Ex VivoHepatic Gene Therapy of a Mouse Model of Hereditary Tyrosinemia Type I

Abstract

Previously, this lab has reported the use of hepatocyte transplantation and in vivo gene therapy for the correction of a mouse model of Hereditary Tyrosinemia Type I (HT1). Here, we demonstrate repopulation of fumarylacetoacetate hydrolase (FAH)-deficient livers with cultured hepatocytes. Correction of the disease phenotype was achieved by retrovirally transducing cultured FAH¯ hepatocytes ex vivo, followed by transplantation and selective repopulation. Treated mice were phenotypically normal and had corrected plasma amino acid levels and liver function tests. Our results demonstrate that efficient hepatic repopulation using ex vivo genetically manipulated hepatocytes is feasible. In vivo selection can greatly enhance the efficiency of hepatic gene therapy. Hepatocytes corrected in situ by either retroviral or adenoviral gene transfer will efficiently repopulate diseased liver in a murine model of hereditary tyrosinemia. For some liver gene therapy applications, however, ex vivo gene transfer into cultured hepatocytes may represent the best approach. Here, we demonstrate that in vitro culture and retroviral transduction of liver cells does not damage their ability to expand and repopulate diseased liver. Thus, the in vivo selection strategy can also be applied to hepatocytes, which were genetically altered in culture.