探讨骨髓间充质干细胞（BMSC）来源的外泌体对大鼠坐骨神经损伤的治疗效果。

随机将24只SD大鼠平均分为3组。各组大鼠暴露出右侧坐骨神经后，在坐骨神经分叉处上方5 mm处用显微止血钳第二齿钳夹神经3次，每次10 s，中间间隔5 s。Exosome组在钳夹伤附近的神经外膜下注射5 μl外泌体，Control组在相同部位注射等量PBS，Sham组仅分离出神经，不进行其他操作。术后4周，运用Catwalk检测大鼠运动功能的恢复情况；运用电生理检测神经传导功能的恢复情况；马松染色检测各组手术侧的腓肠肌肌纤维面积；透射电镜观察神经纤维直径等超微结构变化；对坐骨神经损伤的相应脊髓节段进行免疫荧光染色，观察小胶质细胞和星形胶质细胞的活化数量。

Catwalk示Exosome组大鼠坐骨神经功能指数优于Control组（P＜0.05）。电生理示Exosome组大鼠的运动神经传导速度快于Control组（P＜0.05），且复合肌肉动作电位的振幅高于Control组（P＜0.05）。马松染色示Exosome组的腓肠肌肌纤维面积明显大于Control组（P＜0.05）。透射电镜示Exosome组和Control组的有髓神经纤维直径小于Sham组（P＜0.05），且Exosome组明显高于Control组（P＜0.05），Exosome组的神经纤维排列也较Control整齐。免疫荧光示，Exosome组和Control组的腰段脊髓中的IBA-1和GFAP阳性区域面积百分比较Sham组明显上调（P＜0.05），但Exosome组少于Control组（P＜0.05）。

坐骨神经损伤后，BMSC来源的外泌体促进了运动功能的恢复，其机制与促进轴突再生、缓解疼痛有关。

To investigate the role of bone marrow mesenchymal stem cell (BMSC)-derived exosomes in the repair process of sciatic nerve injury.

Twenty-four SD rats were randomly into three groups: control group, sham group, and exosome group. For inducing sciatic nerve injury, after exposing the sciatic nerve of each rat, the second level strength of microhemostatic forceps was used to clamp the nerve 5 mm above the sciatic nerve bifurcation for 3 times, 10 s for each time, with an interval of 5 s. In the exosome group, 5 μl of exosomes were injected into the subepineurium near the clamp injury. In the control group, 5 μl of PBS was injected in the same site. In the sham group, the nerve was just exposed without any other manipulation. At 4 weeks after surgery, Catwalk was used to detect the recovery of rat motor function. The function of nerve conduction was detected by electrophysiology. Masson staining was used to detect the area of gastrocnemius muscle fiber. The diameter of nerve fibers in each group was detected by transmission electron microscopy. Immunofluorescence staining for GFAP and IBA-1 was applied to demonstrate the positive area of microglia and astrocytes in the lumbar spinal cord segments.

The results of Catwalk showed that the sciatic function index in the exosome group was significantly better than that of the control group (P＜0.05). Electrophysiology showed that both the amplitude of compound muscle action potential and motor nerve conduction velocity were significantly higher than those of the control group (P＜0.05). The area of gastrocnemius muscle fibers detected by Masson staining in the exosome group was significantly larger than that of the control group (P＜0.05). Transmission electron microscopy showed that the cross area of the myelinated nerve fiber of the exosome group was bigger and in better shape than that of the control group (P＜0.05), but smaller than that of the sham group (P＜0.05). The percentages of positive GFAP area and IBA-1 area in the exosome group and control group were significantly larger than that of the sham group (P＜0.05), and they were significantly smaller in the exosome group than in the control group (P＜0.05).

After peripheral nerve injury, BMSC-derived exosomes can promote the functional recovery by promoting axon regeneration and pain relief.