Related Experiment Video
Updated: Jun 28, 2025
Visualization and Analysis of Pharyngeal Arch Arteries using Whole-mount Immunohistochemistry and 3D Reconstruction
Published on: March 31, 2020
Buffering Mechanism in Aortic Arch Artery Formation and Congenital Heart Disease
AnnJosette Ramirez1,2, Christina A Vyzas1,2, Huaning Zhao1
1Department of Cell Biology and Molecular Medicine (A.R., C.A.V., H.Z., S.A.), New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark.
Insights
Embryonic heart development is resilient due to compensatory endothelial cells (ECs) that repair pharyngeal arch artery defects. Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) and T-box 1 (Tbx1) regulate this crucial EC recruitment.
Area of Science:
- Developmental Biology
- Cardiovascular Research
- Genetics
Background:
- Embryonic development exhibits remarkable resilience to perturbations, yet the mechanisms ensuring developmental robustness remain poorly understood.
- Congenital heart disease, often resulting from defective pharyngeal arch artery (PAA) morphogenesis, exemplifies developmental aberrations leading to neonatal lethality.
Purpose of the Study:
- To investigate the mechanisms underlying the formation and repair of pharyngeal arch arteries (PAAs).
- To elucidate the role of vascular endothelial growth factor receptor 2 (VEGFR2) and T-box 1 (Tbx1) in regulating endothelial cell (EC) contribution to PAA development.
Main Methods:
- Utilized mouse genetics, lineage tracing, confocal microscopy, and quantitative image analyses to study PAA development.
- Investigated 3-dimensional EC connectivity, EC fate, and gene expression to understand compensatory EC recruitment.
Main Results:
- Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) expression in the second heart field (SHF) is essential for PAA endothelial cell differentiation.
- Reduced VEGFR2 levels decrease SHF contribution to the PAA endothelium, which is compensated by recruitment of ECs from nearby veins.
- T-box 1 (Tbx1) regulates the non-cell-autonomous recruitment of compensatory ECs, and its absence in Tbx1+/- embryos leads to PAA defects and congenital heart disease.
Conclusions:
- Discovered a novel buffering mechanism involving compensatory endothelial cell recruitment that enhances the resilience of pharyngeal arch artery development and remodeling.
- This compensatory response is critical for preventing embryonic demise and is regulated by VEGFR2 and Tbx1.
Background:
The resiliency of embryonic development to genetic and environmental perturbations has been long appreciated; however, little is known about the mechanisms underlying the robustness of developmental processes. Aberrations resulting in neonatal lethality are exemplified by congenital heart disease arising from defective morphogenesis of pharyngeal arch arteries (PAAs) and their derivatives.
Methods:
Mouse genetics, lineage tracing, confocal microscopy, and quantitative image analyses were used to investigate mechanisms of PAA formation and repair.
Results:
The second heart field (SHF) gives rise to the PAA endothelium. Here, we show that the number of SHF-derived endothelial cells (ECs) is regulated by VEGFR2 (vascular endothelial growth factor receptor 2) and Tbx1. Remarkably, when the SHF-derived EC number is decreased, PAA development can be rescued by the compensatory endothelium. Blocking such compensatory response leads to embryonic demise. To determine the source of compensating ECs and mechanisms regulating their recruitment, we investigated 3-dimensional EC connectivity, EC fate, and gene expression. Our studies demonstrate that the expression of VEGFR2 by the SHF is required for the differentiation of SHF-derived cells into PAA ECs. The deletion of 1 VEGFR2 allele (VEGFR2) reduces SHF contribution to the PAA endothelium, while the deletion of both alleles (VEGFR2) abolishes it. The decrease in SHF-derived ECs in VEGFR2 and VEGFR2 embryos is complemented by the recruitment of ECs from the nearby veins. Compensatory ECs contribute to PAA derivatives, giving rise to the endothelium of the aortic arch and the ductus in VEGFR2 mutants. Blocking the compensatory response in VEGFR2 mutants results in embryonic lethality shortly after mid-gestation. The compensatory ECs are absent in Tbx1+/- embryos, a model for 22q11 deletion syndrome, leading to unpredictable arch artery morphogenesis and congenital heart disease. Tbx1 regulates the recruitment of the compensatory endothelium in an SHF-non-cell-autonomous manner.
Conclusions:
Our studies uncover a novel buffering mechanism underlying the resiliency of PAA development and remodeling.
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