纯钛种植体表面摻锶微纳米形貌调控巨噬细胞表型转化控制骨髓基质干细胞向成骨分化的机制研究

Implant osseointegration is actually a biomaterial-induced foreign body reaction involving multiple cells. The early osseointegration and early functional stability are regulated by macrophage polarization and foreign body equilibrium. Studies showed biomaterial topography is critical for modulating macrophage phenotype. Up to now, it has not been well documented the mechanism of recruitment, proliferation, osteogenic differentiation of bone mesenchymal stem cells regulated by macrophages mediated by nanostructrured Ti surface and bioactive ions-Sr.Our research team has already observed Sr-incorporated nanostructrued Ti surface can affect the recruitment and differentiation of BMSCs. However, the role of macrophage during the process is still unknown. This research intends to investigate the molecular and cell mechanism of osteogenic differentiation of bone mesenchymal stem cells by Sr-incorporated nanostructrued Ti surface stimulating macrophages in vitro and in vivo, observing phenotype switch, correlative factors expression and BMSCs osteogenic differentiation. Thus, this research will provide molecular biology theory foundation of osteoimmunology for implant surface modification research.

种植体植入骨内的骨结合过程可看作是多种细胞参与的、由生物材料引起的异物反应过程。其中巨噬细胞的极化状态以及异物反应平衡调控着种植体的早期骨结合及早期的功能稳定。研究报道生物材料表面形貌可调控巨噬细胞的极化表型。到目前为止，种植体表面微纳米形貌和生物活性锶离子如何影响巨噬细胞，以及其调控骨髓基质干细胞的募集、增殖、成骨分化的具体作用机制尚不清楚。本课题组已观察到掺锶微纳米形貌种植体影响血液中BMSCs的归巢分化，但巨噬细胞在归巢分化中起到怎样的作用尚不清楚。本研究拟通过体外细胞实验及体内去巨噬细胞小鼠动物模型，观察掺锶微纳米形貌下巨噬细胞的表型转化，相关因子表达，BMSCs的成骨向分化，已探明掺锶微纳米形貌通过巨噬细胞来调控骨髓基质干细胞向成骨分化的分子和细胞机制，为今后种植体表面改性研究提供骨免疫学方面的分子生物学理论基础。

种植材料植入体内后不可避免地引起炎症反应，理想的种植材料表面引起的炎症反应水平适宜，有助于后续材料表面与周围骨组织的结合。巨噬细胞是炎症反应主要细胞，种植体表面改性通过影响巨噬细胞功能状态可影响后续成骨。课题组基于前期在钛种植体表面制备掺锶涂层的方法，制备了纯钛种植体表面锶微纳米形貌，其具备良好的理化性质，可抑制巨噬细胞向经典激活M1型巨噬细胞极化，并促进向选择性激活M2型巨噬细胞极化，营造有利于后续骨髓间充质干细胞成骨分化的微环境，这种调节巨噬细胞功能状态的作用可能与ERK信号通路相关。通过体内植入种植体，体内证实了纯钛掺锶微纳米表面可减少骨整合过程中早期M1型巨噬细胞的浸润同时促进愈合期M2型巨噬细胞的浸润，并促进骨整合。为进一步探讨巨噬细胞在骨整合中的作用，课题组通过注射氯膦酸二钠脂体，构建了降低小鼠体内巨噬细胞的模型，发现巨噬细胞的降低显著影响了后续的骨整合过程。本研究为材料的骨免疫调节提供了新理解，为新型种植体表面研发在骨免疫方面上的考虑提供了参考。