DIRECT GENE-TRANSFER TO THE RESPIRATORY-TRACT OF MICE WITH PURE PLASMID AND LIPID-FORMULATED DNA

Direct gene transfer into the respiratory system could be carried out for either therapeutic or immunization purposes, Here we demonstrate t hat cells in the lung can take up and express plasmid DNA encoding a l uciferase reporter gene whether it is administered in naked form or fo rmulated with cationic liposomes, Depending on the lipid used, the tra nsfection efficiency with liposome-formulated DNA may be higher, the s ame as, or less than that with pure plasmid DNA, Tetramethyltetraalkyl spermine analogs with alkyl groups of 16 or 18 carbons and DMRIE/chole sterol formulations proved particularly effective. Similar results for reporter gene expression in the lung were obtained whether the DNA (n aked or lipid formulated) was administered by indirect, noninvasive in tranasal delivery (inhaled or instilled) or by invasive, direct intrat racheal delivery (injected or via a cannula), Reporter gene expression peaks around 4 days, then falls off dramatically by 9 days. The dose- response is linear, at least up to 100 mu g plasmid DNA, suggesting be tter transfection efficiencies might be realized if there was not a vo lume limitation, For a given dose of DNA, the best results are obtaine d when the DNA is mixed with the minimum amount of lipid that can comp lex it completely. These results are discussed in the context of direc t gene transfer for either gene therapy or delivery of a mucosal DNA v accine.