微RNA-21对坐骨神经损伤大鼠模型神经再生的促进作用

Promoting effect of miRNA-21 on neural regeneration of injured sciatic nerve in rats

目的 验证微RNA-21对坐骨神经损伤大鼠模型神经再生的促进作用。方法 选取6~8周龄雄性Sprague-Dawley大鼠50只,体质量(220.3±20.5)(200~250)g。根据损伤模式和治疗方法将大鼠随机分为3组微RNA-21组20只大鼠,体质量(223.5±18.7)(200~250)g;绿色荧光蛋白(GFP)组20只大鼠,体质量(220.3±21.6)(200~250)g;正常组10大鼠,体质量(215.0±21.6)(200~250)g。将微RNA-21组和GFP组大鼠通过手术制作为坐骨神经损伤模型。采用神经导管对两组大鼠的坐骨神经缺损进行桥接治疗,同时于GFP组导管内注射GFP,于微RNA-21组导管内注射含有其编码序列的慢病毒载体逆行转染微RNA-21试剂。采用坐骨神经功能指数(SFI)、坐骨神经传导速度、伤侧与健侧腓肠肌质量比和腓肠肌组织学表现等指标对损伤的大鼠坐骨神经再生情况进行评价,并进行组间比较。采用SPSS 24.0软件对数据进行统计学分析;P<0.05为差异有统计学意义。结果 术后8周全部大鼠存活并接受评价。SFI为微RNA-21组-47.7±2.1,GFP组-59.4±3.7,两组差异有统计学意义(P<0.001);坐骨神经传导速度为正常组(30.2±1.6)m/s,微RNA-21组(16.5±1.3)m/s,GFP组(10.5±1.4)m/s,3组间差异均有统计学意义(均P<0.001);伤侧与健侧腓肠肌质量比为微RNA-21组0.82±0.02,GFP组0.55±0.06,两组差异有统计学意义(P<0.001);光学显微镜下可见两组大鼠腓肠肌均存在肌纤维萎缩,GFP组较微RNA-21组肌纤维萎缩加重。结论 逆行转染微RNA-21可显著促进大鼠坐骨神经损伤后轴突的再生及神经功能的恢复。

Objective To verify the promoting effect of miRNA-21 on neural regeneration of injured sciatic nerve in rats.Methods Fifty Sprague-Dawley rats[aged 6-8 weeks,weighted(220.3±20.5)(200-250)g]were included and divided into 3 groups according to the treatment:20 rats weighted(223.5±18.7)(200-250)g in miRNA-21 group,20 rats weighted(220.3±21.6)(200-250)g in green fluorescent protein(GFP)group and 10 rats weighted(215±21.6)(200-250)g in normal group.Sciatic nerve injury models were made in rats and were treated with nerve conduits filled with miRNA-21 over expressing vectors and nerve conduits filled with GFP vectors in groups of miRNA-21 and GFP,respectively.Wound were closed after sciatic nerve exposure without any treatment in rats in normal group.The effects were evaluated by sciatic nerve function index(SFI),sciatic nerve conduction velocity,mass ratio of injured and healthy gastrocnemius muscle and histological appearance of injured gastrocnemius muscle and compared among the groups.Data were statistically analyzed using SPSS 24.0 and the value of P<0.05 was considered as statistically significant.Results All rats survived 8 weeks after operation and were evaluated.SFI was-47.7±2.1 in miRNA-21 group and-59.4±3.7 in GFP group,and the difference was statistically significant(P<0.001).The conduction velocity of sciatic nerve was(30.2±1.6)m/s in normal group,(16.5±1.3)m/s in miRNA-21 group and(10.5±1.4)m/s in GFP group,and all the differences among the 3 groups were statistically significant(all P<0.001).The mass ratio of injured and healthy gastrocnemius muscle was 0.82±0.02 in miRNA-21 group and 0.55±0.06 in GFP group,and the difference was statistically significant(P<0.001).Under the light microscope,muscle fiber atrophy was observed in the gastrocnemius muscle of rats in both groups of miRNA-21 and GFP,and was aggravated in GFP group compared with miRNA-21 group.Conclusion MiRNA-21 over expressing vectors can effectively promote axonal regeneration and functional recovery of injured sciatic nerve in rats.