Pluripotent fates and tissue regenerative potential of adult olfactory bulb neural stem and progenitor cells

Neural stem cells and progenitor cells reside in the adult olfactory bulb (OB) core of mouse, rat, and human. Adult rodent OB core cells have the capacities for self-renewal and multipotency and form neurospheres. The differentiation fates of these neurosphere-forming cells were studied in vitro and in vivo. Adult OB neurospheres were comprised of stem cells and neuronal and glial progenitor cells. OB neurospheres in co-culture with primary embryonic striatal neurons and cortical neurons generated cells with morphological and neurochemical phenotypes of striatal and cortical neurons, respectively. Transplanted OB cells, delivered as dissociated cells or as intact neurospheres, dispersed, survived for long-term, extended neurites, migrated, expressed neuronal or glial markers, and formed synapses with host neurons when placed into the environment of the nonlesioned and lesioned central nervous system (CNS). Grafted cells in the CNS also showed angiogenic capacity by forming blood vessels. In a model of spinal motor neuron degeneration, adult OB neurosphere cells transplanted into lesioned spinal cord adopted phenotypes of motor neurons and had a robust potential to become oligodendrocytes. OB core cells in co-culture with skeletal myoblasts generated skeletal muscle cells. Chimeric skeletal muscle was formed when mouse OB neurospheres were transplanted into rat skeletal muscle. Within skeletal muscle, adult OB neurosphere cells became myogenic progenitor cells to form myotubes de novo. We conclude that the adult mammalian OB is a source of pluripotent neural stem cells and progenitor cells that have the potential to become, in a context-dependent manner, specific types of cells for regeneration of tissues in brain, spinal cord, and muscle.