Novel Single-Chain Antibody-Targeted Microbubbles for Molecular Ultrasound Imaging of Thrombosis

Abstract

Background-Molecular imaging is a fast emerging technology allowing noninvasive detection of vascular pathologies.However, imaging modalities offering high resolution currently do not allow real-time imaging. We hypothesized that contrast-enhanced ultrasound with microbubbles (MBs) selectively targeted to activated platelets would offer high-resolution, real-time molecular imaging of evolving and dissolving arterial thrombi. Methods and Results-Lipid-shell based gas-filled MBs were conjugated to either a single-chain antibody specific for activated glycoprotein IIb/IIIa via binding to a Ligand-Induced Binding Site (LIBS-MBs) or a nonspecific single-chain antibody (control MBs). Successful conjugation was assessed in flow cytometry and immunofluorescence double staining. LIBS-MBs but not control MBs strongly adhered to both immobilized activated platelets and microthrombi under flow. Thrombi induced in carotid arteries of C57Bl6 mice in vivo by ferric chloride injury were then assessed with ultrasound before and 20 minutes after MB injection through the use of gray-scale area intensity measurement. Gray-scale units converted to decibels demonstrated a significant increase after LIBS-MB but not after control MB injection (9.55Ϯ1.7 versus 1.46Ϯ1.3 dB; PϽ0.01). Furthermore, after thrombolysis with urokinase, LIBS-MB ultrasound imaging allows monitoring of the reduction of thrombus size (PϽ0.001). Conclusion-We

Noninvasive Imaging of Early Venous Thrombosis by 19 F Magnetic Resonance Imaging With Targeted Perfluorocarbon Nanoemulsions

“…In vivo imaging of FXIIIa activity via α2 AP -PFCs could further aid in monitoring of imminent thrombus formation after implantation of such devices as pacemakers, valves, or scaffolds and in identifying latent thrombus generation in structures characterized by low blood flow velocities and prone to stasis such as the left atrial appendage. Besides coupling α2-antiplasmin peptide, SPIT holds the potential to be adapted for single-chain monoclonal antibodies raised against activated glycoprotein IIb/IIIa 47 or peptides that bind to existing thrombi, 10 also enabling the assessment of persistent thrombi by 19 F MRI. The method described here has significant translational potential.…”

Dual-Contrast Molecular Imaging Allows Noninvasive Characterization of Myocardial Ischemia/Reperfusion Injury After Coronary Vessel Occlusion in Mice by Magnetic Resonance Imaging

“…In vitro flow chamber adhesion assays were performed with collagen-coated glass capillaries. 25 Microthrombi were formed by perfusion of whole blood into the capillary with a syringe pump (PhD 2000, Harvard Apparatus). MPIOs were perfused through the capillary for 5 minutes.…”

Fe₃O₄-based PLGA nanoparticles as MR contrast agents for the detection of thrombosis

“…A variety of particles have been reported in the literature for thrombosis detection. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] Compared with ultrasound, [4][5][6][7][8] nuclear medicine, 9,10,18 and computed tomography (CT), 11 the advantages of magnetic resonance imaging (MRI) that are particularly relevant in the context of cardiovascular diseases are its high temporal and spatial imaging resolution, high soft tissue contrast,…”