Description
The future clinical use of embryonic stem cell (ESC)-based hepatocyte replacement therapy depends on the development of an efficient procedure for differentiation of hepatocyes from ESCs. Here we report that a high density of human embryonic stem cell (ESC)-derived fibroblast-like cells (hESdFs) supported the efficient generation of hepatocyte-like cells (HLCs) with functional and mature hepatic phenotypes from primate ESCs and human induced pluripotent stem cells (iPSCs). Molecular and immunocytochemistry analyses revealed that hESdFs caused a rapid loss of pluripotency and induced a sequential endoderm-to-hepatocyte differentiation in the central area of ESC colonies. Knockdown experiments demonstrated that pluripotent stem cells were directed toward endodermal and hepatic lineages by FGF2 and Activin A secreted from hESdFs. Furthermore, we found that the central region of ESC colonies was essential for the hepatic endoderm-specific differentiation, as its removal caused a complete disruption of endodermal differentiation. In conclusion, we describe a novel in vitro differentiation model, and show that hESdF-secreted factors act in concert with regional features of ESC colonies to induce robust hepatic endoderm differentiation in primate pluripotent stem cells.