Figure 4. Exosomes derived from miR-126-modifified MDSCs promote angiogenesis and attenuate apoptosis in HUVECs. (A) Transmission electron photomicrograph of EXs. (B) Protein expression of CD9, CD63 and TSG-101. (C) mRNA-126 levels. (D) Confocal images of PKH67-labeled EXs taken up by HUVECs. (E) Tube formation was measured after seeding HUVECs pretreated with PBS, miR-con EXs or miR-126 EXs. Photomicrographs of tube-like structures and quantification of the tube number. (F) Representative microscopy images and quantitative analysis of apoptosis of HUVECs. (G) Cell viability. (H) Protein expression of α-SMA, CD31, vWF and VEGF in HUVECs. Data are shown as the means ± SD. *P < 0.05, **P < 0.01.