Although iPSC-derived HE expressed click here a number of liver genes, we were also keen to assess their liver-specific function in culture. An important functional marker for HE is the production and export of serum proteins. We assessed iPSC-HE production of these key serum proteins and measured their levels by ELISA (Fig. 3). In all lines tested, we detected substantial amounts of alpha-fetoprotein, transthyretin, fibronectin, and fibrinogen at levels equivalent to those reported for HE derived

from hESCs.5 In order to further functionally validate, iPSC-derived HE was assessed for its metabolic ability. The cytochrome P450 enzymes are critical in drug metabolism, and CYP1A2 and CYP3A4 are key enzymes. The function of these CYP450 components

were examined, and importantly, all lines exhibited CYP1A2 and CYP3A4 activity as assessed by the generation of a luminescent metabolite (Fig. 4). CYP1A2 metabolism was similar between lines PGP9f-iPS1 and NMF-iPS6, but was higher in line JDM-iPS1, whereas we observed only slight variation with CYP3A4 metabolism in Lapatinib molecular weight all three lines tested. Here, we demonstrate for the first time the derivation of HE from human iPSCs of both sexes and two ethnicities. The iPSC-derived HE was functionally equivalent to hESC-derived HE, and interestingly, all iPSC lines tested so far showed higher efficiency to form functional HE. The generic ability of iPSCs to form HE in response to our model5 has not been observed with hESCs in deriving efficient levels of HE. Therefore, one could speculate Sitaxentan that this is due to the consistent manner in which the iPSCs were reprogrammed and may play an important role in their developmental potential. It also suggests that iPSCs may prove a more valuable and uniform starting material for derivation of HE, than are hESCs, which show dramatic line-to-line variability in susceptibility to individual lineage differentiation. Such a resource has the ability to revolutionize the manner in which we define drug metabolism, and model liver disease and human liver development. Because iPSC-derived HE can be differentiated in vitro, an unlimited supply of ethically and genetically diverse HE models can be obtained. This will become

a powerful resource allowing the study of ethnic/polymorphic variation on xenobiotic metabolism involving poor metabolizers (e.g., CYP2C9/warfarin) and disease genotypes (e.g., alpha-1-antitrypsin). In addition, the ability to model liver development in vitro will allow the development of novel biomarkers for both disease and the identification of stage-specific markers during the differentiation process.12 An iPSC library could be developed through identification and reprogramming of human fibroblasts displaying metabolically different features for key polymorphisms. Presently, the ability to model the human liver and disease using hESCs or PHHs is limited by the number of stem cell lines available and the ability to produce functional HE from individual ESC lines.