Comparison of endothelial cell- and endothelial progenitor cell-derived exosomes in promoting vascular endothelial cell repair

Timely endothelial repair after intervention-associated vascular injury is critical to prevent restenosis and thrombosis. Compared to living cell therapies, exosomes may be a better alternative. Thus, we aimed to compare the role of exosomes derived from human umbilical vein endothelial cells (HUVECs) versus those derived from endothelial progenitor cells (EPCs) in vascular endothelial repair.

Exosomes secreted from HUVECs and EPCs were isolated and characterized respectively. In vitro, the effects of the two types of exosomes on migration and proliferation of endothelial cells were studied. In vivo, rats were systemically treated with the two exosome groups respectively after carotid artery endothelial injury induced by a balloon. The efficacy in promoting re-endothelialization was measured by Evans blue dye and histological examination.

Both types of exosomes, sized from 30 nm to 100 nm, had sphere-shaped or cupped morphology, and expressed CD63, CD9, and CD81; but the total yield of exosomes (particles/mL) based on number of cells, was 4.2 times higher from EPCs than HUVECs. Compared with control treatment, both exosome treated groups manifested significant enhancement of migration and proliferation in vitro and vascular recovery at an early stage in vivo. The two exosome-treated groups, however, did not statistically significantly differ.

In conclusion, our results indicated that exosomes derived from HUVECs and EPCs had similar morphology, size distributions and characteristics, but those derived from EPCs were more abundant with comparable biologic activity. Therefore, EPCs may be a robust source of exosomes to promote vascular repair.