Figure 3

iRFP expressed in the atherosclerotic plaque macrophages is responsible for the plaque signal. (A) iRFP-positive cell accumulation was observed in the iRFP → LDLR^−/− mouse atherosclerosis plaques under an iRFP-specific 720 nm filter (red, scale bar, 20 \(\mu \)m). (B) Serial sections of atherosclerotic lesions around the aortic root of iRFP → LDLR^−/− and WT → LDLR^−/− mice fed the HCD for 8 weeks were stained with ORO and anti-Mac2 (macrophage marker, green), and the unstained adjacent section was observed under a Cy5.5 filter for iRFP expression (red; scale bar 500 µm for the first column and 100 µm for the rest). The macrophage-rich plaque area is marked by dotted lines. (C) The intensity of iRFP fluorescence expression in WT → LDLR^−/− and iRFP → LDLR^−/− plaque macrophages was assessed by flow cytometry after 8 weeks of atherosclerosis induction in digested mouse aortas. iRFP expression was measured in the CD11b and F4/80 double-positive cell fraction. The data are from one representative experiment of at least two independent experiments.