Author + information
- Received February 18, 2010
- Revision received June 21, 2010
- Accepted June 30, 2010
- Published online September 1, 2010.
- Owen J.T. McCarty, PhD*,†,
- Robert B. Conley, BS*,
- Weihui Shentu, MD‡,
- Garth W. Tormoen, MS*,
- Daogang Zha, MD‡,
- Aris Xie, BS‡,
- Yue Qi, MD‡,
- Yan Zhao, MD‡,
- Chad Carr, MD‡,
- Todd Belcik, RDCS‡,
- Douglas R. Keene, BS§,
- Philip G. de Groot, PhD∥ and
- Jonathan R. Lindner, MD*,‡,* ()
- ↵*Reprint requests and correspondence:
Dr. Jonathan R. Lindner, Cardiovascular Division, UHN-62, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239
Objectives We hypothesized that noninvasive molecular imaging of activated von Willebrand factor (vWF) on the vascular endothelium could be used to detect a high-risk atherosclerotic phenotype.
Background Platelet-endothelial interactions have been linked to increased inflammatory activation and prothrombotic state in atherosclerosis. These interactions are mediated, in part, by platelet glycoprotein (GP) Ibα, suggesting that dysregulated endothelial vWF is a marker for high-risk atherosclerotic disease.
Methods Microbubbles targeted to activated vWF were prepared by surface conjugation of recombinant GPIbα. Flow-chamber studies were used to evaluate attachment of targeted microbubbles to immobile platelet aggregates bearing activated vWF. Contrast-enhanced ultrasound (CEU) molecular imaging of the aorta from mice was performed: 1) ex vivo after focal crush injury and blood perfusion; and 2) in vivo in mice with advanced atherosclerosis produced by deletion of the low-density lipoprotein receptor and ApoBec-1 editing peptide (LDLR–/–/ApoBec-1–/–).
Results In flow-chamber studies, tracer attachment to vWF was >10-fold greater for microbubbles bearing GPIbα compared with control microbubbles (p < 0.01). In the ex vivo aortic injury model, CEU signal enhancement for vWF-targeted microbubbles occurred primarily at the injury site and was 4-fold greater than at noninjured sites (p < 0.05). In LDLR–/–/ApoBec-1–/– mice, inflammatory cell infiltrates and dense vWF expression on the intact endothelium were seen in regions of severe plaque formation. Scanning electron microscopy demonstrated widespread platelet-endothelial interaction and only few sites of endothelial erosion. On CEU, signal enhancement for vWF-targeted microbubbles was approximately 4-fold greater (p < 0.05) in LDLR–/–/ApoBec-1–/– compared with wild-type mice. En face aortic microscopy demonstrated regions where platelet adhesion and microbubble attachment colocalized.
Conclusions Molecular imaging using GPIbα as a targeting moiety can detect the presence of activated vWF on the vascular endothelium. This strategy may provide a means to noninvasively detect an advanced prothrombotic and inflammatory phenotype in atherosclerotic disease.
Supported by grants from the Oregon Clinical & Translational Institute and the Wallace Coulter Foundation Grant to Drs. McCarty and Lindner. Dr. de Groot is supported by a Dutch Heart Foundation grant. Dr. Lindner is supported by grants R01-HL078610, R01-HL074443, and R01-DK063508, and RC01-100659 from the National Institutes of Health. All other authors report that they have no relationships to disclose.
- Received February 18, 2010.
- Revision received June 21, 2010.
- Accepted June 30, 2010.
- American College of Cardiology Foundation