Internalization of BMDC-derived exosomes. (A) In vitro assay of internalization of pHrodo-exosomes (5 μg, purified by gel filtration) by BMDCs (5 × 10⁵ cells, 1 mL of final volume) assessed by FACS. Numbers are percentages of positive cells. One of 2 independent experiments is shown. (B) In vivo endocytosis of pHrodo-labeled exosomes (300 μg, intravenously, purified by gel filtration) by different splenic leukocytes, analyzed by FACS, 3 hours after exosome administration. Numbers are percentages of positive cells in the corresponding quadrant. Results are representative of 3 mice per group.