Fig. 5

BRCA1-KO fibroblasts internalized exosomes more efficiently than control cells. a Exosomes were isolated as described under Methods. Representative micrographs of transmission electron microscopy on cancer patient sera exosome preparations. The image showed small vesicles of approximately 50–120 nm in diameter. Scale bars 100 nm. b NanoSight analysis of samples prepared as in (a). The size was centered around 94 nm in diameter. c Confocal microscopy monitoring of PKH-26-labeled exosome uptake in vitro into BRCA1-KO fibroblasts, control fibroblasts, and HEK293 cells. Note that exosomes internalized more in BRCA1-KO cells. They were dispersed in the cytoplasm and tended to form aggregates in the perinuclear regions. d The number of PKH-26-labeled exosomes (dots) was counted. Data are expressed as relative number (Rel. Num.) of exosomes per cell compared to that in control fibroblasts. In the insert, data are expressed as mean +/− SD (n = 6 exosome preparations; P = 0.032 for HEK293 cells compared to control fibroblasts, P = 0.028 for BRCA1-KO fibroblasts compared to control fibroblasts, and P = 0.35 for HEK293 cells compared to BRCA1-KO fibroblasts)