Double-label immunofluorescence staining in cultured endothelial cells of hypoxia + pSi group (in the same field) Hoechst fluorescence showing cell nuclei (left), SMA is not expressed in cytoplasm by day1 (top, right); SMA expression is detected in a cytoplasmic pattern by days 7 (bottom, right), but weaker than that in H group by days 7, and the SMA-positive cells are fewer than those in H group by days 7.