Generation of neural stem cells from embryonic stem cells using the default mechanism: in vitro and in vivo characterization.

Neural stem cell-based approaches to repair damaged white matter in the central nervous system have shown great promise; however, the optimal cell population to employ in these therapies remains undetermined. A default mechanism of neural induction may function during development, and in embryonic stem cells (ESCs) neural differentiation is elicited in the absence of any extrinsic signaling in minimal, serum-free culture conditions. The default mechanism can be used to derive clonal neurosphere-forming populations of neural stem cells that have been termed leukemia inhibitory factor-dependent primitive neural stem cells (pNSCs), which subsequently give rise to fibroblast growth factor 2-dependent definitive NSCs (dNSCs). Here we characterized the neural differentiation pattern of these two cell types in vitro and in vivo when transplanted into the dysmyelinated spinal cords of shiverer mice. We compared the differentiation pattern to that observed for neural stem/progenitor cells derived from the adult forebrain subependymal zone [adult neural precursor cells (aNPCs)]. dNSCs produced a differentiation pattern similar to that of aNPCs in vitro and in the shiverer model in vivo, where both cell types produced terminally differentiated oligodendrocytes that associated with host axons and expressed myelin basic protein. This is the first demonstration of the in vivo differentiation of NSCs, derived from ESCs through the default mechanism, into the oligodendrocyte lineage. We conclude that dNSCs derived through the default pathway of neural induction are a similar cell population to aNPCs and that the default mechanism is a promising approach to generate NSCs from pluripotent cell populations for use in cell therapy or other research applications.