EV Separation: Release of Intact Extracellular Vesicles Immunocaptured on Magnetic Particles

Abstract

Extracellular vesicles (EVs) have attracted considerable interest due to their role in cell-cell communication, disease diagnosis, and drug delivery. Despite their potential in the medical field, there is no consensus on the best method for separating micro- and nanovesicles from cell culture supernatant and complex biological fluids. Obtaining a good recovery yield and preserving physical characteristics is critical for the diagnostic and therapeutic use of EVs. The separation of a single class of EVs, such as exosomes, is complex because blood and cell culture media contain many nanoparticles in the same size range. Methods that exploit immunoaffinity capture provide high-purity samples and overcome the issues of currently used separation methods. However, the release of captured nanovesicles usually requires harsh conditions that hinder their use in certain types of downstream analysis. A novel capture and release approach for small extracellular vesicles (sEVs) is presented based on DNA-directed immobilization of antiCD63 antibody. The flexible DNA linker increases the capture efficiency and allows for releasing EVs by exploiting the endonuclease activity of DNAse I. This separation protocol works under mild conditions, enabling the release of vesicles suitable for analysis by imaging techniques. In this study, sEVs recovered from plasma were characterized by established techniques for EV analysis, including nanoparticle tracking and transmission electron microscopy.