Abstract 16370: In vivo Assessment of Silica-Coated Iron Oxide Nanoparticle for Imaging of Macrophages in Murine Atherosclerosis
Introduction: We synthesized polyethylene glycolated silica-coated iron oxide nanoparticle (SION), a bimodal molecular imaging agent for magnetic resonance (MR) imaging and fluorescence reflecting (FR) imaging, and investigated its feasibility in imaging of macrophages in atherosclerosis of apolipoprotein E-deficient (apoE-/-) mice.
Methods: Three different cells, macrophages, endothelial cells, and smooth muscle cells, were incubated separately with the SIONs, and confocal laser scanning microscope (CLSM) and flow cytometry were used to measure the SION uptake. After 24 hours of the SION infusion (Fe, 10 mg/kg) via tail vein of 26-week-old apoE-/- mice fed with hypercholesterol diet, In vivo and ex vivo MR imaging was taken. FR images of the extracted aorta from 4 different mice were taken; two normal-diet-fed C57BL/6 mice infused with saline and the 10 mg/kg SIONs, respectively, and two hypercholesterol-diet-fed apoE-/- mice injected with the 5 mg/kg and 10 mg/kg SIONs, respectively. The harvested aortas were cryosectioned, and stained with immunofluorescence.
Results: The CLSM images of macrophages showed diffuse uptakes of the SION, in contrast with those of endothelial cells and smooth muscle cells. The SIONs uptakes in macrophages were 7-fold and 7.5-fold greater than endothelial cells and smooth muscle cells, respectively. The in vivo and ex vivo MR images and FR images demonstrated the SIONs depositions in the atheroma. After immunohistochemistry staining of the aorta, CLSM images demonstrates co-localization of macrophages and SIONs in the plaque.
Conclusion: The polyethylene glycolated SIONs could function as an effective multimodal imaging agent in the identification of macrophage activity in atherosclerotic plaques.
- © 2013 by American Heart Association, Inc.