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Ontogeny of Tissue-Resident Macrophages.

Hoeffel G, Ginhoux F - Front Immunol (2015)

Bottom Line: The origin of tissue-resident macrophages, crucial for homeostasis and immunity, has remained controversial until recently.These tissue-resident macrophages derive from sequential seeding of tissues by two precursors during embryonic development.Thus, hematopoietic stem cell-independent embryonic precursors transiently present in the YS and the FL give rise to long-lasting self-renewing macrophage populations.

View Article: PubMed Central - PubMed

Affiliation: Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (ASTAR) , Singapore , Singapore.

ABSTRACT
The origin of tissue-resident macrophages, crucial for homeostasis and immunity, has remained controversial until recently. Originally described as part of the mononuclear phagocyte system, macrophages were long thought to derive solely from adult blood circulating monocytes. However, accumulating evidence now shows that certain macrophage populations are in fact independent from monocyte and even from adult bone marrow hematopoiesis. These tissue-resident macrophages derive from sequential seeding of tissues by two precursors during embryonic development. Primitive macrophages generated in the yolk sac (YS) from early erythro-myeloid progenitors (EMPs), independently of the transcription factor c-Myb and bypassing monocytic intermediates, first give rise to microglia. Later, fetal monocytes, generated from c-Myb(+) EMPs that initially seed the fetal liver (FL), then give rise to the majority of other adult macrophages. Thus, hematopoietic stem cell-independent embryonic precursors transiently present in the YS and the FL give rise to long-lasting self-renewing macrophage populations.

No MeSH data available.


Related in: MedlinePlus

Fetal hematopoiesis. Primitive, transient definitive, and definitive waves of fetal hematopoiesis sequentially generate progenitors able to seed the fetal liver. Primitive hematopoiesis starts at E7.0 in the blood islands of the extra-embryonic yolk sac (YS) and generates erythro-myeloid progenitors (EMPs). Early EMPs initially express CD41 and later, CSF-1R, a signature of myeloid/macrophage commitment. Concomitant to the establishment of the blood circulation at E8.5, the YS hemogenic endothelium (HE) generates late EMPs expressing C-Myb. At approximately E9.0, the intra-embryonic mesoderm generates additional HE and emerging progenitors with lymphoid potentials (LMPs) without long-term reconstitution (LTR) capacity. These C-Myb+ EMPs and LMPs constitute the so-called transient definitive wave. Finally, hematopoietic stem cells (HSCs) with LTR activity emerge from the main HE situated in the aorta-gonad-mesonephros (AGM) regions and in the placenta.
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Figure 1: Fetal hematopoiesis. Primitive, transient definitive, and definitive waves of fetal hematopoiesis sequentially generate progenitors able to seed the fetal liver. Primitive hematopoiesis starts at E7.0 in the blood islands of the extra-embryonic yolk sac (YS) and generates erythro-myeloid progenitors (EMPs). Early EMPs initially express CD41 and later, CSF-1R, a signature of myeloid/macrophage commitment. Concomitant to the establishment of the blood circulation at E8.5, the YS hemogenic endothelium (HE) generates late EMPs expressing C-Myb. At approximately E9.0, the intra-embryonic mesoderm generates additional HE and emerging progenitors with lymphoid potentials (LMPs) without long-term reconstitution (LTR) capacity. These C-Myb+ EMPs and LMPs constitute the so-called transient definitive wave. Finally, hematopoietic stem cells (HSCs) with LTR activity emerge from the main HE situated in the aorta-gonad-mesonephros (AGM) regions and in the placenta.

Mentions: Mammalian embryos produce several transient waves of hematopoietic cells before the establishment of HSCs in the BM during late gestation (40, 41). The multiple embryonic waves are differentially regulated in time and space and exhibit distinct lineage potentials. Importantly, they contribute to hematopoietic populations that persist until adulthood. These waves include primitive hematopoiesis in the YS, and definitive hematopoiesis, which comprises a transient definitive stage, generating multi-lineage erythro-myeloid progenitors (EMPs) and lympho-myeloid progenitors (LMPs), and a definitive stage characterized by the production of HSCs in the aorta-gonad-mesonephros (AGM). These transient progenitors establish themselves transiently in the fetal liver (FL) during the mid to late stages of hematopoiesis. The sequential waves of hematopoiesis can overlap in time and space (Figure 1) and remain difficult to separate clearly, even with the most recent fate-mapping tools available.


Ontogeny of Tissue-Resident Macrophages.

Hoeffel G, Ginhoux F - Front Immunol (2015)

Fetal hematopoiesis. Primitive, transient definitive, and definitive waves of fetal hematopoiesis sequentially generate progenitors able to seed the fetal liver. Primitive hematopoiesis starts at E7.0 in the blood islands of the extra-embryonic yolk sac (YS) and generates erythro-myeloid progenitors (EMPs). Early EMPs initially express CD41 and later, CSF-1R, a signature of myeloid/macrophage commitment. Concomitant to the establishment of the blood circulation at E8.5, the YS hemogenic endothelium (HE) generates late EMPs expressing C-Myb. At approximately E9.0, the intra-embryonic mesoderm generates additional HE and emerging progenitors with lymphoid potentials (LMPs) without long-term reconstitution (LTR) capacity. These C-Myb+ EMPs and LMPs constitute the so-called transient definitive wave. Finally, hematopoietic stem cells (HSCs) with LTR activity emerge from the main HE situated in the aorta-gonad-mesonephros (AGM) regions and in the placenta.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585135&req=5

Figure 1: Fetal hematopoiesis. Primitive, transient definitive, and definitive waves of fetal hematopoiesis sequentially generate progenitors able to seed the fetal liver. Primitive hematopoiesis starts at E7.0 in the blood islands of the extra-embryonic yolk sac (YS) and generates erythro-myeloid progenitors (EMPs). Early EMPs initially express CD41 and later, CSF-1R, a signature of myeloid/macrophage commitment. Concomitant to the establishment of the blood circulation at E8.5, the YS hemogenic endothelium (HE) generates late EMPs expressing C-Myb. At approximately E9.0, the intra-embryonic mesoderm generates additional HE and emerging progenitors with lymphoid potentials (LMPs) without long-term reconstitution (LTR) capacity. These C-Myb+ EMPs and LMPs constitute the so-called transient definitive wave. Finally, hematopoietic stem cells (HSCs) with LTR activity emerge from the main HE situated in the aorta-gonad-mesonephros (AGM) regions and in the placenta.
Mentions: Mammalian embryos produce several transient waves of hematopoietic cells before the establishment of HSCs in the BM during late gestation (40, 41). The multiple embryonic waves are differentially regulated in time and space and exhibit distinct lineage potentials. Importantly, they contribute to hematopoietic populations that persist until adulthood. These waves include primitive hematopoiesis in the YS, and definitive hematopoiesis, which comprises a transient definitive stage, generating multi-lineage erythro-myeloid progenitors (EMPs) and lympho-myeloid progenitors (LMPs), and a definitive stage characterized by the production of HSCs in the aorta-gonad-mesonephros (AGM). These transient progenitors establish themselves transiently in the fetal liver (FL) during the mid to late stages of hematopoiesis. The sequential waves of hematopoiesis can overlap in time and space (Figure 1) and remain difficult to separate clearly, even with the most recent fate-mapping tools available.

Bottom Line: The origin of tissue-resident macrophages, crucial for homeostasis and immunity, has remained controversial until recently.These tissue-resident macrophages derive from sequential seeding of tissues by two precursors during embryonic development.Thus, hematopoietic stem cell-independent embryonic precursors transiently present in the YS and the FL give rise to long-lasting self-renewing macrophage populations.

View Article: PubMed Central - PubMed

Affiliation: Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (ASTAR) , Singapore , Singapore.

ABSTRACT
The origin of tissue-resident macrophages, crucial for homeostasis and immunity, has remained controversial until recently. Originally described as part of the mononuclear phagocyte system, macrophages were long thought to derive solely from adult blood circulating monocytes. However, accumulating evidence now shows that certain macrophage populations are in fact independent from monocyte and even from adult bone marrow hematopoiesis. These tissue-resident macrophages derive from sequential seeding of tissues by two precursors during embryonic development. Primitive macrophages generated in the yolk sac (YS) from early erythro-myeloid progenitors (EMPs), independently of the transcription factor c-Myb and bypassing monocytic intermediates, first give rise to microglia. Later, fetal monocytes, generated from c-Myb(+) EMPs that initially seed the fetal liver (FL), then give rise to the majority of other adult macrophages. Thus, hematopoietic stem cell-independent embryonic precursors transiently present in the YS and the FL give rise to long-lasting self-renewing macrophage populations.

No MeSH data available.


Related in: MedlinePlus