Individual cells from these neurospheres could give rise to colonies containing a mixture of neurons, astrocytes, and

oligodendrocytes, judged by immunolabeling with cell type-specific antibodies (Kondo and Raff, 2000). This study suggested that NG2-glia are more plastic than previously believed and suggested an explanation for previous reports that newborn rat optic nerve cells can generate neurons in culture, even though optic nerves do not normally contain neurons (Omlin and Waldmeyer, 1989). These developments took place against a backdrop of exploding interest in stem cells of all sorts and neural stem cells in particular. I-BET-762 datasheet A landmark series of papers had shown that subependymal astrocytes (“type-B cells”) in the subventricular zone (SVZ) of the adult rodent forebrain are in fact neural stem cells that generate migratory neuroblasts Vorinostat supplier (“type-A cells”) destined for the olfactory bulb (Doetsch et al., 1999). These neuroblasts follow the “rostral migratory stream” (RMS) from the SVZ to the olfactory bulb, where they differentiate into new olfactory interneurons of various types throughout adult

life. It seemed (and still seems) possible that the type-2 astrocytes formed by culturing optic nerve NG2-glia with FCS or BMPs (Kondo and Raff, 2000) might be functionally analogous to the subependymal astrocytes (stem cells) of the SVZ. SVZ stem cells, hippocampal stem cells, and cultured type-2 astrocytes all express the glial fibrillary acidic protein (GFAP), for example, and all generate neurosphere-like bodies when cultured in the presence of bFGF. Subsequent reports that SVZ stem cells and their immediate progeny express NG2 and PDGFRa—as also do type-2 astrocytes—lent support to this interpretation (Belachew et al., 2003, Aguirre and Gallo, 2004 and Jackson

et al., 2006). Taken together, these observations implied that SVZ stem cells, type-2 astrocytes and parenchymal NG2-glia might all be close relatives. The world of glia was up-ended. No longer were glial cells Astemizole simply the “support cells of neurons” but rather the precursors of neurons, with neuron-like character of their own. Revolutionary ideas need firm foundations, so several labs geared up to test the differentiation fates of NG2-glia directly in vivo, using Cre-lox technology in transgenic mice. The first wave of such studies is now published and the conclusion is clear, if chastening: by far the most common differentiation products of parenchymal NG2-glia are oligodendrocytes, both in the normal and injured adult CNS.