Characterisation of human induced pluripotent stem cell-derived hepatocyte-like cells and endodermal progenitors

Abstract

Background Human embryonic stem cells (hESCs) have two fundamental characteristics. First is pluripotency, they have the ability to differentiate to all cell types of the three germ layers endoderm, ectoderm and mesoderm in vitro (by formation of embryoid bodies) and in vivo (by teratoma formation in immune deficient mice). Second, hESCs have the capability to self-renew indefinitely. Embryonic stem cells express pluripotency-associated markers such as OCT4, NANOG, SOX2, SSEA-4, TRA-1-60, TRA-181 and alkaline phosphatase. The use of hESCs in research and future regenerative medicine approaches is hampered by ethical and moral concerns as these cells are derived from blastocysts. Besides the derivation of lineage-restricted cells from hESCs as well as the immune rejection of hESCs derived cells are still problematic. To avoid ethical and immune rejection concerns, scientists searched for alternative ways to derive pluripotent cells from mouse somatic cells [1]. Shortly after that two groups managed reprogramming of human adult fibroblasts with viral transduction mediated over-expression of four transcription factors OCT4, SOX2, KLF4 and cMYC or OCT4, SOX2, NANOG and LIN28. In general, derivation of induced pluripotent stem cells (iPSCs) from somatic cells and differentiating these into a donor cell type of interest are promising approaches for (i) modelling human diseases in vitro, (ii) toxicology and drug screening, (iii) future application in tissue replacement therapies. We and others have shown that iPSCs can be differentiated into hepatocyte-like cells that model in vitro the patient’s genetic disease or metabolic capability, thereby adding a further dimension to existing toxicity testing platforms. An iPSC-based strategy thus allows large scale studies impossible to perform on primary cell cultures or from biopsies and also enables studies on hepatocytes genetically susceptible to drug-induced liver injury (DILI) as in vitro models with genotypic relevance for toxicology screening. Furthermore, these patient-specific iPSC-derived hepatocytes can be used for characterising the metabolism of a candidate drug.