Ldlr−/− mice were fed a Western diet for 12 weeks and then injected intravenously with Alexa 647–labeled Ac2-26 NPs or Col IV–Ac2-26 NPs. The diet was continued, and aortic root sections were analyzed by fluorescence microscopy 5 days later. (A) Images of 4′,6-diamidino-2-phenylindole (DAPI)–stained aortic root sections showing NPs (red) and nuclei (blue). The lesions in each image are outlined. To the right of each main image is a zoomed-in image of the subendothelial region depicted by the white box. Scale bar, 100 μm. (B) Sections of aortic root, spleen, and liver (six sections per mouse) were quantified for mean Alexa 647 fluorescence intensity (MFI) using image processing. Data are means ± SEM (n = 3 separate mice). *P < 0.05 versus Ac2-26, Student’s t test.