Factors influencing the efficiency of lipoplexes mediated gene transfer inlung after intravenous administration

The objectives of this study were to test the influence of different parame ters on the in vivo cationic lipid mediated gene transfer in lung after int ravenous administration. Luciferase activity was evaluated in lung tissue 2 4 hours after intravenous administration of different types of lipoplexes. These included lipoplexes prepared using cationic phosphonolipids or DOTAP and various amounts of plasmid DNA. Using two different plasmids we tested the influence of plasmid size on transfection efficiency in vivo. In a last series of experiments, lipoplexes were prepared using different excipients (water, NaCl or 5% glucose solution) and three injection volumes were test ed. We demonstrate that chemical structure modifications such as cation sub stitution and increment of the aliphatic chain length significantly improve transfection efficiency. High luciferase levels are obtained by increasing lipid to DNA charge ratio and plasmid DNA dose and decreasing plasmid size . Lipoplexes prepared in physiological NaCl solution and injected using a v olume of 800 mul are significantly the most effective. Cationic lipid mediated gene transfer in lung tissue after intravenous admi nistration is influenced by factors including cationic lipid chemical struc ture, lipid to DNA ratio and plasmid dose. Nevertheless, plasmid size, inje ction volume and the excipient, used for the lipoplexes preparation, are al so important factors and must be considered for an optimization of in vivo gene delivery using intravenous administration.