Stage specific differentiation of human embryonic stem cells into hepatocyte like cells using conditioned medium from a human hepatoma cell line

Hepatocytes derived from human embryonic stem cells (hESC) promises to be an inexhaustible source of functional cells for use in biomedical research, drug discovery and treatment of liver diseases. We have developed a unique strategy to efficiently differentiate hESC into functional hepatocyte like cells (HLC) in vitro. The robustness of our protocol was assessed by duplicating the process of differentiation in two of our in house derived hESC lines, Relicell hES1 and Relicell hES2 and in the well studied BG01 cell line. To induce early hepatic commitment, undifferentiated hESC were initially primed with conditioned medium from HepG2, a human hepatoma cell line, which resulted in an enriched population of definitive endoderm. Further, we have attempted to recapitulate the hepatogenesis events occurring in vivo by sequential application of growth factors involved in liver development such as aFGF, HGF, oncostatin, dexamethasone and EGF. Our differentiation process yielded a homogenous population of hepatocyte like cells (HLC) exhibiting the typical polygonal morphology of hepatocytes and expressing hepatic lineage markers including HNF4α, AFP and ALBUMIN, also drug metabolizing enzymes like CYP3A4 (Phase I) and GSTA1 (Phase II). FACS analysis showed that over 70% of the differentiated cells expressed albumin and CK8/18. The differentiated HLC exhibited hepatic characteristics such as glycogen storage and production of albumin and urea. Our results indicate that functional HLC generated by this method can be utilized in regenerative medicine and as screening platform in drug discovery and development.