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Induction of Pluripotency and Differentiation
Somatic cells achieve a pluripotent state by pluripotential reprogramming. During pluripotential reprogramming, somatic cells re-established various features of pluripotent cells, such as the expression of pluripotency markers, inactivation of tissue-specific gene expression, developmental potential to contribute to all three germ layers, and an undifferentiated epigenetic state. Induced pluripotent stem (iPS) cells undergo unlimited self-renewal and have differentiation potential into various types of cells like embryonic stem cells. These iPS cells are potentially a valuable source of immune matched pluripotent stem cells that can be differentiated and used for tissue replacement therapies. Recent technical advance in direct reprogramming of somatic cells lead to a safe, viral- free iPS cell generation. Here we develop new techniques to generate iPS cells. Using titanium oxide (TiO2) nanotubes. we could successfully transfer reprogramming proteins (Oct4, Sox2, Klf4, Nanog and c-Myc) into somatic cells. After two weeks of treatment of protein conjugated nanotubes, somatic cells adopted an ES cell-like morphology and activated Oct4-GFP, which is pluripotency marker, indicating that nanotubes can be used for protein delivery carriers, which induce cellular reprogramming. Next, we induced differentiation of iPS cells into neural stem cells (NSCs) and compared with mouse embryonic stem (ES) cell-derived NSCs. NSCs from ES and iPS cells were morphologically indistinguishable from NSCs from brain tissue and rapidly propagated in the presence EGF and bFGF, and stained positive for NSCs markers Nestin and Sox2. Moreover, these NSCs have capacity of differentiation into multiple cell lineages, such as neurons, astrocytes, and oligodendrocytes. Induction of pluripotency and directed differentiation of iPS cells into a specialized cell type hold considerable promise for regenerative medicine as well as basic research.
