Ultrasound Detection of Myocardial Ischemic Memory Using an E-Selectin Targeting Peptide Amenable to Human Application

Abstract

Vascular endothelial leukocyte adhesion molecules, such as E-selectin, are acutely upregulated in myocardial ischemia/reperfusion and are thus "ischemic memory" biomarkers for recent cardiac ischemia. We sought to develop an ultrasound molecular imaging agent composed of microbubbles (MBs) targeted to E-selectin to enable the differential diagnosis of myocardial ischemia in patients presenting with chest pain of unclear etiology. Biodegradable polymer MBs were prepared bearing a peptide with specific human E-selectin affinity (MBESEL). Control MBs had scrambled peptide (MBCTL) or nonspecific IgG (MBIgG). MBESEL adhesion to activated rat endothelial cells (ECs) was confirmed in vitro in a flow system and in vivo with intravital microscopy of rat cremaster microcirculation. Ultrasound molecular imaging of recent myocardial ischemia was performed in rats 4 hours after transient (15 minutes) coronary occlusion. MBESEL adhesion was higher to inflamed versus normal ECs in vitro; there was no difference in MBCTL or MBIgG adhesion to inflamed versus normal ECs. There was greater adhesion of MBESEL to inflamed versus noninflamed microcirculation and minimal adhesion of MBCTL or MBIgG under any condition. Ultrasound imaging after injection of MBSEL demonstrated persistent contrast enhancement of the previously ischemic region. Videointensity in postischemic myocardium after MBESEL was higher than that in the nonischemic bed (11.6 ± 2.7 dB vs 3.6 ± 0.8 dB, p < .02) and higher than that after MBCTL (4.0 ± 1.0 dB, p < .03) or MBIgG (1.7 ± 0.1 dB, p < .03). MBs targeted to E-selectin via a short synthetic peptide with human E-selectin binding affinity enables echocardiographic detection of recent ischemia, setting the stage for clinical myocardial ischemic memory imaging to identify acute coronary syndromes.

Ultrasound Molecular Imaging of Angiogenesis Using Vascular Endothelial Growth Factor-Conjugated Microbubbles

“…18–20, 25 Furthermore, we developed a method for quantifying KDR on the coated surfaces as we were interested in simulating varying degrees of receptor expression in vitro . To prepare KDR coated surfaces, glass coverslips were incubated overnight with 1 mL of goat anti-human IgG (GAMMA, 3 μg/mL, R&D Systems, Minneapolis, MN), and washed with PBS.…”

Translational applications of molecular imaging in cardiovascular disease and stem cell therapy

“…Vascular endothelial leukocyte adhesion molecules, such as E-selectin, are acutely upregulated in myocardial ischemia/reperfusion and can be imaged by echocardiography as "ischemic memory" biomarkers in recent cardiac ischemia model (Fig. 4) [35]. Another marker, RAGE (receptor for advanced glycation end products) expression in myocardial ischemic injury, has been imaged in vivo using a novel 99m Tc-anti-RAGE F(ab 0 ) 2 target for clinical applications [36].…”

Evolution of contrast agents for ultrasound imaging and ultrasound-mediated drug delivery

“…Avidin was incorporated in the shell, so that biotinylated antibodies could be bound functionally to the bubbles ( Korpanty et al, 2005 ). Another more recent approach uses targeted poly- D , L -lactide/albumin hybrid MB for differential diagnosis in patients with chest pain to detect recent ischemia ( Leng et al, 2014 ).…”