The Effect of Human Neural Stem Cells on Neural Regeneration According to Transplantation Timing A Rat Spinal Cord Injury Model

Animal studies have consistently shown that neurologic recovery is enhanced by early decompression, but until now there is no standard regarding the timing of stein cell transplantation in spinal cord injury (SCI) animal model. The purpose of this study is to determine the effects of human neural stem cells (hNSCs) on neural regeneration according to the transplantation timing in a rat SCI model. We selected complete transaction model for preventing spontaneous healing on injured cord. Control group (n = 9) was treated with only media, whereas subacute group (n = 9) was transplanted with both media and hNSCs on 9 days post-SCI. Chroni. c group (n = 9) was transplanted with both media and the hNSCs on 28 days post-SCI. We evaluated the immunohistochemistry using pseudorabies virus (PRV) neurotracing and Basso-Beattie-Bresnahan locomotor scale. Immunohistochemistry showed no neural cells or NSC staining in control group. However, there was some glial cell staining in the subacute and chronic groups. More PRV was detected in chronic group than in controls, but the differences were not statistically significant. Also, PRV was detected in subacute group and this finding was statistically significant (P = 0.048). Basso-Beattie-Bresnahan locomotor scale was not significant when chronic group was compared with control one. However, there were significant changes in acute group (right: P = 0.041 and left: P = 0.015). When transplantation of hNSCs is delayed after SCI, the neurologic recovery was diminished. Therefore, these data suggest that NSC transplantations should be performed during the subacute phase after a SCI to achieve maximum potential recovery.