共价有机框架局部缓释sRAGE和SDF-1对高糖状态下骨缺损修复的影响及调控机制

Bone defect restoration is very difficult in high glucose environment, with slow osteogenesis being one of the most important reasons, so improving the osteogenic effect in high glucose environment has become a hot research topic at present. Covalent Organic Frameworks (COF) is a kind of polymer porous materials with free designed and completely controllable structure, high surface area, controllable degradation and good stability. Our study has demonstrated that COF could promote the proliferation and osteogenic properties of bone marrow stromal stem cells and this feature is almost not affected by high glucose. So we put forward a hypothesis that COF scaffold combined with local releasing of AGEs inhibitor and stem cell recruitment factor (SDF-1) could promote restoration effect of bone defect in high glucose environment. The experiments include synthesizing COF scaffold slow-release system, rat bone marrow stem cells culture in vitro and establishing alveolar bone defect models with diabetic rats, investigating the effect of high glucose environment and COF scaffold on biological properties of stem cells, the degradation and releasing rate of COF scaffold in vivo, the osteogenesis promoting effect of AGEs inhibitor and the regulation effect of Akt signaling pathway in this process, stem cells recruiting function of SDF-1 and osteogenic properties of stem cells after recruiting, trying to explicit the effect of local release of AGEs inhibitor and SDF-1 by COF scaffold on alveolar bone defect restoration in high glucose environment, providing reference for bone defect restoration under high glucose circumstance.

高糖状态下骨缺损修复非常困难，成骨缓慢是重要因素之一，因此改善高糖状态下的成骨效果已成为目前研究热点之一。共价有机框架（COF）是一类结构可自由设计并完全可控的高分子多孔材料，比表面积高、降解可控、稳定性好。我们研究表明COF可显著促进骨髓基质干细胞的增殖及成骨性能，且几乎不受高糖状态影响。因此我们假设：COF支架材料局部缓释AGEs抑制剂和干细胞募集因子（SDF-1）可促进高糖状态下骨缺损修复。实验包括合成COF支架缓释系统，培养大鼠骨髓基质干细胞并建立糖尿病大鼠牙槽骨缺损模型，探讨高糖环境和COF对干细胞生物学性能的影响及COF在体内的降解，缓释速率；AGEs抑制剂的促成骨作用及Akt通路对此的调控作用；SDF-1的干细胞募集作用及募集后干细胞的成骨性能，明确COF支架材料局部缓释AGEs抑制剂和SDF-1对高糖状态下牙槽骨缺损修复的影响，为临床高糖状态骨缺损修复提供参考。

颌面部肿瘤及外伤是导致颌面部骨缺损的两大主要因素，临床非常常见，缺损后对人的外貌，咀嚼、语音以及呼吸等功能均会产生影响，严重者更可威胁生命。大块骨缺损，目前临床上还是以生物支架材料修复为主，并取得了较好的治疗效果，但对于伴有糖尿病等全身疾病的患者，治疗效果尚不理想，随着人民生活水平的提高，我国糖尿病患者越来越多，使这一问题日益突显。本课题正是针对这一临床实际问题展开，探讨高糖状态下促进成骨的新材料及新方法。.首先，我们课题组通过采用含有不同葡萄糖浓度的培养液对大鼠及小鼠骨髓基质干细胞进行体外培养，并构建糖尿病小鼠动物模型，从体内体外两方面阐明高糖环境对骨髓基质干细胞及动物体内各项生化指标的影响，特别是对BMSC的趋化、增殖和成骨作用的影响，并采用基因芯片筛查高糖作用后，成骨相关信号通路在此过程中的变化情况。其次，我们还设计和合成多种成骨支架材料，包括共价有机框架材料（COF），β-磷酸三钙和硅酸钙生物陶瓷颗粒，掺锶羟基磷灰石，含锂介孔玻璃等材料等，并对其理化性能进行表征和测试，通过控制其密度、结构和孔隙率等理化参数，改善材料表面吸附和缓释能力，提高其细胞相容性和骨缺损修复性能，再进一步明确这些材料在生理糖浓度及高糖浓度环境下，对大鼠及小鼠骨髓基质干细胞生物学性能的影响，并深入探讨相关作用机理。最后，构建正常及糖尿病大鼠及小鼠骨缺损动物模型，采用多种材料进行骨缺损的修复，明确不同材料在不同环境下的骨缺损修复效果。结果发现，材料表面性状的改良，或联合无机离子，有机分子一并进行骨缺损的修复，可显著改善高糖状态下骨缺损的修复效果，为临床高糖状态骨缺损修复提供参考，也为新材料的开发转化提供数据支持。