Differentiation potential of human pancreatic stem cells for epithelial- and endothelial-like cell types

Pancreatic stem cells (PSC) have proved their high plasticity by differentiating into cell types of all three germ layers after the formation of organoid bodies. Motivated by this high differentiation potential this study focused on the immanent stem cell, endothelial and epithelial characteristics of PSC to elucidate whether PSC are a possible source for a stem cell-based in vitro model for screening of pharmaceutical substances. Furthermore, it was investigated whether marker expression was influenced by application of protocols for inducing endothelial or epithelial differentiation originating from research with mesenchymal stem cells or by cultivation on extracellular matrices (ECM). PSC showed expression of relevant stem cell markers CD 45, nestin, Oct 4 and c-kit. As endothelial characteristics they displayed the markers endoglin, VCAM 1, VEGFR 1 and vWF as well as the formation of vessel-like structures. Those endothelial properties were not further intensified by application of protocols employing vascular endothelial growth factor (VEGF), basic fibroblastic growth factor (bFGF) and endothelial cell growth medium. As typical epithelial characteristics PSC showed expression of keratin 7, 8, 18 and 19, ZO-1 and catenin beta1. In order to induce epithelial differentiation PSC were cocultured with the lung epithelial cell lines A549 and Calu-3 either by the usage of conditioned medium or by cultivation of PSC on fixed epithelial cells. Depending on the applied coculture system and epithelial cell type used expression of the epithelial marker cadherin-1 was altered compared to control. Cultivation on different ECM changed expression of all investigated markers only marginally. These results confirm that PSC possess endothelial and epithelial properties. Furthermore, epithelial characteristics represented by expression of CDH 1 were altered by coculture with epithelial cell lines.