In Vitro Generated Hepatocyte-Like Cells: A Novel Tool in Regenerative Medicine and Drug Discovery

Abstract Hepatocyte-like cells (HLCs) are generated from either various human pluripotent stem cells (hPSCs) including induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs), or direct cell conversion, mesenchymal stem cells as well as other stem cells like gestational tissues. They provide potential cell sources for biomedical applications. Liver transplantation is the gold standard treatment for the patients with end stage liver disease, but there are many obstacles limiting this process, like insufficient number of donated healthy livers. Meanwhile, the number of patients receiving a liver organ transplant for a better life is increasing. In this regard, HLCs may provide an adequate cell source to overcome these shortages. New molecular engineering approaches such as CRISPR/ Cas system applying in iPSCs technology provide the basic principles of gene correction for monogenic inherited metabolic liver diseases, as another application of HLCs. It has been shown that HLCs could replace primary human hepatocytes in drug discovery and hepatotoxicity tests. However, generation of fully functional HLCs is still a big challenge; several research groups have been trying to improve current differentiation protocols to achieve better HLCs according to morphology and function of cells. Large-scale generation of functional HLCs in bioreactors could make a new opportunity in producing enough hepatocytes for treating end-stage liver patients as well as other biomedical applications such as drug studies. In this review, regarding the biomedical value of HLCs, we focus on the current and efficient approaches for generating hepatocyte-like cells in vitro and discuss about their applications in regenerative medicine and drug discovery. Keywords: Hepatocyte, Cell Therapy, Gene Therapy, Drug Discover

Liver Development and In vitro Differentiation of Embryonic Stem Cells to Hepatocytes

Embryonic stem cells are characterized with two specific properties: self renewal and differentiationpotential. Embryonic stem cells are pluripotent cells that can be differentiatedinto three kind of germ layers; ectoderm, endoderm, mesoderm. These properties makethem ideal for developmental research, toxicology and transplantation in animal model ofhuman diseases. These cells can be differentiated spontaneously into three germ layercells, but in direct differentiation, molecules and growth factors involved in natural developmentof desired cells must well characterized to gain a proper differentiation in vitro.There are increasing numbers of death because of liver disease and failure of organtransplantation in our country and the world. This made stem cell scientists to work onembryonic stem cell differentiation to hepatocyte like cells to create an accessible cellsource in regenerative medicine of liver disease in the future, and also to establish stemcell derived hepatocyte for in vitro screening of drugs.In this review we will summarize the process of liver development including moleculesand growth factors incorporate in the liver development as a template for in vitro differentiationof mouse and human embryonic stem cells and then we will discuss the relatedstudies and techniques for analyzing functionality of differentiated cells

In vitro Generated Hepatocyte- like cells: a Novel Tool in Regenerative Medicine and Drug Discovery

Hepatocyte-like cells (HLCs) generated from various human pluripotent stem cells (hPSCs), mostly induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) or direct cell conversion and also other stem cells like gestational tissues stem cells and mesenchymal stromal cells; provide potential cell sources for biomedical applications. Liver transplantation is the gold standard treatment for patients with end stage liver disease, but there are many practical limits, mostly insufficient number of donated healthy livers. Meanwhile the number of patients to receive a liver organ transplant for a better life is increasing. In this regard, HLCs may provide an adequate cell source to overcome these shortages. New molecular engineering approaches such as CRISPR/Cas systen with iPSCs technology provid the basic principles of gene correction for monogenic inherited metabolic liver diseases as another application of HLCs. It has shown that HLCs could replace primary human hepatocytes in drug discovery and hepatotoxicity tests. However, generation of fully functional HLCs is still a big challenge; research groups have been trying to improve current differentiation protocols to achieve better HLCs according to morphology and function of cells. Large-scale generation of functional HLCs in bioreactors could make a new window in producing enough hepatocytes for treating end-stage liver patients as well as other biomedical applications such as drug studies. In this review, regarding the biomedical value of hepatocyte-like cells, we focus on the current and efficient approaches for generating hepatocyte- like cells in vitro and discuss about their applications in regenerative medicine and drug discovery

Induced pluripotent stem cells: A new era for hepatology

Stem cell transplantation has been proposed as an attractive alternative approach to restore liver mass and function. Recent progress has been reported on the generation of induced pluripotent stem (iPS) cells from somatic cells. Human-iPS cells can be differentiated towards the hepatic lineage which presents possibilities for improving research on diseases, drug development, tissue engineering, the development of bio-artificial livers, and a foundation for producing autologous cell therapies that would avoid immune rejection and enable correction of gene defects prior to cell transplantation. This focused review will discuss how human iPS cell advances are likely to have an impact on hepatology