Transplanted CG4 Cells (an Oligodendrocyte Progenitor Cell Line) Survive, Migrate, and Contribute to Repair of Areas of Demyelination in X-Irradiated and Damaged Spinal Cord but Not in Normal Spinal Cord

In this study, we have examined the behavior of alac-Z-transfected O-2A progenitor cell line, CG4, following transplantation into normal and X-irradiated adult rat spinal cord, and we have also addressed the issue of whether CG4 cells transplanted remotely from ethidium bromide-induced demyelinating lesions in both X-irradiated and nonirradiated spinal cord are able to contribute to their repair. Following transplantation into X-irradiated spinal cord, CG4 cells survive, divide, and migrate extensively. The migration occurs mainly within the parenchymal tissue of the cord without preference for white or gray matter. Moreover, CG4 cells migrating away from their point of introduction are able to enter areas of demyelination and remyelinate the demyelinated axons therein. In contrast, when CG4 cells are transplanted into nonirradiated spinal cord, their survival is limited to areas of damage created by the injection procedure. The CG4 cells do not survive in undamaged, nonirradiated spinal cord. When transplanted remotely from areas of demyelination they are unable to traverse intervening areas of normal white matter, although they may enter lesions if transplanted into their close vicinity. These results have important implications for the development of potential therapeutic strategies for the treatment of multifocal demyelinating disorders that are based on glial cell transplantation.