直流电场诱导神经干细胞桥接横断脊髓的实验研究

The inducing effect of direct current field on embryonic neural stem cells for neural reconstruction after spinal cord injury

目的:探讨直流电场(direct current field,DC)诱导神经干细胞(neural stem cells,NSCs)桥接横断脊髓的作用。方法:将54只雌性成年SD大鼠随机分为脊髓损伤(spinal cord injury,SCI)组、NSCs移植组、NSCs移植联合直流电场诱导组(DC+NSCs组),各组分7,14,28d三个时间点取材,HE染色观察神经纤维再生情况,透射电镜下观察脊髓白质内髓鞘结构变化,免疫荧光染色检测髓磷脂碱性蛋白(myelin basic protein,MBP)表达变化。结果:在光镜下,DC+NSCs组神经纤维较其他两组都多,排布均匀且走行较规则,部分纤维穿越损伤脊髓断端两侧。在电镜下,DC+NSCs组髓鞘松散程度明显减轻,部分髓鞘结构规整,排列有序,线粒体肿胀减轻,微管空泡样变较轻,可发现大量突触,薄髓的再生髓鞘明显增多。DC+NSCs组大鼠脊髓组织中可见直径大小不等的MBP阳性的圆形结构,MBP阳性表达最多,较其他两组有显著性差异(P<0.01)。结论:直流电场诱导NSCs治疗SCI可以促进损伤处脱髓的轴突再髓鞘化和MBP的表达,促进神经纤维再生,从而起到桥接横断脊髓的作用。

Objective： To explore the inducing effect of direct current field on embryonic neural stem cells for neural reconstruction after spinal cord injury. Methods： 54 adult female SD rats were randomly divided into three groups： spinal cord injury group （SCI）, NSCs transplantation group （NSCs）, NSCs transplantation combined with direct current field-induced group （DC＋NSCs）. The injury spinal cords in each group were obtained in 7 d, 14 d, 28 d, respectively, analyzed the regeneration of nerve fibers by HE staining through light microscope and observed structural changes of the myelin sheath in spinal cord white matter under transmission electron microscope. Myelin basic protein expression was detached through immunofluorescence staining. Results： Under the light microscope, nerve fibers in DC＋NSCs group were observed more than those in the other two groups and well-distributed and regular, some fibers across both of the injured spinal cord stumps. In DC＋NSCs group, the extent of myelin loose reduced distinctly, the structure of myelin was clear and neat and the arrangement orderly, the swelling of mitochondria became lightened, vacuolar degeneration of microtubules got less, a lot of synapses were found, thin myelin sheath regeneration increased significantly through electron microscope. A lot of MBP-positive, different sizes and roundish grains were visible in spinal cord tissues of rats in DC＋NSCs group. And the expression of MBP in DC＋NSCs group was most, and difference between DC＋NSCs group and other groups respective was obvious （P0.01）. Conclusion： The treatment of NSCs transplantation with direct current field-inducing helped axons off the marrow in injured spot remyelination, the expression of MBP to promote and nerve fiber regeneration, and thus played a bridging role of spinal cord transaction.