Coup-TFII expression defines two different septum transversum cell compartments crucial to cardiac septation and compact ventricular wall growth

COUP-TFII encodes for an orphan nuclear receptor expressed by multiple embryonic tissues. COUP-TFII functions include the regulation of mesodermal progenitor differentiation and cell fate specification, and is required for completion of cardiovascular development as shown by the early death (E9.5) of COUP-TFII-null mice. In this study, we show that COUP-TFII, which is strongly expressed in the atrial myocardium, is also expressed in two different compartments of the septum transversum (ST, E9.5), a mesodermal folding adjacent to cardiac inflow myocardium. The first ST compartment is COUP-TFII+/Isl1+; cells in this compartment concentrate in the posterior part of the ST, overlap with SHF, and are continuous with the dorsal mesenchymal protrusion (DMP, also known as spina vestibuli). The second compartment is characteristically COUP-TFII+/Isl1-, and comprises the majority of proepicardial cells. To dissect the role of COUP-TFII+ ST cells in cardiac development, we conditionally deleted COUP-TFII in the ST using two different Cre constructs (Wt1Cre; G2-Gata4Cre). We show that COUP-TFII deletion in the ST is most severe in G2-Gata4Cre;COUP-TFII-/- mice, containing various cardiovascular progenitor lineages. Mutant mice display atrial septation and atrioventricular septal defects as well as a severe disruption of compact ventricular myocardial growth and coronary vascularization. We conclude that COUP-TFII plays critical, pleiotropic, tissue-dependent roles during cardiac septation, growth and vascularization.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Centro Nacional de Investigaciones Cardiovasculares (CNIC-ISCIII

A developmental model for the pathogenenesis of cardiac arterio-ventricular fistulae

Coronary Artery Fistulae (CAF) are congenital coronary artery (CA) anomalies consisting of an abnormal communication of a coronary artery with either a cardiac chamber or a large cardiac vessel. Although their incidence in the Western population is low, CAF can lead to complications such as myocardial hypertrophy, endocarditis, heart dilatation and cardiac failure. CAFs can appear as an isolated anomaly or linked to some other forms of congenital heart disease like Left Ventricular Non-Compaction (LVNC) and intrinsic CA anatomy anomalies, but their etiology remains unknown. In this work we have used two different experimental models (transgenic mice and avian embryos) to investigate on the developmental mechanics of CAF formation. In order to tackle this goal, we have manipulated epicardial development and ventricular wall compaction, two inextricably related developmental events during coronary embryogenesis. Conditional integrin α4 gene deletion in the septum transversum/proepicardial (ST/PE) region (G2-Gata4+) disrupts early epicardium development and reduces cardiomyocyte proliferation, leading to the thinning of the ventricular compact myocardial layer. Reduction in compact myocardium thickness associates to the presence of multiple ventricular myocardial discontinuities and focal endocardial extrusion. This same phenotype can be experimentally reproduced in chick embryos using a cryocauterization method (Palmquist-Gomes et al., 2016). Our results suggest that the partial absence of epicardium in α4integrin;G2-Gata4Cre mouse embryos and the cryoinjury in avian embryos generate myocardial discontinuities in the embryonic ventricular wall, which promote endocardial extrusion towards the pericardial cavity and the early contact of the endocardium with coronary progenitors at the epicardial surface of the heart. In the case of avian embryos, this phenomenon leads to precocious smooth muscle differentiation from epicardial mesenchymal cells, and the formation of pouch-like structures that closely resemble CAF. We conclude that anomalous compact myocardial embryonic growth can originate CAF.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A developmental model for the pathogenenesis of cardiac arterio-ventricular fistulae

Coronary Artery Fistulae (CAF) are congenital coronary artery (CA) anomalies consisting of an abnormal communication of a coronary artery with either a cardiac chamber or a large cardiac vessel. Although their incidence in the Western population is low, CAF can lead to complications such as myocardial hypertrophy, endocarditis, heart dilatation and cardiac failure. CAFs can appear as an isolated anomaly or linked to some other forms of congenital heart disease like Left Ventricular Non-Compaction (LVNC) and intrinsic CA anatomy anomalies, but their etiology remains unknown. In this work we have used two different experimental models (transgenic mice and avian embryos) to investigate on the developmental mechanics of CAF formation. In order to tackle this goal, we have manipulated epicardial development and ventricular wall compaction, two inextricably related developmental events during coronary embryogenesis. Conditional integrin α4 gene deletion in the septum transversum/proepicardial (ST/PE) region (G2-Gata4+) disrupts early epicardium development and reduces cardiomyocyte proliferation, leading to the thinning of the ventricular compact myocardial layer. Reduction in compact myocardium thickness associates to the presence of multiple ventricular myocardial discontinuities and focal endocardial extrusion. This same phenotype can be experimentally reproduced in chick embryos using a cryocauterization method (Palmquist-Gomes et al., 2016). Our results suggest that the partial absence of epicardium in α4integrin;G2-Gata4Cre mouse embryos and the cryoinjury in avian embryos generate myocardial discontinuities in the embryonic ventricular wall, which promote endocardial extrusion towards the pericardial cavity and the early contact of the endocardium with coronary progenitors at the epicardial surface of the heart. In the case of avian embryos, this phenomenon leads to precocious smooth muscle differentiation from epicardial mesenchymal cells, and the formation of pouch-like structures that closely resemble CAF. We conclude that anomalous compact myocardial embryonic growth can originate CAF.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Terapias celulares experimentales para el tratamiento del infarto de miocardio: lecciones de la regeneración y reparación cardíaca en vertebrados no humanos

Cardiovascular diseases are the mainpal cause of death in the western world (http://www.who.int/classifications/icd). the heart attack of myocardium associated with coronary disease is the most common cardiovascular disease and the one that carries the highest mortality and morbidityLas enfermedades cardiovasculares son la principal causa de muerte en el mundo occidental (http://www.who.int/classifications/icd). El infarto de miocardio asociado a enfermedad coronaria es lamás frecuente de las enfermedades cardiovasculares y la que conlleva una mayor mortalidad y morbilidad

In vivo and In vitro cartilage differentiation from embryonic epicardial progenitor cells

The presence of cartilage tissue in embryonic and adult hearts of various vertebrate species is a well-recorded fact. However, while the embryonic neural crest has been historically considered as the main source of cardiac cartilage, recently reported results on the wide connective potential of epicardial lineage cells suggest they could also differentiate into chondrocytes. During heart embryogenesis, the epicardial epithelium forms over the originally bare myocardial surface from epicardial progenitor (proepicardial) cells to then give rise to a large population of mesenchymal Epicardial-Derived Cells (EPDCs) that will crucially contribute to the building, growth, and maturation of the ventricle and atrioventricular cardiac structures. In this work, we describe the formation of cardiac cartilage clusters from proepicardial cells, both in vivo and in vitro. Our findings report, for the first time, cartilage formation from epicardial progenitor cells in the embryonic heart, and strongly support the concept of proepicardial cells as multipotent connective progenitors. These results are relevant to our understanding of cardiac cell complexity and responses to pathologic stimuli.Universidad de Málaga (UMA18-FEDERJA-146). Campus de Excelencia Internacional Andalucía Tech; Ministerio de Educación (FPU18/05219); Ministerio de Ciencias (RTI2018-095410-B-I00); ISCIII-RETICs (RD16/0011/0030); Consejería de Salud y Familias, Junta de Andalucía (PIER-0084-2019) Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Developmental bases of cardiac vascularization and regeneration

Fecha de lectura de Tesis Doctoral: 15 de noviembre 2019En esta tesis doctoral se estudian los fenómenos de vascularización y regeneración del corazón en un contexto embrionario usando embriones de ave (codorniz, pollo y pato) y ratón (usando varias líneas transgénicas) como modelos de experimentación

Shaping the mouse heart tube from the second heart field epithelium

International audienceAs other tubular organs, the embryonic heart develops from an epithelial sheet of cells, referred to as the heart field. The second heart field, which lies in the dorsal pericardial wall, constitutes a transient cell reservoir, integrating patterning and polarity cues. Conditional mutants have shown that impairment of the epithelial architecture of the second heart field is associated with congenital heart defects. Here, taking the mouse as a model, we review the epithelial properties of the second heart field and how they are modulated upon cardiomyocyte differentiation. Compared to other cases of tubulogenesis, the cellular dynamics in the second heart field are only beginning to be revealed. A challenge for the future will be to unravel key physical forces driving heart tube morphogenesis

Avian embryonic coronary arterio-venous patterning requires the contribution of different endothelial cell populations

Coronary blood vessels irrigate the heart muscle and are crucial to late embryonic and adult heart function. Despite the developmental significance and clinical relevance of coronary vasculature, the embryonic origin as well as the cellular and molecular regulation of coronary arterio-venous patterning remains obscure. It has been reported that the mammalian coronary vascular network develops from, at least, three different cell sources: the sinus venosus endocardium, the ventricular endocardium and derivatives of the septum transversum. However, it remains unclear how the venous and arterial components of the coronary system integrate into a complex functional coronary tree. In this work, we revisit the avian embryo, a classical animal model in the study of coronary blood vessel development, to dissect the ontogenetic origin and morphohenesis of coronary arteries and veins. Our results, which benefit from the use of experimental techniques (quail-to-chick chimeras, intravascular lectin injections, recombinant fibrin grafting), show that at least three different endothelial populations need to assemble in a coordinated manner for proper coronary vascularization. Our data also confirm that sinus venosus endocardium sprouts and proepicardial angioblasts grow simultaneously into the developing heart, growing towards a VEGF source. Prospective venous and arterial coronary endothelium remain disconnected during the first part of coronary development, so that arterio-venous shunts form just before prospective coronary arterial vessels connect to the aortic root. In summary, our study reveals that the coronary vascular system is a developmental mosaic, formed by the interaction of various vascular populations of different embryological origins.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Avian embryonic coronary arterio-venous patterning involves the contribution of different endothelial and endocardial cell populations.

Coronary vasculature irrigates the myocardium and is crucial to late embryonic and adult heart function. Despite the developmental significance and clinical relevance of these blood vessels, the embryonic origin and the cellular and molecular mechanisms that regulate coronary arterio-venous patterning are not known in detail. In this study, we have used the avian embryo to dissect the ontogenetic origin and morphogenesis of coronary vasculature. We show that sinus venosus endocardial sprouts and proepicardial angioblasts pioneer coronary vascular formation, invading the developing heart simultaneously. We also report that avian ventricular endocardium has the potential to contribute to coronary vessels, and describe the incorporation of cardiac distal outflow tract endothelial cells to the peritruncal endothelial plexus to participate in coronary vascular formation. Finally, our findings indicate that large sinus venosus-independent sections of the forming coronary vasculature develop without connection to the systemic circulation and that coronary arterio-venous shunts form a few hours before peritruncal arterial endothelium connects to the aortic root. Embryonic coronary vasculature is a developmental mosaic, formed by the integration of vascular cells from, at least, four different embryological origins, which assemble in a coordinated manner to complete coronary vascular development. Developmental Dynamics 247:686-698, 2018. © 2017 Wiley Periodicals, Inc