Excess of uranyl acetate was removed by blotting on filter paper. Images were acquired by a Tecnai™ G2 Spirit BioTwin transmission electron microscope (Thermo Fisher/FEI) at 80 kV with an ORIUS SC200 CCD camera and Gatan Digital Micrograph software (both from Gatan Inc./Blue Scientific). Scratch healing assay. IM-HCEpiC were seeded in collagen coated 48-well plates with a seeding density of 15 000 cells/cm 2 . The cells were left until approximately 90% confluency was achieved (2 days). Then a 200 µL pipette tip was used to scratch the monolayer in a cross. The cells were washed twice with DPBS to remove debris and smoothen the edges. 250µL of solutions containing 20µg/mL (110 9 particles), 100µg/mL (110 10 particles) or 200µg/mL (210 10 particles) EVs in Opti-MEM were added. Wells with only Opti-MEM was used as a negative control. Opti-MEM was used to avoid proliferation and only look at the healing of the scratched epithelium.