延迟植入嗅鞘细胞修复成鼠的胸髓损伤

背景:脊髓损伤后在一定的微环境中有再生的能力。嗅鞘细胞兼具星形胶质细胞和许旺细胞的特性,具有促进脊髓轴突再生的能力。目的:制作成鼠胸髓损伤模型,观察嗅鞘细胞对损伤脊髓轴突再生的作用。设计:观察性实验。单位:中山大学附属第二医院。材料:实验于2001-01/2002-11在中山大学附属第二医院完成。20只成年SD雄性大鼠,体质量(380±20)g,由中山大学实验动物中心提供(机构许可证号:SYXK(粤)2004-0020)。低糖的DMEM培养液(L-DMEM,GibcoBRL公司)、胎牛血清(Hyclone公司)、MBP(髓磷脂碱性蛋白,Sigma公司)、抗神经生长因子受体抗体(Sigma公司)。应用随机数字表完全随机化分为细胞移植组和对照组,每组10只。方法:将成年SD大鼠麻醉断颈处死,无菌条件下取出完整嗅球分嗅神经。采用改良Allen法打击脊髓建立胸髓损伤模型。细胞移植组于损伤脊髓处注入10μL嗅鞘细胞悬液(2.5×1010L-1),对照组仅注入相同剂量DMEM/F12(1∶1)培养液。移植后6周通过组织学和免疫组织化学方法观察嗅鞘细胞对脊髓轴突再生的影响。主要观察指标:①抗神经生长因子受体抗体染色鉴定嗅鞘细胞。②髓磷脂碱性蛋白染色观察髓鞘的修复。③嗜银染色观察神经轴突再生。结果:细胞移植组有2只动物死亡,对照组有3只死亡,共15只大鼠进入结果分析。①细胞移植组可见损伤脊膜完整,较正常脊髓稍变细。苏木精-伊红染色见损伤区有多极细胞,且与脊髓组织有移行过度现象,说明存活的嗅鞘细胞与宿主融合良好。新生的轴突多呈束状,周围有小圆淋巴细胞浸润。嗜银染色可见再生轴突长入损伤区组织中,多与束状排列的多极细胞伴行;对照组脊髓损伤处明显变细,脊膜尚完整。苏木精-伊红染色见脊髓损伤区未见新生轴突。嗜银染色未见再生轴突。②细胞移植组可见多极细胞,多呈束状排列,胞浆内有大量抗神经生长因子受体抗体阳性颗粒存在,进一步证明嗅鞘细胞移植6周后仍然存活,且与宿主融合良好。髓磷脂碱性蛋白染色见损伤区有呈线状髓磷脂碱性蛋白阳性纤维,提示损伤区两端均有髓鞘样物质产生,且互相靠拢。同时多极细胞中也发现有髓磷脂碱性蛋白阳性物质存在,说明移植的嗅鞘细胞有产生髓鞘样物质的作用。对照组未见轴突再生。结论:嗅鞘细胞延迟植入成鼠打击伤后脊髓后,可存活并产生髓鞘样物质,促进宿主脊髓轴突再生。

Delayed transplantation of olfactory ensheathing cells for thoracic cord injury in adult rats

BACKGROUND: Spinal cord can regenerate after injury in certain microenvironment. Olfactory ensheathing cells (OECs)have the characteristics of astrocytes and Schwann cells and can accelerate the spinal cord axonal regeneration.OBJECTIVE: To make injured thoracic cord rat models and observe the effect of OECs on injured spinal cord axonal regeneration.DESIGN: Observational experiment.SETTING: Second Affiliated Hospital of Sun Yat-Sen University.MATERIALS: The experiment was performed at the Second Affiliated Hospital of Sun Yat-Sen University from January 2001 to November 2002.Totally 20 adult SD male rats with the body mass of (380±20) g were provided by Experimental Animal Center of Sun Yat-Sen University (number of institution license SYXK2004-0020). There were DMEM culture solution with low glucose (L-DMEM, GibcoBRL), fetal calf serum (FCS) (Hyclone), myelin basic protein (MBP) (Sigma) and nerve growth factor receptor antibody (Sigma). They were divided into cell transplantation group and control group by the method of random digits table with 10 in each group.METHODS: The adult SD rats were anaesthetized and decapitated to obtain the whole olfactory bulb and then isolate olfactory nerve with a sterile operation. Thoracic cord injury models were established by modified Allen method. 10μL OECs suspension (2.5×1010 L-1) was injected into injured spinal cord of the cell transplantation group, whereas DMEM/F12 (1:1) culture solution of the same dose was injected in the control group. The influence of OECs on spinal cord axonal regeneration was observed by histological and immunohistochemical method 6 weeks after transplantation.MAIN OUTCOME MEASURES: ①OECs were identified by nerve growth factor receptor antibody staining. ②Repair of myelin sheath was observed by MBP staining. ③Nerve axonal regeneration was observed by argentaffin staining. RESULTS: Two rats in the cell transplantation group and 3 rats in the control group died, so totally 15 rats were involved in the result analysis. ①In the cell transplantation group,injured spinal meninges were integrated,but spinal cord became thin as compared with the normal spinal cord. By hematoxylin-eosin (HE) staining, multipolar cells appeared in injured region and the cells were fused excessively with myeloid tissues. It proved that survival OECs were integrated well within the host. New axons were clustered in bundles and infiltrated by small round lymphocytes. By argentaffin staining, regenerated axons grew in tissues of injured region, which mostly accompanied with fascicular-arranged multipolar cells. In the control group, spinal cord became thin markedly and spinal meninges were integrated. No new axon appeared in the injured spinal cord by HE staining. No regenerated axon appeared by argentaffin staining, either. ②In the cell transplantation group, most multipolar cells were clustered in bundles. A mass of positive granules of nerve growth factor receptor antibody appeared in cytoplasm, which further verified that OECs still survived and integrated well within the host 6 weeks after transplantation. Linear MBP positive fibers appeared in the injured region by MBP staining,which indicated that myelin-like substance appeared and drew closely in both ends of injured region. At the same time,MBP positive substance also appeared in the multipolar cells, which illustrated that transplanted OECs could induce the occurrence of myelin-like substance. No regenerated axon was found in the control group.CONCLUSION: Delayed transplantation of OECs can survive and induce the occurrence of myelin-like substance in injured spinal cord of adult rats.