Magnetic resonance molecular imaging of vascular cell adhesion molecule-1 expression in inflammatory lesions using a peptide-vectorized paramagnetic imaging probe.

The vascular cell adhesion molecule-1 (VCAM-1) has distinct roles in inflammatory cell recruitment to the damaged vessel wall. In the present work, a cyclic heptapeptide phage displayed library was screened in vitro during four rounds of biopanning. On the basis of Kd and IC50 values, a peptide (encoded as R832) was selected for in vitro and in vivo validation. After conjugation to Gd-DOTA, VCAM-1 imaging was assessed by MRI on a model of T cell mediated hepatitis, induced in mice by concanavalin A. On histological samples, the location of biotinylated R832 (R832-Bt) around liver veins in hepatitis resembles the pattern of MRI enhancement. Gd-DOTA-R832 was then assessed on ApoE(-/-) mice and produced an important signal enhancement of the aortic wall, while R832-Bt interacted with morphologic structures comparable to those marked by anti-VCAM-1 antibody. In conclusion, the in vitro and in vivo evaluation of peptide R832 suggests a specific interaction with the targeted biomolecule. Its conjugation to imaging reporters could assist the diagnosis of inflammatory diseases.