Enhanced intracellular peptide delivery with pH-responsive, endosomolytic nano-polyplexes to modulate vascular smooth muscle cell behavior

Abstract

Peptide-based therapeutics have significant potential for use in a variety of clinical applications ranging from cancer therapy to promotion of cardiovascular health. However, the efficacy of these approaches is limited due to poor cellular uptake and peptide sequestration within endo-lysomal vesicles that are trafficked for exocytosis or lysosomal degradation. The drug delivery platform described herein provides a means to overcome these barriers through the use of cell-permeant, pH-responsive nano-polyplexes that significantly enhance cell internalization and facilitate endosomal escape of a cationic, therapeutic peptide. A reproducible method to synthesize electrostatically complexed nanoparticles containing a therapeutic peptide and a pH-responsive polymer has been developed and optimized to yield nano-polyplexes of approximately 100 nm in diameter. These polyplexes display pH-dependent membrane disruption ideal for endosomal escape, which was verified through microscopic analysis of cellular uptake and intracellular trafficking. The polyplexes were found to have significantly enhanced bioactivity in reducing inflammatory cytokine production in stimulated human vascular smooth muscle cells in vitro compared to the peptide alone (p<0.05). Furthermore, flow cytometric analysis revealed that these polyplexes significantly enhanced cellular uptake and intracellular half-life compared to the peptide alone (p<0.05). This promising platform technology provides a novel method to effectively enhance cytosolic delivery of cationic therapeutic peptides and demonstrates a potentially high-impact therapeutic approach to improving graft patency in vascular bypass grafting applications.