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.