Stearylated INF7 Peptide Enhances Endosomal Escape and Gene Expression of PEGylated Nanoparticles Both in Vitro and in Vivo

We previously reported on a stearylated INF7 peptide (str-INF7), which enhances the endosomal escape of an octaarginine (R8)-modified liposomal particle encapsulating plasmid DNA (pDNA) in a fusion-independent manner. This study examined whether this peptide derivative enhanced the endosomal escape and gene expression of PEGylated liposomes encapsulating pDNA. We used a PEGylated, R8-modified multifunctional envelope-type nanodevice (R8MEND) as a model for PEGylated liposomes. Polyethylene glycol 2000 (PEG2000) attached to two different anchors, distearoylphosphatidylethanolamine (DSPEPEG) or dimyristoylphosphatidylethanolamine (DMPEPEG), was used to modify the R8MEND in the presence or absence of two different concentrations of str-INF7. Modification of the PEGylated R8MEND with str-INF7 resulted in luciferase gene expression levels in HeLa cells that were 73-fold and 24-fold higher than the corresponding value for an unmodified MEND in the case of DSPEPEG and DMPEPEG, respectively. The endosomal escape of the PEGylated R8MEND was improved by str-INF7, as confirmed by confocal laser scanning microscopy. Furthermore, modification with str-INF7 enhanced the hepatic gene expression of the R8MEND modified with DSPEPEG and DMPEPEG by 95-fold and 1885-fold, respectively, after intravenous injection in mice. Collectively, these data demonstrate that str-INF7 can be a useful device for enhancing the endosomal escape even for PEGylated liposomes encapsulating pDNA. (C) 2011 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:879882, 2012