Fluorescence imaging of atherosclerosic plaque using 5-aminolevulinic acid

Abstract

In cells, 5-aminolevulinic acid (ALA) is metabolized to protoporphylinIX (PPIX), which emits fluorescence. This study aimed to reveal theorigin of PPIX fluorescence seen in atherosclerotic plaque of micethat were administered with ALA. LDL-receptor knockout mice, fed withhigh cholesterol diet were intravenously administered with ALA. Theaorta were extracted and sliced for the observation by a confocallaser microscope. The adjacent slice was stained with anti-F4/80antibody for the identification of macrophage. In atheroscleroticplaque, fluorescence sites corresponded to the spots where macrophages(F4/80 positive) were confirmed. The sensitivity and specificity of the degree of agreement between the site exhibiting fluorescence and the macrophage (F4 / 80) positive site was 47% and 95%, respectively.Fluorescent imaging of ALA-induced PPIX might be a specific modalityfor detecting macrophages in atherosclerotic plaque.