Fig. 3

Treatment of human endothelial cells (HUVECs) with MSC-sEVs. Representative confocal microscopy images of the internalization of PKH67-labeled MSC-sEVs (green) in HUVECs (nuclei blue) after (A) 3 h, (B) 6 h, and (C) 24 h incubation. HUVECs incubated with PKH67-labeled PBS without MSC-EVs for (A’) 3 h, (B’) 6 h, and (C’) 24 h do not show any positivity to the probe. Scale bars 20 μm. (D) Proliferation and (E) migration of HUVECs treated with increasing doses of MSC-sEVs (20, 40, 80, 120 µg) compared to control (ctrl; no EVs). (F) Tube formation assay (corresponding total branching length, pixels, measured with the Fiji software) after 4 h incubation with 40 or 120 µg of MSC-sEVs and control. ***p < 0.001 compared to control; ###p < 0.01 compared to 40 µg. (F’-F’’’) Representative imagines after treatment with control, 40 µg, and 120 µg of MSC-sEVs, respectively. Scale bars 20 μm. (G) Gene expression of endothelial cell markers (CD31, KDR, and VWF) after 24 h incubation with MSC-sEVs. *p < 0.05, **p < 0.01, ***p < 0.001 compared to control