Oil Red O staining assay

The aorta, which was cut from the root to the bifurcation of thoracic arteries, was fixed in 10% formalin. Aortic roots were sectioned to 5-µm thick sections and then stained with Oil Red O for 10 min. Subsequently, the sections were counter-stained with hematoxylin to visualize the nuclei. Finally, the plaques were visualized with an optical microscope (Olympus, Tokyo, Japan).