BFGF REGULATES THE PROLIFERATIVE FATE OF UNIPOTENT (NEURONAL) AND BIPOTENT (NEURONAL ASTROGLIAL) EGF-GENERATED CNS PROGENITOR CELLS

In cultures of embryonic and adult mouse striatum, we previously demon strated that EGF induces the proliferation of putative stem cells, whi ch give rise to spheres of undifferentiated cells that can generate ne urons and astrocytes. We report here that the spheres of undifferentia ted cells contain mRNA and protein for the FGF receptor (FGFR1). Indir ect immunocytochemistry demonstrated that many of the cells within the EGF-generated spheres were immunoreactive for FGFR1. Exogenous applic ation of bFGF to the EGF-generated cells induced the proliferation of two progenitor cell types. The first, a bipotent progenitor cell, gave rise to cells with the antigenic and morphological properties of neur ons and astrocytes; the other gave rise to cells with neuronal charact eristics only. bFGF-generated cells with neuronal morphology exhibited electrophysiological properties indicative of immature central neuron s. These results support the hypothesis that sequential actions of gro wth factors play a role in regulating the generation of neurons and as trocytes in the developing CNS.