Different isolation approaches lead to diverse glycosylated extracellular vesicle populations

Abstract

Extracellular vesicles (EVs) are a heterogeneous group of small secreted particles involved in inter-cellular communication and mediating a broad spectrum of biological functions. EVs cargo iscomposed of a large repertoire of molecules, including glycoconjugates. Herein, we report the firststudy on the impact of the isolation strategy on the EV populations’glycosylation profile. The use ofdifferent state-of-the-art protocols, namely differential ultracentrifugation (UC), total exosome isola-tion (TEI), OptiPrepTMdensity gradient (ODG) and size exclusion chromatography (SEC) resulted in EVpopulations displaying different sets of glycoconjugates. The EV populations obtained by UC, ODGand SEC methods displayed similar protein and glycan profiles, whereas TEI methodology isolated themost distinct EV population. In addition, ODG and SEC isolation protocols provided an enhanced EVglycoproteins detection. Remarkably, proteins displaying the tumour-associated glycan sialyl-Tn(STn) were identified as packaged cargo into EVs independently of the isolation methodology. STncarrying EV samples isolated by UC, ODG and SEC presented a considerable set of cancer-relatedproteins that were not detected in EVs isolated by TEI. Our work demonstrates the impact of usingdifferent isolation methodologies in the populations of EVs that are obtained, with consequences inthe glycosylation profile of the isolated population. Furthermore, our results highlight the importanceof selecting adequate EV isolation protocols and cell culture conditions to determine the structuraland functional complexity of the EV glycoconjugates.