Liposome-mediated gene transfer in rat lung transplantation: A comparison between the in vivo and ex vivo approaches

Objective: We compared the efficacy of in vivo and ex vivo liposome transfe ction in rat lung transplantation, Methods: (1) Chloramphenicol acetyltrans ferase group: Fischer rats underwent isogeneic transplantation (n = 4 per g roup). Recipients were put to death on postoperative day 2 for chlorampheni col acetyltransferase activity Ex vivo setting: Grafts received cDNA comple xed or not with liposomes and were transplanted after 1.5 or 10 hours at 10 degrees C. In vivo setting: Donors were intravenously injected with cDNA c omplexed or not with liposomes, Lungs were harvested after 1.5 or 10 hours, preserved at 10 degrees C, and transplanted, (2) Transforming growth facto r-beta 1 group: Brown-Norway rats served as donors and Fischer rats as reci pients. All grafts were preserved for 3 hours at 10 degrees C. On postopera tive day 5, arterial oxygenation and histologic rejection scores were asses sed. Ex vivo setting: Grafts received transforming growth factor-beta 1 sen se (n = 8) or antisense (n = 7) complexed with liposomes or cDNA alone (n = 5), In who setting: Donors were intravenously injected with liposome:trans forming growth factor-beta 1 sense cDNA (n = 7), Exposure time was 3 hours. Results: (1) Chloramphenicol acetyltransferase-transfection was superior i n the ex vivo group but was not statistically different for longer exposure times. (2) Transforming growth factor-beta 1-arterial oxygenation was supe rior in the ex vivo liposome:sense group. cDNA alone was inefficient. Rejec tion scores were not statistically different between ex vivo and in vivo li posome:sense groups but were better when the ex vivo liposome:sense group w as compared with the cDNA alone or the antisense groups. Conclusions: (1) W ith current liposome technology, the ex vivo route is superior to the in vi vo approach; (2) cDNA alone does not provide transgene expression at levels to produce a functional effect.