Isolation and Detection Technologies of Extracellular Vesicles and Application on Cancer Diagnostic

Abstract

The vast majority of cancers are treatable when diagnosed early. However, due to the elusive trace and the limitation of traditional biopsies, most cancers have already spread widely and are at advanced stages when they are first diagnosed, causing everincreasing mortality in the past decades. Hence, developing reliable methods for early detection and diagnosis of cancer is indispensable. Recently, extracellular vesicles (EVs), as circulating phospholipid vesicles secreted by cells, are found to play significant roles in the intercellular communication as well as the setup of tumor microenvironments and have been identified as one of the key factors in the next-generation technique for cancer diagnosis. However, EVs present in complex biofluids that contain various contaminations such as nonvesicle proteins and nonspecific EVs, resulting in the interference of screening for desired biomarkers. Therefore, applicable isolation and enrichment methods that guarantee scale-up of sample volume, purity, speed, yield, and tumor specificity are necessary. In this review, we introduce current technologies for EV separation and summarize biomarkers toward EV-based cancer liquid biopsy. In conclusion, a novel systematic isolation method that guarantees high purity, recovery rate, and tumor specificity is still missing. Besides that, a dual-model EV-based clinical trial system includes isolation and detection is a hot trend in the future due to efficient point-of-care needs. In addition, cancer-related biomarkers discovery and biomarker database establishment are essential objectives in the research field for diagnostic settings.

Extracellular Vesicles: An Emerging Nanoplatform for Cancer Therapy

“…Readily found in different body fluids, the number of circulating EVs is significantly higher in cancer patients, as reported in previous studies ( 7 , 29 , 30 ). Because of its transmission capacity in the tumor microenvironment or specific distant sites, these EVs have increasingly become recognized as key players in the cellular processes related to cancer pathogenesis, including tumorigenesis, angiogenesis, tumor invasion, progression, and metastasis ( Figure 1 ).…”

“…MVs, with a diameter of 100–1,000 nm, are released by outward budding and fission of the plasma membrane. Growing evidence has shown that MVs can package bioactive molecules, nucleic acids (microRNAs (miRNAs) or mRNAs), and proteins that are reflective of the original cell type ( 6 , 7 ). Similarly, exosomes also contain massive and complex cargos of contents derived from parent cells.…”

3D Cell Cultures as Prospective Models to Study Extracellular Vesicles in Cancer

“…Moreover, it has been described that in different tumor models exist a correlation between tumor volumes and the concentration of circulating EVs in blood [ 47 ]. These EVs carry a cargo with precious information about the tumor, and they have become the substrate for biomarker digging in all types of malignancies [ 48 , 49 , 50 ] including prostate cancer [ 51 , 52 , 53 ].…”

A Two-Dimensional Affinity Capture and Separation Mini-Platform for the Isolation, Enrichment, and Quantification of Biomarkers and Its Potential Use for Liquid Biopsy

“…In the last few years, several characterization and validation methods have been developed, for both research and clinical purposes, to analyze exosome purity and to quantify exosomal cargo. These methods include transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), resistive pulse sensing, enzyme-linked immunosorbent assay (ELISA), flow cytometry, fluorescence-activated cell sorting (FACS), and microfluidics and electrochemical biosensors [ 228 , 229 , 230 , 231 , 232 ]. The number of methods for quantifying exosomes has expanded as interest in exosomes has increased.…”