Analysis of gene expressions of embryonic stem-derived Pdx1-expressing cells: implications of genes involved in pancreas differentiation.

We have recently reported the method by which embryonic stem (ES) cells were induced into Pdx1-expressing cells. To gain insights into the ES cell-derived Pdx1-expressing cells, we examined gene expression profiles of the cells by microarray experiments. Microarray analyses followed by a comparison with the data of the cells in developing pancreatic and adult islet suggested that the ES cell-derived Pdx1-positive cells were immature pancreatic progenitor cells with endodermal characteristics. The analyses of the genes upregulated in the ES cell-derived Pdx1-positive cells would give us knowledge on early pancreatic development. Here, we first listed the genes and found that these contained not only those known to be expressed in the endoderm or pancreatic progenitor cells, but also those known to be involved in left-right axis formation. Second, we examined the gene expression patterns and found that several genes were expressed in the ventral foregut lip at the anterior intestinal portal in E8.5 embryo. Given that the Pdx1/GFP-expressing cells are first observed in the same region at the anterior intestinal portal, these results suggest that the pancreatic progenitor cells first give rise at the ventral endoderm prior to the formation of dorsal and ventral pancreatic buds.