Status quo of Extracellular Vesicle isolation and detection methods for clinical utility.

Extracellular vesicles (EVs) are nano-sized particles that hold tremendous potential in the clinical space, as their biomolecular profiles hold a key to non-invasive liquid biopsy for cancer diagnosis and prognosis. EVs are present in most bodily fluids, hence are easily obtainable from patients, advantageous to that of traditional, invasive tissue biopsies and imaging techniques. However, there are certain constraints that hinder clinical use of EVs. The translation of EV biomarkers from "bench-to-bedside" is encumbered by the methods of EV isolation and subsequent biomarker detection currently implemented in laboratories. Although current isolation and detection methods are effective, they lack practicality, with their requirement for high bodily fluid volumes, low equipment availability, slow turnaround times and high costs. The high demand for techniques that overcome these limitations has resulted in significant advancements in nanotechnological devices. These devices are designed to integrate EV isolation and biomarker detection into a one-step method of direct EV detection from bodily fluids. This provides promise for the acceleration of EVs into current clinical standards. This review highlights the importance of EVs as cancer biomarkers, the methodological obstacles currently faced in clinical studies and how novel nanodevices could advance clinical translation.

An epithelial-to-mesenchymal transition induced extracellular vesicle prognostic signature in non-small cell lung cancer.

Despite significant therapeutic advances, lung cancer remains the leading cause of cancer-related death worldwide1. Non-small cell lung cancer (NSCLC) patients have a very poor overall five-year survival rate of only 10-20%. Currently, TNM staging is the gold standard for predicting overall survival and selecting optimal initial treatment options for NSCLC patients, including those with curable stages of disease. However, many patients with locoregionally-confined NSCLC relapse and die despite curative-intent interventions, indicating a need for intensified, individualised therapies. Epithelial-to-mesenchymal transition (EMT), the phenotypic depolarisation of epithelial cells to elongated, mesenchymal cells, is associated with metastatic and treatment-refractive cancer. We demonstrate here that EMT-induced protein changes in small extracellular vesicles are detectable in NSCLC patients and have prognostic significance. Overall, this work describes a novel prognostic biomarker signature that identifies potentially-curable NSCLC patients at risk of developing metastatic NSCLC, thereby enabling implementation of personalised treatment decisions.

Comparative analysis of tangential flow filtration and ultracentrifugation, both combined with subsequent size exclusion chromatography, for the isolation of small extracellular vesicles.

Small extracellular vesicles (sEVs) provide major promise for advances in cancer diagnostics, prognostics, and therapeutics, ascribed to their distinctive cargo reflective of pathophysiological status, active involvement in intercellular communication, as well as their ubiquity and stability in bodily fluids. As a result, the field of sEV research has expanded exponentially. Nevertheless, there is a lack of standardisation in methods for sEV isolation from cells grown in serum-containing media. The majority of researchers use serum-containing media for sEV harvest and employ ultracentrifugation as the primary isolation method. Ultracentrifugation is inefficient as it is devoid of the capacity to isolate high sEV yields without contamination of non-sEV materials or disruption of sEV integrity. We comprehensively evaluated a protocol using tangential flow filtration and size exclusion chromatography to isolate sEVs from a variety of human and murine cancer cell lines, including HeLa, MDA-MB-231, EO771 and B16F10. We directly compared the performance of traditional ultracentrifugation and tangential flow filtration methods, that had undergone further purification by size exclusion chromatography, in their capacity to separate sEVs, and rigorously characterised sEV properties using multiple quantification devices, protein analyses and both image and nano-flow cytometry. Ultracentrifugation and tangential flow filtration both enrich consistent sEV populations, with similar size distributions of particles ranging up to 200 nm. However, tangential flow filtration exceeds ultracentrifugation in isolating significantly higher yields of sEVs, making it more suitable for large-scale research applications. Our results demonstrate that tangential flow filtration is a reliable and robust sEV isolation approach that surpasses ultracentrifugation in yield, reproducibility, time, costs and scalability. These advantages allow for implementation in comprehensive research applications and downstream investigations.

Blood-Derived Extracellular Vesicle-Associated miR-3182 Detects Non-Small Cell Lung Cancer Patients.

With five-year survival rates as low as 3%, lung cancer is the most common cause of cancer-related mortality worldwide. The severity of the disease at presentation is accredited to the lack of early detection capacities, resulting in the reliance on low-throughput diagnostic measures, such as tissue biopsy and imaging. Interest in the development and use of liquid biopsies has risen, due to non-invasive sample collection, and the depth of information it can provide on a disease. Small extracellular vesicles (sEVs) as viable liquid biopsies are of particular interest due to their potential as cancer biomarkers. To validate the use of sEVs as cancer biomarkers, we characterised cancer sEVs using miRNA sequencing analysis. We found that miRNA-3182 was highly enriched in sEVs derived from the blood of patients with invasive breast carcinoma and NSCLC. The enrichment of sEV miR-3182 was confirmed in oncogenic, transformed lung cells in comparison to isogenic, untransformed lung cells. Most importantly, miR-3182 can successfully distinguish early-stage NSCLC patients from those with benign lung conditions. Therefore, miR-3182 provides potential to be used for the detection of NSCLC in blood samples, which could result in earlier therapy and thus improved outcomes and survival for patients.

The role of exosomes in the promotion of epithelial-to-mesenchymal transition and metastasis.

The progression of a solid cancer from a localised disease to metastatic stages is a key reason for mortality in patients. Amongst the drivers of cancer progression, Epithelial-to-Mesenchymal Transition (EMT) has been shown to be of crucial importance. EMT results in the phenotypic shift of an immotile, treatment-sensitive epithelial cell into an elongated, metastatic and treatment-resistant mesenchymal cell. Depending on the cellular and molecular setting, a myriad of studies have demonstrated that EMT causes increased cancer cell motility, invasiveness, resistance to therapies, dormancy and cancer-stem cell phenotypes, all of which are prerequisites for metastasis. The alteration of non-canonical intercellular signalling events in cancer EMT is a phenomenon that is not completely understood. Recently, extracellular vesicles, especially small vesicles called exosomes, have shown to be involved in cancer cell EMT. Most intriguingly, across different cancer types, cancer-derived exosomes have demonstrated to be capable of transferring a mesenchymal phenotype upon recipient epithelial cells, including epithelial cancer cells. The uptake of EMT-inducing exosomes results in molecular changes, altering miRNA, mRNA, and protein levels, either through direct transfer of these components, or by altering gene expression networks involved in EMT. In this review, we are presenting the current state of research of exosomes in cancer EMT, highlight gaps in our current knowledge and propose strategies for future experiments in this area.