Vascular endothelial growth factor promotes proliferation and function of hepatocyte-like cells in embryoid bodies formed from mouse embryonic stem cells

Background/Aims Embryoid bodies (EBs) formed from embryonic stem cells (ESCs) differentiate into hepatocyte-like cells (HLCs), and are thus thought to be a useful cell source for drug testing and bioartificial liver. The aim of this study was to induce proliferation and function of ESC-derived HLCs in EBs using HLC-endothelial cell interaction. Methods EBs were cultured in the presence of vascular endothelial growth factor (VEGF) and/or VEGF receptor (VEGFR) inhibitors. To reproduce HLC-endothelial cell interaction, we overexpressed VEGF in ESC-derived HLCs under the control of Cyp7a1 gene in EBs. Results VEGF added to the cultured EBs increased the proliferation of ESC-derived endothelial cells, resulting in the promotion of proliferation and function of ESC-derived HLCs. In EBs, the VEGFR2 inhibitor suppressed expression of albumin and endothelial cell marker genes, whereas the inhibitor for both VEGFR1 and VEGFR2 suppressed expression of Cyp7a1 and hepatocyte growth factor (Hgf) genes. Upon exposure to VEGF, the endothelial cells in EBs increased Hgf mRNA expression. Forced VEGF expression in ESC-derived HLCs in EBs induced angiogenesis around the HLCs and resulted in an increase in the amount of HLCs. Conclusions VEGF indirectly induces the proliferation and function of ESC-derived HLCs through VEGFR1 and VEGFR2 signaling in endothelial cells.