督脉电针促进干细胞源性神经元靶向性生长修复脊髓损伤的机制研究

Reconstruction of neural networks after spinal cord injured is a key science problem which is unsettled so far. The axons of endogenous neurons do not regenerate to repair neural networks because of the microenvirnment of injured spinal cord. To solve the science problem, an important strategy will be used to improve spinal cord microenvirnment that Governor Vessel (GV) electron-acupuncture combines with a stem cell-derived neural network. Our previous results demonstrated that GV electron-acupuncture can promote the secretion of neurotrophin-3 (NT-3) in spinal cord tissue, of which mechanism was still not known, and that bone marrow mesenchymal stem cell (MSC)-derived neural network can be constructed in vitro. The function of spinal cord are partly improved after the stem cell-derived neural network was transplanted into the injury site of spinal cord. The present study attempts to utilize electroacupuncture to stimulate GV acupoints, which could evoke the depolarization of neurons of spinal cord. The open of L-type voltage-gated Ca2+ channel and Ca2+ influx may activate pathway of Ca2+/calmodulin-dependent protein kinases II (CaMKII) in the neurons of spinal cord to promote synthesis and secretion of NT-3. The targeted growth of MSC-derived neuronal axons could be induced to form synaptic connection with host spinal cord neurons secreting endogenous NT-3. Accordingly, the integration of transplanted MSC-derived neurons and spinal cord neural network is promoted to repair better the function of spinal cord. Therefore, this study will systematically explore a mechanism that the combined application of GV electroacupuncture and MSC-derived neural network transplantation may repair the neural network of spinal cord injured. The study will provide the theory and experimental evidence for applying clinically GV electroacupuncture therapy after stem cells are transplanted into the patient of spinal cord injured.

脊髓受损伤神经网络重建是未解决的关键科学问题，原因是损伤脊髓微环境难以让内源性神经元修复神经网络。联合应用能改善脊髓微环境的督脉电针与干细胞源性神经网络是解决这问题的关键策略。我们已证实：1.督脉电针可促使脊髓分泌内源性神经营养素-3(NT-3)，但机制不清；2.可构建具有功能的骨髓间充质干细胞(MSC)源性神经网络，将其移植到脊髓损伤处仅部分改善脊髓功能。本研究将应用督脉电针刺激脊神经分支引起脊髓神经元去极化，通过钙/钙调蛋白-依赖性蛋白激酶通路激活其胞体分泌NT-3，诱导移植的过表达TrkC (NT-3受体)的MSC源性神经元轴突靶向性生长，与分泌内源性NT-3的宿主脊髓神经元形成突触连接，进而促进MSC源性神经元与脊髓神经网络整合，更好修复脊髓功能。因此，探讨联合应用督脉电针与基因修饰的干细胞移植修复脊髓神经网络机制，为将来临床督脉电针治疗干细胞移植的脊髓损伤患者提供理论和实验依据。

脊髓受损伤神经环路重建是未解决的关键科学问题，原因是受损伤脊髓微环境难以让内源性神经元修复神经环路。联合应用能够改善脊髓组织微环境的督脉电针与干细胞源性神经网络组织移植是解决这问题的关键策略。本研究结果已经证实：电针督脉经穴可通过刺激脊膜支促进背根神经节神经元的传入神经末梢在脊髓内释放降钙素基因相关肽增多，作用于表达降钙素基因相关肽受体的脊髓神经元，激动其细胞膜上的L-型电压门控钙离子通道，通过上调钙/钙调蛋白-依赖性蛋白激酶通路促进神经元合成和分泌神经营养素-3，改善受损伤脊髓组织的微环境。在此研究基础上，督脉电针可以通过提高全横断脊髓损伤组织内神经营养素-3的水平，促进移植入脊髓损伤区的干细胞源性神经网络组织细胞存活，并维持其分化为干细胞源性神经元样细胞的特征，保持干细胞源性神经元样细胞之间形成的突触样结构，促进部分干细胞源性神经元样细胞往脊髓损伤/移植区尾端迁移，并与宿主脊髓神经元形成更多接触，促使干细胞源性神经网络组织与宿主脊髓神经环路整合，从而改善全横断脊髓损伤大鼠的瘫痪肢体自主运动功能。本项研究从督脉经穴电针、内源性神经营养因子表达、移植的干细胞源性神经元与宿主脊髓神经环路整合修复脊髓损伤这主干线，进一步阐明了传统中医在应用针灸(或电针) 治疗脊髓损伤时均要首选督脉穴的机理。同时，为将来临床上解释移植干细胞源性神经网络组织的脊髓损伤患者在手术后，如果联合应用督脉穴电针治疗可以得到更好治疗效果的道理。所以，本项研究既有重要的科学意义，又有潜在的临床转化前景。