In this study, microRNA profiles were analysed in control-non-senescent (CON) and senescent (SEN) HUVECs and microRNA profiling assessed in their cognate EVs, small (SVs) or large (LVs)

The role of epigenetics in endothelial cell senescence is a cutting-edge topic in the research on aging. However, the relative contribution of extracellular vesicles (EVs)-carried microRNAs released by senescent cells to the propagation of pro-senescence signals, is still poorly explored. Here, microRNA and DNA methylation profiles were analysed in control-non-senescent (CON) and senescent (SEN) HUVECs and microRNA profiling assessed in their cognate EVs, small (SVs) or large (LVs). We observed that SEN released a three-fold greater number of SVs than CON. These SVs are enriched in miR-21-5p and miR-217, which can target DNMT1 and SIRT1. Following the treatment of CON cells with senescent SVs, we observed a miR-21/miR-217-related impairment of DNMT1-SIRT1 expression and proliferation rate. Notably, microRNA profiling of SVs purified from plasma of healthy subjects aged 40-100 years showed an inverse U-shaped age-related trend for miR-21-5p, as expected for a senescence-associated biomarker. Our results suggest that miR-21/miR-217 loaded on senescent SVs spread pro-senescence signals, affecting DNA methylation and replication.