Modification of the glycosylation of extracellular vesicles alters their biodistribution in mice

Extracellular vesicles (EVs) are considered sophisticated vehicles for cell-to-cell communication, thanks to the possibility of handling a variable cargo in a shell with multiple types of decoders. Surface glycosylation of EVs is a method that could be used to control their interaction with different cells and, consequently, the biodistribution of the vesicles in the body. Herein, we produced EVs derived from mouse liver proliferative cells, and we treated them with neuraminidase, an enzyme that digests the terminal sialic acid residues from glycoproteins. Afterwards, we labeled the EVs directly with [I-124]Na and injected them in mice intravenously or into the hock. The amount of radioactivity in major organs was measured at different time points after administration both in vivo using positron emission tomography and ex vivo (after animal sacrifice) using dissection and gamma counting. The results showed that intravenous injection leads to the rapid accumulation of EVs in the liver. Moreover, after some hours the distribution led to the presence of EVs in different organs including the brain. Glycosidase treatment induced an accumulation in the lungs, compared with the intact EVs. Furthermore, when the EVs were injected through the hock, the neuraminidase-treated vesicles distributed better at the axillary lymph nodes than the untreated EVs. This result shows that modification of the glycosylated complexes on the EV surface can affect the distribution of these vesicles, and specifically removing the sialic acid residues allows more EVs to reach and accumulate at the lungs.