Embryonic stem (ES) cells are a potential source of neural derivatives that can be used in stem cell-based therapies. To generate specific cell types in a predictable manner, a detailed understanding of cell fate specification is required. To address this, this study employed mouse ES cells as a model to explore how neural identity was acquired and how regional identities were specified in ES cell-derived neural progenitor cells (NPCs). Chemical inhibitors are more stable than recombinant proteins, hence they give more reproducible biological responses. This is crucial when generating specific cell types from ES cells for large-scale analysis. This study explored the effect of two newly discovered small molecule inhibitors of BMP signalling, dorsomorphin (DM) and LDN193189 (LDN) on the neural induction of ES cells, and compared their capabilities with those of recombinant noggin. Both DM and LDN treatments increased the expression of neural markers to levels that were comparable to that achieved by noggin treatment, suggesting that both LDN and DM can potentially substitute recombinant noggin in the generation of NPCs in vitro. Retinoic acid (RA) is an important regulator of regional specification in vivo, but the underlying mechanisms for giving region-specific response are unclear. Here, early and late NPCs were exposed to RA at specific periods and were analysed for neural and positional markers. Results showed that region-specific responses were produced by RA at specific periods, indicating that NPCs display temporal changes in patterning responsiveness to morphogenic cues. The ability of morphogens to impose positional response is lost in late cultures. Since Sox1 expression is associated with a naïve neural progenitor state and neural commitment, the expression of Sox1 was examined over time to test whether it was associated with the responsiveness to patterning cues. Both caudal and ventral markers were induced by RA and, because it plays an essential role in ventral patterning, Hedgehog (Hh) agonist purmorphamine respectively in early NPCs but not in late NPCs in both Sox1 positive and negative populations. This suggested that the expression of positional markers was not dependent on a temporally-defined Sox1 progenitor state.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:585333 |
| Date | January 2013 |
| Creators | Yuen, Shun Ming |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/53933/ |
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