Figure 3. Exo-MSCs-M.tb were internalized by macrophages. (A) The number of exosomes released from M.tb-infected MSCs or PBS-treated control MSCs. (B) Exosomal protein level in M.tb-infected MSCs compared with those in PBS-treated control MSCs. (C) Exo-MSCs-M.tb (20μg) were internalized by macrophages, as imaged by confocal microscopy. Exosomes were stained by DiO (Green). Cytoskeleton was stained by TRITC Phalloidin (red). Nuclei were stained by DAPI (blue). Scale bar: 20 μm. (D) TNF-α levels in macrophages treated with Exo-MSCs-M.tb (20μg) or Exo-MSCs (20μg), as detected by ELISA assay 24 hours after exosome treatment. (E) RANTES levels in macrophages treated with Exo-MSCs-M.tb (20μg) or Exo-MSCs (20μg), as detected by ELISA assay 24 hours after exosome treatment. (F) iNOS levels in macrophages treated with with Exo-MSCs-M.tb (20μg) or Exo-MSCs (20μg), as detected by western blotting assay 24 hours after exosome treatment. *p < 0.05.