Abstract
Background
Despite the use of currently optimized lipofection conditions, including transfection in serum‐depleted media, the efficiency of gene transfer is low and high transfection rates often induce cytotoxicity. A lipid formulation with transfection efficiency not inhibited by serum would provide an advance towards in vivo applications.
Methods
We explored the ability of the cationic lipid SH‐14 to dimerize upon DNA and form lipoplexes, and potentially release nucleic acids in the intracellular reducing milieu. We investigated the critical micelle‐forming concentration of SH‐14 and its intrinsic toxicity, size and Zeta potential measurements, the in vitro cytotoxicity of SH‐14/plasmid DNA lipoplexes and their ability to transfect cells.
Results
Among all the charge ratios (CR, + /−) tested, lipoplexes at CR 10 with a mean diameter of 295 nm and a surface charge of + 20 mV, exhibited the best compromise between transfection efficiency and tolerability. SH‐14 presented the same cytotoxicity level whether alone or complexed in lipoplexes. Lipofections carried out in serum‐free medium shared a transfection efficiency, on average, of 40% and a cytotoxicity of 38%. An increase of 73% in transfection efficiency and 24% in cell viability were obtained, extending lipofection over 48 h in complete‐medium. Moreover, when serum concentration was increased from 10% to 50%, a three‐fold increase in plasmid dose led to more than 72% of cells being transfected with almost no sign of cytotoxicity.
Conclusions
Overall, SH‐14 presents good potential as a novel transfection reagent to be used in the presence of serum. Copyright © 2008 John Wiley & Sons, Ltd.