High-affinity αvβ3 integrin targeted optical probe as a new imaging biomarker for early atherosclerosis: Initial studies in watanabe rabbits

Purpose: A newly developed synthetic αvβ3 integrin targeted optical probe (ITOP) has been demonstrated to target cancer cells, in vivo. Compared to the commercially available cyclic peptide c[RGDfv], this optical probe has at least 20 times better binding affinity for the αvβ3 receptor. The present in vitro study was designed to investigate the possibility of detecting early atherosclerotic plaque by using this ITOP. Procedures: Experiments were performed on five Watanabe heritable hyperlipidemic rabbits and two New Zealand White rabbits for control. Our ITOP was used for detecting the presence of αvβ3 receptors in vitro. Results: Segments of plaque accumulation from two distinct regions of ascending and descending aortas were labeled in Watanabe rabbits. The signal was found principally in the adventitia and proximal intima of the aortic vessel, corresponding directly to the expression of integrin αvβ3 as determined by antibody assay. Moreover, there was a close association between the level of labeling with the αvβ3 targeted probe and the thickness of the adventitia. Conclusions: This high-affinity ITOP identifies the site and extent of αvβ3 expression and correlates with adventitial thickness. Recent evidence associates αvβ3 expression with the inflammatory process in early vulnerable plaque, making this compound a promising potential biomarker for early atherosclerotic disease.