Coronary stem development in wild‐type and Tbx1 null mouse hearts

• Published in: Developmental dynamics 2016-04, Vol.245 (4), p.445-459
• Main Authors: Théveniau‐Ruissy, Magali, Pérez‐Pomares, José‐Maria, Parisot, Pauline, Baldini, Antonio, Miquerol, Lucile, Kelly, Robert G.
• Format: Article
• Language: English
• Subjects: Animals; Aorta; Aorta - embryology; Aorta - pathology; Bridges; Chick Embryo; coronary arteries; Coronary artery; coronary ostia; Coronary Vessels - embryology; Coronary Vessels - pathology; Death; Defects; Differentiation; Embryos; Endothelium; Endothelium, Vascular - embryology; Endothelium, Vascular - pathology; Epithelium; Etiology; Fluorescence; Heart; Heart - embryology; heart development; Mice; Mice, Mutant Strains; Myocardium; Patterning; Stem Cells - metabolism; Stem Cells - pathology; T-Box Domain Proteins - deficiency; Tbx1; Time measurement; Trajectories; Transplantation
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.24380

Background: Coronary artery (CA) stems connect the ventricular coronary tree with the aorta. Defects in proximal CA patterning are a cause of sudden cardiac death. In mice lacking Tbx1, common arterial trunk is associated with an abnormal trajectory of the proximal left CA. Here we investigate CA stem development in wild‐type and Tbx1 null embryos. Results: Genetic lineage tracing reveals that limited outgrowth of aortic endothelium contributes to proximal CA stems. Immunohistochemistry and fluorescent tracer injections identify a periarterial vascular plexus present at the onset of CA stem development. Transplantation experiments in avian embryos indicate that the periarterial plexus originates in mesenchyme distal to the outflow tract. Tbx1 is required for the patterning but not timing of CA stem development and a Tbx1 reporter allele is expressed in myocardium adjacent to the left but not right CA stem. This expression domain is maintained in Sema3c−/− hearts with a common arterial trunk and leftward positioned CA. Ectopic myocardial differentiation is observed on the left side of the Tbx1−/− common arterial trunk. Conclusions: A periarterial plexus bridges limited outgrowth of the aortic endothelium with the ventricular plexus during CA stem development. Molecular differences associated with left and right CA stems provide new insights into the etiology of CA patterning defects. Developmental Dynamics 245:445–459, 2016. © 2015 Wiley Periodicals, Inc. Key Findings Limited outgrowth of the aortic endothelium contributes to murine proximal coronary stems. A periarterial plexus bridges the aortic epithelium with the ventricular coronary plexus. Tbx1 expression reveals differences in myocardium associated with left and right coronary stems. Ectopic myocardial differentiation is observed on the left side of the Tbx1 null common trunk.