Fig. 3

Characterization and cellular uptake of purified exosomes derived from monocytes. The morphology and size of exosomes were observed using (A) transmission electron microscopy. B Representative dynamic light scattering (DLS) number distribution measurement of purified exosomes showed a single peak at ~ 90 nm. C Exosome-specific surface markers CD9 and CD81 were detected in exosomes by western blotting. The cytoplasmic protein marker Calnexin was expressed in the whole cell lysate but was undetectable in the isolated exosomes, indicating that the exosome preparations were not contaminated with other vesicles such as endoplasmic reticulum ones. D Cellular internalization of PKH26-labeled exosomes by MDA-MB-231 BC cells was visualized and imaged under a confocal microscope. The red fluorescence in the cytoplasm showed that exosomes were uptaken by MDA-MB-231 BC cells. The nuclear staining was performed by DAPI