OBJECTIVE

To explore the feasibility of targeted magnetic resonance imaging (MRI)on visualizing tenascin-C (TN-C) expression in atherosclerotic plaque in high-fat diet fed ApoE(-/-) mice.

METHODS

Aorta artery atherosclerosis was induced in high fat diet fed ApoE(-/-) mice. The atherosclerotic plaques were observed by 7.0T micro-MRI after 14 weeks. Specimens of the samples were obtained randomly and stained with HE and oil red O to observe the pathological changes. The plaques were stained with anti-TN-C antibody to detecting the TN-C. Targeted probe (anti-TN-C-USPIO) was synthesized through chemical coupling methods. The experimental group was injected with targeted probe through tail vein (10 mgFe/kg), and USPIO was used as controls. MRI was performed 8 hours thereafter, intima signal changing in abdominal aorta was observed; specimens of abdominal aorta were taken after scanning, and were stained by Perl's Prussian blue, the deposition of iron particles was observed.

RESULTS

Compared with baseline level, MRI evidenced thickened aorta wall; signal was enhanced on T1WI and PDWI, but weakened on T2WI after 14 weeks. HE stained tissue samples demonstrated thicker intima. The plaque was confirmed by the oil red O staining. Immunohistochemistry staining showed significantly upregulated TN-C expression in the plaque. Compared to pre-injection status, MRI signal was lost on T2WI in the atherosclerotic lesions at 8 hours after anti-TNC-USPIO injection (ΔOD =4.78±1.41, t=9.59, P<0.05), while T2WI remained unchanged in control group (ΔOD =1.45±1.01, t=1.93, P>0.05) and matched Perl's Prussian stained section showed enriched blue particles deposition within the plaque while there were only scarce blue particles deposition in the control group.

CONCLUSION

Our results show that targeted MRI is feasible to detect TN-C expression in the plaque in vivo, this method might be used to detect in vivo atherosclerotic plaque in large animals or in humans in the future.