Size-exclusion chromatography as a clinically applicable method for extracellular vesicles collection as liquid biopsies shows potential diagnostic relevance and correlation with poorer outcome in common cancer types

Increasing evidence suggests extracellular vesicles (EVs) are key components of liquid biopsies to aid cancer diagnosis and treatment selection, if their collection can be translated to clinical settings. Size exclusion chromatography (SEC) is relatively simple, fast, and cost-effective, but its potential for “real-world” EVs collection for cancer diagnoses is unknown. Here we aimed to critically evaluate SEC using clinically-relevant plasma volumes and across a range of common cancer types that are frequently diagnosed too late. EVs were collected, using qEV70 or qEV35 SEC columns, from duplicate aliquots of n = 43 plasma samples procured at diagnosis with lung, ovarian, or gastric cancers and characterised on multiple parameters, seeking correlations with patients clinicopathological information. To investigate potential diagnostic relevance, EVs were collected in the same way from n = 10 plasma samples from healthy donors. We found that SEC has many attributes indicating that it is translatable to real-world clinical utility. With both SEC types, relatively large quantities of EVs were successfully collected from small plasma volumes for all three cancer types. No significant differences existed between qEV70 and qEV35 particle sizes, structure, and EVs markers. EVs in qEV35 isolates versus qEV70 isolates had reduced purity and/or increased protein corona, but both isolates revealed clinical correlations. Importantly, depending on the cancer type(s), results suggested that the EVs isolates at the time of cancer diagnosis may inform on lymph node-positivity and advanced stage, and may be prognostic for shorter time to disease progression. Furthermore, analysis of plasma CD63+ EVs and CD81+ EVs appears to have diagnostic relevance, due to their typically significantly greater quantities in cancer types compared to healthy controls. Altogether, SEC shows promise as a potential approach for clinical EVs collection as liquid biopsies and correlations between plasma EVs quantities with a range of clinicopathological characteristics suggests this would be worthwhile.