MM-102 Supplier This early dichotomy between generation of b

This early dichotomy between generation of blood and smooth muscle MM-102 Supplier is further supported by previous studies indicating that while the transcription factor Tal1 (Scl) is critical for the development of hematopoietic cells (Porcher et al., 1996; Robb et al., 1996), it strongly antagonises smooth muscle cell development (Ema et al., 2003; Ema and Rossant, 2003). Ema et al. showed that increased Tal1 expression in FLK1+ mesodermal cells inhibited smooth muscle differentiation, whereas loss of Tal1 promoted smooth muscle formation (Ema et al., 2003). Accordingly to a dichotomy between generation of blood and smooth muscle cells, we recently established that Tal1 is critical for the generation of hemogenic endothelium and blood but appears to be dispensable for smooth muscle development (Lancrin et al., 2010). Altogether these findings are consistent with an early separation between hemogenic endothelium and smooth muscle generation during development. Whether signalling by smooth muscle contributes to some extent, as recently suggested, to the generation of blood cells from hemogenic endothelium is unclear (Clements and Traver, 2013). The observation that some H2B-VENUS+ cells generated from FLK1+ mesodermal cells are TIE2+ (Fig. 2) suggests the possibility of the presence of a bi-potential vascular progenitor that gives rise to smooth muscle and endothelial cells. This idea is supported by the fact that H2B-VENUS+ TIE2+ cells contained smooth muscle-related transcripts but expressed them at lower levels than H2B-VENUS+ TIE2−. However, whether the generation of smooth muscle cells proceeds through a vascular bi-potent progenitor remains to be proven. Alternatively, TIE2 (but not other endothelial markers as indicated in Supplemental Fig. 4) could be expressed in smooth muscle cells independently of endothelial differentiation potential. There is a clear clinical interest to use human ES cells or induced pluripotent stem (iPS) cells to generate endothelial cells to provide neovascularisation to treat ischemic diseases, that represent one of the major causes of morbidity and mortality in the world (Chaudhury et al., 2012; Cheung and Sinha, 2011; Wang et al., 2007). Accumulating evidence indicate that the addition of vascular smooth muscle to endothelial cells leads to enhanced engraftment and vascularization compared with endothelial cells alone (Foubert et al., 2008; Levenberg et al., 2005; Shepherd et al., 2009). It is therefore important to develop new, or improve current, protocols to generate vascular smooth muscle cells from ES cells (Cheung et al., 2012; Cheung and Sinha, 2011; Lindskog et al., 2006). Our findings provide new insights into vascular development from ES cells and indicate that the α-Sma::H2B-Venus reporter ES cell line is a powerful new tool to further improve the generation of smooth muscle cells from ES or iPS cells for vascular grafts. The following are the supplementary data related to this article.
Acknowledgments Work in the authors\' laboratories is funded by Leukaemia & Lymphoma Research (LLR), Cancer Research UK (CRUK) and Biotechnology and Biological Sciences Research Council (BBSRC).
Introduction Embryonic stem cells (ESCs) are a unique cell type with the ability to self-renew and differentiate into all embryonic lineages. Due to multiple issues surrounding the feasibility and ethical considerations of using human ESCs (hESCs), one goal of stem cell biologists is to determine the transcriptional networks controlling stem cell properties in other models of pluripotent stem cells including murine ESCs and/or induced pluripotent stem cells (iPSCs). Our lab determined that the Forkhead transcription factor Foxd3 is required for self-renewal and potency of ESCs (Liu and Labosky, 2008). Without Foxd3, several signature stem cell proteins and their corresponding mRNAs (including Oct4, Sox2, and Nanog) are maintained at relatively normal levels suggesting that Foxd3 is not required for their expression. Despite the maintained expression of these genes, ESCs lacking Foxd3 lose key stem cell properties. They are no longer pluripotent; they differentiate into mesendoderm and trophectoderm lineages under conditions that normally maintain pluripotency. Additionally, inducible-mutant ESCs lose self-renewal capacity and undergo aberrant apoptosis (Liu and Labosky, 2008). While Foxd3 is not one of the “core” transcription factors sufficient for reprogramming somatic cells into iPSCs (Yu et al., 2007), it is indispensable for generating iPSCs; mouse embryonic fibroblasts lacking Foxd3 cannot be reprogrammed into pluripotent stem cells (Suflita, Labosky, and Ess, 2013 unpublished data). Together, these data demonstrate that Foxd3 functions downstream of, or in a pathway parallel to, other stem cell factors and is required for self-renewal and pluripotency of ESCs.