Adult germ line stem cells as a source of functional neurons and glia.

The derivation of autologous pluripotent cells has become a central goal in translational stem cell research. Although somatic cell nuclear transfer and transcription factor-based reprogramming enable the generation of pluripotent cells from adult tissue, both methodologies depend on complex epigenetic alterations. Recent data suggest that the adult germ line may represent an alternative and natural source of pluripotent stem cells. Multipotent adult germ line stem cells (maGSCs) with properties similar to those of embryonic stem cells have been derived from mouse spermatogonial stem cells. These cells exhibit extensive self-renewal, expression of pluripotency markers, and differentiation into derivatives of all three germ layers. Here we report the derivation of multipotent neural and glial precursors as well as adherently proliferating neural stem cells from maGSCs. Characterization of maGSC-derived neurons revealed segregation into GABAergic, glutamatergic, serotonergic, and tyrosine hydroxylase-positive phenotypes. On a functional level, maGSC-derived neurons generate spontaneously active functional networks, which use both glutamatergic and GABAergic synaptic transmission and engage in synchronized oscillatory activity. maGSC-derived oligodendrocytes undergo full maturation and ensheathe host axons in myelin-deficient tissue. Our data suggest that neural stem and precursor cells derived from maGSCs could provide a versatile and potentially autologous source of functional neurons and glia.

Bone morphogenetic protein-mediated modulation of lineage diversification during neural differentiation of embryonic stem cells.

Embryonic stem cells (ES cells) can give rise to a broad spectrum of neural cell types. The biomedical application of ES cells will require detailed knowledge on the role of individual factors modulating fate specification during in vitro differentiation. Bone morphogenetic proteins (BMPs) are known to exert a multitude of diverse differentiation effects during embryonic development. Here, we show that exposure to BMP2 at distinct stages of neural ES cell differentiation can be used to promote specific cell lineages. During early ES cell differentiation, BMP2-mediated inhibition of neuroectodermal differentiation is associated with an increase in mesoderm and smooth muscle differentiation. In fibroblast growth factor 2-expanded ES cell-derived neural precursors, BMP2 supports the generation of neural crest phenotypes, and, within the neuronal lineage, promotes distinct subtypes of peripheral neurons, including cholinergic and autonomic phenotypes. BMP2 also exerts a density-dependent promotion of astrocyte differentiation at the expense of oligodendrocyte formation. Experiments involving inhibition of the serine threonine kinase FRAP support the notion that these effects are mediated via the JAK/STAT pathway. The preservation of diverse developmental BMP2 effects in differentiating ES cell cultures provides interesting prospects for the enrichment of distinct neural phenotypes in vitro.