Electron microscopy
Electron microscopy was carried out from 2µg of EVs that were fixed in PBS-formaldehyde 2% (v/v) for 16 hours at 4°C and shaking. Particles were adsorbed on copper-carbon grids (copper-formwar/carbon-coated grids 200 mesh, Fedelco) for 3 minutes, at room temperature (RT), and were contrasted with uranyl acetate at 1% (v/v) for 30 seconds. Samples were observed in a JEOL 1010 transmission electron microscope (JEOL), using a working voltage of 80kV. The analysis was carried out at the Electron Microscopy Center in the Universidad Complutense of Madrid (UCM), using the Soft Imaging Viewer program.