Endothelial cell derived exosome nanoparticle to deliver siRNA

A. Banizs, T. Huang, J.S. Lee, W. Shi and J. He
University of Virginia, US

Keywords: exosome, gene delivery, RNAi, atherosclerosis

Summary:

Despite the promise of these candidates in local, direct delivery, systemic delivery of siRNA is urgently needed for distribution to a wider range of targets. As natural transporters of nucleic acids, exosomes could represent a more efficient therapeutic delivery vehicle for exogenous siRNA. Exosomes were prepared from mouse endothelial cells (both primary and immortal cells) by sequential ultracentrifugation. Purified exosomes were analyzed under transmission electron microscopy (TEM). Doughnut shaped, nanovesicles were seen uniformly. To further characterize the population of endothelial exosomes, their average size was determined which resulted in 58.4 +/- 27.3 nm. ELISA-63 confirmed the presence of CD63 molecule on endothelial exosomes and the relative particle number was further calculated based on the assay. These exosomes were loaded with luciferase siRNA by electroporation (exosome/siRNA(luc)). The gene silencing effect was evaluated by incubation with pGL2/Fugene (Promega) transfected endothelial cells. The exosome/siRNA (luc) showed significantly lower expression of luciferase compared to controls including exosome loaded with control siRNA (exosome/siRNA(contr), native control siRNA (siRNA (control), and native siRNA (luc) as well as the baseline pGL2/Fugene. In conclusion, we have successfully prepared exosome from endothelial cells and demonstrated that exosome loaded with siRNA has RNAi effect in vitro.