基于磁共振周围神经多模态成像探讨电针联合干细胞促进轴突导向再生的效果及机制

Stem cell transplantation is a promising way for peripheral nerve repair. Electroacupuncture to promote peripheral nerve regeneration and repair is an advantageous project in TCM treatment. However, the low survival rate of BMSCs, tissue adhesion and scar formation still exist after transplantation. These factors impede the oriented regeneration of axon, and nerve function is consequently not restored satisfactorily. Electroacupuncture is an advantageous project to promote peripheral nerve repair in TCM. It can promote axon guidance and regulating the inflammatory microenvironment in the damaged segment. Whether the combined use of the two could synergistically promote peripheral nerve regeneration and whether the enhanced effect produced by MSCs could be monitored by imaging method is the most important problem to be solved. On the basis of previous study and preliminary experiments, in this study, BMSCs were implanted in the rat model of sciatic nerve crush injury, and treated with electroacupuncture afterword. We observe the longitudinal changes of nerve repair with multi-parameters of MRN including T2 value and DTI metrics. Correlative analysis between T2 value/DTI metrics and quantity of histological indexes was conducted to evaluate the ability of T2 value and DTI in monitoring the dynamics of nerve repair, evaluating the synergetic effect generated by electroacupuncture and MSCs. Meanwhile, to evaluate the relationship between these parameters and axon guidance factor Natrin-1 during the repair process.This study provides an intuitive and sensitive means for the evaluation of the efficacy of electroacupuncture combined with stem cells in repairing peripheral nerve injury, and provides imaging basis for the study of its mechanism.

干细胞移植修复周围神经损伤是极有临床运用前景的新策略，但其移植后存活率低、组织粘连和疤痕形成仍有发生，从而阻碍了轴突的导向再生，神经功能恢复欠满意。电针促进周围神经再生修复是中医治疗的优势项目，具有促进轴突导向性修复及调节损伤区炎症微环境等功能。二者联合使用能否协同促进周围神经损伤的修复，并通过影像学方法直接监测神经的导向修复，是目前亟待解决的关键问题。本项目拟在前期工作及预实验基础上，在大鼠坐骨神经挤压伤模型中植入间充质干细胞，同时联合电针治疗，利用磁共振T2-mapping及DTI技术，对损伤神经修复过程进行连续动态监测，观察神经T2值及DTI多参数指标的动态变化，与神经功能及组织病理学指标进行相关性分析，明确二者联合修复神经损伤的效果及对神经导向再生因子Netrin-1的影响，为电针联合干细胞修复周围神经损伤的疗效评估提供直观敏感的技术手段，为其机制研究提供结构及功能影像学依据。

背景：干细胞移植修复周围神经损伤是极有临床运用前景的新策略，但其移植后存活率低，组织粘连和疤痕形成仍有发生，从而阻碍了轴突的导向再生，神经功能恢复欠满意。电针促进周围神经再生修复是中医治疗的优势项目，具有促进轴突导向性修复及调节损伤区炎症微环境等功能。.目的：本研究旨在利用磁共振评估骨间质干细胞（BMSCs）移植和电针（EA）联合治疗大鼠急性坐骨神经损伤的疗效。.研究内容及方法：将92只成年雄性健康Sprague-Dawley大鼠随机分为EA+BMSCs组、EA组、MSCs组和PBS组（对照）。对接受EA治疗的大鼠在黄帝（GB30）和足三里（ST36）进行电针治疗。通过多参数磁共振成像（MRI）得出的T2值和弥散张量成像（DTI）、组织学评估和免疫组化来监测神经的再生。步行轨迹分析被用来评估神经功能恢复。重复测量单因素方差分析被用来评估四组之间T2、DTI和SFI值的意义。单向方差分析用于比较组织学特征。Bonferroni检验用于每个时间点的多对比较。.结果：在FA方面，EA+BMSCs组和EA组在术后所有时间点都比PBS（对照组）恢复得快，EA+BMSCs组在3周时比BMSCs组恢复得更好（P≤0.008）。4周时EA组的FA值高于BMSCs组（P≤0.008）。在RD方面，EA+BMSCs组在2周和4周时比BMSCs组恢复的更好（P≤0.008）。轴突引导分子Netrin-1的免疫荧光染色显示，在1-3周时，EA+BMSCs亚组和EA亚组明显高于对照（PBS）亚组（P<0.001）。S100的免疫荧光染色显示，EA+BMSCs亚组的神经纤维的连续性比BMSCs亚组恢复得更快。.结论及科学意义：MSCs和EA联合可以促进周围神经损伤后轴突延伸、髓鞘再生和功能恢复。EA不仅能自行促进神经修复，还能增强干细胞治疗的有益效果，以及引导再生因子Netrin 1的分泌，并促进神经纤维的有序生长。该修复过程可以通过MRI进行无创和原位监测。从MRI得出的FA和RD值可以成为反映神经修复过程的敏感生物标志物。