A NOVEL CATIONIC LIPID GREATLY ENHANCES PLASMID DNA DELIVERY AND EXPRESSION IN MOUSE LUNG

Effective gene therapy for lung tissue requires the use of efficient v ehicles to deliver the gene of interest into lung cells. When plasmid DNA encoding chloramphenicol acetyltransferase (CAT) was administered intranasally to BALB/c mice without carrier lipids, CAT activity was d etected in mouse lung extracts. Plasmid DNA delivered with optimally f ormulated commercially available transfection reagents expressed up to 10-fold more CAT activity in lung than observed with naked DNA alone. Liposome formulations consisting of 3-aminopropyl)-N,N-dimethyl-2,3-b is(dodecyloxy)-1- propanaminium bromide (GAP-DLRIE) plus the neutral c olipid dioleoylphosphatidylethanolamine (DOPE) enhanced CAT expression by more than 100-fold relative to plasmid DNA alone. A single adminis tration of GAP-DLRIE liposome-CAT DNA complexes to mouse lung elicited peak expression at days 1-4 posttransfection, followed by a gradual r eturn to baseline by day 21 postadministration. Readministration of GA P-DLRIE liposome CAT complexes at day 21 led to another transient peak of reporter gene expression. Histological examination of lungs treate d with GAP-DLRIE complexed beta-galactosidase DNA revealed that alveol ar epithelial cells were the primary locus of expression and that up t o 1% of all alveoli contained epithelial cells expressing the transgen e.