贻贝样纳米结构增益干细胞旁分泌效应促进糖尿病骨缺损修复的研究

Diabetic bone defect is the focus and difficulty in orthopedics because of its slow healing rate, high incidence of delayed healing or non-union. The paracrine effect of mesenchymal stem cells (MSCs) has been demonstrated to change the immune microenvironment, promote angiogenesis, and accelerate bone regeneration. In this case, improving the paracrine effect of MSCs has become a hot research topic in bone tissue engineering. However, how to develop the bone repair materials with superior properties still remains a significant challenge, such as safe, efficient and enhanced the paracrine function of MSCs. Recent findings highlight the importance of topographical cues from these materials in modulating the paracrine functions of MSCs and this will possible be a new strategy to cure diabetic segmental bone defect. We previously found that mussel-like nanostructures formed by polydopamine-coating could promote the expression of immunomodulatory and vascular factors, as well as the secretion of exosomes from MSCs. In view of this, we speculate that mussel-like nanostructures could enhance the paracrine effect of MSCs and promote the repair of diabetic bone defects. To validate this hypothesis, we developed functionalized SDF-1 adsorbed, three-dimensional-printed bioceramic (BC) scaffolds with mussel-inspired surface by polydopamine-coating in order to regulate the paracrine behavior of MSCs. The biological properties and osteogenic activity of the composite scaffolds will be systematically investigated by in vitro and in vivo experiments. Additionally, the probable mechanism of the mussel-like nanostructures regulating the paracrine function of MSCs will be explored. The implementation of this project will provide the experiment evidence for constructing novel scaffolds in diabetic bone defect treatment.

糖尿病骨缺损是骨科临床治疗中的重点和难点。针对这一难题，调控间充质干细胞（MSCs）旁分泌效应改善骨缺损处免疫微环境、促进血管生成、加快骨再生已成为当前骨组织工程的研究热点，但是如何构建安全、高效且能增益干细胞旁分泌效应的骨修复材料仍需探索。据研究报道，生物材料表面改性能够促进MSCs的旁分泌效应，我们前期工作发现聚多巴胺化表面修饰形成的贻贝样纳米结构能够促进MSCs内免疫调节和促成血管因子的表达以及外泌体的分泌。鉴此，我们推测贻贝样纳米结构能够增益MSCs旁分泌效应促进糖尿病骨缺损的修复。在预实验的基础上，本研究拟结合3D打印及表面修饰工艺，制备吸附基质细胞衍生因子（SDF-1）的聚多巴胺化生物玻璃复合支架（SDF-1@DOPA-BC），通过系统性研究该复合支架在干细胞募集以及免疫调控、促血管生成等旁分泌效应中的促进作用及可能的分子机制，为构建新型糖尿病骨缺损修复材料提供实验依据。

本项目成功构建3D生物打印的复合支架调控免疫微环境加快血管化再生从而促进骨缺损修复。通过3D打印及表面修饰工艺成功制备DOPA-BC支架，SEM检测显示支架表面上有均匀的贻贝样纳米层。实验结果表明，具有贻贝仿生样纳米结构表面修饰的生物支架具备调节MSC中与炎症和血管生成有关细胞因子分泌的功能。此外，FAK信号参与贻贝仿生样纳米结构的旁分泌调节功能，并影响Ad-MSCs的免疫调节特性。本研究为组织工程领域促成血管成骨生物活性材料的构建进行了有益的探索和尝试，为解决临床骨缺损修复问题的血管化植骨材料转化应用奠定基础。

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