Author + information
- Received August 24, 2011
- Revision received December 21, 2011
- Accepted January 6, 2012
- Published online June 1, 2012.
- Tetsuya Hara, MD, PhD⁎,
- Brijesh Bhayana, PhD†,
- Brian Thompson, PhD⁎,†,‡,
- Chase W. Kessinger, PhD⁎,
- Ashok Khatri, PhD§,
- Jason R. McCarthy, PhD‡,
- Ralph Weissleder, MD, PhD‡,
- Charles P. Lin, PhD†,‡,
- Guillermo J. Tearney, MD, PhD† and
- Farouc A. Jaffer, MD, PhD⁎,†,⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Farouc A. Jaffer, Simches Research Building, Room 3206, Cardiovascular Research Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114
Objectives The goal of this study was to develop and validate a new fibrin-targeted imaging agent that enables high-resolution near-infrared fluorescence (NIRF) imaging of deep vein thrombosis (DVT).
Background NIRF imaging of fibrin could enable highly sensitive and noninvasive molecular imaging of thrombosis syndromes in vivo.
Methods A fibrin-targeted peptide was conjugated to a near-infrared fluorophore Cy7, termed FTP11-Cy7. The NIRF peptide is based on a fibrin-specific imaging agent that has completed Phase II clinical magnetic resonance imaging trials. In vitro binding of FTP11-Cy7 to human plasma clots was assessed by using fluorescence reflectance imaging. Next, FTP11-Cy7 was intravenously injected in mice with femoral DVT induced by topical 7.5% ferric chloride treatment. Intravital fluorescence microscopy and noninvasive fluorescence molecular tomography–computed tomography were performed in 32 mice with DVT, followed by histological analyses.
Results In vitro human clot-binding analyses showed a 6-fold higher NIRF clot target-to-background ratio (TBR) of FTP11-Cy7 than free Cy7 (6.3 ± 0.34 vs. 1.2 ± 0.03; p < 0.0001). The thrombus TBR of acute and subacute femoral DVT with FTP11-Cy7 obtained by using intravital fluorescence microscopy was >400% higher than control free Cy7. Binding of FTP11-Cy7 to thrombi was blocked by a 100-fold excess of unlabeled competitor peptide both in vitro and in vivo (p < 0.001 for each). Histological analyses confirmed that FTP11-Cy7 specifically accumulated in thrombi. Noninvasive fluorescence molecular tomography–computed tomography imaging of fibrin in jugular DVT demonstrated strong NIRF signal in thrombi compared with sham-operated jugular veins (mean TBR 3.5 ± 0.7 vs. 1.5 ± 0.3; p < 0.05).
Conclusions The fibrin-targeted NIRF agent FTP11-Cy7 was shown to avidly and specifically bind human and murine thrombi, and enable sensitive, multimodal intravital and noninvasive NIRF molecular imaging detection of acute and subacute murine DVT in vivo.
This study was funded by the following sources: National Institutes of HealthR01HL108229 (Dr. Jaffer) and R01HL076398 and R01HL093717 (Dr. Tearney); American Heart Association Scientist Development grant 0830352N (Dr. Jaffer); Howard Hughes Medical Institute Career Development Award (Dr. Jaffer); Broadview Ventures (Dr. Jaffer); and the Society of Nuclear Medicine Wagner-Torizuka Fellowship (Dr. Hara). Dr. Jaffer has received an honorarium from GE Healthcare. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. Tearney and Jaffer share senior authorship on this paper.
- Received August 24, 2011.
- Revision received December 21, 2011.
- Accepted January 6, 2012.
- American College of Cardiology Foundation