Hepatic repopulation with stably transduced conditionally immortalized hepatocytes in the Gunn rat.
ABSTRACT Conditionally immortalized hepatocytes offer a renewable source of hepatocytes, but although preparative maneuvers have been developed for hepatic repopulation with primary hepatocytes, extensive proliferation of transplanted immortalized hepatocytes has not been accomplished heretofore. Our aim was to achieve ex vivo gene therapy of uridinediphosphoglucuronate glucuronosyltransferase-1A1 (UGT1A1)-deficient jaundiced Gunn rats (model of Crigler-Najjar syndrome type-1) by hepatic repopulation with genetically modified and conditionally immortalized hepatocytes.
Gunn rat hepatocytes were conditionally immortalized by stable transduction with a thermolabile mutant simian virus 40 T-antigen ((ts)Tag(A58)) and further transduced with UGT1A1. These hepatocytes proliferate at 33 degrees C, but at 37 degrees C the (ts)Tag(A58) is degraded and the cells become quiescent. The cells were transplanted into Gunn rat livers after preparative hepatic irradiation (50 Gy) and 66% hepatectomy.
The engrafted UGT1A1-positive immortalized hepatocytes replaced approximately 80% of the host hepatocytes in 20 weeks, leading to normalization of hyperbilirubinemia. Liver histology, and serum albumin and alanine aminotransferase levels remained normal.
We achieved complete cure of hyperbilirubinemia in Gunn rats by ex vivo gene therapy via genetically modified and conditionally immortalized hepatocytes.
Article: Long-term reduction of jaundice in Gunn rats by nonviral liver-targeted delivery of Sleeping Beauty transposon.[show abstract] [hide abstract]
ABSTRACT: Asialoglycoprotein receptor (ASGPR)-mediated endocytosis has been used to target genes to hepatocytes in vivo. However, the level and duration of transgene expression have been low because of lysosomal translocation and degradation of the DNA and lack of its integration into the host genome. In this study we packaged the DNA of interest in proteoliposomes containing the fusogenic galactose-terminated F-glycoprotein of the Sendai virus (FPL) for targeted delivery to hepatocytes. After the FPL binds to ASGPR on the hepatocyte surface, fusogenic activity of the F-protein delivers the DNA into the cytosol, bypassing the endosomal pathway. For transgene integration we designed plasmids containing one transcription unit expressing the Sleeping Beauty transposase (SB) and another expressing human uridinediphosphoglucuronate glucuronosyltransferase-1A1 (pSB-hUGT1A1). The latter was flanked by inverted/direct repeats that are substrates of SB. In cell culture, FPL-mediated delivery of the E. coli beta-galactosidase gene (LacZ) resulted in transduction of ASGPR-positive cells (rat hepatocytes or Hepa1 cell line), but not of ASGPR-negative 293 cells. Intravenous injection of the FPL-entrapped pSB-hUGT1A1 (4-8 microg/day, 1-4 doses) into UGT1A1-deficient hyperbilirubinemic Gunn rats (model of Crigler-Najjar syndrome type 1) resulted in hUGT1A1 expression in 5%-10% of hepatocytes, but not in other cell types. Serum bilirubin levels declined by 30% +/- 4% in 2 weeks and remained at that level throughout the 7-month study duration. With histidine containing FPL, serum bilirubin was reduced by 40% +/- 5%, and bilirubin glucuronides were excreted into bile. No antibodies were detectable in the recipient rats against the F-protein or human UGT1A1. Conclusion: FPL is an efficient hepatocyte-targeted gene delivery platform in vivo that warrants further exploration toward clinical application.Hepatology 06/2009; 50(3):815-24. · 11.66 Impact Factor