Subcellular trafficking and transfection efficacy of polyethylenimine-polyethylene glycol polyplex nanoparticles with a ligand to melanocortin receptor-1.

We have synthesized and investigated properties of new PEI-PEG-based polyplexes containing MC1SP-peptide, a ligand specific for melanocortin receptor-1 (targeted polyplexes), and control polyplexes without this ligand peptide (non-targeted polyplexes). The targeted polyplexes demonstrated receptor-mediated transfection of Cloudman S91 (clone M-3) murine melanoma cells that was more efficient than with the non-targeted ones. Transfection with the targeted polyplexes was inhibited by chlorpromazine, an inhibitor of the clathrin-mediated endocytosis pathway, and, to a lesser extent, by filipin III or nystatin, inhibitors of the lipid-raft endocytosis pathway, whereas transfection with the non-targeted polyplexes was inhibited mainly by nystatin or filipin III.

Properties of PEI-based polyplex nanoparticles that correlate with their transfection efficacy.

We have evaluated the key properties of the polyethylenimine (PEI)-polyethylene glycol (PEG)-TAT peptide polyplex nanoparticles including their behavior in cells and compared them with the transfection efficacy (TE) using 11 different cell lines. We found statistically significant positive correlation between TE and the share of 50-75 nm fraction in the whole mixture of nanoparticles estimated with atomic force microscopy. Variations in PEG/PEI and N/P ratios (PEI nitrogen to DNA phosphate ratio) enabled us to find their optimal combinations, which resulted in up to 100% TE for several cell lines.

Modular drug transporters with diphtheria toxin translocation domain form edged holes in lipid membranes.

Modular/chimeric recombinant drugs or drug transporters usually contain a special translocation domain from bacterial toxins, e.g. diphtheria toxin, as a module enabling escape of the chimeric molecules from acidifying endosomes.