Cationic lipids as transfecting agents of DNA in gene therapy.

The use of cationic lipids (CLs) as transfecting agents of DNA has received an increasing attention in the last two decades. In order to improve the transfection efficiency with lower cytotoxicity, many CLs have been synthesized to be used as non-viral vectors, not only of DNA but also for other nucleic acids. Cationic lipids together with a helper lipid form mixed liposomes that compact DNA forming lipoplexes, gene vectors able to transport DNA into the cells without provoke an immune response. This review is focused in the progress and recent advances experimented in this area, mainly during last decade. Special attention has been paid: (a) to the biophysical characterization (electrostatics, structure, size and morphology) of the lipoplexes using a wide variety of experimental methods and, (b) to the biological studies (transfection efficiency and cell viability/cytotoxicity) addressed to confirm the viability and the optimum formulations of these DNA vectors to be used in gene therapy. Finally, and in order to take advantage towards a rational design of improved lipid gene vectors, the lipoplex structure-biological activity relationship has been also reviewed.