Propagation of human hepatocytes in non-human animals

Abstract

The present invention relates to the preparation of non-human animals having chimeric livers, whereby some or substantially all of the hepatocytes present are human hepatocytes. It is based, at least in part, on the discovery that rats, tolerized in utero against human hepatocytes, were found to serve as long-term hosts for human hepatocytes introduced post-natally, and the introduced hepatocytes maintained their differentiated phenotype, as evidenced by continued production of human albumin. The present invention further relates to the use of such animals as models of various liver diseases, including viral invention. Such embodiments are based on the discovery that transplanted human hepatocytes in chimeric livers were found to be susceptible to Hepatitis B virus and Hepatitis C virus infection.

Description

[0001] This patent application is a continuation-in-part of International Patent Application No. PCT / US00 / 05713 filed Mar. 3, 2000 and published in English, which claims priority as a continuation-in-part of United States patent application Ser. No. 09 / 431,901 filed Nov. 2, 1999.1. INTRODUCTION[0003] The present invention relates to the propagation of human hepatocytes in the livers of non-human animals that have been tolerized to the human cells. Such animals provide an in vivo model system of the human liver that may be used in toxicology assays and in the study of human liver diseases, including the various forms of hepatitis (in particular hepatitis B and C) and alcohol--induced liver degeneration. They may also be used as a source of human hepatocytes for reconstitution of liver tissue, thereby providing an alternative to liver transplantation.2. BACKGROUND OF THE INVENTION2.1. The Need for a Culture System for Human Hepatocytes[0004] To accurately study the physiology of human...

AI Technical Summary

Benefits of technology

The present invention relates to a method of preparing non-human animals with chimeric livers containing human hepatocytes. The invention involves inducing tolerance in the non-human animal and then introducing human hepatocytes into the tolerized animal. The resulting chimeric animals can be used as models for human hepatocyte function in toxicology studies, as well as for diseases that specifically affect humans. The animals also have the advantage of having an immune system that is intact but tolerant towards the human cells in their liver. Additionally, the invention provides a source of human hepatocytes for therapeutic applications.

Problems solved by technology

Such systems have proven to be difficult to achieve, because when hepatocytes are removed from their native environment, they tend to lose their specialized functions, or "de-differentiate".

The loss of liver-specific functions makes it difficult or impossible to study the normal functions of hepatocytes as well as their response to chemical or biological agents.

For example, research directed toward infectious diseases of the liver, in particular viral hepatitis, has been hampered by the lack of an adequate model system.

Currently, patients suffering from liver disease may have to wait for long periods of time before a suitable organ for transplant becomes available.

In addition to causing an acute hepatitis, viral infection may lead to chronic infection and consequent liver failure and / or the development of hepatocellular carcinoma (Fields Virology, pp.

One of the major problems in the study of human viral hepatitis is the lack of convenient laboratory models of the disease.

Unfortunately, the interferon / ribavirin combination is less effective against the most common HCV genotype found in the U.S., with only 28 percent of persons infected with that genotype exhibiting a sustained response to treatment (Davis et al., 1998, N. Engl. J. Med. 339:1493-1499).

The development of more successful forms of therapy (and our understanding of HCV biology) has been hampered by the absence of a good model system for HCV infection.

None of these systems has, however, proved satisfactory.

Nonetheless, this system does not generate virus and therefore is not a model of productive infection (Cohen, supra).

A major obstacle to achieving therapeutic liver reconstitution is immune rejection of transplanted hepatocytes by the host, a phenomenon referred to (where the host and donor cells are genetically and phenotypically different) as "allograft rejection".

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