Olfactory bulb core is a rich source of neural progenitor and stem cells in adult rodent and human.

The olfactory bulb (OB) core is an extension of the rostral migratory stream and thus is a potential source of neural progenitor and neural stem cells. We characterized in vivo and in vitro neuronal progenitor and neural stem cells in the adult OB core. In mouse and rat, bromodeoxyuridine (BrdU) labeling showed that the OB core accumulates newly replicated cells. Nestin, a neuroepithelial stem cell marker, was enriched in the OB core. BrdU-positive cells were immunolabeled for nestin and TUC4, a marker for early postmitotic neurons. The distributions of cells labeled for BrdU, TUC4, and nestin were similarly concentrated in the OB core. Nestin- and TUC4-positive cells were also found in the OB of young and aged humans. Isolated and cultured OB core cells from adult rat and mouse had the capacity to generate numerous neurospheres. Adult OB core neurospheres were cryopreserved and subsequently cultured. Single cell clonal analysis of neurospheres revealed the capacity for self-renewal and multipotency. Cultured adult OB core cells differentiated into neurons, astrocytes, and oligodendrocytes. Some neurons expressed choline acetlytransferase, substance P, and glutamic acid decarboxylase. Basic fibroblast growth factor potentiated the self-renewal of cells and beta-nerve growth factor stimulated differentiation. OB-derived neural stem cells in coculture with skeletal muscle cells were induced to become neurons expressing choline acetyltransferase and substance P and formed neuromuscular synaptic junctions on myocytes displaying acetylcholinesterase-positive motor end plates. Cocultured OB-derived neural stem cells with myoblast cells also generated nonneural cell progeny. We conclude that the adult mammalian OB core is a reservoir of neural progenitor cells and pluripotent neural stem cells.