Abstract: Objective To explore the effect and mechanism of bone marrow mesenchymal stem cell-derived exosomes （BMSC-EXOs） on repair of sciatic nerve injury. Methods The bone marrow mesenchymal stem cells （BMSCs） of Sprague Dawley（SD）rats were extracted and cultured. BMSCs-EXOs were extracted by ultracentrifugation and identified by fluoroscopic electron microscopy, particle size analysis, and western blotting. Culture PC12 cells, divide the PC12 cells into the blank contral group, 30 μg exosomes group, and 60 μg exosomes group. Observe the phagocytic effect of PC12 cells and PC12 cells axon regeneration by immunofluorescence. The expression of cellular neurofilament protein （NF-200） and growth-related protein （GAP-43） were detected by Western blotting. The SD rat sciatic nerve crush injury models were divided into injury group and treating group. The sciatic nerve of each group was observed by immunofluorescent staining. Results BMSC-EXOs were successfully extracted from the supernatant of BMSCs by ultracentrifugation, which conformed to the definition of particle size, fluoroscopic electron microscopic morphology, and Western blotting. The phagocytosis of BMSC-EXOs by PC12 cells was detected by immunofluorescence, and the axon regeneration of PC12 cells was increased. The increase of axon-related protein synthesis was detected by Western blotting, and the effect increased with increasing dose. There were statistically significant differences in axon length and axon-related protein expression in the three groups of PC12 cells（P<0.01）. In the sciatic nerve injury model, histological observation of the injury area was reduced and the nerve was reconnected. Conclusion BMSC-EXOs can play a role in the treatment of sciatic nerve injury by promoting the regeneration of nerve axons.

Key words: sciatic nerve injury, bone marrow stem cells, exosomes, axon regeneration

摘要： 目的 探讨骨髓间充质干细胞源性外泌体（BMSC-EXOs）坐骨神经损伤修复的影响及机制。方法 提取并培养SD大鼠的骨髓间充质干细胞（BMSCs）利用超速离心法提取BMSCs-EXOs并使用透视电镜、粒径分析、蛋白免疫印迹法进行鉴定。培养肾上腺嗜铬细胞瘤（PC12）细胞,设计PC12细胞为对照组、30 μg外泌体组、60 μg外泌体组,使用免疫荧光法观察PC12细胞的吞噬标记的外泌体的情况和PC12细胞轴突生长情况;通过蛋白免疫印迹法检测细胞神经丝蛋白（NF-200）和生长相关蛋白（GAP-43）的表达水平。设计SD大鼠坐骨神经挤压损伤模型,将模型分组为损伤组、治疗组,使用免疫荧光法对各组坐骨神经进行检测分析。结果 使用超速离心法从BMSCs上清液中成功提取BMSC-EXOs,符合粒径及透视电镜形态、蛋白免疫印迹法定义。免疫荧光法检测PC12细胞吞噬BMSC-EXOs,并使PC12细胞的轴突再生增强,蛋白免疫印迹法检测轴突相关蛋白合成的增加,并随剂量增加而作用增强。3组PC12细胞轴突长度及轴突相关蛋白表达差异均有统计学意义（P<0.01）。在大鼠坐骨神经损伤模型中组织学观察损伤区域缩小,神经重新连接。结论 BMSC-EXOs可通过促进神经轴突再生而发挥治疗坐骨神经损伤作用。

关键词: 坐骨神经损伤, 骨髓干细胞, 外泌体, 轴突再生