TIRF Microscopy as a Tool to Determine Exosome Composition.

Exosomes are extracellular vesicles (EVs) containing different biomolecules with biological activity, such as proteins, miRNA, long noncoding RNA, and DNA. EVs are efficient platforms for intercellular communication, especially during immune responses, but also in some pathological contexts, such as tumor cell growth. The precise assessment of EV content is relevant for the selection of specific vesicles with specialized biological activities, whose content is hardly visualized due to their small size. We describe herein a protocol for the determination of the content of individual EVs through microscopy imaging and user-friendly analysis using TIRF microscopy.