Heterogeneity of cycling glial progenitors in the adult mammalian cortex and white matter

The heterogeneity and differentiation potential of mitotically active cells in the adult brain were studied by labeling adult rats with BrdU, and isolating an enriched population of cycling cells from neocortex and from subcortical white matter. The majority of this population isolated from either brain region labeled with O4, an early oligodendrocyte marker. In tissue culture, these O4(+) progenitors acquired galactocerebroside, a glycolipid of mature oligodendrocytes, but not GFAP, an intermediate filament of astrocytes, A minority population expressed the intermediate filament protein, vimentin, but not O4, This population expressed GFAP after several days in culture. A third population of cycling cells, expressing the gangliosides labeled with the A2B5 antibody, represented a minority population in subcortical white matter, but one of the major cycling populations in cortex, with substantial overlap with O4, Small populations of cycling NG2(+) cells also were observed. Thus, the cycling cells in the adult brain are heterogeneous, and the majority appear to belong to glial lineages. (C) 2001 John Wiley & sons. Inc.