Purification and characterization of astrocyte precursor cells in the developing rat optic nerve

The signaling interactions that control oligodendrocyte generation from the ir precursor cells have been studied intensively. Much less is known about how astrocyte generation is normally controlled. Here we report the purific ation and characterization of astrocyte precursor cells (APCs) from the dev eloping rat optic nerve. APCs are antigenically distinct from astrocytes. B oth cell types are Pax2(+) and vimentin(+), whereas astrocytes are GFAP(+) and S100 beta(+), and the precursor cells are A2B5(+). In contrast to purif ied astrocytes, purified APCs rapidly die in serum-free culture but can be saved by basic fibroblast growth factor (bFGF) and glial growth factor 2 (G GF2). Unlike oligodendrocyte precursor cells, APCs do not differentiate by default; their differentiation into GFAP(+) cells is induced by ciliary neu rotrophic factor (CNTF) or by leukemia inhibitory factor (LIF). Finally, th e survival, proliferation, and differentiation of APCs were promoted by coc ulture with other embryonic optic nerve cell types but not with purified em bryonic retinal ganglion cells, indicating that interactions with non-neuro nal cells are likely to play an important role in controlling astrocyte gen eration in the developing optic news.