Fig. 6

Exosome uptake is effectively blocked by pharmacologic treatment with heparin. a PKH26 (red dye)-labeled VAMT-derived exosomes were added to MSTO cells on the top of the transwell/Boyden chamber; and to the lower chamber, we added MSTO cells pre-treated with or without 10 μg/mL heparin. Extent of exosomal uptake of cells in the lower chamber was analyzed after 24 h for both conditions (scale bar = 20 μm). The reduction in red fluorescence in heparin pre-treated cells indicates efficient blocking of exosome uptake. b This experiment was performed in triplicate; representative images were taken from each replicate and subsequently used for calculations to compare the Corrected Total Cell Fluorescence (CTCF) per area of the control and heparin-treated cells. CTCF/area was calculated for 36 cells in the control group, and 72 cells in the heparin-treated group, and the results were averaged. Our results demonstrate that heparin treatment of recipient cells can significantly block uptake of the majority of remaining exosomes. Mean values are shown with ± standard error. p-value = 0.04