Abstract Or128: Exosomes carrying VEGF-A mRNA rescues ischemic tissue with low immunogenicity

Background and aims: Lackluster results from recently completed gene therapy clinical trials of VEGF-A delivered by viral vectors have heightened the need to develop alternative delivery strategies. This study aims to demonstrate the preclinical efficacy and safety of extracellular vesicles (EVs) loaded with VEGF-A mRNA for the treatment of ischemic vascular disease. Methods: After encapsulation of full-length VEGF-A mRNA into fibroblast-derived EVs via cellular nanoporation (CNP), collected VEGF-A EVs were delivered into mouse models ischemic injury. Target tissue delivery was verified by in situ analysis of protein and gene expression. Functional rescue was confirmed by in vivo imaging and histology. The safety of single and serial delivery was demonstrated using immune-based assays. Results: VEGF-A EVs were generated with high mRNA content using a CNP methodology. VEGF-A EV administration demonstrated expression of exogenous VEGF-A mRNA by in situ RNA hybridization and elevated protein expression by Western blot, microscopy, and ELISA. Mice treated with human VEGF-A EVs after femoral or coronary artery ligation exhibited heightened neovascularization in ischemic tissues with increased arterial perfusion and improvement in left ventricular function, respectively. Serial delivery of VEGF-EVs in injured skin showed improved wound healing with repeat administration. Importantly, as compared with AAV and LNP VEGF-A gene therapy modalities, murine VEGF-A EV delivery did not trigger innate or adaptive immune responses at the injection site or systemically. Conclusions: This study demonstrated that VEGF-A EV therapy offers efficient, dose-dependent VEGF-A protein formation with low immunogenicity, resulting in new vessel formation in murine models of ischemic vascular disease.