Development of Anti-Inflammatory Extracellular Vesicles by Surface Expression of Syndecan-4.

The biological functions of extracellular vesicles (EVs) depend on their cellular source. Further, different subpopulations of EVs from the same cells carry different cargo, but differences in their biological functions are less understood. We here identify a very small EV subpopulation released by HEK293F cells (miniEVs). These EVs, in contrast to the larger EVs, were found to have anti-inflammatory properties. Quantitative proteomics identified a potential anti-inflammatory molecule, Syndecan-4 (SDC4), on the surface of the miniEVs, but not on larger EVs. We engineered HEK293F cells to overexpress SDC4, which results in the molecule being highly expressed in all EV subpopulations. Expression of SDC4, a proteoglycan, also increased the presence of heparan sulfate on the EV surface. Furthermore, these EVs were found to have potent anti-inflammatory effects in vitro, which heparinase treatment could slightly reduce. Furthermore, the SDC4 EVs showed anti-inflammatory effects in vivo in a model of peritonitis. We conclude that HEK293F miniEVs convey anti-inflammatory properties, and SDC4-expressing HEK293F-EV potentially could become an anti-inflammatory therapeutic.