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PORTLAND, OR, United States

Tarlow B.D.,Oregon Health And Science University | Pelz C.,Oregon Health And Science University | Naugler W.E.,Oregon Health And Science University | Wakefield L.,Oregon Health And Science University | And 3 more authors.
Cell Stem Cell | Year: 2014

Adult liver progenitor cells are biliary-like epithelial cells that emerge only under injury conditions in the periportal region of the liver. They exhibit phenotypes of both hepatocytes and bile ducts. However, their origin and their significance to injury repair remain unclear. Here, we used a chimeric lineage tracing system to demonstrate that hepatocytes contribute to the progenitor pool. RNA-sequencing, ultrastructural analysis, and in vitro progenitor assays revealed that hepatocyte-derived progenitors were distinct from their biliary-derived counterparts. In vivo lineage tracing and serial transplantation assays showed that hepatocyte-derived proliferative ducts retained a memory of their origin and differentiated back into hepatocytes upon cessation of injury. Similarly, human hepatocytes in chimeric mice also gave rise to biliary progenitors in vivo. We conclude that human and mouse hepatocytes can undergo reversible ductal metaplasia in response to injury, expand as ducts, and subsequently contribute to restoration of the hepatocyte mass. ©2014 Elsevier Inc.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 230.67K | Year: 2012

DESCRIPTION (provided by applicant): Chimeric mice with highly humanized livers have multiple potential applications in research and preclinical drug development both in the academic and commercial settings [1]. The applications include studies of human infectious diseases (hepatitis B and B, malaria etc.), drug metabolism and pharmacokinetics, drug-drug interactions, toxicology and gene therapy among others. In the current human chimeric liver models up to 90% of hepatocytes are of human origin and displayall the typical functions of mature human cells. Our company uses immune deficient fumarylacetoacetate hydrolase (Fah) knockout mice[2], bearing additional mutations in Rag2 and the interleukin common gamma chain receptor (Il2rg) designated as FRGN to generate such chimeric animals. Human hepatocytes from commercial vendors are transplanted into the animals and over time the human hepatocytes replace the mouse cells generating chimeric animals with livers that constitute 90% human cells. Currently, hepatocytes are the only human cell type present in FRGN chimeric livers and this represents a limitation for some applications of the model. Specifically, hematopoietic cell types are known to contribute significantly to liver biology, including pathobiology. Inflammation is present in many settings, particularly in liver infections, but also chemical injuries. Furthermore, the liver macrophages (Kupffer cells) are important players in liver toxicology. All of the hematopoietic cells in the current generation ofchimeric FRGN mice are of murine origin and they are completely deficient in T- and B-cells rendering the in sufficient for the afore mentioned studies. Chimeric mice bearing significant percentages of all human hematopoietic cells can be readily generated by transplantation of human cord blood into immune deficient mice, including Rag2/Il2rg/Nod mice. In this application we propose to optimize a protocol that permits the efficient generation of double- chimeric FRGN mice, with high levels of human hematopoiesis as well as high percentages of liver repopulation. Aim 1: To optimize a transplant protocol in FRGN mice which reproducibly yields gt70% human chimerism in both the liver and blood. 1a) Different time points for transplantation and different protocols or conditioning by irradiation will be compared using a single human hepatocyte donor. 2a) the two best protocols will be applied to 3 additional hepatocyte donors validate and further optimize the procedure. PUBLIC HEALTH RELEVANCE: Drug metabolism is phenotypically specific and can vary significantly between individuals of the same species and the variance between individuals can be attributed to genetic differences in the expression and activity of liver enzymes responsible for the metabolismof the drugs as well as significant contributions by the immune system in response to the metabolites produced by the liver. Yecuris Corporation has developed an in vivo genetic selection system (the FRG KO mouse) that permits extensive humanization of murine liver by transplanted human hepatocytes. With the addition of a humanized hematopoietic system in conjunction with the humanized liver, the new dual chimeric model could revolutionize development and screening of therapeutics in addition to providingmodels for studying hepatic infectious diseases.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 243.21K | Year: 2014

DESCRIPTION (provided by applicant): Yecuris has developed an in vivo genetic selection system (the FRG KO mouse) that permits extensive humanization of murine liver by transplantation with human hepatocytes. This model has many potential commercial applications in drug development and testing, both in the in vivo and in vitro markets, .The mouse, however, is a small rodent and therefore the number of human hepatocytes that can be obtained for in vitro studies is limited to 80-150 million hepatocytes/animal. A larger animal that could be similarly repopulated would provide significant cost savings and economy of scale. Furthermore, the rat is the animal model of choice in many preclinical applications, particularly toxicology. For these reasons, we decided to generate an FRG KO rat, with mutations completely analogous to those in the FRG KO mouse: Fumary lacetoacetate hydrolase (Fah), Rag2 and common gamma chain of the interleukin receptor (Il2rg). Using TALEN and other gene editing technologies, st


Frg

Trademark
Yecuris Corporation | Date: 2012-08-27

Live laboratory and experimental animals; live mice, rats and pigs for scientific, laboratory or medical research.


Described herein are rats with a hepatic deficiency comprising decreased function, activity, or expression of an enzyme in the tyrosine catabolic pathway (such as fumarylacetoacetate hydrolase), and methods of using the same for in vivo engraftment and expansion of heterologous hepatocytes, such as human hepatocytes, analysis of human liver disease, and analysis of xenobiotics. Also disclosed is the use of immunodeficient rats for the engraftment and expansion of heterologous hepatocytes.

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