Three-armed biodegradable polyesters with ionization-mimicking cationic lipid properties for VEGF mRNA delivery in critical limb ischemia

A novel biodegradable polyester was designed to replace non-degradable cationic lipids, thereby eliminating long-term toxicity risks associated with mRNA delivery. • The ester-rich backbone facilitates endosomal/lysosomal escape, achieving superior VEGF mRNA transfection efficiency compared to conventional MC3- and DOTAP-based LNPs. • This polyester exhibits dual bioactivities: reactive oxygen species (ROS) scavenging and nitric oxide release, which synergistically mitigate oxidative stress and promote angiogenesis. Gene therapy has demonstrated promising efficacy in the treatment of peripheral arterial disease (PAD). However, conventional cationic lipids used in mRNA lipid nanoparticles (LNPs) lack degradable bonds, which may pose potential toxicity and long-term accumulation risks. Although many ionizable lipids have been designed with degradable ester linkages, the development of fully biodegradable cationic alternatives with favorable safety profiles remains of great interest. To address these limitations, we developed a biodegradable cationic alternative via ring-opening polymerization of ε-caprolactone initiated by triethanolamine, forming a three-armed polyester (3s-PCL) with tertiary ammonium groups. Subsequent conjugation with arginine or lysine yielded terminal-functionalized polyesters (3sPA /3sPL) as sustainable substitutes for conventional cationic lipids. In vitro and in vivo studies demonstrated that 3sPA-containing LNPs exhibit higher transfection efficiency than conventional LNPs (e.g., MC3- or DOTAP-based LNPs). Notably, arginine-modified 3sPA-LNPs displayed dual bioactivity: effective reactive oxygen species (ROS) scavenging and nitric oxide (NO) release. When loaded with VEGF mRNA, 3sPA-LNPs synergistically promoted angiogenesis in critical limb ischemia by elevating VEGF expression, reducing inflammation through ROS scavenging, and improving microcirculation via NO release. Collectively, these findings establish 3sPA-LNPs as a potent and safe mRNA delivery platform for critical limb ischemia, offering a promising treatment strategy for regenerative therapy. Download: Download high-res image (109KB) Download: Download full-size image