ASCs优化微环境联合神经嵴干细胞修复脊髓损伤的实验研究

Pathological changes after spinal cord injury(SCI) primarily involves the deterioration of the microenvironment in the lesion site, therefore, the improvement of microenvironment after SCI is a key point to promote the recovery of neurologic function.It has been reported that the overexpression of pro-BDNF in the lesion site leads to imbalance of the microenvironment through the participance ofp75NTR in various physiological reactions.Activated Schwann cells (ASCs) accompanied with a large number of secretion of BDNF can effectively regulate microenvironmentby the BDNF/pro-BDNF/p75NTR axis, this subject proposed to explore the effect and molecular mechanism of the optimization to the microenvironmentby ASCs in multi-ways. Neural crest stem cells(NCSCs) are known as ideal seed cells for their strong ability to differentiate into neurons, thus the applicant proposed to figure out the inherent relationship of the differentiation from NCSCs towards neurons promoted by ASCs in vitro experimental observation,and the mechanism of repair after SCI by NCSCs transplantation under the microenvironment optimized by ASCs in rats is to be observed in vivo experimental observation . This subject aims to improve the effect of stem cell transplantation under optimized microenvironment, providing new schema for cell transplantation in the process of repair after SCI.

脊髓损伤后的病理改变集中体现在损伤局部微环境的变化，因此如何改善脊髓损伤后微环境是促进神经功能恢复的关键。目前研究发现，损伤后局部pro-BDNF表达量增加并通过P75NTR参与多项生理过程导致微环境失衡。激活态雪旺细胞（ASCs）大量分泌的BDNF可通过BDNF/pro-BDNF/p75NTR轴调节脊髓损伤后微环境，本课题拟通过观察ASCs分泌的BDNF抑制pro-BDNF对微环境中不同细胞系的负性作用，探索ASCs多途径优化损伤后微环境的效果及分子机制。神经嵴干细胞具有较强的向神经元分化的能力，是理想的“种子细胞”，因此本课题拟通过体外实验揭示ASCs促进神经嵴干细胞向神经元方向分化的内在规律，通过体内实验探索ASCs改善损伤微环境下联合神经嵴干细胞移植修复脊髓损伤的效果及作用机理。本课题在“优化微环境”下移植干细胞修复脊髓损伤，提高干细胞移植修复的效果，为脊髓损伤修复提供新的思路。

脊髓损伤（spinal cord injury,SCI）是一种对中枢神经系统造成严重损害的疾病，常伴随明显的局部微环境的变化。脑源性神经营养因子前体（pro-Brain Derived Neurotrophic Factor,pro-BDNF）作为一种神经营养因子前体，被认为在早期神经损伤微环境中对神经细胞及胶质细胞有明显的抑制作用，而其成熟体BDNF则可以促进神经细胞的生长发育。有实验研究发现从外周神经系统提取的激活态雪旺细胞可以大量分泌成熟BDNF从而改善脊髓损伤微环境。干细胞移植已被广泛用于脊髓损伤后的治疗研究，其中神经嵴干细胞由于其突出的神经元分化特性被视为是理想的脊髓损伤后移植细胞之一。因此本课题组团队通过体外模拟脊髓损伤后微环境改变对移植细胞带来的抑制作用，探究有效的改善脊髓损伤微环境变化的方式，从而提高神经嵴干细胞移植修复脊髓损伤的效果。.本课题组通过体外培养神经嵴干细胞、星形胶质细胞等细胞，并向细胞微环境中加入pro-BDNF进行干预，构建pro-BDNF细胞损伤模型，探究最佳pro-BDNF损伤模型浓度条件，模拟脊髓损伤后局部微环境。通过细胞活性实验、细胞增殖实验及细胞分化等实验发现在体外模拟环境中pro-BDNF对神经嵴干细胞、神经干细胞和星型胶质细胞等细胞存在抑制作用，而通过与激活态雪旺细胞（Activated Schwann Cells,ASCs）共培养，可改善pro-BDNF对细胞的抑制作用。同时本课题组通过体内实验，构建大鼠脊髓损伤模型，在大鼠脊髓损伤后联合移植神经嵴干细胞及雪旺细胞，监测脊髓损伤后大鼠运动功能恢复情况。发现联合移植激活态雪旺细胞及神经嵴干细胞可以有效改善脊髓损伤后大鼠运动功能，减小脊髓损伤后大鼠脊髓局部损伤组织空洞面积。.通过以上实验课题组发现激活态雪旺细胞可以有效改善脊髓损伤后微环境变化，同时可以促进神经嵴干细胞移植分化效果，促进脊髓损伤后大鼠运动功能的恢复。激活态雪旺细胞联合神经嵴干细胞移植作为一种干细胞移植的干预方式，为脊髓损伤的修复提供了新的思路。