New Approaches in the Differentiation of Human Embryonic Stem Cells and Induced Pluripotent Stem Cells toward Hepatocytes

Transplant Research Program, Department of Internal Medicine, University of California Davis Medical Center, 4635 2nd Ave. Suite 1001, Sacramento, CA 95817, USA.
Stem cell reviews (Impact Factor: 2.77). 02/2011; 7(3):748-59. DOI: 10.1007/s12015-010-9216-4
Source: PubMed


Orthotropic liver transplantation is the only established treatment for end-stage liver diseases. Utilization of hepatocyte transplantation and bio-artificial liver devices as alternative therapeutic approaches requires an unlimited source of hepatocytes. Stem cells, especially embryonic stem cells, possessing the ability to produce functional hepatocytes for clinical applications and drug development, may provide the answer to this problem. New discoveries in the mechanisms of liver development and the emergence of induced pluripotent stem cells in 2006 have provided novel insights into hepatocyte differentiation and the use of stem cells for therapeutic applications. This review is aimed towards providing scientists and physicians with the latest advancements in this rapidly progressing field.

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Available from: Tijess P Ahuja
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    • "Assessment of hepatotoxicity remains difficult because of challenges associated with in vivo models [3] and the high cost and limited availability of liver tissue for in vitro studies [4]. Current in vitro models for assessing hepatotoxicity are limited by (a) scarcity, variability, and short life span in culture of primary human hepatocytes [4]; (b) lack of metabolic activity in widely used liver cell lines such as HepG2 [5]; and (c) the complex long-term protocols required to differentiate progenitor cells [6]. "
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    ABSTRACT: High-throughput imaging-based hepatotoxicity studies capable of analyzing individual cells in situ hold enormous promise for drug safety testing but are frequently limited by a lack of sufficient metabolically competent human cells. This study examined cryopreserved HepaRG cells, a human liver cell line which differentiates into both hepatocytes and biliary epithelial cells, to determine if these cells may represent a suitable metabolically competent cellular model for novel High Content Analysis (HCA) applications. Characterization studies showed that these cells retain many features characteristic of primary human hepatocytes and display significant CYP3A4 and CYP1A2 induction, unlike the HepG2 cell line commonly utilized for HCA studies. Furthermore, this study demonstrates that CYP3A4 induction can be quantified via a simple image analysis-based method, using HepaRG cells as a model system. Additionally, data demonstrate that the hepatocyte and biliary epithelial subpopulations characteristic of HepaRG cultures can be separated during analysis simply on the basis of nuclear size measurements. Proof of concept studies with fluorescent cell function reagents indicated that further multiparametric image-based assessment is achievable with HepaRG. In summary, image-based screening of metabolically competent human hepatocyte models cells such as HepaRG offers novel approaches for hepatotoxicity assessment and improved drug screening tools.
    Full-text · Article · Sep 2014 · Journal of Toxicology
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    • "Also, the utility of primary hepatocytes as a therapy is hindered by their antigenicity, slow growth, loss of function and de-differentiation in vitro. Human embryonic stem cells (hESCs) or human induced pluripotent stem cells (iPSCs), which possess the ability to provide an unlimited source to generate human hepatocytes, could provide an answer to this problem [1] [2] [3]. Moreover, use of iPSCs would circumvent ethical issues, and, in particular, use of iPSCs derived from the same patient would overcome immunological rejection. "
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    ABSTRACT: Background Human induced pluripotent stem cells, which can be differentiated into hepatocyte-like cells, could provide a source for liver regeneration and bio-artificial liver devices. However, the functionality of hepatocyte-like cells is significantly lower than that of primary hepatocytes. Aims To investigate whether serum from patients undergoing hepatectomy might promote differentiation from human induced pluripotent stem cells to hepatocyte-like cells. Methods Serum from patients undergoing hepatectomy (acquired pre-hepatectomy and 3 hours, 1 day and 3 days post-hepatectomy) was used to replace foetal bovine serum when differentiating human induced pluripotent stem cells into hepatocyte-like cells. Properties of hepatocyte-like cells were assessed and compared with cells cultured in foetal bovine serum. Results The differentiation efficiency and functionality of hepatocyte-like cells cultured in human serum 3 hours and 1 day post-hepatectomy were superior to those cultured in foetal bovine serum and human serum pre-hepatectomy. Human serum 3 days post-hepatectomy had an equal effect to that of human serum pre-hepatectomy. Some cytochrome P450 isozyme transcript levels of hepatocyte-like cells cultured in human serum were higher than those cultured in foetal bovine serum. Conclusion Human serum, particularly that acquired relatively soon after hepatectomy, can enhance the differentiation efficiency and functionality of hepatocyte-like cells derived from human induced pluripotent stem cells.
    Full-text · Article · Aug 2014 · Digestive and Liver Disease
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    • "Furthermore, many recent studies have shown that low oxygen facilitates directional differentiation and helps to maintain the multipotency of stem and progenitor cells [8]–[11]. Subsequently, the reduced oxygen levels significantly increase production of desired cell populations from induced pluripotent stem cells (iPSCs) [12]–[15]. Moreover, low oxygen also potentiates generation of iPSCs from mouse and human fibroblasts [16]. "
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    ABSTRACT: Low oxygen tension (hypoxia) contributes critically to pluripotency of human embryonic stem cells (hESCs) by preventing spontaneous differentiation and supporting self-renewal. However, it is not well understood how hESCs respond to reduced oxygen availability and what are the molecular mechanisms maintaining pluripotency in these conditions. In this study we characterized the transcriptional and molecular responses of three hESC lines (H9, HS401 and HS360) on short (2 hours), intermediate (24 hours) and prolonged (7 days) exposure to low oxygen conditions (4% O2). In response to prolonged hypoxia the expression of pluripotency surface marker SSEA-3 was increased. Furthermore, the genome wide gene-expression analysis revealed that a substantial proportion (12%) of all hypoxia-regulated genes in hESCs, were directly linked to the mechanisms controlling pluripotency or differentiation. Moreover, transcription of MYC oncogene was induced in response to continuous hypoxia. At the protein level MYC was stabilized through phosphorylation already in response to a short hypoxic exposure. Total MYC protein levels remained elevated throughout all the time points studied. Further, MYC protein expression in hypoxia was affected by silencing HIF2α, but not HIF1α. Since MYC has a crucial role in regulating pluripotency we propose that induction of sustained MYC expression in hypoxia contributes to activation of transcriptional programs critical for hESC self-renewal and maintenance of enhanced pluripotent state.
    Full-text · Article · Nov 2013 · PLoS ONE
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