Abstract : Experimental transplantation in rodent models of CNS demyelination has led to the idea that Schwann cells may be candidates for cell therapy in human myelin diseases. Here we investigated the ability of Schwann cells autografts to generate myelin in the demyelinated monkey spinal cord. We report that monkey Schwann cells derived from adult peripheral nerve biopsies retain, after growth factor expansion and transduction with a lentiviral vector encoding green fluorescent protein, the ability to differentiate in vitro into promyelinating cells. When transplanted in the demyelinated nude mouse spinal cord, they promoted functional and anatomical repair of the lesions (n = 12). Furthermore, we obtained evidence by immunohistochemistry (n = 2) and electron microscopy (n = 4) that autologous transplantation of expanded monkey Schwann cells in acute lesions of the monkey spinal cord results in the repair of large areas of demyelination; up to 55% of the axons were remyelinated by donor Schwann cells, the remaining ones being remyelinated by oligodendrocytes. Autologous grafts of Schwann cells may thus be of therapeutic value for myelin repair in the adult CNS.