Extracellular vesicles (EVs), including exosomes and microvesicles, are present in a variety of bodily fluids, and the concentration of these sub-cellular vesicles and their associated biomarkers (proteins, nucleic acids, and lipids) can be used to aid clinical diagnosis. Although ultracentrifugation is commonly used for isolation of EVs, it is highly time-consuming, labor-intensive and instrument-dependent for both research laboratories and clinical settings.
Researchers at Zhejiang University have developed an integrated double-filtration microfluidic device that isolated and enriched EVs with a size range of 30–200 nm from urine, and subsequently quantified the EVs via a microchip ELISA. Their results showed that the concentration of urinary EVs was significantly elevated in bladder cancer patients (n = 16) compared to healthy controls (n = 8). Receiver operating characteristic (ROC) analysis demonstrated that this integrated EV double-filtration device had a sensitivity of 81.3% at a specificity of 90% (16 bladder cancer patients and 8 healthy controls). Thus, this integrated device has great potential to be used in conjunction with urine cytology and cystoscopy to improve clinical diagnosis of bladder cancer in clinics and at point-of-care (POC) settings.
Isolation and detection of EVs from urine using an integrated
double-filtration microfluidic device
(A) Schematic of a double-filtration microfluidic device for isolation and detection of EVs. Based on size-exclusion, particles larger than 200 nm are excluded by the membrane with a pore size of 200 nm in the sample chamber, whereas particles smaller than 30 nm pass through the double-filtration device. EVs with a size between 30 and 200 nm are isolated and enriched in the isolation chamber. (B) Image of an assembled double-filtration device. (C) Schematic of direct ELISA for EV detection on-chip. The EVs isolated in the double-filtration device are labeled with biotinylated anti-CD63 antibodies, and then with streptavidin-HRP. Addition of TMB substrate enables blue color development in the double-filtration device. (D) The ELISA result is imaged using a smart phone and then transferred to a laptop for data analysis using ImageJ.