胚胎脊髓细胞悬液在大鼠损伤脊髓中的突触发育过程

目的　观察分析胚胎脊髓细胞悬液在损伤脊髓移植区中的突触发育过程。　方法　对 4 2只 Wistar成年大鼠以改良 Allen法 (10 g× 5 cm)打击脊髓 ,3天后将孕 14天 (E14 ) 5只胚胎脊髓细胞悬液 (FSCS) 2 0 μl植入损伤空腔 ,移植后 2、4、6、8、10和 12周 ,以组织学、免疫组织化学观察移植物成活、分化及其与宿主之间关系。　结果　移植区成神经细胞最先展示了胞质突起 ,随之出现了低电子密度的突触前后膜 ,突触前、后膜电子密度逐渐增高形成良好的致密突起。突触小泡数量和种类逐渐增多 ,突触小泡有圆形清亮小泡、椭圆形小泡、颗粒状小泡和扁平小泡 - f型。突触的连接方式由单个的胞体 -树突突触 ,出现多个的胞体 -树突和树突 -树突突触。同时 ,移植成神经细胞、成少突胶质细胞及成星形细胞的细胞器日渐完善 ,细胞功能活跃。血脑屏障也随之出现。移植区可见神经微丝 (NF)、组织胺 (5 - HT)、降钙素基因相关肽 (CGRP)、胶原纤维酸性蛋白 (GFAP)阳性纤维。　结论　胚胎脊髓细胞悬液在成年大鼠损伤脊髓内可发育为成熟的突触 ,显示了 FSCS与宿主脊髓重建突触方式的信息交换的潜在可行性。

SYNAPSES DEVELOPING PROCESS OF NEUROBLASTS AFTER ACUTE SPINAL CORD TRANSPLANTATION IN RATS

OBJECTIVE: To explore the potential possibility of synaptic connection and 3D adhesion between fetal spinal cord cell suspension (FSCS) and host, and to observe the synapses developing process of FSCS transplantation. METHODS: Spinal cord injury model produced in 42 Wistar rats on T7 by use of modified Allen's impact method (10 g x 5 cm); 3 days after injury, 20 microliters FSCS with a density of 1 x 10(5)/microliter prepared from E14 rat were injected into the epicenter of the traumatized cavity. Animals were sacrificed after 2, 4, 6, 8, 10 and 12 weeks of transplantation, the graft survival, its differentiation and integration with the host were observed by light and electronmicroscopic study as well as immunohistochemical assay (NF, GFAP, CGRP, 5-HT). RESULTS: In the transplantation area, the neuroblasts stretched out the terminal endings 4 weeks after implantation, followed by the presenting of the pre- and postsynaptic membrane. After 8 weeks, the dense or developed projections were observed in the pre- and postsynaptic membrane; the synaptic cleft filled with the high electron dense substance. All the spherical clear vesicles, granular vesicles, elliptical vesicles and flattened-f type vesicles were seen under the electronmicroscope. After 10 weeks, the axosomatic, dendrosomatic, dendro-dendritic, axo-axonic, dendro-axonic synapses coexisted. Light microscopy showed that the graft cell grew gradually. Immunohistochemical assay showed that NF, 5-HT, CGRP and GFAP positive fibers were in the graft. Synapses, gliafibers and blood brain barrier integrated each other. CONCLUSION: (1) The transplanted FSCS can develop mature synapses with miscellaneous synaptic vesicles in the acute injured spinal cord, host injury cavity wall may induce the FSCS into 3D adhesion. (2) Co-existence of different type of synapse and the immunohistochemistry findings indicate the possibility of synaptic connection between FSCS and host.