Postnatal Mouse Aorta Contains Yolk Sac-Derived Haemangioblasts with Myeloid and Endothelial Plasticity and Vasculogenic Capacity

Converging evidence indicates that extra-embryonic yolk sac is the source of both macrophages and endothelial cells in adult mouse tissues. Prevailing views are that these yolk sac-derived cells are maintained after birth by proliferative self-renewal in their differentiated states. Here we identify clonogenic, self-renewing endothelial-macrophage (EndoMac) progenitor cells in postnatal mouse aorta, heart and lung, that are independent of definitive hematopoiesis and derive from a CX3CR1+ and CSF1R+ yolk sac source. These bipotent progenitors are highly proliferative and vasculogenic, contributing to adventitial neovascularization in the aortic wall and forming perfused blood vessels after adoptive transfer into ischemic tissue. We establish a regulatory role for angiotensin II, which enhances their clonogenic, self-renewal and differentiation properties. Our findings demonstrate that tissue-resident EndoMac progenitors participate in local inflammatory and vasculogenic responses by contributing to the renewal and expansion of yolk sac-derived macrophages and endothelial cells postnatally.

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Fibroblastic Potential of CD41+Cells in the Mouse Aorta-Gonad-Mesonephros Region and Yolk Sac

Stem Cells and Development ◽

10.1089/scd.2011.0572 ◽

2012 ◽

Vol 21 (14) ◽

pp. 2592-2605 ◽

Cited By ~ 4

Author(s):

Junnian Zhou ◽

Haixu Chen ◽

Siting Li ◽

Yifan Xie ◽

Wenyan He ◽

...

Keyword(s):

Yolk Sac ◽

Mouse Aorta

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P5384Postnatal mouse aorta contains yolk sac-derived haemangioblasts with myeloid and endothelial plasticity and vasculogenic capacity

European Heart Journal ◽

10.1093/eurheartj/ehz746.0344 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

A Williamson ◽

D F Toledo ◽

N Schwarz ◽

S Fernando ◽

C Dimasi ◽

...

Keyword(s):

Endothelial Cells ◽

Progenitor Cells ◽

De Novo ◽

Cell Types ◽

Yolk Sac ◽

Vasa Vasorum ◽

Clonal Level ◽

Endothelial Plasticity ◽

Lineage Mapping

Abstract Background Macrophages and endothelial cells share an intimate relationship during neovessel formation in different pathophysiological conditions. Recent studies have determined that in some tissues, both cell types are derived embryonically from yolk sac (YS) progenitor cells and are maintained postnatally without contribution from circulating sources. The mechanism by which this local “self-maintenance” occurs is unknown. Purpose We previously identified that mouse arteries contain macrophage and endothelial progenitor cells in their adventitial Sca-1+CD45+ compartment. Here we investigated at a clonal level for the existence of postnatal adventitial haemangioblasts and studied their developmental origins. Methods and results Single cell digests were prepared from murine aortas to perform colony-forming unit (CFU) assays in methylcellulose. Aortic cells from C57BL/6J mice selectively generated macrophage colonies (CFU-M) which contained progenitor cells that displayed >95% positive for expression of CD45, Sca-1, c-Kit, CX3CR1 and CSF1R, but negative for Lineage markers, as well as mature monocyte/macrophage (CD11b, F4/80) and endothelial (CD144) markers. Secondary replating of CFU-M progenitors from adult aortas revealed their self-renewal capacity, with 1 in 10 cells forming new CFU-M. Lineage mapping using Flt3CrexRosamT/mG mice demonstrated that aortic CFU-M progenitors were FLT3-ve, indicating that they were not derived from definitive bone marrow haematopoiesis. CFU-M prevalence in C57BL/6J aortas was highest in neonatal mice and diminished progressively with increasing age (∼100 per 105 cells at P1, ∼15 at 12w, ∼5 at 52w, P<0.01, n>4/gp), consistent with prenatal seeding. Embryonic profiling determined that CFU-M progenitors first appeared in extra-embryonic yolk sac around E9.5 and in aorta-gonad-mesonephros at E10.5, before the emergence of definitive haematopoietic stem cells. Inducible fate-mapping then confirmed that aortic CFU-M progenitors originated from CX3CR1+ and CSF1R+ cells in E9.5 yolk sac. Both yolk sac and postnatal aortic CFU-M progenitors generated vascular-like networks when cultured in Matrigel in vitro, containing M2-like macrophages (CD11b+F4/80+CD206+) and endothelial cells (CD31+CD144+). They produced similar progeny and rescued adventitial vascular sprouting when seeded around aortic rings whose adventitia had been stripped. Finally, adoptive transfer of CFU-M progenitors into a mouse model of hindlimb ischaemia resulted in 80% augmentation in hindlimb perfusion compared to cell-free control, with de novo transformation of donor cells into macrophages, endothelial cells and perfused neovessels (n=6). Conclusion To the best of our knowledge, this is the first ever definitive proof at a clonal level for the existence of haemangioblasts in postnatal tissue. Adventitial haemangioblasts originate from extra-embryonic YS and are a source of vasculogenesis in the arterial wall, relevant to vasa vasorum formation. Acknowledgement/Funding NHMRC of Australia (GNT1086796, CDF1161506), NHFA (FLF100412, FLF102056) Royal Australasian College of Physicians

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Visualization of Antibody Transport in Rat Visceral Yolk-Sac Placenta

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053899 ◽

1982 ◽

Vol 40 ◽

pp. 246-247

Author(s):

William P. Jollie

Keyword(s):

Phosphate Buffer ◽

Yolk Sac ◽

Female Rats ◽

Thin Sections ◽

Visceral Yolk Sac ◽

Antibody Complex ◽

Cytochemical Reaction ◽

Hind Foot ◽

Antigen Antibody ◽

Yolk Sac Placenta

A technique has been developed for visualizing antibody against horseradish peroxidase (HRP) in rat visceral yolk sac, the placental membrane across which passive immunity previously has been shown to be transferred from mother to young just prior to birth. Female rats were immunized by injecting both hind foot pads with 1 mg HRP emulsified in complete Freund's adjuvant. They were given a booster of 0.5mg HRP in 0.1 ml normal saline i.v. after one week, then bred and autopsied at selected stages of pregnancy, viz., 12, 1 7 and 22 days post coitum, receiving a second booster, injected as above, five days before autopsy. Yolk sacs were removed surgically and fixed immediately in 2% paraformaldehye, 1% glutaraldehye in 0.1 M phosphate buffer with 0.01% CaCl2 at pH 7.4, room temperature, for 3 hr, rinsed 3X in 0.1 M phosphate buffer plus 5% sucrose, then exposed to 1 mg HRP in 1 ml 0.1 M phosphate buffer at pH 7.4 for 1 hr. They were refixed in aldehydes, as above, for 1 5 min (to assure binding of antigen-antibody complex). Following buffer washes, the tissues were incubated in 3 mg diaminobenzidine tetrahydrochloride and 0.01% H2O2 in 0.05 M Tris-HCl buffer for 30 min. After brief buffer washes, they were postfixed in 2% OsO4. in phosphate buffer at pH 7.4, 4°C for 2 hr, dehydrated through a graded series of ethanols, and embedded in Durcupan. Thin sections were observed and photographed without contrast-enhancement with heavy metals. Cytochemical reaction product marked the site of HRP (i.e., antigen) which, in turn, was present only where it was bound with anti-HRP antibody.

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