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Updated: Feb 8, 2026
Isolation and Culture of Resident Cardiac Macrophages from the Murine Sinoatrial and Atrioventricular Node
Published on: May 7, 2021
Delineating the origins, developmental programs and homeostatic functions of tissue-resident macrophages
1Developmental Biology of the Innate Immune System, LIMES-Institute, University of Bonn, Bonn, Germany.
Abstract:
A literature covering 150 years of research indicates that macrophages are a diverse family of professional phagocytes that continuously explore their environment, recognize and scavenge pathogens, unfit cells, cell debris as well as metabolites, and produce a large range of bioactive molecules and growth factors. A new paradigm suggests that most tissue-resident macrophages originate from fetal precursors that colonize developing organs and self-maintain independently of bone marrow-derived cells throughout life. The differentiation of these precursors is driven by a core macrophage transcriptional program and immediately followed by their specification through expression of tissue-specific transcriptional regulators early during embryogenesis. Despite our increasing understanding of ontogeny and genetic programs that shape differentiation processes and functions of macrophages, the precise developmental trajectories of tissue-resident macrophages remain undefined. Here, I review current models of fetal hematopoietic waves, possible routes of macrophage development and their roles during homeostasis. Further, transgenic mouse models are discussed providing a toolset to study the developmentally and functionally distinct arms of the phagocyte system in vivo.
Insights
Macrophages, essential immune cells, originate from fetal precursors and self-maintain in tissues. Their precise developmental paths and roles in homeostasis are still being defined, requiring further study of these phagocytes.
Area of Science:
- Immunology
- Developmental Biology
- Cell Biology
Background:
- Macrophages are versatile phagocytes involved in pathogen clearance and tissue homeostasis.
- A paradigm shift suggests tissue-resident macrophages arise from fetal precursors, independent of adult bone marrow-derived cells.
- Understanding macrophage ontogeny is crucial for comprehending their diverse functions.
Purpose of the Study:
- To review current models of macrophage development and ontogeny.
- To explore the differentiation pathways and self-maintenance mechanisms of tissue-resident macrophages.
- To discuss the utility of transgenic mouse models in studying macrophage biology.
Main Methods:
- Literature review of 150 years of research on macrophages.
- Analysis of current models of fetal hematopoietic waves.
- Discussion of transgenic mouse models for in vivo studies.
Main Results:
- Tissue-resident macrophages primarily originate from fetal precursors that colonize organs early in development.
- These precursors undergo differentiation driven by core transcriptional programs and tissue-specific regulators.
- Macrophages self-maintain throughout life, largely independent of adult hematopoietic stem cells.
Conclusions:
- The precise developmental trajectories of tissue-resident macrophages remain incompletely defined.
- Further research utilizing advanced models is necessary to elucidate the distinct arms of the phagocyte system.
- Understanding macrophage ontogeny is key to their roles in homeostasis and disease.
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