血管内皮生长因子活化的细胞外基质对大鼠坐骨神经缺损的修复作用

EFFECTS OF VASCULAR ENDOTHELIAL GROWTH FACTOR GENE-ACTIVATED MATRIX ON REPAIR OF SCIATIC NERVE DEFECTS IN RATS

目的探讨以去细胞的周围神经细胞外基质(extracellular matrix,ECM)为支架,复合携带血管内皮生长因子(vascular endothelial growth factor,VEGF)的质粒DNA,桥接修复大鼠坐骨神经缺损的效果。方法30只雌性SD大鼠作为供体,用化学萃取方法获得去细胞的周围神经ECM支架,黏附携带VEGF的质粒DNA,制备VEGF基因活化基质(gene-activated matrix,GAM),用于体内实验。将30只雌性Wistar大鼠制备坐骨神经缺损动物模型,再随机分为三组,每组10只。A组用VEGF-GAM修复,B组用浸浴多聚赖氨酸的ECM支架修复,C组为自体神经移植修复。术后12周,采用激光共聚焦显微镜、光镜、透射电镜等形态学方法及神经电生理学方法评价再生神经功能。结果VEGF-GAM作为一种局部的基因缓释系统释放VEGF,表达12周以上。术后12周,A组前角运动神经元存活率为79.13%±2.53%,C组为75.26%±4.48%,二者比较差异无统计学意义(P>0.05);B组为56.09%±1.89%,A、C组均优于B组,且差异有统计学意义(P<0.01)。A组远端再生神经轴突数为13463±794个/mm2,较C组16809±680个/mm2差,但优于B组10260±1117个/mm2,差异均有统计学意义(P<0.01)。A组动作电位传导速度为16.44±1.65m/s,较C组23.79±2.75m/s差,优于B组12.87±1.42m/s,差异均有统计学意义(P<0.01)。A组腓肠肌湿重恢复率为71.40%±3.05%,较C组87.00%±1.87%差,优于B组50.00%±4.90%,差异均有统计学意义(P<0.01)。A组坐骨神经指数恢复至39.37%±4.81%,较C组26.27%±2.71%差,优于B组46.93%±2.96%,差异均有统计学意义(P<0.01)。结论VEGF GAM可促进大鼠坐骨神经功能的恢复,但效果差于自体神经移植。

Objective To evaluate an effect of the vascular endothelial growth factor （VEGF） gene-activated matrix （GAM） on repair of the sciatic nerve defect in rats. Methods The peripheral nerve extraeellular matrix（ECM） was harvested by the chemical extraction from 30 SD rats. The VEGF-GAM comprised of ECM and the plasmids encoding VEGF. Thirty adult Wistar rats were made as a model of the asciatic nerve defect and were randomly divided into the following 3 groups （n = 10）.. Group A （VEGF-GAM conduits）, Group B （ECM conduits）, and Group C （autografts）. At 12 weeks, the rats from each group were subjected to an inspection for the walking tract analysis and electrophysiological and histomorphological studies. Results The VEGF DNA could be retained in GAM, promoting the transgene expressing in the sciatic nerve, and more importantly, in the axotomized neurons in the spinal cord for 12 weeks. The motor neuron recovery rate in Group A （79.13%±2.53%） was similar to that in Group C （75.26%±4.48%, P〉0.05）, but significantly better than that in Group B （56. 09%±1.89%, P〈0.01）. The number of the regeneration axons in the distal sciatic nerve in Group A （13 463±794/mm^2） was significantly lower than that in Group C （16 809±680/mm^2, P〈 0.01）, but significantly higher than that in Group B （10 260±1 117/mm^2, P〈0.01）. The motor nerve conduction velocity in Group A （16.44±1.65 m/s） was significantly lower than that in Group C （23.79±2.75 m/s, P〈0. 01）, but significantly higher than that in Group B （12.8 ±1.42 m/s, P〈0. 01）. The recovery rate of the gastrocnemius muscle wet weight in Group A （71.40%±3.05%） was significantly lower than that in Group C （87.00%±1.87% ,P〈0. 01 ）, but significantly higher than that in Group B （50. 00%±4.90%, P〈0.01 ）. The sciatic nerve function index in Group A （39. 37%±4. 81%） was significantly lower than that in Group C （26.27%±2.71%, P〈0.01）, but significantly higher than that in Group B （46.93%±2.96%, P〈0.01）. Conelusion The results indicate that VEGF-GAM as a bridge can promote the functional recovery of the defected sciatic nerve in rats, but the effect is not so good as that by autografts.