ISOLATED-ORGAN PERFUSION FOR LOCAL GENE DELIVERY - EFFICIENT ADENOVIRUS-MEDIATED GENE-TRANSFER INTO THE LIVER

Targeted gene delivery is essential for gene therapy involving in vivo gene transfer. In the present study we analyzed the efficiency and ti ssue-specificity of gene transfer into the liver with recombinant aden oviruses. Adenovirus vectors carrying the E. coli lacZ gene (Ad.RSV.be ta-gal) and the firefly luciferase gene (AdCMV-luc) as reporters were administered to the liver of adult Wistar rats, either via infusion in to the portal vein (intraportal infusion; IPI) or via perfusion of the vascularly isolated liver (isolated liver perfusion; ILP). Ex vivo li ver perfusion experiments with Ad.RSV.beta-gal were used to optimize t he conditions for hepatic gene transfer. Ex vivo perfusion of rat live rs with 2 x 10(9) plaque forming units (p.f.u.) Ad.RSV.beta-gal was su fficient to infect about 20% of the liver parenchymal cells. Perfusion with chelating agents (1 mM EGTA, or 2 mM EDTA) prior to the administ ration of the vector increased the efficiency to at least 40%. Similar efficiencies were obtained in experiments with liver lobes of Rhesus monkeys. In vivo administration of AdCMV-luc via ILP resulted in a sig nificantly more efficient (P = 0.028) and also more reproducible gene transfer when compared to IPI. Although detectable in both groups, ext rahepatic luciferase expression was considerably reduced in the ILP gr oup. Our data demonstrate that IPL can be used for efficient and repro ducible liver-specific gene delivery. Therefore, we think that the per fusion of vascularly isolated organs is useful as a modality for the t issue-specific administration of recombinant adenovirus vectors.