Isolation and Visible Detection of Tumor-Derived Exosomes from Plasma

Abstract

Exosomes are nanosized extracellular vesicles (ranging from 30 to 120 nm) released from many cells that provide promising biomarkers for the noninvasive diagnosis of cancer. However, traditional exosome-isolation methods are tedious, nonstandardized, and require bulky instrumentation, thus limiting its clinical applications. In this paper, an anion-exchange (AE)-based isolation method was first proposed to isolate exosomes directly from plasma and cell-culture medium with AE magnetic beads within 30 min. Exosomes isolated with AE magnetic beads had higher recovery efficiency (>90%) and less protein impurities than those isolated by ultracentrifugation (UC). Prostate-cancer (PCa) exosomes in plasma were detected in a visual, label-free, and quantitative manner with aptamer-capped Fe3O4 nanoparticles for the first time. The linear range of PCa exosomes was estimated from 0.4 × 108 to 6.0 × 108 particles/mL with a detection limit of 3.58 × 106 particles/mL. The present study provides an efficient and practical approach for the rapid isolation and visible detection of exosomes, which is promising for the early diagnosis of PCa.

Application of exosomes as liquid biopsy in clinical diagnosis

“…At the same time, a size-based exosome total isolation chip, which was easy to operate, with higher yield and similar purity compared to ultracentrifugation and required small sample volumes (10-100 μl), was designed to simplify EV extraction from clinical biofluids, such as plasma, urine, and lavage. 153 Complementarily, Chen et al 154 proposed an anion-exchange-based method for separating exosomes directly from plasma or cell culture media by anion magnetic beads within 30 min. More importantly, the exosome isolation kit, the most representative commercial product, is becoming more prevalent recently and includes the ExoQuick precipitation solution, 155,156 Total Exosome Isolation Reagent kit 126 and ME™ kit 157 based on precipitation; Exo-Spin™ 158 based on precipitation and size exclusion; and exoEasy Maxi Kit, 55 ExoCap TM Exosome Isolation and Enrichment kit, and Exo-Flow TM 159 based on immunocapture.…”

“…At the same time, a size-based exosome total isolation chip, which was easy to operate, with higher yield and similar purity compared to ultracentrifugation and required small sample volumes (10–100 μl), was designed to simplify EV extraction from clinical biofluids, such as plasma, urine, and lavage. 153 Complementarily, Chen et al 154 proposed an anion-exchange-based method for separating exosomes directly from plasma or cell culture media by anion magnetic beads within 30 min.…”

Progress in exosome associated tumor markers and their detection methods

“…Phosphatidylserine (PS) on the surface of exosome membrane is negative charged [105]. Based on this characteristics, Chen et al [106] used AE magnetic beads to directly enrich exosome in plasma. During the exosome isolation, negatively charged exosomes bind with positively charged AE magnetic beads, while impurities like cell debris, large particles and other positive charged protein will be washed away.…”

Applications of Bionano Sensor for Extracellular Vesicles Analysis

“…The developed system could also be used to characterize the differential expression of exosomal CD63 between the breast cancer cell line (MCF-7) and a control cell line (MCF-10A). Xia et al quantified EVs based on aptamer-CD63-functionalized single-walled carbon nanotubes (s-SWCNTs) [56]. As the functionalization with ssDNA exhibited enhanced peroxidase activity of s-SWCNTs, the addition of EVs resulted in a decrement of catalytic ability and a color change as well.…”