Adenovirus-mediated gene transfer in the transplant setting: ii. successful expression of transferred cdna in syngeneic liver grafts

These experiments establish a model for gene transfer to transplanted liver grafts ex vivo using adenoviral vectors. Rat liver grafts (n=8) were harvested, and preserved in UW or lactated Ringer's. The grafts were infected ex-vivo via portal vein perfusion with replication-defective Ad vectors encoding the β-galactosi-dase (β-gal) gene diluted in UW solution. The infected grafts were stored at 4ºC for 1 hr, then transplanted into syngeneic hosts. Liver biopsies were taken at 1, 7, and 15 days after transplantation. Infection rate was assessed by histochemical staining for β-gal. Liver DNA and RNA were assayed for the [beta]-gal sequences, and recombinant protein production measured at 24 hr and 7 days after transplantation. Under conditions mimicking liver graft cold storage, efficient gene transfer was achieved with an infection rate of 10-15%, as assessed by X-gal staining. Viral DNA and RNA presence in the graft was confirmed; gene expression with protein production were verified by western blots and a functional protein assay. All studies were negative in control livers. Gene expression persisted for at least 2 weeks after transplantation. We conclude that efficient adenovirus-mediated gene insertion and expression of gene products can be accomplished in whole-liver grafts under hypothermic preservation conditions currently used in clinical transplantation.