EX-VIVO LIPOSOME-MEDIATED GENE-TRANSFER TO LUNG ISOGRAFTS

Objective: Gene therapy is a promising strategy to modify ischemia-rep erfusion injury and rejection after transplantation. We evaluated vari ables that may affect ex vivo gene transfer to rat lung isografts. Met hods: Left lungs were harvested and perfused via the pulmonary vein wi th chloramphenicol acetyltransferase complementary deoxyribonucleic ac id complexed with cationic liposomes. Several variables were examined: (1) Influence of temperature: In group I (n = 4), grafts were stored for 4 hours at 23 degrees C and transplanted. Chloramphenicol acetyltr ansferase activity was assessed on postoperative day 2. In groups II a nd III (n = 4), grafts were stored at 10 degrees and 4 degrees C, resp ectively. Arterial oxygen tension and inflammatory infiltrate were als o determined, (2) Influence of storage time: Grafts were preserved at 10 degrees C for 1, 2, 3, 4 (n = 4), and 10 hours (n = 5), Chloramphen icol acetyltransferase activity was assessed on postoperative day 2. ( 3) Rapidity and duration of transgene expression: Grafts were preserve d at 10 degrees C for 1 hour and then transplanted, Chloramphenicol ac etyltransferase activity was assessed 2, 4, 6, 12, and 24 hours and 2, 7, 14, 21, and 28 days after implantation. Results: Chloramphenicol a cetyltransferase expression was apparently less in lungs transfected a t 4 degrees C than in those transfected at 10 degrees and 23 degrees C . Storage for 1 hour at 10 degrees C was sufficient to yield significa nt expression. Increasing the exposure time to 10 hours did not increa se toxicity. There were no differences in arterial oxygen tension betw een transfected and nontransfected lungs. Chloramphenicol acetyltransf erase expression was detected for at least 28 days, Conclusion: Ex viv o liposome-mediated transfection of lung isografts can he achieved aft er a short time of cold storage, with minimal toxicity.