Optimal location and time for neural stem cell transplantation into transected rat spinal cord.

Implanted neural stem cells (NSC) could improve neurological functions following spinal cord injury (SCI), but the optimal conditions for NSC transplantation are largely unknown, especially in transected spinal cord. This study investigated the effect and fate of NSC engrafted into spinal cords at different locations and time points following T(9) spinal cord transection. Engrafted NSC could survive and migrate in host spinal cords. Significant improvement in hindlimb locomotor functions associated with NSC survival was found in rats receiving NSC transplantation in the spinal cords rostral to the transection site at the subacute stage (7 days post operation), compared with those caudal to the transection site at the acute stage (at the time of injury). At 4 weeks post operation, CD68 immunohistochemical staining confirmed that macrophages were less in rostrally transplanted sites and in subacute groups than seen in caudal and acute transplanted rats. The present findings indicated that NSC transplantation into spinal cords rostral to transection site at the subacute stage is an optimal strategy for engrafted NSC survival and host behavioral improvement. It therefore would be available to the usage of NSC for the treatment of SCI in the future clinic trial.