Isolation of Extracellular Vesicles for Proteomic Profiling

Extracellular vesicles (EVs) are nano-sized lipid bilayer surrounded by structures released from most cells, including archaea, bacteria, and eukaryotic cells. EVs play multiple roles in cell-to-cell communication, including immune modulation, angiogenesis, and phenotypic transformation of cells by transferring genetic material and functional proteins. They contain specific subsets of proteins, DNA, RNA, and lipids that represent their cellular origin. Furthermore, EVs are enriched in cell type- or disease-specific proteins, especially plasma membrane proteins, which have pathophysiological functions; many of these vesicular proteins are investigated as novel diagnostic biomarkers, as well as therapeutic targets. To profile the global EV proteome, their various purification methods have been developed, of which density gradient ultracentrifugation is considered especially promising. In this chapter, we describe the isolation of EVs derived from SW480 cells with serum-free media and from U373 cells with EV-depleted serum-containing media, and the preparation of tryptic peptides for mass-spectrometry-based proteomic analysis.