tretinoin and Transposition-of-Great-Vessels

Retinoic acid signaling plays a critical role during embryogenesis and requires tight regulation. Exposure to exogenous retinoic acid during fetal development is known to have teratogenic effects, producing a recognizable embryopathy.. We describe a case of retinoic acid embryopathy secondary to maternal isotretinoin use until the ninth week of gestation and expand the phenotype to include the rare features of parietal bone agenesis and athelia. Histology of the parietal region showed fibrous tissue with no intramembranous ossification. The fetus also had multiple craniofacial dysmorphisms, thymic agenesis, and transposition of the great arteries with double outlet right ventricle and subaortic perimembranous ventricular septal defect. Neuropathology revealed enlarged ventricles with agenesis of the cerebellar vermis, focal duplication of the central canal and scattered parenchymal ependymal rests, and possible cerebral heterotopias with associated abnormal neuronal lamination. A chromosomal microarray was normal.. Parietal bone agenesis and athelia are both rare congenital anomalies not previously reported in retinoic acid embryopathy. However, retinoic acid or its degrading enzyme has been demonstrated to exert effects in both of these developmental pathways, offering biological plausibility. We propose that this case may represent an expansion of the phenotype of retinoic embryopathy.

Topics: Abnormalities, Drug-Induced; Abnormalities, Multiple; Breast Diseases; Congenital Microtia; Female; Fetal Diseases; Humans; Parietal Bone; Phenotype; Tamoxifen; Transposition of Great Vessels; Tretinoin

Transposition of the great arteries is one of the most commonly diagnosed conotruncal heart defects at birth, but its etiology is largely unknown. The anterior heart field (AHF) that resides in the anterior pharyngeal arches contributes to conotruncal development, during which heart progenitors that originated from the left and right AHF migrate to form distinct conotruncal regions. The aim of this study is to identify abnormal AHF development that causes the morphology of transposition of the great arteries.. We placed a retinoic acid-soaked bead on the left or the right or on both sides of the AHF of stage 12 to 14 chick embryos and examined the conotruncal heart defect at stage 34. Transposition of the great arteries was diagnosed at high incidence in embryos for which a retinoic acid-soaked bead had been placed in the left AHF at stage 12. Fluorescent dye tracing showed that AHF exposed to retinoic acid failed to contribute to conotruncus development. FGF8 and Isl1 expression were downregulated in retinoic acid-exposed AHF, and differentiation and expansion of cardiomyocytes were suppressed in cultured AHF in medium supplemented with retinoic acid.. The left AHF at the early looped heart stage, corresponding to Carnegie stages 10 to 11 (28 to 29 days after fertilization) in human embryos, is the region of the impediment that causes the morphology of transposition of the great arteries.

Topics: Animals; Cell Differentiation; Chick Embryo; Female; Fibroblast Growth Factors; Heart; LIM-Homeodomain Proteins; Myocardium; Pregnancy; Transcription Factors; Transposition of Great Vessels; Tretinoin

Congenital heart defect (CHD) account for 25% of all human congenital abnormalities. However, very few CHD-causing genes have been identified so far. A promising approach for the identification of essential cardiac regulators whose mutations may be linked to human CHD, is the molecular and genetic analysis of heart development. With the use of a triple retinoic acid competitive antagonist (BMS189453) we previously developed a mouse model of congenital heart defects (81%), thymic abnormalities (98%) and neural tube defects (20%). D-TGA (D-transposition of great arteries) was the most prevalent cardiac defect observed (61%). Recently we were able to partially rescue this abnormal phenotype (CHD were reduced to 64.8%, p = 0.05), by oral administration of folic acid (FA). Now we have performed a microarray analysis in our mouse models to discover genes/transcripts potentially implicated in the pathogenesis of this CHD.. We analysed mouse embryos (8.5 dpc) treated with BMS189453 alone and with BMS189453 plus folic acid (FA) by microarray and qRT-PCR. By selecting a fold change (FC) ≥ ± 1.5, we detected 447 genes that were differentially expressed in BMS-treated embryos vs. untreated control embryos, while 239 genes were differentially expressed in BMS-treated embryos whose mothers had also received FA supplementation vs. BMS-treated embryos. On the basis of microarray and qRT-PCR results, we further analysed the Hif1α gene. In fact Hif1α is down-regulated in BMS-treated embryos vs. untreated controls (FCmicro = -1.79; FCqRT-PCR = -1.76; p = 0.005) and its expression level is increased in BMS+FA-treated embryos compared to BMS-treated embryos (FCmicro = +1.17; FCqRT-PCR = +1.28: p = 0.005). Immunofluorescence experiments confirmed the under-expression of Hif1α protein in BMS-treated embryos compared to untreated and BMS+FA-treated embryos and, moreover, we demonstrated that at 8.5 dpc, Hif1α is mainly expressed in the embryo heart region.. We propose that Hif1α down-regulation in response to blocking retinoic acid binding may contribute to the development of cardiac defects in mouse newborns. In line with our hypothesis, when Hif1α expression level is restored (by supplementation of folic acid), a decrement of CHD is found. To the best of our knowledge, this is the first report that links retinoic acid metabolism to Hif1α regulation and the development of D-TGA.

Topics: Base Sequence; Dietary Supplements; Down-Regulation; Embryo, Mammalian; Embryonic Development; Fluorescent Antibody Technique; Folic Acid; Gene Expression Profiling; Gene Expression Regulation, Developmental; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Molecular Sequence Data; Repressor Proteins; Response Elements; Retinoids; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sequence Alignment; Trans-Activators; Transposition of Great Vessels; Tretinoin

Although normal coronary artery embryogenesis is well described in the literature, little is known about the development of coronary vessels in abnormal hearts.. We used an animal model of retinoic acid (RA)-evoked outflow tract malformations (e.g., double outlet right ventricle [DORV], transposition of the great arteries [TGA], and common truncus arteriosus [CTA]) to study the embryogenesis of coronary arteries using endothelial cell markers (anti-PECAM-1 antibodies and Griffonia simplicifolia I (GSI) lectin). These markers were applied to serial sections of staged mouse hearts to demonstrate the location of coronary artery primordia.. In malformations with a dextropositioned aorta, the shape of the peritruncal plexus, from which the coronary arteries develop, differed from that of control hearts. This difference in the shape of the early capillary plexus in the control and RA-treated hearts depends on the position of the aorta relative to the pulmonary trunk. In both normal and RA-treated hearts, there are several capillary penetrations to each aortic sinus facing the pulmonary trunk, but eventually only 1 coronary artery establishes patency with 1 aortic sinus.. The abnormal location of the vessel primordia induces defective courses of coronary arteries; creates fistulas, a single coronary artery, and dilated vessel lumens; and leaves certain areas of the heart devoid of coronary artery branches. RA-evoked heart malformations may be a useful model for elucidating abnormal patterns of coronary artery development and may shed some light on the angiogenesis of coronary artery formation.

Topics: Animals; Biomarkers; Coronary Vessel Anomalies; Disease Models, Animal; Endothelial Cells; Female; Heart Ventricles; Mice; Mice, Inbred Strains; Pregnancy; Transposition of Great Vessels; Tretinoin; Truncus Arteriosus, Persistent

We previously reported that retinoic acid shows a dose-dependent differential induction of various cardiac outflow anomalies: transposition of the great arteries is induced mainly by a high dose (70 mg/kg) and dextroposition of the aorta by a low dose (40-60 mg/kg; Yasui et al., 1995). We subsequently delineated the aberrant outflow tract septation process leading to the transposition (Yasui et al., 1997). The aim of the present study was to illustrate a spectrum of developmental abnormalities by examining mouse embryos treated with a low dose of retinoic acid and comparing them with embryos administered a high dose. We employed in situ observation on live embryos to discern the blood flow streams and scanning electron microscopy to clarify the internal structure. The embryos treated with a low dose of retinoic acid showed several basic phenotypes common to the high dose retinoic acid group, although variable and relatively mild, such as hypoplasia and dysplasia in the proximal outflow cushions, decreased counter-clockwise rotation in the distal outflow tract, and deviation of the edges of the developing outflow septum. In typical cases, the right-sided edge of the developing outflow septum shifted ventrally by various degrees, allowing for the right ventricle-to-aorta pathway, whereas the left-sided edge preserved the continuity with the interventricular septum, as in the normal embryo. These findings indicate that morphogenesis of dextroposition of the aorta and transposition of the great arteries are not only distinct but also show some basic pathways in common.

Topics: Animals; Dose-Response Relationship, Drug; Female; Male; Mice; Mice, Inbred ICR; Microscopy, Electron, Scanning; Microscopy, Video; Phenotype; Pregnancy; Transposition of Great Vessels; Tretinoin

It has been reported that all-trans retinoic acid induces transposition of the great arteries (TGA) at 80-90% in ICR mice. The authors revealed that retinoic acid affects the initial formation of the conus cushions leading to a loss of spirality in the cardiac outflow tract. However, the aberrant process of septation has not been precisely defined. In this study, we observed the hearts of live embryos using a video system followed by scanning electron microscopic examination. First, we found that, in the retinoic acid-treated embryos, the proximal outflow tract cushions, in addition to hypoplasia and dysplasia, did not establish the continuity with the distal outflow tract cushions and could not contribute to the outflow septation. Second, the distal outflow tract did not rotate counter-clockwise, retaining the outflow septum anlage in the superoinferior position. Third, a tongue-like mesenchymal tissue had developed on the right anterior rim of the muscular interventricular septum and was incorporated into the interventricular septum. Altogether, these processes contributed to establishing a reversed relationship between the outflow septum anlage and the ventricular septum anlage. On the other hand, right-ward deviation of one or both of the distal outflow tract cushions, relative to the mesenchymal tissue, gave rise to variable degrees of overriding of the pulmonary artery orifice. We conclude that, due to hypoplasia and dysplasia of the proximal outflow tract cushions and lack of distal outflow tract rotation, the outflow septum anlage took an inverted relationship with the ventricular septum anlage. Various types of rightward shift of the outflow tract cushions produced a morphological spectrum of TGA-type cono-truncal anomalies.

Topics: Animals; Cardiac Output; Coronary Circulation; Embryonic and Fetal Development; Endocardial Cushion Defects; Female; Heart; Heart Septum; Male; Mice; Mice, Inbred ICR; Microscopy, Electron, Scanning; Morphogenesis; Myocardium; Pregnancy; Transposition of Great Vessels; Tretinoin; Ventricular Function, Left; Videotape Recording

In the mouse model of complete transposition of the great arteries (TGA) produced by all-trans retinoic acid (RA), parietal and septal ridges in the outflow tract (OT) are hypoplastic. At first, these ridges are generated by an expanded cardiac jelly (mainly myocardial basement membrane). Thereafter, endothelial cells delaminate and invade into the adjacent cardiac jelly to form endocardial cushion tissue (formation of cushion ridge). During cushion tissue formation, basement membrane antigens play an important role in the regulation of this endothelial-mesenchymal transformation.. To examine whether the myocardial basement membrane components are altered in the RA-treated heart OT, immunohistochemistry for fibronectin, type I collagen, type IV collagen, and laminin was carried out in mouse embryonic hearts at 9.5 and 10.5 ED (embryonic day; vaginal plug = day 0) with or without prior exposure to RA.. Particulate/fibrillar fibronectin and fibrillar type I collagen were observed in the thick cardiac jelly of the control heart at the onset of mesenchymal formation. In the RA-treated heart, an intermittent patchy staining for fibronectin and a sparse distribution of type I collagen were observed in the thin cardiac jelly. Laminin and type IV collagen were distributed continuously on the basal surface (layer adjacent to the basal plasma membrane) of endocardium and myocardium in both control and RA-treated hearts.. The alterations in the antigens of the myocardial basement membrane (cardiac jelly) may be responsible for the hypoplasticity of parietal and septal ridges that characterizes RA-induced TGA morphology. This may be one of the reasons why mesenchymal cell formation is inhibited in the RA-induced TGA.

Topics: Animals; Basement Membrane; Collagen; Extracellular Matrix; Female; Fetal Heart; Fibronectins; Heart Defects, Congenital; Immunohistochemistry; Laminin; Male; Mice; Mice, Inbred ICR; Pregnancy; Transposition of Great Vessels; Tretinoin

Complete transposition of the great arteries (TGA) is inducible by treatment with all-trans retinoic acid in the ICR mouse. In this model, hypoplasia and dysplasia of the proximal outflow tract cushion tissue lead to non-spiral septation. In order to evaluate the effect of retinoic acid on the extracellular matrix of the cardiac outflow tract, we examined the distribution of collagen type I and hyaluronic acid, immunohistochemically, on days 8-9 of gestation. In controls, collagen type I fibrils ran mainly in a radial direction, extending towards the endocardium in the cardiac jelly of the proximal outflow tract. Also, a pair of longitudinal fiber bundles were formed stretching to the distal outflow tract. As for hyaluronic acid, intense staining was observed in the submyocardial and intermyocardial space of the outer curvature of the heart. On the other hand, in retinoic acid-treated embryos, the submyocardial radial fibrils or longitudinal fiber bundles of collagen type I were diminished, and irregular and dense deposits of collagen type I were observed along the endocardium. Furthermore, hyaluronic acid showed a loss of differential localization between the outer and inner curvature. Instead, irregular and intense staining was observed uniformly along the outflow myocardium. Thus, retinoic acid appeared to have perturbed the differentiation in the proximal outflow tract causing an altered organization of multiple extracellular matrix molecules, including collagen type I and hyaluronic acid, which led to an abnormal molecular network of the cardiac jelly in the cardiac outflow tract, abnormal septation and, further, to TGA or TGA-type anomalies.

Topics: Animals; Collagen; Disease Models, Animal; Female; Heart; Hyaluronic Acid; Immunohistochemistry; Mice; Mice, Inbred ICR; Morphogenesis; Myocardium; Pregnancy; Transposition of Great Vessels; Tretinoin

Endocardial cushion tissue formation, the primordia of valves and septa, is a critical event in cardiac morphogenesis. Maternally administrated all-trans retinoic acid is known to induce complete transposition of the great arteries (TGA) in the mouse embryo. To address the mechanisms of TGA, the effect of retinoic acid on cushion tissue formation was examined.. Using a three-dimensional collagen gel culture model, we performed various types of endothelial-mesenchymal transformation assays of co-cultured endocardium with myocardium obtained from 9.5-day mouse embryonic hearts. In vivo immunohistochemical detections of extracellular matrices, fibronectin and type I collagen, were also performed.. Endothelial-to-mesenchymal transformation at the onset of cushion tissue formation was suppressed in the outflow tract of embryos exposed to retinoic acid in culture. This inhibitory effect of retinoic acid was spatially restricted to the outflow tract and reversed by treatment with embryonic myocardial conditioned medium enriched in extracellular inductive molecules. Mesenchyme formation in the outflow tract was inhibited at a lower concentration of retinoic acid (10(-10) mol/l) than that which inhibited the atrio-ventricular canal (10(-7) mol/l) in culture. The fibronectin and type I collagen depositions in pre-migratory outflow tract cardiac jelly in retinoic acid-treated embryonic heart were reduced compared to those in the control.. Exogenously applied retinoic acid inhibits outflow tract cushion mesenchyme formation in the embryonic heart with TGA. It is suggested that retinoic acid inhibits the expression of extracellular matrices and inductive molecules synthesized by myocardium in the outflow tract.

Topics: Animals; Collagen; Endocardium; Extracellular Matrix; Fibronectins; Immunohistochemistry; Mesoderm; Mice; Mice, Inbred ICR; Morphogenesis; Myocardium; Organ Culture Techniques; Transposition of Great Vessels; Tretinoin

The major morphologic change associated with retinoic acid (RA)-induced complete transposition of the great arteries (TGA), a congenital malformation of the heart, was investigated in a mouse model in which TGA was found in 80% of surviving fetuses.. Corrosion casts of embryonic hearts with or without prior exposure to retinoic acid were observed under a scanning electron microscope.. In control hearts, indentations caused by expanded parietal and septal ridges in the outflow tract established right ventricle-to-left ventral pulmonic and left ventricle-to-right dorsal aortic routes before the aorticopulmonary septum completion. In RA-treated hearts, indentations of proximal regions of the parietal and septal ridges were small in the proximal outflow tract, whereas those in the distal regions developed well. These morphological features in the RA-treated hearts elicited right ventricle-to-right ventral aortic and left ventricle-to-left dorsal pulmonic routes in the TGA morphology.. Hypoplasticity of the proximal regions of parietal and septal ridges in the outflow tract is one of the primary morphological abnormalities of the RA-induced TGA.

Topics: Animals; Aorta; Corrosion Casting; Endocardial Cushion Defects; Endocardium; Female; Heart; Mice; Mice, Inbred ICR; Microscopy, Electron, Scanning; Pregnancy; Transposition of Great Vessels; Tretinoin

The pathogenesis of complete transposition of the great arteries (TGA) is still controversial because useful animal models have not been established. We previously reported that all-trans retinoic acid induced complete TGA at a high proportion in mice. The aim of the present study was to clarify the morphogenesis of the cardiac outflow tract in the retinoic acid-treated embryos destined to develop TGA.. We first examined the morphology of TGA in mouse fetuses treated with retinoic acid to establish an animal model of TGA (experiment 1) and then examined the retinoic acid-treated embryonic hearts by means of ink injection and histology (experiment 2). All mouse fetuses and embryos showed visceroatrial situs solitus and d-ventricular loop. In experiment 1, among 45 embryos treated with retinoic acid 70 mg/kg at day 8.5 of gestation, 35 (78%) had TGA and 3 (6.7%) had a double-outlet right ventricle with a subpulmonary ventricular septal defect. In experiment 2, all hearts already exhibited d-loop at gestation day 8.5. At gestation day 9.5, conus swellings, composed of acellular cardiac jelly, where hypoplastic, and the conotruncal cavity was nonspiral or tubular. At gestation day 11.0, aberrant conus swellings located anteroposteriorly to give a straight orientation to the conotruncal cavity. At gestation day 12.0, side-by-side great arteries were transposed in that the aorta arose from the right ventricle and the pulmonary artery arose above the interventricular foramen.. These results suggest that a reproducible animal model of TGA can be produced in mice by treatment with retinoic acid; that there was no loop anomaly, such as an A-loop or L-loop, in our model; and that hypoplasia of the conus swellings appears to be the primary event leading to TGA.

Topics: Animals; Embryonic and Fetal Development; Female; Heart; Mice; Mice, Inbred ICR; Myocardium; Pregnancy; Transposition of Great Vessels; Tretinoin