| Objective Transplantation of peripheral nerve can enhance neuronal survival,axonal regeneration and functional rehabilitation after spinal cord injury (SCI). Barium-alginate microcapsules, which reveal an immunoisolation effect, make the xenotransplantation be possible. Here, the pretreated sciatic nerve tissue/cells from rabbit were microencapsulated and transplanted into the injured site of spinal cord in adult Sprague-Dawley (SD) rats. The alterations in T lymphocyte subsets of these SD rats were observed. And the possible mechanism of the rehabilitation induced by the transplantation of the microencapsulated xeno-sciatic nerve tissue/cells treated SCI were discussed.Method Experiments were performed in 8 adult rabbits and 88 adult SD rats of either sex. All of the SD rats were randomly divided into three groups: Group A (transplantation of microencapsulated xeno-sciatic nerve tissue/cells, n=40), Group B (transplantation of xeno-tissue/cells suspension, n=40) and Group C (control group, n=8). After dividing, BBB score was enforced on right hindlimb of all rats. Bilateral sciatic nerves pretreated from rabbits were dissected under aseptic condition and made into nerve tissue/cells suspension. Following centrifugation at a low speed, the tissue/cells were mixed with 1.5% sodium alginate solution, which was then extruded into 20 mmol/L barium chloride solution by using a droplet generation device, forming microencapsulated sciatic nerve tissue/cells suspension. Group A and B were performed a right hemisection of spinal cord at T10 level and subsequently transplanted with the gelatin sponge sticking 10μl microencapsulated nerve tissue/cells suspension and the gelatin sponge sticking 10μl tissue/cells suspension respectively. On the 1st,3rd,7th,14th and 28th days postoperatively, 6 SD rats in group A and B, respectively and randomly, were subjected to behavioral testing using a Basso, Beattie and Bresnahan (BBB) scoring system. Peripheral blood were collected from 8 SD rats in group A and B, respectively and randomly, by tail cutting on the 1st,3rd,7th,14th and 28th days postoperatively and the number of CD4~+ and CD8~+ T lymphocyte subsets were taken account of by using the flow cytometer. Same operations were performed in the 8 rats of group C. Result After operation, an increase was found in CD4~+ T cells of group B on the 3rd day postoperatively, comparing with group C (P<0.05). This increase became significant on the 7th,14th and 28th days postoperatively; the number of CD8~+ T cells increased comparing with group C on the 7th,14th and 28th days postoperatively(P<0.05). The difference of the number of CD4~+ T cells and CD8~+ T cells between group A and C does not possess statistic significance on each time phase. The difference of the number of CD4~+ T cells between group A and B was distinct on the 7th,14th and 28th days postoperatively, meanwhile the number of CD8~+ T cells of group B was higher than their counterpart in group A on the 7th,14th and 28th days postoperatively. BBB score of locomotive function was normal in group A, B and C before surgery, however it became low and no difference among each group on the 1st, 3rd, 7th days after SCI. Subsequently, the comparison between Group A and B existed a difference on the 14th days postoperatively (P <0.05). The score of Group A was significantly superior to that of Group B on the 28th days postoperatively, whose difference was remarkable (P <0.01), but them didn't reach the normal level. The locomotive function of right hindlimbs of all rats got recovered to a greater or less extent, but Group A was the best.Conclusion: microencapsulated sciatic nerve tissue can prevent the rat's CD4~+ T and CD8~+ T cells from activation and proliferation and improve the rehabilitation of locomotive function of hind limb of the rats with SCI.
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