammation response, which is crucial for the clinical outcome of the bone implant, is the initial and indispensable event after implant insertion. The macrophage is the key cell during inflammation regulation. Previously, we have developed hierarchical micro/nanotopogrpahies on titanium bone implant by mimicking the structure of natural bone, which show enhanced effects on the osteogenic differentiation of osteoblasts and bone marrow mesenchymal stem cells (MSCs). Recently, our study indicates that such hierarchical micro/nanotopogrpahies also influence the behavior of macrophages. Nonetheless, the exact effect of topography on macrophage function, the underlying mechanism as well as the influence of this process on implant osseointegration are largely unknown. Our present project tries to explore the correlation of macrophage to osseointegration in vivo, to observe the influence of the hierarchical micro/nanotopogrpahies on M1/M2-polarization and the following secreting profiles of the macrophages, to uncover the molecular mechanism underlying the regulatory effect of the hierarchical micro/nanotopogrpahy on the functions of macrophages and MSCs by concentrating on the integrin and cell shape related signal pathways, and lastly to study the influence of the macrophage secretions, either alone or combined with the topographical cues, on the osteogenic differentiation of MSCs and the underlying mechanism. The project will lead to a clear understanding on the influence of bone implant surface micro/nanotopography on the osteogenic differentiation of mesenchymal stem cells via modulating M1/M2-polarization of macrophage as well as the related mechanism, hopefully to guide the bone implant surface topographical design and rationalize the in vitro evaluation model.

评价骨植入材料须全面考虑机体反应，而目前评价多考虑成骨相关细胞，忽视了种植体周围成骨微环境的影响。种植体植入后的成骨微环境中炎症反应是最早发生且必经的机体反应，而巨噬细胞则是调控炎症转归的关键细胞。我们前期实验表明模拟骨组织结构构建的可促进间充质干细胞（MSCs）成骨分化的微纳米结构明显影响巨噬细胞的形状和因子分泌。然而，形貌调控巨噬细胞功能的规律、机制以及该过程对骨结合的影响仍是未知。本课题通过体内实验探索巨噬细胞与骨结合的关系，体外研究微纳米形貌对巨噬细胞M1/M2极化和细胞因子分泌的影响，通过对整合素及细胞形态相关信号通路的研究，探明微纳米形貌调控巨噬细胞和MSCs功能的机制，最后研究巨噬细胞分泌产物单独或与形貌联合对MSCs成骨分化的影响及机制。通过此项目揭示微纳米形貌周围成骨微环境中的巨噬细胞和MSCs相互作用的规律和机制，从调控炎症角度指导骨植入材料功能评价和表面设计。

评价骨植入材料须全面考虑机体反应，而目前评价多考虑成骨相关细胞，忽视了种植体周围成骨微环境的影响。种植体植入后的成骨微环境中炎症反应是最早发生且必经的机体反应，而巨噬细胞则是调控炎症转归的关键细胞。我们前期实验表明模拟骨组织结构构建的可促进间充质干细胞（MSCs）成骨分化的微纳米结构明显影响巨噬细胞的形状和因子分泌。然而，形貌调控巨噬细胞功能的规律、机制以及该过程对骨结合的影响仍是未知。. 本项目首先体内观察炎症与骨结合的关系及巨噬细胞对骨结合的影响；然后体外观察材料形貌对巨噬细胞和间充质干细胞功能的影响并深入探索其分子机制；最后，根据研究结果对微纳米形貌进行优化并评价其骨结合。 . 研究发现：骨植入材料植入体内的早期炎症反应及愈合期的巨噬细胞功能与远期骨结合存在联系，证实了种植体植入后骨结合的能力与局部炎症反应程度以及愈合期浸润巨噬细胞的功能有关，引领了骨植入材料研究的新方向；首次发现材料表面形貌在常规状态及炎症刺激状态下均对巨噬细胞极化具有重要影响，阐明了材料表面形貌对巨噬细胞极化调控的新机制；首次发现材料表面形貌作用下巨噬细胞极化与BMSCs成骨分化的交互作用，并阐明了其调控机制。证实了巨噬细胞分泌产物影响了BMSCs的功能，同时BMSCs的分泌产物又具有反馈效应，影响了巨噬细胞的破骨分化进程。. 本项目的创新发现在于：体内环境下材料表面形貌对巨噬细胞极化的影响是决定最终骨结合形成的关键因素，在科学意义上提示了对骨植入材料的成骨性能评价不能仅关注成骨相关细胞，巨噬细胞的反应在植入材料的骨结合中起着重要的作用。通过此项目揭示微纳米形貌周围成骨微环境中的巨噬细胞和MSCs相互作用的规律和机制，从调控炎症角度指导骨植入材料功能评价和表面设计。