PEO/LDH复合涂层镁基植入体通过巨噬细胞调节骨修复的作用及TRPM7/PI3K通路的机制研究

Magnesium and its alloys, known as the "next-generation medical metal materials", could self-degrade to avoid second operation for its remove, and enable to promote bone repair with proper mechanical property. However, Mg's high rate of degradation leads to an excessive inflammatory response, hindering a good binding between Mg and bone tissue. The osteoimmunomodulatory property of bone biomaterials is a vital property determining the in vivo fate of the implants. Endowing Mg with favorable degradation rate and osteoimmunomodulatory property is of great importance in clinical practice. In this work, a multifunctional bilayer composite coating of PEO/LDH with plasma electrolytic oxidization and hydrothermal synthesis was developed on a pure Mg metal to seal the pores of PEO substrate. Macrophage behavior was systematically analyzed from genetic, protein and histological levels. We explored the regulatory role of the transient receptor potential cation channel, subfamily M, member 7 (TRPM7)/phosphoinositide 3-kinase (PI3K) signaling pathway in the process. At the same time, the project will evaluate the osteoinductive ability of modified magnesium based on the behavior of bone marrow stromal cells directly seeded on the material or influenced in the local microenvironment created by macrophage. Canines are used for the systematic evaluation of in vivo osseointegration and degradation rate. The constructed PEO/LDH multilayer coating on magnesium is expected to provide a new idea and theoretical basis for the clinic application of Mg.

镁基金属材料具有良好的物理机械性能和促成骨效应，且因其体内可降解无需二次手术取出被誉为“下一代医用金属材料”，但是镁基金属材料在体内降解速率过快，易对宿主免疫系统产生不良刺激，从而阻碍材料和骨组织之间的良好结合。生物材料的免疫调节性能是决定其体内应用效果的关键之一，因此亟需精确调控镁基降解速率、改善其免疫调节性能，使其满足临床需求。本项目拟采用等离子体电解氧化联合水热合成技术，在纯镁表面构建PEO/LDH复合涂层，封闭PEO基底涂层孔洞，调控镁基降解；从基因、蛋白和组织学层面上系统研究改性镁基对巨噬细胞的影响及TRPM7/PI3K通路在其中的作用，分析改性镁基对宿主免疫反应的影响；从材料表面巨噬细胞创造的局部炎症微环境和材料直接对骨髓基质细胞的行为影响两方面来评价改性镁基的骨诱导能力，并通过动物实验系统性评价材料的体内应用效果，为镁基金属材料的临床应用提供理论依据。

镁基金属材料具有良好的物理机械性能和促成骨效应，且因其体内可降解无需二次手术取出被誉 为“下一代医用金属材料”，但是镁基金属材料在体内降解速率过快，易对宿主免疫系统产生不良刺激，从而阻碍材料和骨组织之间的良好结合。本项目采用了等离子体电解氧化联合水热合成技术，在纯镁表面构建PEO/LDH复合涂层，成功封闭PEO基底涂层孔洞，在体外成功降低材料在溶液中的镁离子快速释放，首日镁离子释放量不足纯镁组的三分之一，在体内成功降低材料周围软组织中的炎症细胞量；细胞增殖试验结果发现PEO/LDH复合涂层不影响细胞正常生存，从碱性磷酸酶染色、半定量、成骨相关基因表达量等方面发现PEO/LDH复合涂层显著提高材料浸提液对大鼠成骨细胞的成骨诱导作用，这种成骨作用在材料与周围骨组织的结合中也被再次验证，体内植入改性材料3个月后，相比于纯镁，PEO/LDH复合涂层材料周围新生骨组织面积和速率都有所提高，并且体内存留材料体积接近是纯镁的2.5倍。本研究课题成功为未来可降解的镁基金属材料在体内的应用提供一种可行的新型涂层技术，方法简便易于推广，结果有效。