Promoting the differentiation of pluripotent embryonic stem cells into endoderm derivatives
We are using the signals and genes that direct endoderm and pancreas differentiation in the embryo to direct the differentiation of pluripotent embryonic stem (ES) cells into therapeutically important endoderm derivatives, such as insulin-producing beta cells. The goal of this work is to generate cells that could be used in a transplantation-based therapy to treat Type 1 diabetes (Figure 1 from Spence and Wells, 2007). Embryonic stem cells have enormous therapeutic potential because they are genetically un-programmed and can form all cell types of the body.
| Figure 1: The lineage of the developing pancreas in vivo and in ES cultures. |
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The left panels are mouse embryos at different stages of development (embryonic day 3.5 through 13.5 (E3.5-E13.5)) and the black bars on the right indicate the equivalent stages in human development. Embryos are oriented with anterior to the left and posterior to the right. The E13.5 stage shows the dissected stomach, pancreas and duodenum with the stomach (s) and dorsal pancreas (dp) to the left and the ventral pancreas (vp) and duodenum (d) to the right. The LacZ staining in the E9.5 and 13.5 embryos shows expression of Pdx1 (Pdx1LacZ/+ animals were from Chris Wright at Vanderbilt university and were described in (Offield et al., 1996)). The lower left panel is a pancreatic islet showing glucagon-expressing a-cells (green) and insulin-expressing b-cells (red). The curved arrows highlight several signaling pathways involved pancreas development that have been used to direct HESC differentiation into the pancreatic lineage (D’Amour et al. 2005, D’Amour et el. 2006). The middle panel indicates the lineage of the developing endocrine pancreas. The arrowheads in the cell lineage diagram highlight to two separate roles of Nodal/Activin signaling: to initiate gastrulation and to promote endoderm versus mesoderm fate in a dose-dependant manner. |  |
Differentiation of HES cells into endoderm organ derivatives
Given the complexity of cell types generated in the vertebrate embryo, directing the differentiation of ES cells into specific cell types represents a significant challenge. We have used specific culture conditions to direct the differentiation of human embryonic stem cells (HESCs) into definitive endoderm as previously published (D’Amour et al., 2005, Nature Biotechnology). Like definitive embryonic endoderm, definitive endoderm derived from HESCs expresses many of the same genes including Sox17, Foxa1 and Foxa2. In addition, HESC-derived endoderm cells bear a striking morphological similarity to embryonic endoderm. We have begun using information from our studies of endoderm organogenesis to direct promote the differentiation of HESC-derived endoderm cells into specific organ lineages including lung, liver, pancreas and intestine. As with embryonic endoderm, HESC-derived endoderm cells respond to endoderm-patterning cues in similar fashion where we can promote formation of anterior and posterior cell types. This demonstrates that information from basic developmental biology can be directly translated into our efforts to derive therapeutically important endoderm derivatives from embryonic stem cells.
| Figure 2: Directing the differentiation of human embryonic stem cells into endoderm and then into specific organ derivatives. |
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| A. The upper panel shows human ES cells grown in high concentrations of activin will differentiate into endoderm like cells (HESC-DE: Foxa2/Sox17 co-expression). The bottom panel demonstrates that HESC-DE will continue to differentiate into specific organ lineages. We can recapitulate early embryonic signaling to direct human endoderm cells into specific organ lineages that can ultimately be used for transplantation-based therapies, such as pancreatic beta cells for people with type-1 diabetes. |
Relavent Publications
Spence JR, Wells JM. Translational embryology: Using embryonic principles to generate pancreatic endocrine cells from embryonic stem cells. Dev Dyn 2007;236:3218-27.
Wells JM. Genes expressed in the developing endocrine pancreas and their importance for stem cell and diabetes research. Diabetes Metab Res Rev 2003;19:191-201.
Click here for some general information about embryonic and adult stem cells and their potential therapeutic uses. For other general information check out the Juvenile Diabetes Foundation web site.
