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OBJECTIVES: Optical coherence tomography (OCT) is a high resolution imaging technique used to assess superficial atherosclerotic plaque morphology. Utility of OCT may be enhanced by contrast agents targeting molecular mediators of inflammation. METHODS AND RESULTS: Microparticles of iron oxide (MPIO; 1 and 4.5 μm diameter) in suspension were visualized and accurately quantified using a clinical optical coherence tomography system. Bound to PECAM-1 on a plane of cultured endothelial cells under static conditions, 1 μm MPIO were also readily detected by OCT. To design a molecular contrast probe that would bind activated endothelium under conditions of shear stress, we quantified the expression (basal vs. TNF-activated; molecules μm(-2)) of VCAM-1 (not detected vs. 16 ± 1); PECAM-1 (132 ± 6 vs. 198 ± 10) and E-selectin (not detected vs. 46 ± 0.6) using quantitative flow cytometry. We then compared the retention of antibody-conjugated MPIO targeting each of these molecules plus a combined VCAM-1 and E-selectin (E+V) probe across a range of physiologically relevant shear stresses. E+V MPIO were consistently retained with highest efficiency (P < 0.001) and at a density that provided conspicuous contrast effects on OCT pullback. CONCLUSION: Microparticles of iron oxide were detectable using a clinical OCT system. Assessment of binding under flow conditions recommended an approach that targeted both E-selectin and VCAM-1. Bound to HUVEC under conditions of flow, targeted 1 μm E+V MPIO were readily identified on OCT pullback. Molecular imaging with OCT may be feasible in vivo using antibody targeted MPIO.

Original publication

DOI

10.1016/j.atherosclerosis.2011.07.127

Type

Journal article

Journal

Atherosclerosis

Publication Date

12/2011

Volume

219

Pages

579 - 587

Keywords

Animals, Antibodies, Monoclonal, Antigens, CD31, Arterioles, Biomarkers, Cells, Cultured, Coronary Vessels, E-Selectin, Ferric Compounds, Flow Cytometry, Human Umbilical Vein Endothelial Cells, Humans, Immunohistochemistry, Inflammation Mediators, Ligands, Male, Microscopy, Fluorescence, Microscopy, Video, Molecular Imaging, Molecular Probes, Particle Size, Protein Binding, Rats, Rats, Wistar, Research Design, Stress, Mechanical, Tomography, Optical Coherence, Tumor Necrosis Factor-alpha, Vascular Cell Adhesion Molecule-1