嗅鞘细胞移植促进急性脊髓损伤的修复作用

目的研究嗅鞘细胞(OEG)移植后在体内存活情况以及对大鼠脊髓损伤长期的修复作用.方法用新生Wistar大鼠嗅球做OEG培养,大量增殖并标记.80只大鼠,随机分为4组,每组20只.A、B、C组以250 mm·g打击T13脊髓致运动诱发电位和体感诱发电位完全消失,A组在打击区中央用尖刀横行切断脊髓;D组仅做与A、B组相同节段的椎板减压,不挫伤脊髓.A、B组在脊髓远近断端距离挫伤区边缘1 mm的脊髓中线上,深度分别为1.75、1.5、1.0、0.5 mm处,各注入200 000个OEG;C组用同样的方法注射等量的DMEM培养液;D组不做处理.术后观察脊髓功能恢复情况(BBB运动功能评分法)和体重变化.术后24周取脊髓标本,做HE染色、嗜银染色、抗神经原纤维(NF)免疫组化染色、荧光显微镜下观察Hoechst标记的OEG在体内存活情况.结果手术后4周,A、B、C组开始有运动功能恢复,术后4～24周BBB运动功能评分A、B组均高于C组(P＜0.01),16周以后BBB评分变化较小.HE染色A、B两组脊髓损伤区结构紊乱,纤维走行方向扭曲不一致,细胞数目较多,C组大鼠脊髓损伤段常有明显空洞存在,纤维含量少且扭曲.嗜银染色和免疫组化抗NF染色显示无论在损伤区还是损伤头、尾端,A、B组神经纤维数量多于C组,但都少于相同节段的D组(P＜0.01).荧光显微镜下观察到Hoechst标记的OEG大量存在于脊髓损伤段周围.术后各组大鼠均出现体重减轻.术后2周,D组大鼠体重恢复至术前重量,此后逐渐增加.术后4周,A、B、C组大鼠体重降至最低,与D组(Sham组)比较差异有显著性(P＜0.01);此后,A、B组大鼠体重逐渐增加,而C组大鼠体重增加不明显;A、B组大鼠体重与C组比较差异有显著性(P＜0.05).结论OEG移植具有一定促进脊髓损伤神经纤维再生和功能恢复的作用.

Repair of acute spinal cord injury promoted by transplantation of olfactory ensheathing glia

OBJECTIVES: To observe olfactory ensheathing glia (OEG) survival and repair in vivo for spinal cord injury after OEG transplantation. METHODS: The OEG was cultured with the olfactory bulb of Wistar neonate rats. The spinal cords contusion was made in group A, B, and C with the New York University impactor, then complete transection was performed in the contusion area in group A. OEG labeled by Hoechst was transplanted in group A and B. In group C, DMEM were injected. In group D, laminectomies were done without cord contusion and transection. The functional recovery of the spinal cord injury Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale scores] and changes of body weight were observed. The tissue sections were done 24 weeks postoperatively. HE staining, neurofibril (NF) immunohistochemical staining, and silver staining were performed respectively to observe the pathologic changes and axon regeneration. The survival of OEG labeled by Hoechst was observed under the fluorescence microscope. RESULTS: Locomotive behaviour improved 4 weeks postoperatively. The BBB locomotion scores of group A and B were significantly higher than that of group C in all periods (from 4 weeks to 24 weeks) (P < 0.01). Sixteen weeks after operation, the BBB locomotion scores became stable and showed no change. HE staining showed that the area of spinal cord injury was disorder and the number of nerve cell was more in group A and B. In group C, there was the obvious cavum and few wring nerve fiber in the area of spinal cord injury. The nerve fibers innervated to the injuried area in group A and B were more than that of group C, but less than that of group D. A great number of OEG labeled by Hoechst were observed around spinal injuried area under fluorescence microscope. After operation, the body weight reduced in every group. The body weight of group D had recovered after 2 weeks and gradully increased. After 4 weeks, the body weight in group A, B, and C decreased to the minimum and were significantly less than that of group D (P < 0.01). After this, body weight in group A and B increased and was significantly more than that of group C (P < 0.05). CONCLUSIONS: OEG transplantation can promote the axons regeneration and the recovery of locomotion function in experimental spinal cord injuries.