| Neurons in the adult mammalian lesioned central nervous system(CNS) are not able to regenerate axons by themselves, and damaged neuronal pathways can not be reconstructed, Which results in permanent functional loss of the CNS. However, when a peripheral nerve is injured and reconnected, axons regenerate successfully into the distal stump eventually leading to a considerable degree of functional recovery. .Therefore, to look for the method of promoting axonal regeneration in the CNS has been concerned by neurologists for many years. They found that the microenvironment may be one of the most important factors which affect axonal regeneration in the CNS. It is different environments that lead to complete distinctness in axonal regeneration between peripheral nerve and axons in the CNS. Schwann cells are the important factor which determine the microenvironment in the peripheral nerve. Recently, there have been many studies on Schwann cell grafts promoting regeneration of axons in the CNS. It is hoped that transplantation of Schwann cells will bring a new prospect of regeneration hi the CNS. The purpose of the present study was to observe the presence of Schwann cells and the regeneration of AchE fibers hi the brain by transplanting Schwann cells in the lesioned Septo-hippocampal Cholinergic Pathway in order to find out the correlation between Schwann cells and regeneration of the CNS.This experiment was devided into two parts. In the first part, Sciatic nerves of 1-3 clays old Si) rats were taken out in 10 cases. The Schwann cells were cultured and purified by modified repeat-explaritation , and fibroblastic cells were removed by rapid trysinization , differential adhesion and anti-mitosis methods. The Schwann cells were identified by indirectly immunocytochemistry with mouse anti-S-100 protein McAb. In the second part, lesions of Septo-hippocampal Cholinergic Pathway were made by method firstly introduced by Kromer (1985 ) .After that, the SC suspension grafts were injected into the lesion site. 72 SD rats were randomly devided into 4 groups: 1 week, 2week, 4 week and 6 week after transplantation. And every group was randomly devided into 3 groups: early transplantation (SCs were transplanted at the lesion time) , late transplantation(SCs were transplanted at 6 days post-damaging) and control groups, in that,animals were only injected culture medium in the brains. The samples of each rat were taken for HE and AChE stain, and were stained with Anti-LNGFr antibody for immunohistochemistry. The lesioned volumes were also measured.The result showed that the purity of Schwann cells was more than 95% ultimately. Schwann cells were long spindle shape and have obvious narrow elongated nucleus. In S-100 immunocytochemistry, Sc showed brown. The defect volume of every group is silimar at 1 week post-grafting. Those of both early transplantation groups and late transplantation groups are much smaller than that of control groups. The transplanted Sc expressed LNGFr at 2 weeks post-grafting. It reached the peak at 4 weeks and declined at 6 weeks. The early transplantation groups and late transplantation groups have the similar expressions. In fiber growth analysis, transplanted animalspresented AChE-positive fibers in the lesion sittx Sc grafts ;mcl around Sc grafts. Jn early transplantation groups ,these fibers were already visible at 2 weeks post-grafting. At 2 and 4 weeks post-transplantion, there is an increase in fiber density in the grafted area. The density of regenerated fibers began to lower down at 6 weeks post-transplantion; In late transplantation groups, AChE-positive fibers could be found at 1 week post-transplantion and were increasing in the next 5 weeks; In control groups, there were few AChE-positive fibers in the lesion site. At 4 week post-grafting, the AChE staining intensity was also analysed in the CA1,CA3 and dentate gyrus region at 0.5mm, 1.5mm and 2.5mm from the lesion, which revealed a significantly greater fiber density in the grafted animals compared to the lesion but non-graf...
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