BACKGROUND AIMS: Exosomes, a key component of cell paracrine secretion, can 
exert protective effects in various disease models. However, application of 
exosomes in vascular repair and regeneration has rarely been reported. In this 
study, we tested whether endothelial progenitor cell (EPC)-derived exosomes 
possessed therapeutic effects in rat models of balloon-induced vascular injury 
by accelerating reendothelialization.
METHODS: Exosomes were obtained from the conditioned media of EPCs isolated from 
human umbilical cord blood. Induction of the endothelial injury was performed in 
the rats' carotid artery, and the pro-re-endothelialization capacity of 
EPC-derived exosomes was measured. The in vitro effects of exosomes on the 
proliferation and migration of endothelial cells were investigated.
RESULTS: We found that the EPC-derived exosomes accelerated the 
re-endothelialization in the early phase after endothelial damage in the rat 
carotid artery. We also demonstrated that these exosomes enhanced the 
proliferation and migration of endothelial cells in vitro. Moreover, endothelial 
cells stimulated with these exosomes showed increased expression of 
angiogenesis-related molecules.
CONCLUSIONS: Taken together, our results indicate that exosomes are an active 
component of the paracrine secretion of human EPCs and can promote vascular 
repair in rat models of balloon injury by up-regulating endothelial cells 
function.