Extracellular vesicles such as prostate cancer cell fragments as a fluid biopsy for prostate cancer

Extracellular vesicles (EVs) are cell-derived vesicles generated through a process of cell membrane shedding or storage vesicle release, as occurs during apoptosis, necrosis or exocytosis. Initially perceived as cellular by-products or 'dust' of insignificant biological importance, recent research has shed light on the role of EVs as mediators of intercellular communication, blood coagulation and disease progression. The prostate is a source of EVs and their abundance in complex biological fluids such as plasma, serum and urine make them compelling entities for a 'fluid biopsy'. As such, prostate cancer cell fragments (PCCF) are EVs generated by the tumor resident within the prostate and are also present in blood, expressing a portion of biomarkers representative of the primary tumor. High-throughput analytical techniques to determine biomarker expression on EVs is the last hurdle towards translating the full potential of prostate EVs for clinical use. We describe current state-of-the-art methods for the analysis of prostate-derived EVs in patient fluids such as plasma and the challenges that lie ahead in this emerging field of translational research.