Purification and characterization of cultures of oligodendroglia from rat brain.

It is possible to purify small dark cells from rat brain which by ultrastructural criteria are oligodendroglia. The modified technique involves the use of an isolation medium less damaging to the initial cell suspension and then differential plating of a stratified primary cell culture obtained from 1-3-day-old rat brain which has been described. Five percent serum encourages the growth of oligodendroglia. In this system, the oligodendroglia can be harvested several times from the primary cultures. To retain the homogeneous populations of oligodendroglia, it is necessary to constantly manipulate the cultures by hitting the flasks and replating the suspended cells. Electron microscopy reveals that the small dark cells are differentiated oligodendroglia with prominent microtubules. Immunofluorescence staining of the cells shows that the majority of the cells are negative for known surface markers which include cerebrosides and 04 antigen (markers for oligodendroglia), glial fibrillary acidic protein, and fibronectin. Interestingly, it is possible to increase the number of 04-positive cells by the addition of dibutyryl cyclic AMP to the medium. Rat oligodendroglia are able to incorporate about 20% of the radioactivity into cerebrosides, using the substrate, [3H]galactose; this is a biochemical feature unique to oligodendroglia. The expression of all the oligodendroglial antigens should be remarkably enhanced when the cells are induced to produce myelin.