脊髓损伤后运动神经环路重建的细胞分子机制研究

Spinal cord is very important part of the central nerve system. The spinal descending nerve pathways include corticospinal tract (CST), serotonergic raphespinal tract (sRST) and rubrospinal tract (RuST). Their axons terminate in specific area in spinal cord, branch into gray matter, and finally innervate to spinal motor neurons directly or indirectly. All these components including descending axons, spinal motor neurons and their axons targeting to peripheral muscles, form the spinal motor circuit (SMC). The SMC is the primary function unit to control the body locomotion. After spinal cord injury, the structure of SMC is damaged because descending axons are broken. The patients lose motor function partly or entirely with paralysis. SCI induced paralysis is one of incurable symptoms in spinal cord injury. In previous studies, research was mainly focused on the individual nerve fiber regeneration after SCI. Now evidence indicates that the SMC reconstruction is required for fully recovery of locomotion after SCI besides axons regeneration. Therefore, based on the molecular and cellular knowledge we obtained previously in the SMC construction in developing spinal cord and axons regeneration in injured spinal cord. In this proposal, we plan to explore the potential molecular and cellular mechanism underlying SMC reconstruction in injured spinal cord. We also try to establish a SMC reconstructed SCI animal model by combined molecular and cellular methods. By this study, we hope we could find novel hints for molecules or cellular therapy in locomotion recovery after SCI.

脊髓是重要的中枢神经组成部分。脊髓中重要的下行神经通路：皮质脊髓束(CST)、5-羟色胺能的缝核脊髓束(sRST)、红核脊髓束(RuST)轴突从脑区投射到脊髓特定区域后，进入脊髓灰质，直接或间接控制脊髓运动神经元，与外周运动神经一起构成脊髓运动神经环路(SMC)，是机体运动功能的基本结构单位。脊髓损伤(SCI)后,下行神经通路损害导致脊髓运动神经环路结构破坏和肢体运动功能丧失，引发瘫痪，是脊髓损伤后最难以治愈的病症之一。对于脊髓损伤的治疗，早期的研究多集中在单一神经损伤后的再生机制。而重建运动神经环路是恢复运动功能、治愈脊髓损伤所致瘫痪的根本途径。因此我们拟在已有的工作基础上，研究脊髓运动神经环路发育中重要的分子信号和功能细胞，在损伤后重建过程中所具有的作用和机制。尝试通过多种分子细胞调控手段建立脊髓运动环路损伤后重建的动物模型。为脊髓损伤后运动功能的恢复提供新的分子细胞治疗线索。

脊髓损伤后，损伤平面以下运动感觉功能丧失导致截瘫，是全世界所面临的医学难题。本项目拟揭示脊髓损伤后影响运动神经环路重建的细胞分子机制，尝试通过多种分子细胞干预手段的结合来重建具有完整形态和生理功能的脊髓运动神经环路、并恢复脊髓运动功能，从而为脊髓损伤这一重大疾病的治疗提供重要线索和创新性思路。项目研究工作发现：脊髓损伤后，NB-3信号通路被诱导启动，胶质瘢痕形成细胞和神经轴突上的NB-3同源性结合，通过神经元中CHL1和PTP sigma抑制下游mTOR通路活性，介导损伤神经轴突与胶质瘢痕对话。阻断NB-3信号通路，可以促进脊髓中控制运动功能的多条下行神经通路（皮质脊髓束和5-羟色胺能的缝核脊髓束）神经轴突的再生、环路重建和运动功能的恢复；构建了干细胞来源的Olig2PC-Astros/NPC-Astros新型星形胶质细胞，其移植后对损伤脊髓具有多种修复作用，同时解析了其移植后对脊髓修复的相关蛋白质组学机制；发现Ryk通过调控Wnt-PCP信号通路控制皮质脊髓束神经轴突在脊髓中定向生长的分子信号机制，以及Wnt-PCP信号通路和Shh-Ptch1-Smo信号通路联合作用控制5-羟色胺能的缝核脊髓束神经轴突在脊髓中定向生长的分子信号机制；建立了脊髓损伤后神经环路重建的神经调控技术(精确光遗传学调控技术和闭环电刺激系统)。上述研究结果为今后进一步开展脊髓损伤治疗的转化医学研究打下了坚实的基础。