Liver perfusate contains melanoma-specific exosomes. (A) A representative electron microscopy image of an exosome derived from the liver perfusate of a patient (patient 4) with metastatic uveal melanoma. The image shows a small vesicle, approximately 50 nm in diameter, and immune-gold labelled with anti-CD63. (B) Flow cytometry analysis showing exosomes coupled to CD63 coated latex beads and immunostained with antibodies against the tetraspanins CD9, CD63, CD81 and isotype control. All three patients were shown to be positive for the three markers, with variations between the patients. (C) A representative Western blot analysis showing liver perfusate exosomes from two patients positive for the melanoma-specific marker Melan-A. Abbreviations: IC = Isotype control, Pat = Patient.