Exosomes are small membrane-enclosed vesicles of endocytic origin approximately 30–150 nm in diameter. The lipid bilayer contains both transmembrane and non-membrane proteins and encloses a variety of molecules including non-coding RNAs, mRNAs, miRNAs, either single-stranded or double-stranded DNA and proteins. Exosomes are actively secreted by most cells, including primary or metastatic tumour cells, into biological fluids including serum, plasma, urine, breast milk, and saliva3,. Studies have found that the analysis of exosome-associated nucleic acids, proteins and/or lipids can indicate the presence of a range of cancers, including pancreatic cancer3, colorectal cancer, breast cancer, and non-small cell lung cancer.
Direct isolation of circulating nucleic acids (miRNA and DNA) and circulating tumour cells from blood or serum for cancer diagnosis may not be as feasible as first thought, owing to their low abundance. Therefore, exosomes signify an exciting new avenue of cancer diagnosis. Abnormal levels of exosomal biomarkers likely indicate the presence of cancer or even cancer of a more advanced stage. As a group of promising biomarkers, the analysis of biomarkers associated with exosomes in blood may offer a minimally invasive route for cancer diagnosis and prognosis.
The discovery of exosomes has opened a huge and untapped market for liquid biopsy-based diagnostics using isolated exosomes. As they are easily accessible in vivo and maintain stability in vitro, exosomes have been regarded as the most promising and fundamental indicators for the early diagnosis of cancer patients or for predicting outcomes after different types of treatments4. The discovery of exosomes has opened a huge and untapped market for liquid biopsy-based diagnostics using isolated exosomes. Along with the complete decoding of exosomes and their functionalities, more exciting applications of exosomes especially in clinical practice are expected soon.
Extraction and isolation
Much work has been done to identify and validate exosomal biomarkers for cancer diagnosis. Despite this explosion in exosome research and their potential in disease (especially cancer) diagnostics, exosome-associated biomarkers have not yet been translated to meet the rapid developments in molecular medicine for commercial liquid biopsy applications. The discovery of miRNAs in exosomes has helped to shape the techniques for miRNA analysis in the laboratory, but not yet universally used for clinical benefit.
Translation and commercialisation of significant and impactful discoveries in the field of exosome research will only be possible with the development of highly efficient exosome isolation techniques. Isolation of exosomes from body fluids is currently carried out by technologies that are based on the biophysical properties (size, morphology, density), immunoaffinity capture or by precipitation method1. In 2017, Li et al. reviewed the field of exosome capture and stated “…research efforts should be focused on the development of exosome isolation and detection techniques and devices that are capable of not only isolating, subtyping, and quantifying the total population of exosomes, but also analysing the contents of exosomes to facilitate both basic research and clinical applications”. Ideally, the isolation of exosomes from many types of sources will be achieved by a single technique.
EXO-NET™ for exosome capture
EXO-NET™ technology allows for fast, accurate and efficient capture and isolation of exosomes from any liquid biopsy sample. The technology is highly scalable and is compatible with existing automated testing systems making it ideal for high volume clinical laboratory applications.
The EXO-NET™ matrix has the following features that make it a unique universal technology to facilitate the development of a range of exosome isolation applications:
The EXO-NET™ technology demonstrates superior exosome capture ability in comparison to a commercial competitor (see below), as evidenced by the concentration of known CD63 and CD9 exosome specific biomarkers. In addition to demonstrating outperformance compared to commercial products, EXO-NET™ demonstrated outperformance against ultra-centrifugation (the recognised research gold-standard method), in a fraction of the time (15 minutes versus 6-12 hours).
EXO-NET™ outcompetes other bead-based approaches. Source: data on file
EXO-NET™ is the exosome capture technology of choice
Clinical applications for diagnostics based on liquid biopsies need to be low cost, reliable and rapid, combined with scalability. A review of the current technologies available for capture of exosomes shows that only the Company’s EXO-NET™ technology meets these requirements.
Comparison of currently available exosome isolation techniques with EXO-NET™ (adapted from Li et al.,2017).
 Mathai RA, Vidya RV, Reddy BS, et al. Potential utility of liquid biopsy as a diagnostic and prognostic tool for
the assessment of solid tumors: Implications in the precision oncology. J Clin Med 2019; 8(3):373
 Qi Z-H, Xu H-X, Shi-Rong Zhang S-R, Xu J-Z, et al. The significance of liquid biopsy in pancreatic cancer. J
Cancer 2018; 9(18): 3417-3426. doi: 10.7150/jca.24591
 Chen Y, Xie Y, Xu L, et al. Protein content and functional characteristics of serum-purified exosomes from
patients with colorectal cancer revealed by quantitative proteomics. Int J Cancer 2017; 140: 900–913
 Meng Y, Sun J, Wang X, et al. Exosomes: A promising avenue for the diagnosis of breast cancer. Technol
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 Masaoutis C, Mihailidou C, Tsourouflis G, Theocharis S. Exosomes in lung cancer diagnosis and treatment.
From the translating research into future clinical practice. Biochimie 2018; 151: 27-36. doi:
 Bhome R, Del Vecchio F, Lee GH, et al. Exosomal microRNAs (exomiRs): Small molecules with a big role in
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 Li P, Kaslan M, Lee SH, Yao J, Gao Z. Progress in exosome isolation techniques. Theranostics 2017; 7(3):