| Objective:The cell transplantation is an important research direction for treating spinal cord injury (SCI). To explore the role of transplantation of microencapsulated rabbit Schwann cells for spinal cord regeneration, we observed basic fibroblast growth factor (bFGF) expression and movements recovery after transplantation of microencapsulated Schwann cells, which had the effect of immunoisolation, in rats subjected to hemisection injury of spinal cord.Methods:Under sterile conditions, the sciatic nerves taken out from rabbits were digested with mixed enzymes and were made into Schwann cells suspension. Then we used air-jet method to make Schwann cells microcapsule. Using the same method, empty microcapsules were made. Eighty Sprague Dawley rats were randomly divided into four groups:cell group(n=25),empty microcapsule group (n=25,microcapsule group(n=25)and normal group(n=5). In the first three groups, the rats underwent right hemisection injury of the spinal cord at the T10 level, into which were respectively implanted with gelatin sponge with 10μL Schwann cells suspension(cell group), gelatin sponge with 10μL empty microcapsule(empty microcapsule group) and 10μL microencapsulated Schwann cells(microcapsule group). The rats in normal group were left intact. After operation, we observed hindlimb movements recovery in rats with the Basso, Beattie, and Bresnahan (BBB) scale, and made spinal cord paraffin sections. At 1,3,7,14 and 28 days, the rats were perfused with saline followed by fixing in 4% paraformaldehyde, spinal cord tissues were obtained from the centre of the injury, in the cell group,empty group and microcapsule group, or the equivalent site in the normal group. All tissues underwent routine paraffin sections. Pathological changes were observed by using hematoxylin-eosin and Nissal staining; bFGF expression was quantified by using immunohistochemical staining and image analysis system.Results:After SCI, the rat right hindlimb affected paralysis immediately, the BBB score was zero. Locomotor function of rat hindlimbs in each group gradually got differently recovery after operation, but all experimental groups did not get normallevel. At 7,14 and 28 days following implantation, in microcapsule group, hindlimb movements recovery was better and the BBB scores were significantly higher than those in cell and empty microcapsule groups (P<0.05 or P<0.01). Through pathological examination, it were observed that a great deal of neurophils and macrophages infiltrated into the injury zone, while glial cells proliferated, at 3rd day. The cells infiltration was significantly lower that in microcapsule group; however glial cells proliferation was higher than that in cell and empty microcapsule groups. At 7th day, a lot of glial cells proliferated, nerurophils and macrophage hardly infiltrated in the microcapsule group, but some nerurophils and macrophages could been observed in the cell group and empey microcapsule group. bFGF positive products were mainly distributed in cytoplasm of the spinal neuron and nucleus of glial cell. The numbers of bFGF positive glial cells mainly appeared surrounding the SCI site on days 1,3,7, and rose to its peak on day 3; bFGF positive products began to appear in neuronal cells on day 14, and they in microcapsule group were significantly higher than that in cell group and empty microcapsule group. From then on, the bFGF expression was significantly decreased in each group.Conclusion:These indicated that transplantation of microencapsulated Schwann cells can inhibit the immunological rejection after xenotransplantation, suppress inflammatory reaction, increase the expression of bFGF, improve hindlimb movements recovery and spinal cord regeneration after SCI.
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