Fig. 1

Atrial myocytes secrete exosomes and exert a profibrotic effect through their miRNA cargo. A Electron microscopy image of atrial myocyte-derived exosomes. The image shows small vesicles approximately 100 nm in diameter; scale bar: 200 nm. B, C Western blot characterization of atrial myocyte-derived exosomes based on the expression of the exosomes markers ALIX, CD63 and CD81 (*P < 0.05 and **P < 0.01 compared with the Ctr group). D Confocal imaging analysis of exosomes uptake experiment. Purified atrial myocyte-derived exosomes were labeled with PKH67 (green), and incubated with atrial fibroblasts. Scale bar: 10 μm. E, F Western blot analysis of the expression levels of collagen I, collagen IIIand α-SMA in atrial fibroblasts treated with atrial myocytes-derived exosomes. (*P < 0.05 and **P < 0.01 compared with EXO-siNC; #P < 0.05 and ##P < 0.01 compared with EXO-Pacing). G Immunofluorescence staining showing the relative expression levels of α-SMA (green) in atrial fibroblasts; nuclei were stained with DAPI (blue). Scale bar: 10 μm