title: Retroviral gene transfer to the liver in vivo during tri-iodothyronine induced hyperplasia.
abstract: The liver is an important target organ for gene therapy but its mitotic quiescence makes it resistant to integrative gene transfer. Retrovirus-based vectors integrate into liver cells in vivo but require the liver to be primed before transduction; experimentally a 70% hepatectomy is commonly used to stimulate regeneration, rendering the liver susceptible to transduction during the resulting wave of cell proliferation. Our aim was to develop a clinically acceptable method of inducing hepatocyte replication before in vivo retroviral gene transfer which is both simple and effective. We have used the physiological hormone tri-iodothyronine (T3) to stimulate hepatocyte replication. A single dose of T3 (400 micrograms/100 g bw) was given subcutaneously to euthyroid rats. This produced a labelling index of 31.7% in the hepatocyte population without histological or biochemical evidence of preceding liver damage. Following T3 administration the rat livers were transfected in vivo with an amphotropic retrovirus, TELCeB/AF-7 which encodes the beta-galactosidase reporter gene together with a nuclear localisation signal. Transgene expression was noted only within the liver where 1.3% of hepatocytes expressed the beta-galactosidase enzyme. This compared to 5.2% of hepatocytes transduced following a 70% hepatectomy, and 0.02% in animals receiving neither T3 nor partial hepatic resection before transduction. T3 administration is a simple way to prime the liver before in vivo retroviral vector-based gene transfer.
authors.affiliation: Liver Group Laboratory, Imperial College Medical School at The Hammersmith Hospital, London, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Forbes
authors.forename: M
authors.initials: M
authors.lastname: Themis
authors.forename: M R
authors.initials: MR
authors.lastname: Alison
authors.forename: C
authors.initials: C
authors.lastname: Selden
authors.forename: C
authors.initials: C
authors.lastname: Coutelle
authors.forename: H J
authors.initials: HJ
authors.lastname: Hodgson
mesh_terms: D000818:Animals; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006498:Hepatectomy; D008099:Liver / Q000378:metabolism*; D008115:Liver Regeneration; D051381:Rats; D012190:Retroviridae; D014284:Triiodothyronine / Q000627:therapeutic use*; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D014284:Triiodothyronine; D001616:beta-Galactosidase