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Updated: Jun 24, 2025

Isolation of Macrophage Subsets and Stromal Cells from Human and Mouse Myocardial Specimens
Published on: December 17, 2019
Dissecting and Visualizing the Functional Diversity of Cardiac Macrophages
Megan Holt1, Julia Lin2,3, Markus Cicka1
1Division of Cardiology, Department of Medicine, Center for Cardiovascular Research, Washington University School of Medicine (M.H., M.C., K.J.L.).
Insights
Cardiac macrophages are diverse and play key roles in heart health and disease. New imaging techniques allow noninvasive tracking of these cells, paving the way for clinical applications.
Area of Science:
- Cardiovascular Biology
- Immunology
- Cell Biology
Background:
- Cardiac macrophages are crucial for heart homeostasis, repair, and remodeling.
- Recent single-cell technologies reveal diverse macrophage subsets with distinct functions.
- Understanding macrophage ontogeny (embryonic vs. adult progenitors) is key to their cardiac roles.
Purpose of the Study:
- To elucidate the diversity and functional roles of cardiac macrophage subsets.
- To highlight advancements in noninvasively detecting and measuring cardiac macrophages in vivo.
- To explore the clinical translation potential of cardiac macrophage imaging.
Main Methods:
- Single-cell technologies (transcriptional signatures, cell surface proteins).
- Fate-mapping and parabiosis studies for macrophage ontogeny and dynamics.
- Molecular tracers for noninvasive imaging (PET/CT, PET/MRI).
Main Results:
- Identified distinct cardiac macrophage subsets derived from embryonic and adult progenitors.
- Tissue-resident macrophages are protective, while monocyte-derived macrophages have context-dependent roles.
- Noninvasive imaging enables serial visualization and measurement of cardiac macrophages in disease.
Conclusions:
- Cardiac macrophages exhibit significant functional diversity influencing heart health and disease.
- Noninvasive imaging of cardiac macrophages is advancing rapidly.
- These advancements are critical for clinical translation and therapeutic strategies.
Abstract:
Cardiac macrophages represent a functionally diverse population of cells involved in cardiac homeostasis, repair, and remodeling. With recent advancements in single-cell technologies, it is possible to elucidate specific macrophage subsets based on transcriptional signatures and cell surface protein expression to gain a deep understanding of macrophage diversity in the heart. The use of fate-mapping technologies and parabiosis studies have provided insight into the ontogeny and dynamics of macrophages identifying subsets derived from embryonic and adult definitive hematopoietic progenitors that include tissue-resident and bone marrow monocyte-derived macrophages, respectively. Within the heart, these subsets have distinct tissue niches and functional roles in the setting of homeostasis and disease, with cardiac resident macrophages representing a protective cell population while bone marrow monocyte-derived cardiac macrophages have a context-dependent effect, triggering both proinflammatory tissue injury, but also promoting reparative functions. With the increased understanding of the clinical relevance of cardiac macrophage subsets, there has been an increasing need to detect and measure cardiac macrophage compositions in living animals and patients. New molecular tracers compatible with positron emission tomography/computerized tomography and positron emission tomography/ magnetic resonance imaging have enabled investigators to noninvasively and serially visualize cardiac macrophage subsets within the heart to define associations with disease and measure treatment responses. Today, advancements within this thriving field are poised to fuel an era of clinical translation.
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