An efficient PEGylated gene delivery system with improved targeting: Synergism between octaarginine and a fusogenic peptide.

Because of their ability to translocate different cargos into cells, arginine-rich cell penetrating peptides (CPPs) are promising vehicles for drug and gene delivery. The use of CPP-based carriers, however, is hampered by the lack of specificity and by interactions with negative serum components. Polyethylene glycol (PEG) is used to decrease such non-specific interactions, albeit its use is associated with reduced transfection efficiency. In this study, we describe the development of PEGylated CPP-based gene carrier with an improved targeting and a high transfection activity. The system was prepared by condensing DNA with a polycation followed by coating with a lipid envelope containing the octaarginine (R8) peptide as a model CPP. R8-modified nanoparticles produced high transfection activities, but the efficiency was reduced by PEG shielding. The reduced activity could be fully restored by the addition of a targeting ligand and a pH-sensitive fusogenic peptide. The efficiency of the proposed system is quite high, even in the presence of serum, and shows improved targeting and selectivity. Surprisingly, the effect of the fusogenic peptide was dramatically reduced in the absence of R8. Although shielded, R8 augmented the activity of the fusogenic peptide, suggesting a synergistic effect between the two peptides at the intracellular level.