Atheroscleroris (AS) is a risk factor of cardiovascular disease (CVD). AS initiates at the endothelial level in areas of perturbed blood flow contributing to the recruitment of inflammatory cells. Extracellular vesicles (EVs) have emerged as mediators of intercellular crosstalk. Endothelial EVs are considered as potential biomarkers of CVD and are biological effectors. Atheroprone conditions (shear stress- SS) influence EV release and these EVs transport miRNA cargo to recipient cells contributing to phenotypical changes. Mechanisms linking EV-mediated transfer of information to AS development have not been defined.

We hypothesize that endothelial EVs are selectively released as function of SS and transferred to the spleen given its importance in regulating the immune response in AS.

Mouse endothelial cells were exposed to Low SS (LSS) or High SS (HSS) for 24h. Large EVs (lEVs) and small EVs (sEVs) were isolated from conditioned medium by differential centrifugation; characterized by Western blot (WB) using EV markers and tunable resistive pulse sensing EV uptake by splenocytes was assessed by flow cytometry using labelled EVs with Vybrant DiD (VD). EV miRNA content was analyzed by microarray and qPCR.

HSS increased EV release as compared to LSS without affecting EV size. WB analysis showed that SS conditions did not affect EV markers. Analysis of EV biodistribution revealed that LSS lEVs are preferentially transferred to B and T lymphocytes as compared to HSS EVs. LSS and HSS sEVs do not exhibit any specific tropism and are poorly transferred to cells. We found that lEVs and sEVs contain different miRNAs. Among these, miR-24 is packaged into LSS lEVs and that its transfer could modulate targets in splenocytes.

These findings revealed that SS affects EV release, miRNAs content and biodistribution to splenocytes. Future work involves deciphering the in vivo role of these EVs in the context of AS.