Multifunctional peptides based on low molecular weight protamine (LMWP) in the structure of polyplexes and lipopolyplexes: Design, preparation and gene delivery characterization

The development of an effective and safe gene carrier is one of the main challenges in gene therapy. In this study, we designed two new cationic peptides (VV45 and VV32) based on low molecular weight protamine (LMWP) which were upgraded by adding a histidine tag (H10) and nuclear localization signal (NLS) peptide and evaluated their transfection efficiency and cytotoxicity in the formulation of Peptide-DNA (PD) and Liposome-Peptide-DNA (LPD) complexes. Using the gel retardation assay for assessment of condensation ability, three carriers to plasmid (C/P) ratios of 1, 3, and 6 for PD and LPD formulations were selected, and prepared vectors were evaluated in terms of size distribution and zeta potential. All vectors in deionized water (DW) had a size below 200 nm (PD complexes: 65–120 nm, and LPD complexes: 140–185 nm) and a positive zeta potential (PD: 3–15 mV, and LPD: 32–48 mV). Generally, the LPD complexes revealed higher GFP expression than PD complexes, up to four-folds. Compared to,polyethyleneimine 25 kDa, as a transfection standard, the LPD VV45 at C/P ratios of 3, 6 and LPD VV32 at C/P ratio of 6 had a higher transfection. In terms of cytotoxicity, PD complexes have no cytotoxicity, and at the LPD complexes, increasing in C/P ratio decreased the cell viability to 30–50%. So newly designed peptides are effective gene carriers in the formulation of LPD with a promising safety profile in polyplex formulation.