Re-evaluation of nestin as a marker of oligodendrocyte lineage cells

Maturation of oligodendrocyte progenitors (O2A) is characterized by morphol ogical changes and the sequential expression of specific antigens leading t o the formation of myelin membrane. Monoclonal antibodies A2B5, A007, anti- vimentin, and anti-galactocerebroside, recognize oligodendroglia at differe nt stages of development. The neuroepithelial precursor marker nestin is al so expressed by the oligodendroglial lineage; we have used enriched populat ions of progenitors isolated from neonatal rat brain cultures to further ex amine the cellular distribution of this intermediate filament protein. The phenotypic distribution of nestin positive cells among the oligodendrocyte Lineage showed that 65% reacted with A2B5, whereas only 5% were A007(+), an d 4% galactocerebroside(+)'. The remaining 25% of the cells were not labele d and had small cellular bodies devoid of processes, characteristic of the pre-O2A progenitor. Further analysis of the nestin(+) population showed tha t the majority of the cells were also vimentin(+). Antibody-dependent compl ement mediated cytolysis of A2B5(+) (O2A cells) and galactocerebroside(+) ( mature oligodendrocytes) cells left a population of nestin(+) cells that we re induced to proliferate in the presence of growth factors and to differen tiate into A2B5(+) and galactocerebroside(+) cells. Proliferating cells mai ntained in the presence of platelet-derived growth factor or basic fibrobla st growth factor retained nestin expression along with A2B5. By contrast, i n serum-free medium nestin expression decreased while postmitotic cells acq uired A007 and galactocerebroside. Our results suggest that nestin expressi on is a marker of pre-O2A cells that is maintained in proliferating glial p rogenitors, but is quickly down-regulated in postmitotic oligodendrocytes ( A007(+)/galacto-cerebroside(+)) along with A2B5 and vimentin. However, othe r glial cells including type 2 astrocytes and some amoeboid microglia also share nestin expression. (C) 2001 Wiley-Liss, Inc.