THE ISOLATION AND IDENTIFICATION OF THE DEFINITIVE ADULT NEURAL STEM CELL FOLLOWING ABLATION OF THE NEUROGENIC GFAP EXPRESSING SUBEPENDYMAL CELL

Neural stem cells (NSCs) in the adult forebrain are thought to comprise a subpopulation of cells that express glial fibrillary acidic protein (GFAP), termed B cells. These GFAP+ cells generate proliferating neuroblasts that migrate from the lateral ventricle subependyma along the rostral migratory stream to become olfactory bulb interneurons. Based on this lineage, we set out to create a NSC deficient mouse through targeted ablation of dividing GFAP+ cells in vivo. We successfully depleted the GFAP+ cells as seen using an in vitro colony forming assay in multiple kill paradigms, however we were unable to permanently eliminate the multipotent, self-renewing colony forming cells. Instead, the targeted ablation of GFAP+ cells revealed an upstream, GFAP- cell that was induced to proliferate in the presence of leukemia inhibitory factor (LIF). These findings support the hypothesis that a population of GFAP-, LIF responsive cells are the definitive adult NSC upstream of GFAP+ cells.