Exosome Isolation and Quantification

Exosomes were isolated as previously described 67 (link). Briefly, cell culture medium was sequentially centrifuged at 1000×g for 10 min, followed by 10,000×g for 30 min. The supernatant was collected and filtered with a 0.22 µm filter (Millex, Germany), followed by ultracentrifugation at 100,000×g for 1 h. Exosome pellets were washed in a large volume of PBS and recovered by centrifugation at 100,000×g for 1 h and was resuspended in sterile PBS for the following experiments. The protein concentration of isolated exosomes was quantified by using the Bradford assay kit (Sangon Biotech, China).