Theranostics 2016; 6(11):1768-1779. doi:10.7150/thno.15929 This issue

Research Paper

Targeting Amino Acid Metabolism for Molecular Imaging of Inflammation Early After Myocardial Infarction

James T. Thackeray1✉, Jens P. Bankstahl1, Yong Wang2, Kai C. Wollert2, Frank M. Bengel1

1. Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany;
2. Division of Molecular and Translational Cardiology, Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany.

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Thackeray JT, Bankstahl JP, Wang Y, Wollert KC, Bengel FM. Targeting Amino Acid Metabolism for Molecular Imaging of Inflammation Early After Myocardial Infarction. Theranostics 2016; 6(11):1768-1779. doi:10.7150/thno.15929. Available from

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Graphic abstract

Acute tissue inflammation after myocardial infarction influences healing and remodeling and has been identified as a target for novel therapies. Molecular imaging holds promise for guidance of such therapies. The amino acid 11C-methionine is a clinically approved agent which is thought to accumulate in macrophages, but not in healthy myocytes. We assessed the suitability of positron emission tomography (PET) with 11C-methionine for imaging post-MI inflammation, from cell to mouse to man. Uptake assays demonstrated 7-fold higher 11C-methionine uptake by polarized pro-inflammatory M1 macrophages over anti-inflammatory M2 subtypes (p<0.001). C57Bl/6 mice (n=27) underwent coronary artery ligation or no surgery. Serial 11C-methionine PET was performed 3, 5 and 7d later. MI mice exhibited a perfusion defect in 32-50% of the left ventricle (LV). PET detected increased 11C-methionine accumulation in the infarct territory at 3d (5.9±0.9%ID/g vs 4.7±0.9 in remote myocardium, and 2.6±0.5 in healthy mice; p<0.05 and <0.01 respectively), which declined by d7 post-MI (4.3±0.6 in infarct, 3.4±0.8 in remote; p=0.03 vs 3d, p=0.08 vs healthy). Increased 11C-methionine uptake was associated with macrophage infiltration of damaged myocardium. Treatment with anti-integrin antibodies (anti-CD11a, -CD11b, -CD49d; 100µg) lowered macrophage content by 56% and 11C-methionine uptake by 46% at 3d post-MI. A patient study at 3d after ST-elevation MI and early reperfusion confirmed elevated 11C-methionine uptake in the hypoperfused myocardial region. Targeting of elevated amino acid metabolism in pro-inflammatory M1 macrophages enables PET imaging-derived demarcation of tissue inflammation after MI. 11C-methionine-based molecular imaging may assist in the translation of novel image-guided, inflammation-targeted regenerative therapies.

Keywords: inflammation, myocardial infarction, 11C-methionine, macrophages, positron emission tomography (PET).