Impact of PEGylation on biodistribution and tumor accumulation of Lipid-Mu peptide-DNA.

For gene-based therapeutic approaches that require transfection of specific cell targets in vivo, it is important to design the delivery system to have optimized tissue distribution. Surface PEGylation of liposomes and polymer nanoparticles has been shown to lead to prolonged blood circulation and also preferential accumulation in tumor sites resulting from the enhanced permeability and retention (EPR) effect. The aim of this study was to investigate the effect of different surface PEGylation densities on resulted biodistribution profiles of Lipid-Mu peptide-DNA (LMD) nanoparticles. LMD particles containing the near infrared fluorescent lipid dye, Cy5.5-DSPE, were injected intravenously, and whole-body fluorescence images of the live animal were recorded. Analysis of these time series of images indicated that LMDs with different surface PEG(2000) densities had distinctively different biodistribution and tumor accumulation profiles. LMDs containing approximately 15-25% of surface PEG(2000) were shown to have the highest accumulation and longest residence time in tumor. LMD distribution and pharmacokinetic profiles in other organs were also observed to be different and were analyzed.