Differentiation and dedifferentiation of embryonic stem cell-derived neural progenitor cells

• Main Authors: Ching-Wen Chen, 陳靜雯
• Other Authors: 蘇鴻麟
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/06229040709378492799

博士 === 國立中興大學 === 生命科學系所 === 99 === Neurogenesis is a complex process. The mechanism of neural differentiation and the way to maintain the self-renewal of neural stem cells (NSCs) are still not very clear. Fibroblast growth factor (FGF) is essential for uncommitted ectoderm to acquire a neural fate and the self-renewal of NSCs. By using serum-free neural induction method, we demonstrated that FGF1 dose-dependently promoted the induction of Sox1/N-cadherin/nestin triple positive cells, which represent primitive neuroblasts, from mouse embryonic stem (ES) cells. FGF-enhanced neurogenesis is not mediated through the rescue of the apoptosis or the enhancement of the proliferation of Sox1+ cells. We further showed that the inactivation of c-Jun N-terminal kinases (JNKs) and extracellular signal-related kinases (ERKs), but not p38 mitogen-activated protein kinase (MAPK), inhibited the neural formation through the inhibition of ES differentiation, but not through the formation of endomesodermal cells. We also demonstrated that FGF cannot rescue the inhibition effect of BMP and Wnt in neural induction, but can interfere with the endogenous BMP/IdⅠ or Wnt/Tcf signaling in differentiating cells. The evidence indicated that FGF-mediated neural induction of ES cells was through MAPK activation and partially through BMP and Wnt signaling inhibition. The part of maintenance for NSCs self-renewal, by using puromycin selection and supplement FGF and EGF in the culture medium, we obtained the long-term Sox1-GFP+ expression cells (LS cells). These cells expressed neural stem cell markers and had the capacity to differentiate into neural lineages, but they formed teratoma in nude mice. LS cells could reprogram to pluripotent state (LSP cells) and expressed pluripotent and differentiation makers. The Oct4 and Nanog promoter DNA methylation in LS and LSP cells exhibited hypomethylation, which was similar to that of 46C ES cells. All of these data showed that LS and LSP cells may be EpiSC-like cells. Therefore, if we want to use the ES-derivatives for clinical purposes in the future, we should heed, monitor and try to avoid the possible formation of tumors.