tretinoin and Heart-Defects--Congenital

Congenital heart disease (CHD) has many forms and a wide range of causes. Clinically, it is important to understand the causes. This allows estimation of recurrence rate, guides treatment options, and may also be used to formulate public health advice to reduce the population prevalence of CHD. The recent advent of sophisticated genetic and genomic methods has led to the identification of more than 100 genes associated with CHD. However, despite these great strides, to date only one-third of CHD cases have been shown to have a simple genetic cause. This is because CHD can also be caused by oligogenic factors, environmental factors, and/or gene-environment interaction. Although solid evidence for environmental causes of CHD have been available for almost 80 years, it is only very recently that the molecular mechanisms for these risk factors have begun to be investigated. In this review, we describe the most important environmental CHD risk factors, and what is known about how they cause CHD.

Topics: Alcohol Drinking; Animals; Diabetes Mellitus; Environmental Exposure; Gene-Environment Interaction; Genomics; Heart; Heart Defects, Congenital; Humans; Hyperthermia; Hypoxia; Obesity; Phenylketonurias; Prevalence; Risk Factors; Thalidomide; Tretinoin; Vitamin A

Appropriate levels of retinoic acid (RA) signaling are critical for normal heart development in vertebrates. A fascinating property of RA signaling is the thoroughness by which positive and negative feedback are employed to promote proper embryonic RA levels. In the present short review, we first cover the advancement of hypotheses regarding the impact of RA signaling on cardiac specification. We then discuss our current understanding of RA signaling feedback mechanisms and the implications of recent studies, which have indicated improperly maintained RA signaling feedback can be a contributing factor to developmental malformations.

Topics: Animals; Heart; Heart Defects, Congenital; Humans; Teratogenesis; Tretinoin

During cardiac looping the heart tube elongates by addition of progenitor cells from adjacent pharyngeal mesoderm to the arterial and venous poles. This cell population, termed the second heart field, was first identified ten years ago and many studies in the intervening decade have refined our understanding of how heart tube elongation takes place and identified signaling pathways that regulate proliferation and differentiation during progressive contribution of second heart field cells to the embryonic heart. It has also become apparent that defective second heart field development results in common congenital heart anomalies affecting both the conotruncal region and venous pole of the heart, including atrial and atrioventricular septal defects. In this review we focus on a series of recent papers that have identified new regulators of second heart field development, in particular the retinoic acid signaling pathway and HOX, SIX and EYA transcription factors. We also discuss new findings concerning the regulation of fibroblast growth factor signaling during second heart field deployment and studies that have implicated FGF10 and FGF3 in outflow tract development in addition to FGF8. Second heart field derived parts of the heart share common progenitor cells in pharyngeal mesoderm with craniofacial skeletal muscles and recent findings from xenopus, zebrafish and the protochordate Ciona intestinalis provide insights into the evolution of the second heart field during vertebrate radiation.

Topics: Animals; Cell Differentiation; Cell Proliferation; Disease Models, Animal; Fibroblast Growth Factors; Fibroblasts; Heart; Heart Defects, Congenital; Mesoderm; Mice; Myocytes, Cardiac; Organogenesis; Signal Transduction; Transcription Factors; Tretinoin

Tbx1 is a member of the Tbox family of binding domain transcription factors. TBX1 maps within the region of 22q11 deleted in humans with DiGeorge or velocardiofacial syndrome. Mice haploinsufficient for Tbx1 have phenotypes that recapitulate major features of the syndrome, notably abnormal growth and remodelling of the pharyngeal arch arteries. The Tbx1 haploinsufficiency phenotype is modified by genetic background and by mutations in putative downstream targets. Homozygous null mutations of Tbx1 have more severe defects including failure of outflow tract septation, and absence of the caudal pharyngeal arches. Tbx1 is a transcriptional activator, and loss of this activity has been linked to alterations in the expression of various genes involved in cardiovascular morphogenesis. In particular, Fgf and retinoic acid signalling are dysregulated in Tbx1 mutants. This article summarises the tissue specific and temporal requirements for Tbx1, and attempts to synthesis what is know about the developmental pathways under its control.

Topics: Animals; Branchial Region; DiGeorge Syndrome; Disease Models, Animal; Gene Deletion; Heart; Heart Defects, Congenital; Mice; Mutation; Phenotype; Signal Transduction; Syndrome; T-Box Domain Proteins; Tretinoin

Insight into the mechanisms underlying congenital heart defects and the use of stem cells for cardiac repair are major research goals in cardiovascular biology. In the early embryo, progenitor cells in pharyngeal mesoderm contribute to the rapid growth of the heart tube during looping morphogenesis. These progenitor cells constitute the second heart field (SHF) and were first identified in 2001. Direct or indirect perturbation of SHF addition to the heart results in congenital heart defects, including arterial pole alignment defects. Over the last 3 years, a number of studies have identified key intercellular signaling pathways that control the proliferation and deployment of SHF progenitor cells. Here, we review data concerning Wnt, fibroblast growth factor, bone morphogenetic protein, Hedgehog, and retinoic acid signaling that have begun to identify the ligand sources and responding cell types controlling SHF development. These studies have revealed the importance of signals from pharyngeal mesoderm itself, as well as critical inputs from adjacent pharyngeal epithelia and neural crest cells. Proliferation is emerging as a central checkpoint in the regulation of SHF development. Together, these studies contribute to defining the niche of cardiac progenitor cells in the early embryo, and we discuss the implications of these findings for the regulation of resident stem cell populations in the fetal and postnatal heart. Characterization of signals that maintain, expand, and regulate the differentiation of cardiac progenitor cells is essential for understanding both the etiology of congenital heart defects and the biomedical application of stem cell populations for cardiac repair.

Topics: Animals; Autocrine Communication; beta Catenin; Bone Morphogenetic Proteins; Branchial Region; Cell Differentiation; Cell Movement; Cell Proliferation; Embryonic Stem Cells; Endoderm; Fibroblast Growth Factors; Heart; Heart Defects, Congenital; Hedgehog Proteins; Homeodomain Proteins; Humans; LIM-Homeodomain Proteins; Mesoderm; Myocardium; Neural Crest; Pluripotent Stem Cells; Signal Transduction; Stem Cell Transplantation; Transcription Factors; Tretinoin; Wnt Proteins

Retinoic acid (RA), the active derivative of vitamin A, by acting through retinoid receptors, is involved in signal transduction pathways regulating embryonic development, tissue homeostasis, and cellular differentiation and proliferation. RA is important for the development of the heart. The requirement of RA during early cardiovascular morphogenesis has been studied in targeted gene deletion of retinoic acid receptors and in the vitamin A-deficient avian embryo. The teratogenic effects of high doses of RA on cardiovascular morphogenesis have also been demonstrated in different animal models. Specific cardiovascular targets of retinoid action include effects on the specification of cardiovascular tissues during early development, anteroposterior patterning of the early heart, left/right decisions and cardiac situs, endocardial cushion formation, and in particular, the neural crest. In the postdevelopment period, RA has antigrowth activity in fully differentiated neonatal cardiomyocytes and cardiac fibroblasts. Recent studies have shown that RA has an important role in the cardiac remodeling process in rats with hypertension and following myocardial infarction. This chapter will focus on the role of RA in regulating cardiomyocyte growth and differentiation during embryonic and the postdevelopment period.

Topics: Animals; Antioxidants; Cell Differentiation; Heart; Heart Defects, Congenital; Humans; Morphogenesis; Myocytes, Cardiac; Tretinoin

Retinoic acid, the biologically active form of vitamin A, is a critical player in normal development. The concentration of retinoic acid is highly regulated by the embryo to prevent either a deficit or an excess of this molecule, conditions that have been shown to produce cardiac defects that vary depending on the severity and the timing of the insult. The vast majority of these defects are associated with the valves or the membranous septa of the heart, suggesting a problem with the formation of the cardiac mesenchyme from both within and outside the heart. While the exact role of retinoic acid in cardiac development is not known, it is believed that retinoic acid influences development by up- or down-regulating cardiac specific genes. This review briefly discusses the role of cardiac mesenchyme and cardiac neural crest in septation of the heart. This is followed by a discussion of vitamin A metabolism and the cardiac defects associated with abnormal levels of retinoic acid. Finally, a mechanism is proposed concerning the ways abnormal levels of retinoic acid lead to similar cardiac defects by disrupting the production of the extracellular matrix.

Topics: Animals; Extracellular Matrix; Heart; Heart Defects, Congenital; Humans; Mesoderm; Neural Crest; Situs Inversus; Tretinoin; Vitamin A

Topics: Abnormalities, Drug-Induced; Animals; Ethanol; Heart Defects, Congenital; Humans; Teratogens; Tretinoin; Vitamin A

Approximately 120,000 women of childbearing age used isotretinoin in the first 16 months after its release for the treatment of cystic acne. In September, 1983, the American Academy of Dermatology requested its members to relate the outcome of pregnancies of women inadvertently exposed to isotretinoin ( Accutane ) during pregnancy to its Adverse Drug Reaction Reporting System ( ADRRS ). Of nine pregnancies reported, seven ended in spontaneous abortion or the birth of an infant with birth defects. Of thirty-five pregnancies with isotretinoin exposure reported to the ADRRS or the U.S. Food and Drug Administration, twenty-nine (83%) resulted in spontaneous abortion or infants with birth defects. The most frequently reported severe birth defects involved the central nervous system (microcephaly or hydrocephalus) and the cardiovascular system (anomalies of the great vessels). Microtia or absence of external ears were also noted in a majority of cases. These findings illustrate the usefulness of specialty-based reporting of adverse drug effects and emphasize the teratogenic risk of isotretinoin in humans. Physicians need to fully and carefully inform women of childbearing age of these risks.

Topics: Abnormalities, Drug-Induced; Abortion, Spontaneous; Acne Vulgaris; Female; Heart Defects, Congenital; Humans; Hydrocephalus; Infant, Newborn; Isotretinoin; Microcephaly; Pregnancy; Pregnancy Complications; Pregnancy Trimester, First; Tretinoin

Retinoic acid (RA) signalling is essential for heart development, and dysregulation of the RA signalling can cause several types of cardiac outflow tract (OFT) defects, the most frequent congenital heart disease (CHD) in humans. Matthew-Wood syndrome is caused by inactivating mutations of a transmembrane protein gene STRA6 that transports vitamin A (retinol) from extracellular into intracellular spaces. This syndrome shows a broad spectrum of malformations including CHD, although murine Stra6-null neonates did not exhibit overt heart defects. Thus, the detailed mechanisms by which STRA6 mutations could lead to cardiac malformations in humans remain unclear. Here, we investigated the role of STRA6 in the context of human cardiogenesis and CHD.. To gain molecular signatures in species-specific cardiac development, we first compared single-cell RNA sequencing (RNA-seq) datasets, uniquely obtained from human and murine embryonic hearts. We found that while STRA6 mRNA was much less frequently expressed in murine embryonic heart cells derived from the Mesp1+ lineage tracing mice (Mesp1Cre/+; Rosa26tdTomato), it was expressed predominantly in the OFT region-specific heart progenitors in human developing hearts. Next, we revealed that STRA6-knockout human embryonic stem cells (hESCs) could differentiate into cardiomyocytes similarly to wild-type hESCs, but could not differentiate properly into mesodermal nor neural crest cell-derived smooth muscle cells (SMCs) in vitro. This is supported by the population RNA-seq data showing down-regulation of the SMC-related genes in the STRA6-knockout hESC-derived cells. Further, through machinery assays, we identified the previously unrecognized interaction between RA nuclear receptors RARα/RXRα and TBX1, an OFT-specific cardiogenic transcription factor, which would likely act downstream to STRA6-mediated RA signalling in human cardiogenesis.. Our study highlights the critical role of human-specific STRA6 progenitors for proper induction of vascular SMCs that is essential for normal OFT formation. Thus, these results shed light on novel and human-specific CHD mechanisms, driven by STRA6 mutations.

Topics: Animals; Gene Expression Regulation; Heart; Heart Defects, Congenital; Humans; Membrane Proteins; Mice; Muscle, Smooth, Vascular; Tretinoin; Vitamin A

Cardiac malformations (CVMs) are a leading cause of infant morbidity and mortality. CVMs are particularly prevalent when the developing fetus is exposed to high levels of phenylalanine in-utero in mothers with Phenylketonuria. Yet, elucidating the underlying molecular mechanism leading to CVMs has proven difficult. In this study we used RNA-Seq to investigate an avian model of MPKU and establish differential gene expression (DEG) characteristics of the early developmental stages HH10, 12, and 14. In total, we identified 633 significantly differentially expressed genes across stages HH10, 12, and 14. As expected, functional annotation of significant DEGs identified associations seen in clinical phenotypes of MPKU including CVMs, congenital heart defects, craniofacial anomalies, central nervous system defects, and growth anomalies. Additionally, there was an overrepresentation of genes involved in cardiac muscle contraction, adrenergic signaling in cardiomyocytes, migration, proliferation, metabolism, and cell survival. Strikingly, we identified significant changes in expression with multiple genes involved in Retinoic Acid (RA) metabolism and downstream targets. Using qRTPCR, we validated these findings and identified a total of 42 genes within the RA pathway that are differentially expressed. Here, we report the first elucidation of the molecular mechanisms of cardiovascular malformations in MPKU conducted at early developmental timepoints. We provide evidence suggesting a link between PHE exposure and the alteration of RA pathway. These results are promising and offer novel findings associated with congenital heart defects in MPKU.

Topics: Animals; Chickens; Disease Models, Animal; Female; Heart Defects, Congenital; Metabolic Networks and Pathways; Phenotype; Phenylalanine; Phenylketonuria, Maternal; Pregnancy; Sequence Analysis, RNA; Transcriptome; Tretinoin; Zygote

Multiple syndromes share congenital heart and craniofacial muscle defects, indicating there is an intimate relationship between the adjacent cardiac and pharyngeal muscle (PM) progenitor fields. However, mechanisms that direct antagonistic lineage decisions of the cardiac and PM progenitors within the anterior mesoderm of vertebrates are not understood. Here, we identify that retinoic acid (RA) signaling directly promotes the expression of the transcription factor Nr2f1a within the anterior lateral plate mesoderm. Using zebrafish nr2f1a and nr2f2 mutants, we find that Nr2f1a and Nr2f2 have redundant requirements restricting ventricular cardiomyocyte (CM) number and promoting development of the posterior PMs. Cre-mediated genetic lineage tracing in nr2f1a; nr2f2 double mutants reveals that tcf21+ progenitor cells, which can give rise to ventricular CMs and PM, more frequently become ventricular CMs potentially at the expense of posterior PMs in nr2f1a; nr2f2 mutants. Our studies reveal insights into the molecular etiology that may underlie developmental syndromes that share heart, neck and facial defects as well as the phenotypic variability of congenital heart defects associated with NR2F mutations in humans.

Topics: Animals; Animals, Genetically Modified; Body Patterning; Cell Lineage; COUP Transcription Factor II; Craniofacial Abnormalities; DNA-Binding Proteins; Embryonic Stem Cells; Heart Defects, Congenital; Heart Ventricles; Humans; Mesoderm; Models, Animal; Mutation; Myocytes, Cardiac; Pharyngeal Muscles; Promoter Regions, Genetic; Signal Transduction; Transcription Factors; Tretinoin; Zebrafish; Zebrafish Proteins

Organogenesis involves integration of diverse cell types; dysregulation of cell-type-specific gene networks results in birth defects, which affect 5% of live births. Congenital heart defects are the most common malformations, and result from disruption of discrete subsets of cardiac progenitor cells

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Cell Differentiation; Cell Movement; Cluster Analysis; Female; Heart; Heart Defects, Congenital; Male; Mice; Sequence Analysis, RNA; Single-Cell Analysis; Tretinoin

The arterial and venous poles of the mammalian heart are hotspots of congenital heart defects (CHD) such as those observed in 22q11.2 deletion (or DiGeorge) and Holt-Oram syndromes. These regions of the heart are derived from late differentiating cardiac progenitor cells of the Second Heart Field (SHF) located in pharyngeal mesoderm contiguous with the elongating heart tube. The T-box transcription factor Tbx1, encoded by the major 22q11.2 deletion syndrome gene, regulates SHF addition to both cardiac poles from a common progenitor population. Despite the significance of this cellular addition the mechanisms regulating the deployment of common progenitor cells to alternate cardiac poles remain poorly understood. Here we demonstrate that Tbx5, mutated in Holt-Oram syndrome and essential for venous pole development, is activated in Tbx1 expressing cells in the posterior region of the SHF at early stages of heart tube elongation. A subset of the SHF transcriptional program, including Tbx1 expression, is subsequently downregulated in Tbx5 expressing cells, generating a transcriptional boundary between Tbx1-positive arterial pole and Tbx5-positive venous pole progenitor cell populations. We show that normal downregulation of the definitive arterial pole progenitor cell program in the posterior SHF is dependent on both Tbx1 and Tbx5. Furthermore, retinoic acid (RA) signaling is required for Tbx5 activation in Tbx1-positive cells and blocking RA signaling at the time of Tbx5 activation results in atrioventricular septal defects at fetal stages. Our results reveal sequential steps of cardiac progenitor cell patterning and provide mechanistic insights into the origin of common forms of CHD.

Topics: Abnormalities, Multiple; Animals; Coronary Vessels; DiGeorge Syndrome; Gene Expression Regulation, Developmental; Heart Defects, Congenital; Heart Septal Defects; Heart Septal Defects, Atrial; Lower Extremity Deformities, Congenital; Mice; Mice, Transgenic; Signal Transduction; Stem Cells; T-Box Domain Proteins; Tretinoin; Upper Extremity Deformities, Congenital

Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants that may pose significant health-risks to various organisms including humans. Although the mixed PCB Aroclor 1254 is widespread in the environment, its potential toxic effect on heart development and the mechanism underlying its developmental toxicity have not been previously studied. Here, we used the zebrafish as a toxicogenomic model to examine the effects of Aroclor 1254 on heart development. We found that PCB exposure during zebrafish development induced heart abnormalities including pericardial edema and cardiac looping defects. Further malformations of the zebrafish embryo were observed and death of the larvae occurred in a time- and dose-dependent manner. Our mechanistic studies revealed that abnormalities in the arylhydrocarbon receptor, Wnt and retinoic acid signaling pathways may underlie the effects of PCBs on zebrafish heart development. Interestingly, co-administration of Aroclor 1254 and diethylaminobenzaldehyde, an inhibitor of retinaldehyde dehydrogenase, partially rescued the toxic effects of PCBs on zebrafish heart development. In conclusion, PCBs can induce developmental defects in the zebrafish heart, which may be mediated by abnormal RA signaling.

Topics: Animals; Chlorodiphenyl (54% Chlorine); Environmental Pollutants; Heart; Heart Defects, Congenital; Receptors, Aryl Hydrocarbon; Signal Transduction; Tretinoin; Wnt Proteins; Zebrafish; Zebrafish Proteins

Precise tissue concentration of retinoic acid (RA) is indispensable for proper interaction of second heart field cells with cardiac neural crest cells and induction of signalling pathways important for normal myocardial growth.. Since RA deficiency during embryogenesis induces noncompaction, we hypothesised that excess RA at the stage of heart tube elongation may cause thinning of the myocardial wall which leads to noncompaction.. RA was administered at 70 mg/kg b.w. on 8.5 days post coitus (dpc) to pregnant mice to elicit cardiac malformations in foetuses. We studied noncompaction development in RA-treated mouse offspring. The cardiac noncompaction was evaluated in different stages of heart development as the quotient of the distance between the epicardial surface and trabecular tips(represented by a) and the distance between the epicardial surface and trabecular recesses (represented by b) in RA-treated hearts compared to control non-treated.. We demonstrated that apart from outflow tract defects such as double outlet right ventricle, transposition of the great arteries and tetralogy of Fallot in foetuses in mouse offspring, noncompaction occurs in about 42% of cases. At the stage of 13 dpc and later in development the ratio a/b was higher in RA-treated hearts exhibiting noncompaction compared to the control hearts. This cardiomyopathy was more evident in the right ventricle than in the left ventricle.. Noncompaction caused by RA overdose can be elicited in part of the mouse offspring by administering RA at the stage of cardiac tube elongation.

Topics: Animals; Disease Models, Animal; Drug Overdose; Female; Heart; Heart Defects, Congenital; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Myocardium; Pregnancy; Prenatal Exposure Delayed Effects; Tomography, X-Ray Computed; Tretinoin

Fatty acid-binding protein 3 (FABP3) is a member of the intracellular lipid-binding protein family, and is primarily expressed in cardiac muscle tissue. Previously, we found that FABP3 is highly expressed in patients with ventricular-septal defects and is often used as a plasma biomarker in idiopathic dilated cardiomyopathy, and may play a significant role in the development of these defects in humans. In the present study, we aimed to investigate the role of FABP3 in the embryonic development of the zebrafish heart, and specifically how morpholino (MO) mediated knockdown of FABP3 would affect heart development in this species. Our results revealed that knockdown of FABP3 caused significant impairment of cardiac development observed, including developmental delay, pericardial edema, a linear heart tube phenotype, incomplete cardiac loop formation, abnormal positioning of the ventricles and atria, downregulated expression of cardiac-specific markers and decreased heart rate. Mechanistically, our data showed that the retinoic acid (RA) catabolizing enzyme Cyp26a1 was upregulated in FABP3-MO zebrafish, as indicated by in situ hybridization and real-time PCR. On the other hand, the expression level of the RA synthesizing enzyme Raldh2 did not significantly change in FABP3-MO injected zebrafish. Collectively, our results indicated that FABP3 knockdown had significant effects on cardiac development, and that dysregulated RA signaling was one of the mechanisms underlying this effect. As a result, these studies identify FABP3 as a candidate gene underlying the etiology of congenital heart defects.

Topics: Animals; Cytochrome P-450 Enzyme System; Fatty Acid Binding Protein 3; Fatty Acid-Binding Proteins; Gene Deletion; Heart; Heart Defects, Congenital; Humans; Retinal Dehydrogenase; Retinoic Acid 4-Hydroxylase; Signal Transduction; Tretinoin; Zebrafish; Zebrafish Proteins

The cardiac venous pole is a common focus of congenital malformations and atrial arrhythmias, yet little is known about the cellular and molecular mechanisms that regulate its development. The systemic venous return myocardium (sinus node and sinus horns) forms only late in cardiogenesis from a pool of pericardial mesenchymal precursor cells.. To analyze the cellular and molecular mechanisms directing the formation of the fetal sinus horns.. We analyzed embryos deficient for the Wt1 (Wilms tumor 1) gene and observed a failure to form myocardialized sinus horns. Instead, the cardinal veins become embedded laterally in the pleuropericardial membranes that remain tethered to the lateral body wall by the persisting subcoelomic mesenchyme, a finding that correlates with decreased apoptosis in this region. We show by expression analysis and lineage tracing studies that Wt1 is expressed in the subcoelomic mesenchyme surrounding the cardinal veins, but that this Wt1-positive mesenchyme does not contribute cells to the sinus horn myocardium. Expression of the Raldh2 (aldehyde dehydrogenase family 1, subfamily A2) gene was lost from this mesenchyme in Wt1(-/-) embryos. Phenotypic analysis of Raldh2 mutant mice rescued from early cardiac defects by retinoic acid food supply revealed defects of the venous pole and pericardium highly similar to those of Wt1(-/-) mice.. Pericardium and sinus horn formation are coupled and depend on the expansion and correct temporal release of pleuropericardial membranes from the underlying subcoelomic mesenchyme. Wt1 and downstream Raldh2/retinoic acid signaling are crucial regulators of this process. Thus, our results provide novel insight into the genetic and cellular pathways regulating the posterior extension of the mammalian heart and the formation of its coelomic lining.

Topics: Aldehyde Oxidoreductases; Animals; Apoptosis; Cell Lineage; Coronary Sinus; Fetal Death; Gene Expression Regulation, Developmental; Genotype; Gestational Age; Heart Defects, Congenital; Mesoderm; Mice; Mice, Knockout; Mice, Transgenic; Mutation; Pericardium; Phenotype; Pleura; Signal Transduction; Sinoatrial Node; T-Box Domain Proteins; Tretinoin; WT1 Proteins

Corrosion casting and immunohistochemical staining with anti-alpha smooth muscle actin and anti-CD34 was utilized to demonstrate the capillary plexus and venous system in control and malformed mouse hearts.. Outflow tract malformations (e.g., double outlet right ventricle, transposition of the great arteries, and common truncus arteriosus) were induced in progeny of pregnant mice by retinoic acid administration at day 8.5 of pregnancy.. Although control hearts exhibited areas in which capillaries tended to be oriented in parallel arrays, the orientation of capillaries in the respective areas of malformed hearts was chaotic and disorganized. The major branch of a conal vein in control hearts runs usually from the left side of the conus to its right side at the root of the pulmonary trunk and opens to the right atrium below the right auricle; thus, it has a curved course. On the other hand, a conal vein in malformed hearts courses from the left side or from the anterior side of the conus and tends to traverse straight upwards along the dextroposed aorta or along the aortopulmonary groove with its proximal part located outside of the heart. Other cardiac veins in outflow tract malformations are positioned in the same locations as in control hearts.. We postulate that the changed location of the conal vein and disorganized capillary plexus result from malformed morphogenesis of the outflow tract and/or a disturbed regulation of angiogenic growth factor release from the adjacent environment.

Topics: Animals; Capillaries; Coronary Vessel Anomalies; Disease Models, Animal; Female; Heart Defects, Congenital; Mice; Mice, Inbred BALB C; Models, Theoretical; Pregnancy; Tretinoin; Veins

Excess retinoic acid (RA) signaling can be teratogenic and result in cardiac birth defects, but the cellular and molecular origins of these defects are not well understood. Excessive RA signaling can completely eliminate heart formation in the zebrafish embryo. However, atrial and ventricular cells are differentially sensitive to more modest increases in RA signaling. Increased Hox activity, downstream of RA signaling, causes phenotypes similar to those resulting from excess RA. These results suggest that Hox activity mediates the differential effects of ectopic RA on atrial and ventricular cardiomyocytes and may underlie the teratogenic effects of RA on the heart.

Topics: Animals; Embryo, Nonmammalian; Embryonic Development; Heart Defects, Congenital; Homeodomain Proteins; Signal Transduction; Teratogens; Tretinoin; Zebrafish; Zebrafish Proteins

This study was aimed at determining whether the chick cardiomyocyte micromass (MM) system could be employed to predict the teratogenicity/embryotoxicity of exogenous chemicals. Two documented teratogens/embryotoxins, sodium valproate (the sodium salt of valproic acid; VPA) and all-trans retinoic acid (tRA), were used in the initial phase of the study. White Leghorn 5-day-old embryo hearts were dissociated to produce a cardiomyocyte suspension in Dulbecco's Modified Eagle's Medium. Cultures were incubated at 37 degrees C in 5% CO(2) in air, and observations were made every 24 hours over 5 days, for the detection of beating. Culture viability was assessed by using the resazurin reduction assay for determining culture activity and the kenacid blue assay for determining cell number. It was found that tRA significantly reduced cell activity and beating, whilst not affecting total cell number. VPA up to 500 microM induced no cytotoxicity in the MM cardiomyocyte cultures, whilst all the VPA concentrations tested reduced beating. The results demonstrate the potential of the chick cardiomyocyte MM culture assay to identify teratogens/embryotoxins that alter functionality, which may result in a teratogenic outcome, whilst not causing cytotoxicity (direct embryotoxicity). This could form part of a screen for developmental toxicity related to cardiac function, whilst limb cultures and brain cultures based on the same system could be relevant to teratogenic effects on those tissues.

Topics: Animal Testing Alternatives; Animals; Anticonvulsants; Antineoplastic Agents; Cell Culture Techniques; Cell Differentiation; Chick Embryo; Heart Defects, Congenital; Immunohistochemistry; Models, Biological; Myocytes, Cardiac; Oxazines; Proteins; Toxicity Tests; Tretinoin; Valproic Acid; Xanthenes

We analyzed the expression of neuronal regulatory genes Mash-1 and c-ret by immunohistochemistry and reverse transcriptase-polymerase chain reaction in the developing heart of rat embryos following exogenous retinoic acid (RA) treatment of the pregnant dams. On E12, expression of Mash-1 and c-ret was confined to cells migrating via the common cardinal vein. On E16.5, Mash-1 and c-ret expression were restricted to cardiac ganglia around the great vessels and posterior atrial wall. While Mash-1 expression was down-regulated at birth, that of c-Ret was maintained. RA-treated hearts showed a down-regulation of both Mash-1 and c-Ret at the mRNA as well as at the protein level on E16.5. The present results show that differentiation of cardiac ganglionic cells is affected after RA treatment, by the down-regulation of Mash-1 and c-Ret.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Cell Differentiation; Cell Movement; Cell Survival; DNA-Binding Proteins; Drosophila Proteins; Female; Fetus; Ganglia, Autonomic; Gene Expression Regulation, Developmental; Heart; Heart Defects, Congenital; Immunohistochemistry; Neural Crest; Pregnancy; Prenatal Exposure Delayed Effects; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-ret; Rats; Rats, Wistar; Receptor Protein-Tyrosine Kinases; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stem Cells; Transcription Factors; Tretinoin

The vitamin A deficient (VAD) quail embryo lacks active retinoids, fails to express normally GATA-4, and develops a nonlooping heart tube morphogenetic defect that is a model for congenital cardiomyopathy. VAD quail embryos, or chick embryos depleted specifically for GATA factors, show in addition abnormal foregut development, characterized by apoptosis of the endoderm cells associated with presumptive myocardium during the process of heart tube formation. Exogenous retinoic acid or transplantation of normal chick embryo anterior endoderm is sufficient to rescue apoptosis as well as GATA-4 expression and results in normal development and heart tube morphogenesis. Normal posterior endoderm also contains retinoids but is unable to rescue the VAD defect. Our results indicate that a retinoid-dependent transcriptional program, mediated at least in part by GATA factors, is critical in presumptive foregut endoderm for normal heart tube morphogenesis.

Topics: Animals; Apoptosis; Chick Embryo; Chimera; Digestive System; DNA-Binding Proteins; Endoderm; GATA4 Transcription Factor; GATA5 Transcription Factor; GATA6 Transcription Factor; Gene Expression; Heart; Heart Defects, Congenital; In Situ Hybridization; Phenotype; Quail; RNA, Messenger; Transcription Factors; Transplantation, Heterologous; Tretinoin; Vitamin A Deficiency

To determine the ventricular looping pattern in relation to cardiac laterality, we studied rat embryos treated with retinoic acid (RA). A total of 243 Wistar rat embryos from an in vivo treated group (a single dose of 20-40 mg/kg all-trans RA administered to pregnant rats on day 6.5 to 9.5) and 29 control embryos were examined on day 13 of gestation. Twenty-nine embryos from the in-vitro treated group (treated by all-trans RA at 2 x 10(-7) M for 6 hr on day 9.0 or 9.5 during the entire embryo culture for 72 hr) and seven control embryos were examined on day 12 of gestation. Abnormalities in cardiac laterality and ventricular looping were found in the in-vivo groups treated on day 8.5 and 8.75 and in the in-vitro group on day 9.0. Among 25 animals with abnormal laterality, right isomerism was the most common feature (22 cases), while the type of ventricular looping varied. Cases with normal laterality had a low incidence of abnormal looping (1.4%). In rat embryos treated with all-trans RA, normal cardiac looping was expected when cardiac laterality was normal. But in cases with abnormal laterality, the type of abnormal ventricular looping was unexpected.

Topics: Animals; Cell Division; Female; Heart; Heart Defects, Congenital; Heart Ventricles; Incidence; Male; Pregnancy; Rats; Rats, Wistar; Tretinoin

Determination of the left-right position (situs) of visceral organs involves lefty, nodal and Pitx2 genes that are specifically expressed on the left side of the embryo. We demonstrate that the expression of these genes is prevented by the addition of a retinoic acid receptor pan-antagonist to cultured headfold stage mouse embryos, whereas addition of excess retinoic acid leads to their symmetrical expression. Interestingly, both treatments lead to randomization of heart looping and to defects in heart anteroposterior patterning. A time course analysis indicates that only the newly formed mesoderm at the headfold-presomite stage is competent for these retinoid effects. We conclude that retinoic acid, the active derivative of vitamin A, is essential for heart situs determination and morphogenesis.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Body Patterning; DNA-Binding Proteins; Gene Expression Regulation, Developmental; Heart; Heart Defects, Congenital; Homeobox Protein Nkx-2.5; Homeobox Protein PITX2; Homeodomain Proteins; Left-Right Determination Factors; Mesoderm; Mice; Mice, Transgenic; Nodal Protein; Nuclear Proteins; Paired Box Transcription Factors; Transcription Factors; Transforming Growth Factor beta; Tretinoin; Xenopus Proteins

To study the specification of inflow structures in the heart we generated transgenic animals harboring the human alkaline phosphatase (HAP) gene driven by the proximal 840 bp of a quail SMyHC3 promoter. In transgenic mice, the SMyHC3-HAP reporter was expressed in posterior heart precursors at 8.25 dpc, in sinus venosa and in the atrium at 8.5 and 9.0 dpc, and in the atria from 10.5 dpc onwards. SMyHC3-HAP transgene expression overlapped synthesis and endogenous response to retinoic acid (RA) in the heart, as determined by antibodies directed against a key RA synthetic enzyme and by staining of RAREhsplacZ transgenic animals. A single pulse of all-trans RA administered to pregnant mice at 7.5, but not after 8.5, dpc induced cardiac dismorphology, ranging from complete absence of outflow tract and ventricles to hearts with reduced ventricles expressing both SMyHC3-HAP and ventricular markers. Blockade of RA synthesis with disulfiram inhibited RA-induced transcription and produced hearts lacking the atrial chamber. This study defines a novel marker for atrial-restricted transcription in the developing mouse heart. It also suggests that atrial-specific gene expression is controlled by localized synthesis of RA, and that exclusion of RA from ventricular precursors is essential for correct specification of the ventricles.

Topics: Alkaline Phosphatase; Animals; Disulfiram; Enzyme Inhibitors; Female; Gene Expression Regulation, Developmental; Genetic Markers; Heart; Heart Atria; Heart Defects, Congenital; Heart Ventricles; Humans; Mice; Mice, Transgenic; Pregnancy; Promoter Regions, Genetic; Response Elements; Signal Transduction; Transcription, Genetic; Transgenes; Tretinoin

Visceroatrial heterotaxy syndrome is characterized by abnormality of visceral laterality and complex cardiovascular anomalies usually involving both the outflow and inflow tract. Morishima et al. (1995) showed that mouse embryos treated with all-trans retinoic acid at embryonic day 6.5 (primitive streak stage) induces this syndrome.. To investigate the morphogenetic process of visceroatrial heterotaxy syndrome, we examined retinoic acid-treated mouse embryos at embryonic days 9-15 using scanning electron microscopy.. The sinoatrial connection was first distinguished for the determination of situs as early as at embryonic day 10.5. Normal visceroatrial situs was found in 57% of all treated embryos, and the rest had abnormal situs, in which right isomerism was found in 81%. In the right-isomeric mouse, the cardiac morphology was characterized by abnormal looping together with dysplasia of the inflow and outflow tract cushion; that is, the primitive right ventricle was usually deviated cranially to various degrees, the atrioventricular cushion appeared trilobed in a half of them, and unilateral ventricular hypoplasia was noted in about one-third of them after embryonic day 14.5.. An anomalous relation between the atrioventricular cushions and the interventricular septum appeared to have caused a restrictive inflow to the unilateral ventricle, leading to ventricular chamber hypoplasia on the ipsilateral side. Thus, we clarified that retinoic-acid treatment at the primitive streak stage disturbed cardiac looping and formation of atrioventricular cushion development, which secondarily influenced ventricular chamber development.

Topics: Abnormalities, Drug-Induced; Animals; Endocardial Cushion Defects; Female; Fetal Heart; Gastrula; Heart Atria; Heart Defects, Congenital; Heart Septal Defects, Ventricular; Heart Ventricles; Male; Mice; Microscopy, Electron, Scanning; Morphogenesis; Tretinoin

Stage 34 chicken hearts have shown a spectrum of looping disturbances, changed hemodynamics, and changed growth of both right ventricular myocardium and atrioventricular cushion tissue after retinoic acid treatment. To obtain more information about the onset of the malformations we studied stage 24, the stage between the previously studied stage 34 and the moment of treatment. Sixteen stage 24 chicken embryos were examined after treatment with 1 microg all-trans retinoic acid at stage 15 and compared with 6 sham operated embryos. Morphological examination was supported by graphic reconstructions. Absolute volumes of atrial, atrioventricular, and ventricular myocardia were measured by a point counting method. The absolute volumes of the endocardial cushions were measured as well. Fifteen (15/16) retinoic acid-treated hearts did not show marked malformations as far as could be detected with our current macroscopic and microscopic techniques. One (1/16) retinoic acid-treated heart showed an abnormal tubular C-shape with a less bended inner curvature and with an abnormal horizontally oriented atrioventricular canal. The dorsal cushion tissue of this atrioventricular canal was discontinuous with the dorsal mesocardium and covered the malpositioned myocardial border between the atrium and the atrioventricular canal. The volume measurements did show a difference between retinoic acid treatment and sham operations. The retinoic acid-treated hearts showed a significant volume decrease of the atrioventricular cushions. No significant differences were found in the volumes of the ventricular myocardium compared to the sham operated embryos. We hypothesize that, between stages 15 and 24, retinoic acid directly affects the myocardial wall and the cushion tissue formation. In the present material this has resulted in decreased atrioventricular cushion growth, in changed hemodynamics, and in a severe looping disturbance of one embryo. We further hypothesize that, between stages 24 and 34, the malformations with minor looping disturbances will become apparent. Thus, development beyond stage 24 would result in the spectrum of looping disturbances as has been found at stage 34. These latter morphological malformations would lead to increasing hemodynamic changes, resulting in changes in growth as a secondary effect.

Topics: Animals; Atrioventricular Node; Chick Embryo; Heart; Heart Defects, Congenital; Hemodynamics; Terminology as Topic; Tretinoin

A recessive lethal insertional mutation on chromosome 13 has been identified in a transgenic mouse line that displays a segmental form of cardiac defect along the anterior-posterior axis in all homozygous mice identified. The most anterior segment (future conus and right ventricle) of the single heart tube fails to develop normally and the endocardial cushions in both the conus and the atrioventricular regions are missing. Analysis of the beta-galactosidase reporter portion of the transgene during embryonic development shows a segmental expression of activity primarily in the defective outlet of the primitive heart. In addition to expression in the heart tube, hemizygous embryos show transgene expression in the chondrogenic regions of first and second branchial arches, the appendicular skeleton, and the dermal papillae of the vibrissae. The restricted pattern of beta-galactosidase expression in the heart can be disrupted with retinoic acid exposure and extended posteriorly along the anterior-posterior axis in hemizygous mice. Although cushion mesenchyme fail to form in the homozygous mutant, the myocardial and endothelial cells explanted from the mutant atrioventricular, but not the conus, are capable of forming mesenchyme in vitro. Mice trisomic for chromosome 13 have also been shown to display segmental anomalies associated with the anterior primitive outlet segments of the heart. Our data show that this insertional mutation identifies a new gene locus, hdf (heart defect), on mouse chromosome 13 that may be required for mechanisms that initially establish and/or maintain continued development of the anterior limb of the developing heart. The hdf mouse mutation also provides a new model system to evaluate the molecular requirements of normal endocardial cushion formation and the segmental interactions that form the adult heart.

Topics: Animals; beta-Galactosidase; Culture Techniques; DNA Primers; Embryo, Mammalian; Female; Fibronectins; Gene Expression Regulation, Developmental; Heart; Heart Defects, Congenital; Male; Mesoderm; Mice; Mice, Inbred CBA; Mice, Transgenic; Mutagenesis, Site-Directed; Phenotype; Pregnancy; Transgenes; Tretinoin

The growth and differentiation factor transforming growth factor-beta2 (TGFbeta2) is thought to play important roles in multiple developmental processes. Targeted disruption of the TGFbeta2 gene was undertaken to determine its essential role in vivo. TGFbeta2-null mice exhibit perinatal mortality and a wide range of developmental defects for a single gene disruption. These include cardiac, lung, craniofacial, limb, spinal column, eye, inner ear and urogenital defects. The developmental processes most commonly involved in the affected tissues include epithelial-mesenchymal interactions, cell growth, extracellular matrix production and tissue remodeling. In addition, many affected tissues have neural crest-derived components and simulate neural crest deficiencies. There is no phenotypic overlap with TGFbeta1- and TGFbeta3-null mice indicating numerous non-compensated functions between the TGFbeta isoforms.

Topics: Abnormalities, Multiple; Animals; Bone and Bones; Cleft Palate; Craniofacial Abnormalities; Cyanosis; Ear, Inner; Embryonic Induction; Epithelium; Eye Abnormalities; Genes, Homeobox; Heart Defects, Congenital; Mesoderm; Mice; Mice, Inbred C57BL; Mice, Knockout; Phenotype; Transforming Growth Factor beta; Tretinoin; Urogenital Abnormalities

The effect of ethanol on early avian cardiovascular development was investigated in stage 8 quail embryos grown in culture for 24 hr. When the culture medium contained 1% ethanol, 50% of the embryos developed abnormalities of the cardiovascular system, some of which resembled vitamin A deficiency. Only 15% of the embryos grown in control media developed abnormalities attributed to the manipulation of the embryo. When all-trans-retinoic acid, the active form of vitamin A, was added at 10(-8) M to the ethanol-containing medium, the cardiovascular development was similar to that of untreated controls. Inclusion of 4-methylpyrazole and citral, enzyme inhibitors for the conversion of retinol to retinoic acid, produced cardiovascular abnormalities in embryos similar to those observed in vitamin A deficiency. These abnormalities were partially prevented by the presence of 10(-8) M all-trans-retinoic acid in the medium. Immunohistochemical studies using antibodies specific for the heart muscle myosin heavy chain (MF-20) and quail endothelial cells (QH-1) revealed that looping of the heart of ethanol-treated embryos was prevented, and the embryonal circulation had no or minimal vascular connections to the extraembryonic circulation. Our studies provide indirect evidence that ethanol is producing vitamin A deficiency during embryonic cardiovascular development and that these effects are specifically prevented by the presence of retinoic acid. These findings may explain some of the symptoms of fetal alcohol syndrome.

Topics: Animals; Dose-Response Relationship, Drug; Embryo, Nonmammalian; Ethanol; Fetal Alcohol Spectrum Disorders; Heart Defects, Congenital; Quail; Tretinoin; Vitamin A Deficiency

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

To obtain insight into the hemodynamics of abnormal cardiac development, a chick embryo model was recently developed in which a spectrum of double outlet right ventricle was induced with all-trans-retinoic acid. In Hamburger and Hamilton (HH) stage 34 white Leghorn chick embryos, we simultaneously measured dorsal aortic flow velocities with a 20 MHz pulsed Doppler velocity meter and vitelline artery blood pressures with a servonull system. These measurements were performed in embryos treated at HH stage 15 with 1 microgram of all-trans-retinoic acid (n = 47), or with the solvent DMSO (n = 15), and in control embryos (n = 21). After the wave form recordings were collected, all embryos were examined histologically. Embryos treated with all-trans-retinoic acid showed in 15 cases hearts with a rightward positioned aorta with an additional subaortic ventricular septal defect and 32 cases without septation abnormalities of the heart. The hemodynamic data were correlated with the morphology. Statistical comparison was performed between control and experimental values. There was no significant discrepancy in hemodynamics of sham-operated and control embryos. Heart rate, peak systolic and mean velocities, peak systolic and mean blood flows, and peak acceleration and stroke volume were reduced in embryos treated with all-trans-retinoic acid (p < 0.01). Furthermore, in the presence of a subaortic ventricular septal defect the diameter of the dorsal aorta was reduced. Pressure readings were not statistically significant. Our findings suggest that the hemodynamic changes are the result of a decrease in cardiac contraction force.

Topics: Animals; Aorta; Blood Flow Velocity; Body Weight; Chick Embryo; Disease Models, Animal; Heart; Heart Defects, Congenital; Heart Septal Defects, Ventricular; Hemodynamics; Humans; Organ Size; Tretinoin; Vascular Resistance

In a recently developed chick model the teratogen retinoic acid has appeared to induce a spectrum of double outlet right ventricle, which needs further detailed evaluation. It is known that retinoic acid is able to induce cardiac malformations. Although the exact mechanism is not known, an interaction with neural crest cell function is thought to exist.. After treatment with 1 microgram all-trans retinoic acid at Hamburger and Hamilton stage 15 and reincubation until stage 34 of development 41 chicken embryos were evaluated macroscopically and microscopically, supported by graphic reconstructions. These retinoic acid treated embryos were compared with a control group (n = 8).. The retinoic acid treated embryos could be divided in three groups. Group 1 (23/41) had an intact septum, group 2 (11/41) had an isolated ventricular septal defect (VSD), and group 3 (7/41) had a double outlet right ventricle (DORV). Besides, in the group with an intact septum 11 hearts showed an abnormal course of the subaortic outflow tract. In the group with DORV a straddling tricuspid orifice (7/8) and a double inlet left ventricle (1/8) could be distinguished. Considering the external contour, the hearts in the DORV group all showed a dextroposed arterial pole. Malformed pharyngeal arch arteries were found in all three groups (11/41) and with a great diversity.. The present cardiac malformations in the chicken as a result of retinoic acid treatment are part of a continuous spectrum, varying from hearts with an intact ventricular septum and a normal course of the subaortic outflow tract to a double outlet right ventricle with a straddling tricuspid orifice or even a double inlet left ventricle. A remarkable observation in this spectrum concerns the correlation of malformations of the inflow and outflow tracts, which is explained as a cardiac looping disturbance. The disturbance of the looping process seems to lead to malalignment of septal components, although, in the chick, retinoic acid does not in general interfere with the formation of these septal components themselves.

Topics: Animals; Chick Embryo; Heart Defects, Congenital; Heart Septal Defects; Heart Ventricles; Models, Anatomic; Tretinoin

Visceral heterotaxy syndrome causes abnormal arrangement of thoracoabdominal organs and severe complex cardiac anomalies by abnormal laterality. The purpose of the present study is to analyze the incidence and pattern of heterotaxy syndrome in etretinate and all-tran retinoic acid treated pregnant DDY mice. Pregnant DDY mice were intragastrically given a single dose of 15 mg/kg of etretinate at day 6, 7 of gestation, 30 mg/kg of etretinate at day 7 of gestation and 20 mg/kg of all-trans retinoic acid at day 7 of gestation. The incidence of visceral heterotaxy was highest in the etretinate 15 mg/kg treated group on day 7 of gestation (38.5%). The major cardiovascular anomalies in heterotaxy syndrome were common atrium, common atrioventricular valve, atrioventricular septal defect, transposition of great arteries, pulmonary atresia, pulmonary artery hypoplasia and aortic arch anomalies. Atrial situs of heterotaxy syndrome were right isomerism, solitus-like, inversus-like and left atrial aplasia, but right isomerism was observed most frequently. The results suggest that retinoic acid exerts a significant effect on the determination of atrial situs during the development of mouse embryo.

Topics: Abnormalities, Drug-Induced; Animals; Blood Vessels; Female; Heart Defects, Congenital; Mice; Pregnancy; Syndrome; Tretinoin

Compound null mutations of retinoic acid receptor (RAR) genes lead to lethality in utero or shortly after birth and to numerous developmental abnormalities. In the accompanying paper (Lohnes, D., Mark., M., Mendelsohn, C., Dollé, P., Dierich, A., Gorry, Ph., Gansmuller, A. and Chambon, P. (1994). Development 120, 2723-2748), we describe malformations of the head, vertebrae and limbs which, with the notable exception of the eye defects, were not observed in the offspring of vitamin A-deficient (VAD) dams. We report here abnormalities in the neck, trunk and abdominal regions of RAR double mutant mice, which include: (i) the entire respiratory tract, (ii) the heart, its outlow tract and the great vessels located near the heart, (iii) the thymus, thyroid and parathyroid glands, (iv) the diaphragm, (v) the genito-urinary system, and (vi) the lower digestive tract. A majority of these abnormalities recapitulate those observed in the fetal VAD syndrome described by Joseph Warkany's group more than fourty years ago [Wilson, J. G., Roth, C. B. and Warkany, J. (1953) Am. J. Anat., 92, 189-217; and refs therein]. Our results clearly demonstrate that RARs are essential for vertebrate ontogenesis and therefore that retinoic acid is the active retinoid, which is required at several stages of the development of numerous tissues and organs. We discuss several possibilities that may account for the apparent functional redundancy observed amongst retinoic acid receptors during embryogenesis.

Topics: Abnormalities, Multiple; Animals; Cardiovascular System; Endocrine Glands; Genitalia; Heart Defects, Congenital; Kidney; Lung; Mice; Mice, Mutant Strains; Morphogenesis; Receptors, Retinoic Acid; Trachea; Tretinoin

Cardiac troponin I (troponin Ic) expression is restricted to the heart at all stages of Xenopus development. Whole-mount in situ hybridization and Northern blot analysis indicates that troponin Ic is first expressed in tailbud embryos (stage 28) about the time of the first cytological heart differentiation and about 24 hr before beating tissue is observed. We have used this marker to examine abnormal heart morphogenesis in embryos treated with retinoic acid and lithium. When retinoic acid is administered to embryos prior to heart specification, heart tissue is reduced and often completely ablated. When embryos are treated after heart specification, but before the heart primordium migrates to the ventral midline, the migration is unaffected but smaller, abnormal hearts result. Lithium treatment of cleavage stage embryos causes an increase in heart tissue. In severely dorsalized embryos, heart tissue can be found around the entire embryo with the exception of a small gap at the most dorsal point. This gap indicates that migration of the heart to the ventral midline does not occur in these embryos. Later in development, a centrally located, beating heart is observed in dorsalized embryos. The timing of its appearance suggests that it is formed by movements normally associated with heart morphogenesis rather than migration.

Topics: Animals; Base Sequence; Biomarkers; Cloning, Molecular; DNA Primers; Gene Expression; Heart; Heart Defects, Congenital; In Situ Hybridization; Lithium; Molecular Sequence Data; Morphogenesis; Myocardium; RNA, Messenger; Tretinoin; Troponin; Troponin I; Xenopus laevis

Experiments in vitro with cultured rat conceptuses demonstrated that 9-cis-retinoic acid (9-cis-RA) (300 ng/mL amniotic fluid) produced branchial arch and somite defects similar to those elicited by equal concentrations of all-trans-retinoic acid (all-trans-RA), but with an increase in cephalic defects that included missing optic vesicles. After conceptuses were intraamniotically microinjected with 600 ng 9-cis-RA/mL amniotic fluid on day 10 of gestation, an unusual heart defect was also observed. HPLC analyses indicated that 9-cis-RA readily underwent conversion to the less active metabolite, 13-cis-retinoic acid (13-cis-RA), in cultured conceptuses during the first 4 hr after treatment but only after 6 hr could elevated levels of the potent dysmorphogen all-trans-RA be detected. In separate experiments, conversion of 13-cis-RA or of all-trans-RA to 9-cis-RA could not be detected during a 6-hr embryo culture period. Endogenous levels of 9-cis-RA in whole rat embryos also were below limits of detection but small quantities of this isomer could be detected in neonatal rat eye and human embryonic brain. Our present study strongly suggests that 9-cis-RA is a direct-acting dysmorphogen with probable specific target sites of action.

Topics: Animals; Brain; Branchial Region; Culture Techniques; Heart Defects, Congenital; Rats; Rats, Sprague-Dawley; Rats, Wistar; Teratogens; Tretinoin

A case of retinoic acid embryopathy which was retrospectively diagnosed after delivery is presented. The affected fetus was exposed to the drug during the first month of pregnancy and second-trimester sonographic examination showed hydrocephalus and cardiac malformation. The diagnosis was made on the basis of autopsy findings and genetic enquiry.

Topics: Abnormalities, Multiple; Abortion, Therapeutic; Adult; Facial Bones; Female; Heart Defects, Congenital; Humans; Hydrocephalus; Maternal-Fetal Exchange; Pregnancy; Pregnancy Trimester, Second; Tretinoin; Ultrasonography, Prenatal

The effects of 13-cis-retinoic acid on the developing chick embryo were investigated. Fertilized eggs were injected via the yolk sac with single 50 microliters doses of either 1.5 micrograms, 15 micrograms, or 150 micrograms of 13-cis-retinoic acid in dimethyl sulfoxide on varying days of incubation (embryonic days 2, 3, 4, 5, or 6). Control embryos were given solvent alone or a mock injection. The embryos were examined on day 14 of incubation. The effects of retinoic acid on mortality and total malformations were both dose and developmental-stage responsive. The defects caused by 13-cis-retinoic acid occurred in mesenchymal tissues derived in part from the cranial neural crest ectomesenchyme. The craniofacial and cardiovascular malformations produced in the chick are analogous to those seen in animal models of retinoid teratogenesis and in human fetuses exposed to 13-cis-retinoic acid during maternal therapy for cystic acne. Following 13-cis-retinoic acid treatment, craniofacial and specific cardiovascular malformations were increased significantly compared to those in matched solvent and mock treated controls. The greatest number of malformations occurred when 13-cis-retinoic acid was given after cranial neural crest cell migration was complete. We propose that the primary effect of 13-cis-retinoic acid is on region-specific localization and differentiation of the mesenchymal subpopulation of cranial neural crest cells.

Topics: Abnormalities, Drug-Induced; Animals; Chick Embryo; Dose-Response Relationship, Drug; Face; Female; Heart Defects, Congenital; Neural Crest; Pregnancy; Pregnancy Outcome; Tretinoin

Topics: Abnormalities, Drug-Induced; Acne Vulgaris; Adult; Brain; Female; Heart Defects, Congenital; Humans; Hydrocephalus; Isomerism; Isotretinoin; Pregnancy; Teratogens; Tretinoin

Retinoic acid, an analogue of vitamin A, is known to be teratogenic in laboratory animals and has recently been implicated in a few clinical case reports. To study the human teratogenicity of this agent, we investigated 154 human pregnancies with fetal exposure to isotretinoin, a retinoid prescribed for severe recalcitrant cystic acne. The outcomes were 95 elective abortions, 26 infants without major malformations, 12 spontaneous abortions, and 21 malformed infants. A subset of 36 of the 154 pregnancies was observed prospectively. The outcomes in this cohort were 8 spontaneous abortions, 23 normal infants, and 5 malformed infants. Exposure to isotretinoin was associated with an unusually high relative risk for a group of selected major malformations (relative risk = 25.6; 95 per cent confidence interval, 11.4 to 57.5). Among the 21 malformed infants we found a characteristic pattern of malformation involving craniofacial, cardiac, thymic, and central nervous system structures. The malformations included microtia/anotia (15 infants), micrognathia (6), cleft palate (3), conotruncal heart defects and aortic-arch abnormalities (8), thymic defects (7), retinal or optic-nerve abnormalities (4), and central nervous system malformations (18). The pattern of malformation closely resembled that produced in animal studies of retinoid teratogenesis. It is possible that a major mechanism of isotretinoin teratogenesis is a deleterious effect on cephalic neural-crest cell activity that results in the observed craniofacial, cardiac, and thymic malformations.

Topics: Abnormalities, Drug-Induced; Abortion, Spontaneous; Acne Vulgaris; Adolescent; Adult; Female; Fetal Death; Heart Defects, Congenital; Humans; Infant, Newborn; Isotretinoin; Male; Pregnancy; Pregnancy Trimester, First; Prospective Studies; Retrospective Studies; Risk; Tretinoin

Topics: Abnormalities, Drug-Induced; Brain; Ear; Heart Defects, Congenital; Humans; Isotretinoin; Syndrome; Teratogens; Tretinoin

Topics: Abnormalities, Drug-Induced; Chemical and Drug Induced Liver Injury; Female; Heart Defects, Congenital; Humans; Hydrocephalus; Infant, Newborn; Infant, Premature, Diseases; Isotretinoin; Liver Diseases; Tretinoin

In order to determine the effect of retinoic acid on the developing mammalian heart, pregnant golden Syrian hamsters were given single doses of 80 mg/kg of the teratogen by gavage, at various times in gestation. Examination of the surface features of hearts from near-term fetuses was followed by microdissection to reveal internal cardiac structures. This has proven to give more reliable results than other methods of determining congenital heart malformation. The results of the study demonstrate that retinoic acid is a potent cardiac teratogen capable of inducing high frequencies of heart abnormalities in a reproducible fashion. The highest rates of malformation resulted from maternal treatment on day 7 (69%), 8 (74%), and 9 (30%) of gestation. Ventriculo-bulbar malformations including double outlet right ventricle, complete transposition, and an overriding aorta complex were the most commonly seen abnormalities. The findings support the hypothesis that these abnormalities are not entirely discrete entities but are instead part of a single spectrum of malformation.

Topics: Animals; Cricetinae; Female; Fetal Heart; Gestational Age; Heart Defects, Congenital; Mesocricetus; Pregnancy; Teratogens; Tretinoin