Changes Of GFAPin Injured Spinal Cord Of Adult Rats Following Xenotransplantation Of Microencapsulated Sciatic Nerve's Tissue

Objective: To study the recovery of function of injured spinal cord by xenotransplantation of microencapsulatrd Schwann cells,we observed the changes of GFAP after spinal cord injured and the changes after transplantation of microencapsulated sciatic nerve's tissue/cells by using immohistochemistry method.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. A total of 130 adult Sprague-Dawley rats were randomly divided into four groups: Group A,B,C and D. Ten rats of Group D were normal control. Forty animals in each group of C, B and A were performed a lateral hemisection of spinal cord at left T10 level,then gelatin sponge alone, with nerve's tissue/cells suspension and with microencapsulated nerve's tissue/cells were implanted into the injured area respectively. 3,7,14 and 28 days postinjury, 10 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, freezed,Samples were cut and processed using standard procedures for hematoxylin-eosin(HE) and Nissl staining. Using appropriate antibodies, sections were also stained immunohisto-chemically for glia fibrillary acidic protein(GFAP).Results: After SCI the number of the neurons reduced and the part of neurons contracted,the boundary of cell was obscure,there were a number of macrophagocytes surrounding injury distract,small cavity was observed in the gray matter of spinal cord. On the 14th day we observed the state of hypertrophy and hyperplasia of astrocytes. These changes were not seen evidently in Group A. On the 28th day the form of neurons in Group A generally resume normal appearance. GFAP positive reaction was observed on the 3st day postinjury and rose to its peak on the 14th day, which in Group A was inferior to that in Group B or C(P <0.01).The expression of GFAP decreased on the 28th day, but still there was superior than normal group.The expression of GFAP showed an increasing tendency after SCI, the number of positive cell ,the Volume Density (Vv),the Number Density (Nv), the Surface Density (Sv) and the average volume of cell(—V) were raised. On the 7th day the number of positive cell,Sv,Vv,Nv and —V in Group A differed significantly from it in Group B or C until the 14th day postoperatively(P <0.05). Compared to that in Group B or C,all the Sterological parameters were lower in Group A on the 28th day(P <0.01). Conclusion: The results indicate that xenotransplantation of micro-encapsulated sciatic nerve's tissue/cells can decrease the express of GFAP in astrocytes of injured spinal cord,and reduce glial scar caused by reactive astrogliosis.