Characterization of EV. Particle numbers (A) and relative protein concentrations (B) in the fractions eluted following qEV size-exclusion chromatography. Data are mean ± SEM. (C) Tetraspanin (CD9, CD63, and CD81) content of purified EVs was analyzed in the indicated elution fractions by immunoblotting. (D) Size distribution of pooled fractions 7 to 10 from HDFs (left panel) and L3.6 cells (right panel). (E) Electron microscopy image of EV from HDFs (left panel) and L3.6 cells (right panel).