CATIONIC LIPIDS FOR REPORTER GENE AND CFTR TRANSFER TO RAT PULMONARY EPITHELIUM

Increasing evidence indicates that cationic liposomes are capable of s afely transferring foreign genes to pulmonary epithelium in vitro and in vivo. To transfer reporter genes and the cystic fibrosis transmembr ane conductance regulator(CFTR) to mammalian respiratory epithelium we used two cationic lipid formulations: N-[1-(2,3-dioleoyloxy)propyl] N ,N,N-triethylammonium chloride (DOTMA), and imyristyloxy-propyl-3-dime thylhydroxyethylammonium bromide (DMRIE) at a 1:1 molar ratio with dio leoyl phosphatidylethanolamine (DOPE). Lipid-DNA conjugates containing either CFTR or LacZ were instilled directly into the airways of Sprag ue-Dawley rats. Rats treated with LacZ cDNA in vivo demonstrated expre ssion in 30-50% of the large and medium-sized airways with some airway s showing high efficiency gene transfer and expression (in the most pr oximal airways, 70-80% of surface epithelial cells were positive for e xpression of a nuclear targeted LacZ). While control and LacZ treated tracheas mounted in Ussing chambers showed minimal stimulation of tran sepithelial chloride (Cl-) currents by cAMP (suggesting low levels of endogenous fat CFTR activity), tracheas taken from animals receiving C FTR exhibited significant forskolin-stimulated currents at 72 h after gene transfer Human CFTR gene expression was also detected by polymera se chain reaction (PCR) analysis of reverse transcribed lung RNA. Thes e results, together with previous studies using lipid-mediated gene tr ansfer in mice, help confirm the potential for cationic lipid-mediated gene transfer in the gene therapy of cystic fibrosis in humans.