Cancer-derived small extracellular vesicles PICKER

Cancer-derived small extracellular vesicles (csEVs) play critical roles in the genesis and development of various cancers. However, accurate detection of low-abundance csEVs remains particularly challenging due to the complex clinical sample composition. Researchers at Chongqing University have now constructed a Programmable Isothermal Cascade Keen Enzyme-free Reporter (PICKER) for the reliable detection and acquisition of the relative abundance of csEVs in total sEVs (tsEVs) by integrating dual-aptamer recognition (cancer-specific protein EpCAM and tetraspanin protein CD63) with a catalytic hairpin assembly (CHA) amplification. By employing this strategy, they researchers were able to achieve a detection limit of 420 particles/μL csEVs. Particularly, they propose a novel particle ratio index of csEV against tsEV (PR_csEV/tsEV) to greatly eliminate errors from inconsistent centrifugation, which was calculated from the fluorescence ratio produced by csEVs and tsEVs. The PICKER showed a 1/10,000 discrimination capability by successfully picking out 1.0 × 10³ csEV from 1.0 × 10⁷ tsEV per microliter. The researchers also found that the PR_csEV/tsEV value increased proportional to the stages of breast cancer by analyzing EVs from clinical patients’ plasma. Taken together, the established PICKER strategy capable of accurately discriminating csEVs, and the proposed PR_csEV/tsEV are a potential indicator of breast cancer staging, paving the way toward facilitating cancer diagnosis and precision therapeutics.