| Objective Transplantation of peripheral nerve or Schwann cells can enhance neuronal survival,axonal regeneration and functional recovery after spinal cord injury (SCI). Barium-alginate microcapsules, which develop an effective immunoisolation system, makes it possible to overcome the immune rejection in xenotransplantation. Here the effects of transplantation of microencapsulated sciatic nerve's tissue/ cells from rabbits on the regeneration of hemisected spinal cord in adult rats were observed. Methods Bilateral sciatic nerves of rabbits were dissected under sterile conditions and made into nerve's tissue/cells suspension. Following centrifugation, the tissue/cells were mixed with 1.5% sodium alginate solution. The mixture was then extruded using a droplet generation device into 20mmol/L barium chloride solution to form barium-alginate capsules. Empty microcapsules without nerve's tissue/ cells were made using the same method. A total of 80 adult Sprague-Dawley rats were randomly divided into four groups: Group A,B,C and D.Five rats of Group A were normal control. Twenty-five animals in each group of B, C and D were performed a lateral hemisection of spinal cord at left T10 level,then gelatin sponge alone, with empty microcapsules and with microencapsulated nerve's tissue/cells were implanted into the injured area respectively. 1,3,7,14 and 28 days postinjury, five rats of each group in B, C and D as well as the normal rats were anesthetized and perfused transcardially with 4% paraformaldehyde. The thoracic cord including the injured site and the spinal cord of the normal rats at corresponding level were removed, postfixed and embedded in paraffin. Samples were cut in 5-μm-thick transverse sections and processed using standard procedures for hematoxylin-eosin(HE) and Nissl staining. Using appropriate antibodies, sections were also stained immunohisto- chemically for growth-associated protein-43 (GAP-43) and neurofilament-200 (NF200).In addition, the locomotor function of the left hindlimbs of the rats in Group B,C and D was detected by Tarlov and BBB scales. Results After SCI the number of the neurons reduced and the Nissl substance lost or dissolved. On the 14th day the number of the Nissl stained neurons rose remarkably and their volume increased. These changes were seen most evidently in Group D(P <0.05).On the 28th day the Nissl substance in Group D generally resume normal appearance and the number of the Nissl stained neurons was much more than it was in Group B or C (P <0.01).GAP-43 positive reaction was observed on the 1st day postinjury and rose to its peak on the 14th day, which in Group D was superior to that in Group B or C(P <0.01).The expression of GAP-43 decreased on the 28th day, but still there was a significant difference among the three groups(P <0.05). The expression of NF200 showed an increasing tendency after transplantation, the Volume Density (Vv),the Number Density (Nv) and the Surface Density (Sv) were raised. On the 7th day Sv in Group D differed significantly from it in Group B or C, while the similar change of Vv and Nv in Group D didn't occurred until the 14th day postoperatively(P <0.05). Compared to that in Group B or C,all the Sterological parameters were higher in Group D on the 28th day(P <0.01).The locomotor function also recovered, especially in Group D. Conclusion The results indicate that xenotransplantation of micro- encapsulated sciatic nerve's tissue/cells can promote the spinal cord regeneration and improve the functional recovery. |
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