Myelination by cryopreserved xenografts and allografts in the myelin-deficient rat.

This study examined the ability of freshly prepared and cryopreserved canine oligodendrocytes to myelinate axons following transplantation into the myelin deficient (md) rat. The effects of immunosuppression, and the age of the donor tissue, were also examined. Canine glial cells, dissociated from the spinal cords at E50, P2, P20, P28, and P50, were transplanted into the spinal cords of myelin-deficient rats as single cell suspensions. Both cryopreserved (E50 and P28) and freshly dissociated tissue (P2, P20, and P50) were able to form myelin within 13 days of transplantation. Cells from younger donors (< P20) myelinated more md axons than those from older donors. In those rats which received xenografts and which were treated with cyclosporin A there was markedly less cellular infiltration than in untreated animals. For comparison with these xenografts, fresh and cryopreserved adult rat glia were also transplanted. Eight days after transplantation, myelination by allografts of cryopreserved rat glia was qualitatively similar to that produced by freshly prepared cells. These results show that oligodendrocytes transplanted as xenografts are capable of myelinating rat axons, and that cryopreserved glia retain their capacity to myelinate in vivo.