Kawai H, Chaudhry F, Shekhar A, Petrov A, Nakahara T, Tanimoto T, Kim D, Chen J, Lebeche D, Blankenberg FG, Pak KY, Kolodgie FD, Virmani R, Sengupta P, Narula N, Hajjar RJ, Strauss HW, and Narula J
Objectives: The purpose of this study was to evaluate the feasibility of imaging apoptosis in experimental ischemia-reperfusion model by technetium-99m ( 99m Tc)-labeled Duramycin, and compare it to an established tracer, 99m Tc-labeled Annexin-V, which has a relative disadvantage of high radiation burden to nontarget organs., Background: During apoptosis, the cell membrane phospholipids-phosphatidylserine (PS) and phosphatidylethanolamine (PE) are exposed and can be targeted by Annexin-V and Duramycin, respectively, for in vivo imaging. Identification of a reversible cell death process should permit therapeutic intervention to help reduce myocyte loss and left ventricle dysfunction., Methods: In a 40-min left coronary artery ischemia-reperfusion model in 17 rabbits, 7 mCi of 99m Tc-labeled Duramycin (n = 10), 99m Tc-linear Duramycin (a negative tracer control; n = 3), or 99m Tc-Annexin-V (a positive tracer-control; n = 4) were intravenously administered 30 min after reperfusion. Of the 10 Duramycin group animals, 4 animals were treated with an antiapoptotic agent, minocycline at the time of reperfusion. In vivo and ex vivo micro-single-photon emission computed tomography (μSPECT) and micro-computed tomography (μCT) imaging was performed 3 h after reperfusion, followed by quantitative assessment of tracer uptake and pathological characterization. Fluorescent Duramycin and Annexin-V were injected in 4 rats to visualize colocalization in infarct areas in a 40-min left coronary artery occlusion and 30-min reperfusion model., Results: Intense uptake of Duramycin and Annexin-V was observed in the apical (infarcted) areas. The percent injected dose per gram uptake of Duramycin in apical region (0.751 ± 0.262%) was significantly higher than remote area in same animals (0.045 ± 0.029%; p < 0.01). Duramycin uptake was insignificantly lower than Annexin-V uptake (1.23 ± 0.304%; p > 0.01) but demonstrated substantially lower radiation burden to kidneys (0.358 ± 0.210% vs. 1.58 ± 0.316%, respectively; p < 0.001). Fluorescence studies with Duramycin and Annexin V showed colocalization in infarct areas. Minocycline treatment substantially resolved Duramycin uptake (0.354% ± 0.0624%; p < 0.01)., Conclusions: Duramycin is similarly effective in imaging apoptotic cell death as Annexin-V with lower nontarget organ radiation. Clinical feasibility of apoptosis imaging with a PE-seeking tracer should be tested., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)