过表达microRNA-224骨髓间充质干细胞对大鼠坐骨神经损伤的作用及其机制研究*

目的 探讨过表达microRNA-224（miR-224）骨髓间充质干细胞（BMMSC）对大鼠坐骨神经损 伤的治疗效果及其机制。方法 将Sprague Dawley大鼠分为5组：假手术组、模型组、BMMSC组（坐骨神经损 伤+BMMSC）、LV-BMMSC 组 （坐骨神经损伤+LV-BMMSC） 和 miR-224-BMMSC 组 （坐骨神经损伤+ miR-224-BMMSC），利用钳夹法复制坐骨神经损伤模型，BMMSC组、LV-BMMSC组和miR-224-BMMSC组 大鼠分别于手术当天注射BMMSC、LV-BMMSC和miR-224-BMMSC。检测各组大鼠在手术当天、术后第12天 和第24天的BBB运动评分和坐骨神经功能指数（SFI）。采用Western blotting检测脑源性神经营养因子（BDNF）、 髓鞘碱性蛋白（MBP）和生长相关蛋白-43（GAP-43）的蛋白相对表达量，流式细胞术检测各组大鼠坐骨神经 的凋亡情况。结果 5组大鼠的BBB评分和SFI在不同时间、不同组间及变化趋势上有差异（P <0.05）。与模型组 比较，BMMSC组BBB评分升高，SFI降低（P <0.05）；与BMMSC组比较，miR-224-BMMSC组BBB评分升 高，SFI降低（P <0.05）。miR-224-BMMSC组坐骨神经组织BDNF、MAP和GAP-43蛋白相对表达量高于模型 组和BMMSC组（P <0.05）。miR-224-BMMSC组大鼠坐骨神经凋亡率低于模型组和BMMSC组（P <0.05）。 结论 过表达miR-224可以增强BMMSC对坐骨神经损伤的治疗作用，其机制与抑制BMMSC凋亡有关。

Protective effects of bone marrow mesenchymal stem cells overexpressing miR-224 on sciatic nerve injury in rats*

Objective To investigate the protective effects of bone marrow mesenchymal stem cells (BMMSC) over-expressing miR-224 on sciatic nerve injury in rats and the possible mechanisms. Methods Sprague Dawley rats were divided into sham group, model group, BMMSC group (sciatic nerve injury + BMMSC), LVBMMSC group (sciatic nerve injury + LV-BMMSC) and miR-224-BMMSC group (sciatic nerve injury + miR-224- BMMSC). The sciatic nerve injury was modeled and BMMSC, LV-BMMSC and miR-224-BMMSC were injected respectively into the latter three groups. The Basso, Beattie, Bresnahan Locomotor Rating Scale (BBB) score and sciatic function index (SFI) were measured on the day of operation, and 12 days and 24 days after operation. Western blotting was used to detect the expression of brain-derived neurotrophic factor (BDNF), myelin basic protein (MBP) and growth associated protein 43 (GAP-43), and the neuronal apoptosis of sciatic nerve in rats in each group was detected by flow cytometry. Results The BBB scores and SFI were different among the groups and altered at different time points (on the day of operation, and 12 days and 24 days after operation) with distinct changing trends (P < 0.05). The BBB score of the model group was lower than that of the sham group, while the SFI of the model group was higher than that of the sham group (P < 0.05). The BBB score of the BMMSC group was higher than that of the model group, while the SFI of the BMMSC group was lower than that of the model group (P < 0.05). The BBB score of the miR-224-BMMSC group was higher than that of the BMMSC group, while the SFI of the miR224-BMMSC group was lower than that of the BMMSC group (P < 0.05). The expression of BDNF, MAP and GAP43 in the miR-224-BMMSC group was higher than that in model group and BMMSC group (P < 0.05). The neuronal apoptosis rate of sciatic nerve in the miR-224-BMMSC group was lower than that in model group and BMMSC group (P < 0.05). Conclusion The miR-224 overexpression can enhance the therapeutic effect of BMMSC on sciatic nerve injury, and its mechanism is related to the inhibition of BMMSC apoptosis.