FETAL NEURAL GRAFTS AND REPAIR OF THE INJURED SPINAL-CORD

Solid or suspension grafts of fetal spinal cord (FSC), caudal brainste m (FBSt), neocortex (FNCx) or a combination of either FSC/FNCx or FSC/ FBSt were placed into cavities produced by static loading (i.e., compr ession) of the spinal cord of adult cats two to 30 weeks after injury. Extensively vascularized, viable graft tissue was found in all animal s with the exception of two cats which showed active rejection of thei r transplants. Surviving grafts showed many immature characteristics 6 -9 weeks after transplantation. However, by 20-30 weeks, FSC and FBSt grafts were more mature. Grafts integrated with the host gray and whit e matter and neuritic processes from both host and graft were seen cro ssing the host-graft interface. Host calcitonin gene related peptide ( CGRP)-like immunoreactive axons could be traced into FSC and FBSt graf ts. A more restricted ingrowth of host serotonin (5-HT)-like immunorea ctive fibers was seen in FSC grafts. Our results suggest that the capa city of homotypic transplants to promote recovery of function is great er than heterotypic transplants. Additionally, it appears that the fun ctional capacity of the graft depends upon graft survival, the time in terval between injury and transplantation, and whether or not the lesi on cavity was debrided prior to grafting.