S4(13)-PV cell penetrating peptide and cationic liposomes act synergistically to mediate intracellular delivery of plasmid DNA.

BACKGROUND Cell penetrating peptides have been successfully used to mediate the intracellular delivery of a wide variety of molecules of pharmacological interest. The main aim of the present work was to evaluate the potential of the S4(13)-PV cell penetrating peptide to mediate the intracellular delivery of plasmid DNA, aiming at its use in gene therapy applications. The S4(13)-PV cell penetrating peptide is a chimeric peptide that results from the combination of a cell penetrating sequence derived from the Dermaseptin S4 peptide with the nuclear localization signal present in the Simian Virus 40 (SV40) large T antigen. METHODS S4(13)-PV cell penetrating peptide and cationic liposomes composed of 1,2-dioleoyl-3-trimethylammonium-propane:1,2-dioleoyl-sn-glycero-3-phosphoethanolamine were complexed with pDNA at different charge ratios. Complexation of pDNA was assessed by gel electrophoresis. Luciferase assay, fluorescence microscopy and fluorescence-activated cell sorting analysis were used to evaluate reporter gene delivery to TSA and HeLa cells. Cytotoxicity of the pDNA complexes was assessed by Alamar blue assay. RESULTS Complexes obtained through electrostatic association of the S4(13)-PV cell penetrating peptide with plasmid DNA are able to very efficiently mediate transfection, particularly at high peptide/DNA charge ratios. Additionally, our results clearly demonstrate that, both in HeLa and TSA cells, ternary complexes, resulting from association of cationic liposomes to peptide/DNA complexes, are significantly more efficient in mediating transfection than the corresponding peptide/DNA or cationic liposome/DNA complexes. CONCLUSIONS Overall, our data highlight the potential of cell penetrating peptides for the development of improved nonviral gene delivery systems.