Abstract
Rat primary microglia (MG) acquired a multipotent property to give rise to neuroectodermal cells through two-step culture in 10 and 70% serum-supplemented media for 5 d (Yokoyama et al., Glia 2004; 45, 96-104). Such multipotent MG called promicroglioblasts (ProMGB) formed cell aggregates, which generated cells with neuroectodermal phenotypes shortly after transfer into serum-free medium. As revealed by immunohistochemistry, there were a few MG expressing NG2-chondroitin sulfate proteoglycan (NG2) in the neonatal rat brain. Primary culture from the neonatal brain contained NG2+ MG, which appeared being the source of NG2+-ProMGB aggregates. The aggregates were MG-markers+/GFAP+/NCAM+/S-100b- and possessed an alkaline phosphatase activity. Marked accumulation of NG2+ MG was observed in the close vicinity of stab wounds made in mature rat brain. The NG2+ MG in the wounds separated with trypsin-EDTA formed NG2+ aggregates in 70% serum-supplemented medium and then turned into cells with neuroectodermal phenotypes in serum-free medium. Although it is quite difficult to separate viable neurons from mature brains, cells from the stab wounds generated process bearing b-tubulin III+ cells easily. These data suggest that NG2+ MG in normal developing or pathologic brains are involved in genesis or regeneration of the brain. [J Physiol Sci. 2006;56 Suppl:S120]
