EXPANSION OF RAT OLIGODENDROCYTE PROGENITORS INTO PROLIFERATIVE OLIGOSPHERES THAT RETAIN DIFFERENTIATION POTENTIAL

The limited availability of enriched populations of oligodendroglial p rogenitors has impeded the exploration of the complex spatio-temporal mechanisms which dictate the chemical ''language'' of their biology, W e have developed a technique to prepare homotypic aggregates of oligod endrocyte progenitors called ''oligospheres.'' These were obtained usi ng various approaches (sieving, Percoll gradient separation and differ ential adhesion) to purify oligodendroglial progenitors from newborn r at brain, Culturing cells in a mixture of N1 defined medium and condit ioned medium from the B104 neuronal cell line in the absence of adhesi ve substrate allowed to expand routinely and extensively for several m onths, the oligodendrocyte progenitor population, Under these conditio ns, the resulting population consisted of 98% GD3-positive/GFAP-negati ve cells. After dissociation and plating on polyornithine coated subst rates, in the presence of low (2%) or high (20%) serum, oligosphere-de rived oligodendrocyte progenitors were induced to differentiate into G alC-positive oligodendrocytes or GFAP-positive astrocytes, respectivel y, When transplanted into the newborn shiverer mouse brain, oligospher es were able to provide a focal reservoir of migrating and myelinating cells, Oligospheres are thus ideal tools for exploring the biological and molecular events of the oligodendrocyte lineage both in vitro and in vivo. (C) 1996 Wiley-Liss, Inc.