Detection and photodynamic therapy of inflamed atherosclerotic plaques in the carotid artery of rabbits

Abstract Photodynamic therapy (PDT) has been applied in the treatment of artery restenosis following balloon injury. This study aimed to detect the accumulation of 5-aminolevulinic acid (ALA)-derived protoporphyrin IX (PpIX) in inflamed atherosclerotic plaque in rabbit model and evaluate the efficacy of PDT. The inflamed atherosclerotic plaque in the common carotid artery was produced by combination of balloon denudation injury and high cholesterol diet. After intravenous administration of ALA, the fluorescence of PpIX in plaque was detected. At the peak time, the correlation between the fluorescence intensity of PpIX and the macrophage infiltration extent in plaque was analyzed. Subsequently, PDT (635 nm at 50 J/cm 2 ) on the atherosclerotic plaques ( n  = 48) was performed and its effect was evaluated by histopathology and immunohistochemistry. The fluorescence intensity of PpIX in the plaque reached the peak 2 h after injection and was 12 times stronger than that of adjacent normal vessel segment, and has a positive correlation with the macrophage content ( r  = 0.794, P P P P P