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A role for macrophages in hematopoiesis in the embryonic head

Research output: Contribution to journalArticle

Original languageEnglish
JournalBlood
DOIs
Publication statusPublished - 28 Nov 2019

Abstract

Along with the aorta-gonad-mesonephros region, the head is a site of hematopoietic stem and progenitor cell (HS/PC) development in the mouse embryo. Macrophages are present in both these embryonic hemogenic sites and recent studies indicate a functional interaction of macrophages with hematopoietic cells as they are generated in the aorta. Whereas, brain macrophages or ‘microglia’ are known to affect neuronal patterning and vascular circuitry in the embryonic brain, it is unknown whether macrophages play a role in head hematopoiesis. Here we characterize head macrophages and examine whether they affect the HS/PC output of the hindbrain-branchial arch (HBA) region of the mouse embryo. We show that HBA macrophages are CD45+F4/80+CD11b+Gr1- and express the macrophage-specific Csf1r-GFP reporter. In the HBA of chemokine receptor deficient (Cx3cr1-/-) embryos, a reduction in erythropoiesis is concomitant with a decrease in HBA macrophage percentages. In cocultures, we show that head macrophages boost HPC numbers from HBA endothelial cells >2-fold, and that the pro-inflammatory factor TNFα is produced by head macrophages and influences HBA hematopoiesis in vitro. Taken together, head macrophages play a positive role in HBA erythropoiesis and HS/PC expansion and/or maturation, acting as micro-environmental cellular regulators in hematopoietic development.

ID: 113877236