Optimization of cationic liposome-mediated gene transfer to human bronchial epithelial cells expressing wild-type or abnormal cystic fibrosis transmembrane conductance regulator (CFTR)

We determined optimum conditions for delivering DNA to transformed human br onchial epithelial cells expressing wild-type (BEAS) or abnormal (2CF) cyst ic fibrosis transmembrane conductance regulator (CFTR) using cationic lipos omes (Lipofectin, [N- (N,N-dimethylaminoethane)carbamyl] cholesterol[DC-Cho l]/dioleoylphosphatidylethanolamine[DOPE], or LipofectAMINE) and reporter g enes which measured overall transgene expression (luciferase) or the fracti on of cells transfected (heat-stable alkaline phosphatase). All liposomes s howed dose-related toxicity. Optimal liposome and lipid: DNA ratios were di fferent for BEAS than for 2CF cells. For all 3 liposome preparations, small particle size and net cationic charge related to transfection efficiency. Both LipofectAMINE and DC Chol/DOPE transfected a maximum of 3% of BEAS cel ls, but luciferase expression could be increased without increasing the fra ction of cells transfected. LipofectAMINE transfected a maximum of 6% of 2C F cells, and luciferase expression could be increased with no further incre ase infraction of transfected cells. DC-Chol/DOPE transfected over 12% of 2 CF cells with relatively small increases in luciferase expression. We concl ude that an optimal cationic liposome and lipid : DNA ratio for transfectin g bronchial epithelial cells depends on: (I) small particle size and net ca tionic charge, (2) whether the cells have the cystic fibrosis defect, and ( 3) whether the desired outcome is transfection of the maximum fraction of t he cells or maximum total expression of the transgene.