Optimization of blood handling for plasma extracellular vesicle isolation

Extracellular vesicles (EVs) are emerging targets for biomarker discovery. However, suitable clinical collection and storage methods for blood plasma-derived EVs have not been fully described. We investigated the long- and short-term effects of temperature and time on the plasma-derived EV concentration, size, protein, and RNA content. EVs isolated from freshly collected human blood stored for various periods of time at either room temperature (RT) or 4°C were analyzed for concentration, size, and protein content. In addition, EVs isolated from plasma stored at −80°C were compared to frozen EV pellets. We found that the number, size, protein, and RNA content of EVs were similar between blood samples stored at RT for 24h compared to samples processed shortly after collection or stored at 4°C vs. −80°C. It is therefore feasible to isolate and analyze comparable, stable EVs from blood plasma stored for varying periods of time and at various temperatures. Graphical abstract