Exogenous 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbocyanine iodide (DiR)-labeled enhanced green-fluorescent-protein (eGFP) macrophages are recruited into macrophage-rich carotid artery plaques. (A) Photomicrographs depicting CD68-positive macrophages in carotid artery lesions 14 days after guidewire injury (scale bar: 20 µm). (B) 4′,6-Diamidin-2-phenylindol (DAPI)-, eGFP- and DiR-fluorescence microscopy images were merged to demonstrate the homing of injected DiR-labeled eGFP-transgenic macrophages into atherosclerotic plaques. Double-positive cells (white arrows) were detectable in accelerated atherosclerotic lesions 7 days after intravenous injection of exogenous macrophage (scale bar: 20 µm).