Enhanced invasiveness of MSC through matrigel induced by prominin-1-purified exosomes. In vitro invasion assays were performed in BioCoat invasion chambers holding matrigel-coated-8 μm-pore PET membrane cell culture inserts, using non-coated inserts as control. The lower chambers were filled with medium containing 2% FBS, and equal aliquots of MSC, pre-incubated with or without prominin-1-purified exosomes, were added in serum-free medium to the inserts. Following 24 h incubation at 37°C, as recommended by the manufacturer, the cells on the upper side of the membrane were gently removed with wet cotton swabs. The cells on the lower surface of the membranes were fixed with 4% para-formaldehyde for 10 min, and then stained with DAPI. Matrigel invasiveness is expressed as the percentage of the number of matrigel-invading cells respect to the control of chemotactic migration. Columns, mean values of three separate experiments; bars, SD; *p < 0.05, unpaired Student’s t test.