Characterization of exosomes: (A) Exosomal pellets derived from primary neurons infected with AAV-V1S/SV2, AAV-S1/S2, AAV- αsyn-ires-GFP were resuspended in 1xPBS and analyzed by Western blotting using exosome specific antibodies anti Alix and anti flotillin. Also total cell lysates and exosome free supernatant (sup) were loaded as positive and negative controls, respectively. (B) Exosomes from S1/S2 transfected H4 cells were prepared as described before. After fixation vesicles were negatively stained with 2% uranyl acetate and observed under electron microscopy. Scale bar, 100 nm. (C) Exosomes from primary neurons infected with AAV-V1S/SV2 were negatively stained with 2% uranyl acetate and immunolabeled with CD63 antibody as exosomal marker. Scale bar, 100 nm.