Differentiation of neural stem cells into cells of oligodendroglial lineage.

We described three different conditions that induce differentiation of dissociated neural stem cells derived from mouse embryonic CNS. In the first set of experiments, where the cell differentiation was triggered by cell adhesion, removal of growth factors and serum-supplemented medium, only sporadic neuronal and astroglial cells survived longer than two weeks and the latter formed a monolayer. When differentiation was induced in serum-free medium supplemented with retinoic acid, rapid and massive cell death occurred. A prolonged survival was observed in cultivation medium supplemented with serum and growth factors EGF plus FGF-2. One third of the cells did not express cell differentiation markers and were responsible for an increase in cell numbers. The remaining cells differentiated and formed the astrocytic monolayer on which occasional neuronal cells grew. One third of the differentiated phenotypes were represented by cells of oligodendroglial lineage. Differentiation of oligodendroglial cells occurred in a stepwise mechanism because the culture contained all successive developmental stages, including oligodendrocyte progenitors, preoligodendrocytes and immature and mature oligodendrocytes. Maturing oligodendrocytes displayed immunocytochemical and morphological features characteristic of cells that undergo physiological development. The cultivation conditions that supported growth and differentiation of neural stem cells were optimal for in vitro developmental studies and the production of oligodendroglial cells.