Efficiency of non-viral gene delivery systems to rat lungs

Objective: Transient expression of therapeutic genes within lung allografts may modulate the pathological processes following allotransplantation. Whi lst efficient gene transfer to lungs has been reported with viral vectors, their usefulness is limited on the grounds of safety. Since non-viral syste ms overcome many of these safety issues, our studies were designed to evalu ate the efficiency of several non-viral gene delivery vectors for in vivo t ransfer of plasmid DNA to rat lungs via the airways. Methods: Fischer rats (230-260,a) underwent a thoracotomy, right main bronchus occlusion and inst illation of 300 mug naked or complexed DNA (pClluci, luciferase gene/CMV pr omoter) to the left lung followed by ventilation for 10 min. Rats were divi ded into five treatment groups (n = 5): (1) Glucose, (2) Naked DNA, (3) Lin ear polyethylenimine (PEI), (4) Branched PEI, (5) Lipid CL-67/DOPE and (6) DOTAP/cholesterol. Animals were sacrificed 24 h after gene delivery for mea surement of reporter gene activity and gas exchange of the left lung. Resul ts: Linear PEI was the most efficient gene delivery vector and was signific antly better than DOTAP/cholesterol (P = 0.00002) and naked DNA (P = 0.004) . All gene delivery vectors impaired function of the transfected left lung compared with DNA alone. Of all the gene delivery vectors tested, lipid GL- 67/DOPE exerted the least effect on lung function whilst DOTAP/cholesterol mediated the most adverse effect. Conclusion: Linear PEI was the most effic ient vector for gene delivery to rat lungs in our experimental setting alth ough it mediated a moderate impairment in lung function. Further studies ar e needed to evaluate whether this effect is transient. (C) 2001 Elsevier Sc ience B.V. All rights reserved.