The origin of remyelinating cells in the central nervous system

A clear understanding of the cellular events underlying successful remyelin ation of demyelinating lesions is a necessary prerequisite for an understan ding of the failure of remyelination in multiple sclerosis (MS). The potent ial for remyelination of the adult central nervous system (CNS) has been we ll-established, However, there is still some dispute whether remyelinating oligodendrocytes arise from dedifferentiation and/or proliferation of matur e oligodendrocytes, or are generated solely from proliferation and differen tiation of glial progenitor cells. This review focuses on studies carried o ut on remyelinating lesions in the adult rat spinal cord produced by inject ion of antibodies to galactocerebroside and serum complement that show: (1) oligodendrocytes which survive within an area of demyelination do not cont ribute to remyelination, (2) remyelination is carried out by oligodendrocyt e progenitor cells, (3) recruitment of oligodendrocyte progenitors to an ar ea of demyelination is a local response, and (4) division of oligodendrocyt e progenitors is symmetrical, resulting in chronic depletion of the oligode ndrocyte progenitor population in the normal white matter around an area of remyelination. Such results suggest that repeated episodes of demyelinatio n could lead to a failure of remyelination due to a depletion of oligodendr ocyte progenitors. (C) 1999 Elsevier Science B.V. All rights reserved.