诱导神经元再生修复脊髓损伤的纳米层状双氢氧化物复合体系的制备及机理研究

英文摘要：.Spinal cord injury is one of the highest morbidity human diseases, and its treatment has become a major medical problem to be solved in the world. At present, how to build new types of injury zone filler to construct microenvironment so as to control inflammation and promote regeneration of neurons of spinal cord injury is a key scientific issue. In the previous study of our group, we found that the nano layered double hydroxides (LDH) composite NT3@LDH can promote the regeneration of neurons, and has anti-inflammatory properties remarkably. Therefore, according to the requirements of mechanical and physiological function for repair of spinal cord injury, we select safe, biodegradable, anti-inflammatory nano hydroxides which can promote the proliferation of neural stem cells combined with the induction factors and GFP labeled neural stem cells, thus to build the nano materials - stem cell- inductive factors into a constructive composite system. In addition, temperature sensitive matrigel is induced into the composite system to provide the microenvironment for neurogenesis, to build the NSCs - NT3 @ LDH @ matrigel multistage nano composite system. Then inject it into the injury zone, where the composite system will be fixed by body temperature, make it meet the requirements of neuronal cell growth and repair of spinal cord injury. Finally, we will investigate the mechanism of the multilevel nano composite system repairing spinal cord injury. By exploring the feasibility of nano composit on the repair of spinal cord injury without residue, our project will provide new technical support for the therapeutic area.

脊髓损伤是人类致残率最高的疾患之一，其治疗已成为全球亟待解决的重大医学问题。脊髓损伤修复现在的一大问题是如何通过新型填充材料构建微环境，控制其炎症并促进脊髓损伤区神经元的再生。课题组前期研究发现纳米层状双氢氧化物（LDH）复合物NT3@LDH能促进神经元再生，同时具有显著的抗炎性能。本课题拟根据脊髓损伤修复所需生理功能和力学性能要求，筛选出安全、可降解、抗炎并可促进神经干细胞增殖的纳米材料，搭载诱导因子，引入GFP标记的神经干细胞，构建可诱导神经元再生的纳米材料-干细胞-因子复合体系；导入具有温敏和细胞生长微环境的Matrigel，构建NSCs-NT3@LDH@Matrigel多级纳米复合体系，注射填充缺损区，由体温固定成型，使其满足神经元细胞生长和脊髓损伤修复的要求，明确复合材料对脊髓损伤修复的作用机制，探索纳米复合体系对脊髓损伤高效无残留修复的可行性，为脊髓损伤修复提供新的技术保障。

脊髓损伤（SCI）是人类致残率最高的疾病之一，其治疗是临床医学领域亟待解决的重大难题。课题组前期工作发现LDH能够搭载神经营养因子NT3，并且显示出促进神经干细胞（NSCs）向神经元分化的能力，然而其在体内修复SCI的能力以及发挥效果的作用机制仍待解决。. 为了阐明上述问题，该项目进一步就LDH-NT3在体外诱导NSCs迁移、定向分化的能力进行评价。通过检测LDH-NT3诱导后的NSCs中Nestin、Map2、NeuN、Tuj1等基因的表达、突触的增长以及细胞的迁移能力进一步证实LDH能协同NT3的作用，增强对NSCs向神经元分化的诱导能力。同时，我们构建了SCI小鼠模型，检测LDH-NT3移植入损伤位点后小鼠后肢运动功能BMS评分、电生理反应以及病灶处Tuj1、NeuN等基因的表达情况，进一步证实LDH-NT3在治疗SCI中表现出显著的效果。更为有趣的是，我们通过对损伤位点进行Brdu+NeuN+细胞的共定位和Brdu+Nestin+细胞的共定位，揭示LDH-NT3能调动内源性NSCs参与脊髓损伤的修复。.通过转录组测序进一步探究LDH-NT3修复SCI的分子机制并利用通路分析（IPA）工具筛选出LDH-NT3的调控靶点为TGF-β2受体（TGFBR2）。LDH-NT3能激活TGFBR2促进TGF-β2的表达，暗示LDH-NT3能够抑制炎症反应。在骨髓来源巨噬细胞（BMDCs）及小胶质细胞中进行验证，证实LDH-NT3能通过TGFBR2促进二者向抗炎的M2型极化，由此进一步证实LDH-NT3能通过激活TGFBR2，诱导巨噬细胞和小胶质细胞的极性转化，改善损伤部位的免疫微环境，治疗SCI。.该项目揭示了LDH作为生物活性材料在SCI修复中的作用以及修复机制，为SCI的治疗提供生物材料的免疫调控新思路，为LDH的临床转化奠定了理论基础。