The Fatty Acid Transporter CD36 Mediates Uptake, Biodistribution, and Cardioprotection by Small Extracellular Vesicles From HEK293 Cells.

Cardiac endothelial cells internalised small extracellular vesicles more efficiently than cardiomyocytes in vitro.

• sEVs were derived from HEK293 cells and labelled with NanoLuc for tracking purposes.
• Both cardiac endothelial cells and cardiomyocytes were tested for sEV uptake in vitro.
• The difference in uptake efficiency between cell types was assessed in the in vitro setting.

In healthy mice, intravenously administered HEK293-derived sEVs accumulated mainly in the lungs, liver, and spleen.

• Biodistribution was assessed in vivo using NanoLuc-labelled sEVs.
• sEVs were purified by size-exclusion chromatography and tangential flow filtration prior to administration.
• The primary organs of accumulation were the lungs, liver, and spleen in the healthy (non-injured) mouse model.

Administration of HEK293-derived sEVs post-ischaemia-reperfusion significantly reduced myocardial infarct size in mice.

• Infarct size was reduced from 58% ± 8% to 36% ± 3% following sEV administration.
• The reduction was statistically significant (p < 0.05, n = 5).
• sEVs were administered post-ischaemia and reperfusion (IR) injury in the mouse model.
• The cardioprotective effect was observed when sEVs were given after the ischaemic insult.

Inhibition of CD36 with sulfosuccinimidyl oleate (SSO) impaired sEV uptake and abolished cardioprotection.

• CD36 is a scavenger/lipid-binding receptor expressed in both cardiomyocytes and endothelial cells.
• Sulfosuccinimidyl oleate (SSO) was used as the pharmacological inhibitor of CD36.
• SSO treatment both impaired sEV uptake in cardiac cells and abolished the cardioprotective reduction in infarct size.
• These results identify CD36 as a key mediator of sEV uptake and function.

CD36, a lipid-binding scavenger receptor, was hypothesised and confirmed to mediate uptake of small extracellular vesicles in cardiac cells.

• CD36 is expressed in both cardiomyocytes and cardiac endothelial cells.
• The hypothesis was that CD36's lipid-binding properties could facilitate sEV internalisation.
• Experimental inhibition of CD36 provided functional evidence for its role as a key mediator of sEV uptake.
• This represents a mechanistic finding linking a known lipid receptor to EV biodistribution and therapeutic function.