Molecular Imaging Visualizes Recruitment of Inflammatory Monocytes and Macrophages to the Injured Heart

Rationale: Paradigm shifting studies have revealed that the heart contains functionally diverse populations of macrophages derived from distinct embryonic and adult hematopoietic progenitors. Under steady-state conditions, the heart is largely populated by CCR2− (C-C chemokine receptor type 2) macrophages of embryonic descent. After tissue injury, a dramatic shift in macrophage composition occurs whereby CCR2+ monocytes are recruited to the heart and differentiate into inflammatory CCR2+ macrophages that contribute to heart failure progression. Currently, there are no techniques to noninvasively detect CCR2+ monocyte recruitment into the heart and thus identify patients who may be candidates for immunomodulatory therapy. Objective: To develop a noninvasive molecular imaging strategy with high sensitivity and specificity to visualize inflammatory monocyte and macrophage accumulation in the heart. Methods and Results: We synthesized and tested the performance of a positron emission tomography radiotracer (6...