Noninvasive Imaging of Angiogenesis With a 99mTc-Labeled Peptide Targeted at αvβ3 Integrin After Murine Hindlimb Ischemia

Background— Noninvasive imaging strategies play a critical role in assessment of the efficacy of angiogenesis therapies. The αvβ3 integrin is activated in angiogenic vessels and represents a potential target for noninvasive imaging of angiogenesis. Methods and Results— We evaluated a 99mTc-labeled peptide (NC100692) targeted at αvβ3 integrin for imaging in an established murine model of angiogenesis induced by hindlimb ischemia. Control mice (n=9) or mice with surgical right femoral artery occlusion (n=29) were injected with NC100692 (1.5±0.2 mCi IV) at different times after femoral occlusion (1, 3, 7, and 14 days) for in vivo pinhole planar gamma camera imaging. Tissue from hindlimb proximal and distal to occlusion was excised for gamma well counting and for immunostaining. On in vivo pinhole images, increased focal NC100692 activity was seen distal to the occlusion at days 3 and 7. This increase in relative NC100692 activity was confirmed by gamma well counting. Lectin staining confirmed increased angio...