Extracellular vesicle (EV)-polyphenol nanoaggregates for microRNA-based cancer diagnosis

Small extracellular vesicles (EVs), including exosomes, in body fluids have important applications in the noninvasive liquid biopsy-based diagnosis of cancer. Current EV-based diagnostic techniques still face practical challenges, such as inefficient EV isolation. Here, we report an efficient, resource-free pre-enrichment approach using (–)-epigallocatechin-3-gallate (EGCG), a polyphenolic biomolecule, to isolate and detect exosomal microRNAs (miRNAs) in human blood plasma samples. Our system comprises three steps: (1) EGCG-mediated EV aggregation, (2) filter-based EV isolation, and (3) molecular beacon-based detection of target miRNA in EVs. Using blood samples from cancer patients with gastric cancer or hepatocellular carcinoma, we constructed an EGCG-assisted miRNA diagnostic system. For both cancers, the levels of target miRNAs (miR-21, -27a, and -375) in EVs were strongly correlated with those in the publicly available GEO database. Our approach, an easy-to-use method for efficient EV isolation and the detection of miRNA in clinical samples, is applicable for molecular diagnostics in precision medicine. An easy-to-use method for efficient collection of potential biomarkers for cancer has been developed by researchers in South Korea. Cells release membranous sacs known as extracellular vesicles that contain proteins, RNA, DNA and other cellular components. The contents can provide an indication of many diseases including cancer but difficulties in isolating such biomarkers have limited the development of practical diagnostic techniques. Pilnam Kim from the Korea Advanced Institute of Science and Technology, Daegeon, and co-workers have developed an efficient method for isolating and detecting small RNA molecules in extracellular vesicles from human blood plasma samples. The improved efficiency was achieved using a polyphenolic biomolecule to control the binding and aggregation of the vesicles. The team confirmed the effectiveness of their collection system using blood samples from patients with gastric cancer and hepatocellular carcinoma. An efficient and resource-free pre-enrichment method using epigallocatechin gallate (EGCG), a polyphenolic biomolecule, has been developed, which enables to isolate and detect exosomal miRNA in human blood plasma samples. The system comprises three steps: (1) EGCG-mediated exosome aggregation, (2) filter-based exosome isolation, and (3) molecular beacon-based detection of target exosomal miRNA. Using blood samples from cancer patients, including those with gastric cancer and hepatocellular carcinoma, our EGCG-assisted miRNA diagnostic system can detect levels of target miRNAs (miR-21, -27a, and -375) in exosomes correlated well with those in an open-geodatabase. Our study highlights the use of a bio-adhesive-mediated preparation method in clinical samples, which can effectively achieve sample isolation and enrichment for exosome-based molecular diagnostics.