Oil red O staining to evaluate the severity of AS plaque

To evaluate the severity of the lesions and to quantify the atherosclerotic burden, the surface area of the Oil Red O-positive lesions on the surface of the whole aorta was measured. The aorta was opened lengthwise and the edges and corners were flattened on black boards. The en face analysis of the lesion area on the whole aorta was quantified based on Oil Red O staining, using Image-Pro Plus 6.0 software (Media Cybernetics, Bethesda, USA) [46].