Cellular decisions in cardiac outflow tract and coronary development: an act by VEGF and NOTCH

Interplay analysis of lead exposure with key cardiovascular gene polymorphisms on blood pressure in a cross-sectional study of occupational workers

An increasing number of studies have shown that lead is an important cardiovascular risk factor, but the impact of cardiovascular related gene polymorphisms on lead induced cardiovascular diseases is still unclear. To assess the interaction of lead exposure and related key cardiovascular regulating gene polymorphisms on blood pressure traits, three single-nucleotide polymorphisms including NOTCH1 rs3124591, Cerebral cavernous malformations 3 (CCM3) rs3804610 and Vascular endothelial growth factor receptor type 2 (VEGFR2) rs2305948 were selected and genotyped using improved multiplex ligase detection reaction method in 568 lead exposure workers in South China. General characteristics, blood lead and biochemical parameters including glucose, lipid profile and creatinine were also collected according to standard protocols. Regression analysis was used to evaluate the association of blood pressure with lead exposure, polymorphisms and their interaction. This study displayed that CCM3 rs3804610 had a positive interaction with lead and VEGFR2 rs2305948 had a negative interaction with lead. Specifcally, compared with the wild-type population, the blood lead of the genotype population carrying the risk allele increased by 1 µg/dL, systolic blood pressure increased by 0.53 mmHg (p < 0.01) and diastolic blood pressure increased by 0.34 mmHg (p < 0.05) for CCM3 rs3804610, and systolic blood pressure decreased by 0.28 mmHg (p < 0.05) and diastolic blood pressure decreased by 0.22 mmHg (p < 0.05) for VEGFR2 rs2305948. Thus our findings showed that the interaction between CCM3 rs3804610 and VEGFR2 rs2305948 and lead exposure were associated with blood pressure and may provide guidance for future research on hypertension prevention and personalized clinical treatment in lead exposed populations.

Tetralogy of Fallot: Hypoxia, the villain of the story?

BACKGROUND

Tetralogy of Fallot (ToF) is a cyanotic congenital heart disease, composed of four malformations: persistent communication between the right and the left ventricle, pulmonary stenosis, overriding aorta, and right ventricle hypertrophy. The etiology of this disease is not entirely known as yet, but it has been proposed that the pathology has genetic components. During embryonic development, the fetus is exposed to a physiological hypoxia to facilitate the formation of blood vessels and blood cells through de novo processes.

METHODS

After researching scientific databases on the implications of oxygen on the normal and abnormal development of organs, especially the heart, we were able to propose that oxygen deprivation may be the cause of the disease.

RESULTS

During this period, the hypoxia-inducible factor is activated and triggers transcriptional responses that enable adaptation to the hypoxic environment through angiogenic activation. High levels of this protein can alter certain physiological pathways, such as those related to the vascular endothelial growth factor. Research has shown that prolonged oxygen deprivation during embryological development can lead to the occurrence of congenital heart diseases, such as ToF.

CONCLUSIONS

Studies using animal models have demonstrated that the deficiency or disruption of a protein called "CITED2," which plays an important role in cardiac morphogenesis and its loss, results in the alteration of pluripotent, cardiac, and neural lineage differentiation, thereby disrupting the normal development of the heart and other tissues.

Evaluating High-Confidence Genes in Conotruncal Cardiac Defects by Gene Burden Analyses

Background In nonsyndromic conotruncal cardiac defects, the use of next-generation sequencing for clinical diagnosis is increasingly adopted, but gene-disease associations in research are only partially translated to diagnostic panels, suggesting a need for evidence-based consensus. Methods and Results In an exome data set of 245 patients with conotruncal cardiac defects, we performed burden analysis on a high-confidence congenital heart disease gene list (n=132) with rare (<0.01%) and ultrarare (absent in the Genome Aggregation Database) protein-altering variants. Overall, we confirmed an excess of rare variants compared with ethnicity-matched controls and identified 2 known genes (GATA6, NOTCH1) and 4 candidate genes supported by the literature (ANKRD11, DOCK6, NPHP4, and STRA6). Ultrarare variant analysis was performed in combination with 3 other published studies (n=1451) and identified 3 genes (FLT4, NOTCH1, TBX1) to be significant, whereas a subgroup analysis involving 391 Chinese subjects identified only GATA6 as significant. Conclusions We suggest that these significant genes in our rare and ultrarare burden analyses warrant prioritization for clinical testing implied for rare inherited and de novo variants. Additionally, associations on ClinVar for these genes were predominantly variants of uncertain significance. Therefore, a more stringent assessment of gene-disease associations in a larger and ethnically diverse cohort is required to be prudent for future curation of conotruncal cardiac defect genes.

Energy metabolism disorder dictates chronic hypoxia damage in heart defect with tetralogy of fallot

Background

Tetralogy of Fallot (TOF) belongs to cyanotic heart damage, which is the most common in clinic. In the chronic myocardial hypoxia injury related to TOF, the potential molecular mechanism of cardiac energy metabolism remains unclear.

Materials and methods

In our study, microarray transcriptome analysis and metabonomics methods were used to explore the energy metabolism pathway during chronic hypoxia injury. The gene expression omnibus (GEO) dataset GSE132176 was obtained for analyzing the metabolic pathways. The clinical samples (right atrial tissues) of atrial septal defect (ASD) and TOF were analyzed by metabonomics. Next, we screened important pathways and important differential metabolites related to energy metabolism to explore the pathogenesis of TOF.

Results

Gene set enrichment analysis (GSEA) indicated that fructose 6-phosphate metabolic process, triglyceride metabolic process, and et al. were significantly enriched. Gene set variation analysis (GSVA) results showed that significant difference of ASD group and TOF group existed in terpenoid metabolic process and positive regulation of triglyceride metabolic process. Pathways with significant enrichment (impact > 0.1) in TOF were caffeine metabolism (impact = 0.69), sphingolipid metabolism (impact = 0.46), glycerophospholipid metabolism (impact = 0.26), tryptophan metabolism (impact = 0.24), galactose metabolism (impact = 0.11). Pathways with significant enrichment (impact > 0.1) in ASD are caffeine metabolism (impact = 0.69), riboflavin metabolism (impact = 0.5), alanine, aspartate and glutamate metabolism (impact = 0.35), histidine metabolism (impact = 0.34) and et al.

Conclusion

Disturbed energy metabolism occurs in patients with TOF or ASD, and further investigation was needed to further clarify mechanism.

Automated endocardial cushion segmentation and cellularization quantification in developing hearts using optical coherence tomography

Of all congenital heart defects (CHDs), anomalies in heart valves and septa are among the most common and contribute about fifty percent to the total burden of CHDs. Progenitors to heart valves and septa are endocardial cushions formed in looping hearts through a multi-step process that includes localized expansion of cardiac jelly, endothelial-to-mesenchymal transition, cell migration and proliferation. To characterize the development of endocardial cushions, previous studies manually measured cushion size or cushion cell density from images obtained using histology, immunohistochemistry, or optical coherence tomography (OCT). Manual methods are time-consuming and labor-intensive, impeding their applications in cohort studies that require large sample sizes. This study presents an automated strategy to rapidly characterize the anatomy of endocardial cushions from OCT images. A two-step deep learning technique was used to detect the location of the heart and segment endocardial cushions. The acellular and cellular cushion regions were then segregated by K-means clustering. The proposed method can quantify cushion development by measuring the cushion volume and cellularized fraction, and also map 3D spatial organization of the acellular and cellular cushion regions. The application of this method to study the developing looping hearts allowed us to discover a spatial asymmetry of the acellular cardiac jelly in endocardial cushions during these critical stages, which has not been reported before.

Sequencing of a Chinese tetralogy of fallot cohort reveals clustering mutations in myogenic heart progenitors

Tetralogy of Fallot (TOF) is the most common cyanotic heart defect, yet the underlying genetic mechanisms remain poorly understood. Here, we performed whole-genome sequencing analysis on 146 nonsyndromic TOF parent-offspring trios of Chinese ethnicity. Comparison of de novo variants and recessive genotypes of this data set with data from a European cohort identified both overlapping and potentially novel gene loci and revealed differential functional enrichment between cohorts. To assess the impact of these mutations on early cardiac development, we integrated single-cell and spatial transcriptomics of early human heart development with our genetic findings. We discovered that the candidate gene expression was enriched in the myogenic progenitors of the cardiac outflow tract. Moreover, subsets of the candidate genes were found in specific gene coexpression modules along the cardiomyocyte differentiation trajectory. These integrative functional analyses help dissect the pathogenesis of TOF, revealing cellular hotspots in early heart development resulting in cardiac malformations.

Clinical Genetic Risk Variants Inform a Functional Protein Interaction Network for Tetralogy of Fallot

BACKGROUND

Tetralogy of Fallot (TOF)-the most common cyanotic heart defect in newborns-has evidence of multiple genetic contributing factors. Identifying variants that are clinically relevant is essential to understand patient-specific disease susceptibility and outcomes and could contribute to delineating pathomechanisms.

METHODS

Using a clinically driven strategy, we reanalyzed exome sequencing data from 811 probands with TOF, to identify rare loss-of-function and other likely pathogenic variants in genes associated with congenital heart disease.

RESULTS

We confirmed a major contribution of likely pathogenic variants in FLT4 (VEGFR3 [vascular endothelial growth factor receptor 3]; n=14) and NOTCH1 (n=10) and identified 1 to 3 variants in each of 21 other genes, including ATRX, DLL4, EP300, GATA6, JAG1, NF1, PIK3CA, RAF1, RASA1, SMAD2, and TBX1. In addition, multiple loss-of-function variants provided support for 3 emerging congenital heart disease/TOF candidate genes: KDR (n=4), IQGAP1 (n=3), and GDF1 (n=8). In total, these variants were identified in 63 probands (7.8%). Using the 26 composite genes in a STRING protein interaction enrichment analysis revealed a biologically relevant network (P=3.3×10-16), with VEGFR2 (vascular endothelial growth factor receptor 2; KDR) and NOTCH1 (neurogenic locus notch homolog protein 1) representing central nodes. Variants associated with arrhythmias/sudden death and heart failure indicated factors that could influence long-term outcomes.

CONCLUSIONS

The results are relevant to precision medicine for TOF. They suggest considerable clinical yield from genome-wide sequencing, with further evidence for KDR (VEGFR2) as a congenital heart disease/TOF gene and for VEGF (vascular endothelial growth factor) and Notch signaling as mechanisms in human disease. Harnessing the genetic heterogeneity of single gene defects could inform etiopathogenesis and help prioritize novel candidate genes for TOF.

Vascular endothelial growth factor on Runt-related transcript factor-2 in aortic valve cells

BACKGROUND

Calcific aortic valve disease is associated with ageing and high mortality. However, no effective pharmacological treatment has been developed. Vascular endothelial growth factor (VEGF) and its receptor are overexpressed in the calcified aortic valve tissue. However, the role of VEGF in calcific aortic valve disease pathogenesis and its underlying mechanisms remain unclear.

MATERIALS AND METHODS

Runt-related transcription factor 2 expression and calcium-related signalling were investigated in porcine valvular interstitial cells with or without human VEGF-A recombinant protein (VEGF₁₆₅ , 1-100 ng/mL) treatment and/or calmodulin-dependent kinase II (CaMKII) inhibitor (KN93, 10 µmol/L) and inositol triphosphate receptor inhibitor (2-aminoethyldiphenyl borate, 30 µmol/L) for 5 days.

RESULTS

VEGF₁₆₅ -treated cells had higher Runt-related transcription factor 2 expression and CaMKII/ adenosine 3',5'-monophosphate response element-binding protein (CREB) signalling activation than did control cells. KN93 reduced Runt-related transcription factor 2 expression and CREB phosphorylation in VEGF₁₆₅ -treated cells. The 2-aminoethyldiphenyl borate also reduced Runt-related transcription factor 2 expression in VICs treated with VEGF₁₆₅ .

CONCLUSION

VEGF upregulated Runt-related transcription factor 2 expression in VICs by activating the IP3R/CaMKII/CREB signalling pathway.

Computed Tomography Angiographic Features of Anomalous Origination of the Coronary Arteries in Adult Patients: A Literature Review and Coronary Computed Tomography Angiographic Illustrations

Computed tomography angiography not only detects atherosclerotic coronary artery disease but also helps delineate the anomalous coronary arterial anatomy that may be more than just an incidental finding and could contribute to patients' symptomatology. Additionally, identification of coronary artery anomalies is clinically significant for preoperative planning and optimizing the approach for coronary catheterizations or surgical treatments. In this work, we review rare origination anomalies of coronary arteries and illustrate their characteristics through computed tomography images.

The impact of coronary anomalies on the outcome in aortic valve surgery: comparison of bicuspid aortic valve versus tricuspid aortic valve morphotype

OBJECTIVES

The association of anomalous anatomy of coronary arteries and bicuspid aortic valve (BAV) has been sporadically reported. Our aim was to evaluate the prevalence of coronary anomalies between BAV and tricuspid aortic valve (TAV) and to analyse their impact on major adverse cardiac events during and after aortic valve surgery.

METHODS

A total of 1099 consecutive patients who received preoperative coronary evaluation and elective aortic valve replacement/repair between January 2013 and July 2016 at our institution were involved. Based on surgical inspection at the open-heart surgery, a total of 345 (32%) patients were diagnosed with BAV, whereas the remaining 754 (68%) patients had TAV. Coronary anatomy was evaluated by preoperative coronary angiography (n = 1084) or multislice computed tomography (n = 15). The primary end-point was the prevalence of coronary anomalies in BAV versus TAV cohort. Secondary end-points included postoperative cardiac ischaemia markers, postoperative coronary artery imaging or interventions and hospital mortality.

RESULTS

A total of 46 (4%) coronary anomalies were detected and were significantly more frequent in the BAV group (7% vs 3%, P = 0.001). Postoperative markers of myocardial injury (creatine kinase/creatine kinase-MB and troponin) were increased and the need for postoperative coronary angiography/percutaneous coronary intervention was significantly higher in patients with coronary anomalies (12% vs 1%, P < 0.001).

CONCLUSIONS

Our study revealed significantly increased prevalence of coronary anomalies in BAV patients when compared with their tricuspid counterparts. Patients with diagnosed coronary anomalies had more postoperative ischaemic cardiac events that resulted in increased morbidity of this cohort.

Embryology of coronary arteries and anatomy/pathophysiology of coronary anomalies. A comprehensive update

OBJECTIVES

This paper reviews new findings in both embryology of coronary arteries and in clinical observations of coronary artery anomalies.

FOCUS

Our presentation emphasizes studies based on: 1) newer methods of coronary development in animals and humans, and 2) intravascular ultrasonography to interpret pathophysiology and guide treatment of coronary anomalies.

CONCLUSIONS

New data reveal the roles of many cellular interactions and signaling pathways involved in the normal and abnormal formation of the coronary arterial system and the consequences of their defective formation. Pathogenetic developmental mechanisms include dysfunction of the Notch and Hypo signaling pathways, angiogenic and arteriogenic molecules, and neural crest cells. We addressed numerous clinically significant coronary anomalies and their prevalence in a general population (especially those characterized by an ectopic origin with aortic intramural course), and point out the critical relevance of understanding the variable mechanisms of coronary dysfunction, especially, fixed versus phasic stenoses or intermittent spasm, and individual severity of clinical presentations.

Functional annotation of differentially expressed fetal cardiac microRNA targets: implication for microRNA-based cardiovascular therapeutics

Gene expression pattern of a failing heart depicts remarkable similarity with developing fetal heart. Elucidating genetic as well as epigenetic mechanisms regulating the gene expression during cardiac development will improve our understanding of cardiovascular diseases. In the present study, we aimed to validate and characterize differentially expressed known microRNAs (miRNA) obtained from next generation sequencing data of two fetal cardiac developmental stages (days 4th and 14th) from chicken (G. gallus domesticus) using bioinformatic approaches. Potential mRNA targets of individual miRNA were identified and classified according to their biological, cellular, and molecular functions. Functional annotation of putative target genes was performed to predict their association with cardiovascular diseases. We identified a total of 19 differentially expressed miRNAs between 4th and 14th day sample from the data sets obtained by next generation sequencing. A total of nearly 1522 potential targets ranging from 15 to 270 for each miRNA were predicted out of which 1221 were unique, while 301 were overlapping. Gene ontology and KEGG analysis revealed that majority of these target genes regulate critical cellular and molecular processes including transcriptional regulation, protein transport, signal transduction, matrix remodeling, Ras signaling, MAPK signaling, and TGF-beta signaling pathways indicating the complex nature of microRNA-mediated gene regulation during cardiogenesis. We found a significant association between potential target genes and cardiovascular diseases validating a link between fetal cardiac miRNAs and regulation of cardiovascular disease-related genes. These important findings may lay a foundation for further understanding the regulatory mechanisms operative in gene re-programming in the failing heart.

Hemodynamics in Cardiac Development

The beating heart is subject to intrinsic mechanical factors, exerted by contraction of the myocardium (stretch and strain) and fluid forces of the enclosed blood (wall shear stress). The earliest contractions of the heart occur already in the 10-somite stage in the tubular as yet unsegmented heart. With development, the looping heart becomes asymmetric providing varying diameters and curvatures resulting in unequal flow profiles. These flow profiles exert various wall shear stresses and as a consequence different expression patterns of shear responsive genes. In this paper we investigate the morphological alterations of the heart after changing the blood flow by ligation of the right vitelline vein in a model chicken embryo and analyze the extended expression in the endocardial cushions of the shear responsive gene Tgfbeta receptor III. A major phenomenon is the diminished endocardial-mesenchymal transition resulting in hypoplastic (even absence of) atrioventricular and outflow tract endocardial cushions, which might be lethal in early phases. The surviving embryos exhibit several cardiac malformations including ventricular septal defects and malformed semilunar valves related to abnormal development of the aortopulmonary septal complex and the enclosed neural crest cells. We discuss the results in the light of the interactions between several shear stress responsive signaling pathways including an extended review of the involved Vegf, Notch, Pdgf, Klf2, eNos, Endothelin and Tgfβ/Bmp/Smad networks.

Mesenchymal state of intimal cells may explain higher propensity to ascending aortic aneurysm in bicuspid aortic valves

Individuals with a bicuspid aortic valve (BAV) are at significantly higher risk of developing aortic complications than individuals with tricuspid aortic valves (TAV) and defective signaling during the embryonic development and/or life time exposure to abnormal hemodynamic have been proposed as underlying factors. However, an explanation for the molecular mechanisms of aortopathy in BAV has not yet been provided. We combined proteomics, RNA analyses, immunohistochemistry, and electron microscopy to identify molecular differences in samples of non-dilated ascending aortas from BAV (N = 62) and TAV (N = 54) patients. Proteomic analysis was also performed for dilated aortas (N = 6 BAV and N = 5 TAV) to gain further insight into the aortopathy of BAV. Our results collectively showed the molecular signature of an endothelial/epithelial-mesenchymal (EndMT/EMT) transition-like process, associated with instability of intimal cell junctions and activation of RHOA pathway in the intima and media layers of ascending aorta in BAV patients. We propose that an improper regulation of EndMT/EMT during the spatiotemporally related embryogenesis of semilunar valves and ascending aorta in BAV individuals may result in aortic immaturity and instability prior to dilation. Exasperation of EndMT/EMT state in post embryonic life and/or exposure to non-physiological hemodynamic could lead to the aneurysm of ascending aorta in BAV individuals.

Notch: A multi-functional integrating system of microenvironmental signals

The Notch signaling cascade is an evolutionarily ancient system that allows cells to interact with their microenvironmental neighbors through direct cell-cell interactions, thereby directing a variety of developmental processes. Recent research is discovering that Notch signaling is also responsive to a broad variety of stimuli beyond cell-cell interactions, including: ECM composition, crosstalk with other signaling systems, shear stress, hypoxia, and hyperglycemia. Given this emerging understanding of Notch responsiveness to microenvironmental conditions, it appears that the classical view of Notch as a mechanism enabling cell-cell interactions, is only a part of a broader function to integrate microenvironmental cues. In this review, we summarize and discuss published data supporting the idea that the full function of Notch signaling is to serve as an integrator of microenvironmental signals thus allowing cells to sense and respond to a multitude of conditions around them.

The effect of epigenetic silencing and TP53 mutation on the expression of DLL4 in human cancer stem disorder

The Li-Fraumeni Syndrome (LFS), a genetically rare heterogeneous cancer syndrome, is characterized primarily by a germline p53 (TP53) gene mutation. We recently discovered a balanced reciprocal chromosomal translocation t(11;15)(q23;q15) in the non-cancerous skin fibroblasts of a bilateral breast cancer patient in LFS family. This prompted us to investigate the breakpoint region of the translocation, which uncovered a gene that encodes a Notch ligand, DLL4, (locus at 15q15.1), a key target in tumor vasculature. We analyzed DLL4 gene expression and protein level in LFS non-cancerous skin fibroblast cell lines and non-LFS cancer cell lines. DLL4 is abrogated in all the LFS cells and drastically down-regulated in breast (MCF7) and brain (IMR32) cancer cells and tumor tissue samples. However, DNA methylation studies revealed that DLL4 promoter is silenced only in MCF7 but not in LFS cells. We further investigated the regulation of DLL4 gene expression by ChIP assays, which demonstrated that p53 binds to DLL4 promoter through its association with CTCF, a chromosomal networking protein CCCTC binding factor. This implies a possible karyotype-phenotype correlation with respect to DLL4 in LFS and breast cancer initiation and progression. The drastic reduction or absence in the expression of DLL4 in LFS as well as breast and brain cancer cells is significant and supports the concept that this ligand may also play a role in cancer immune-surveillance; and its resuscitation in the tumor microenvironment may stimulate T-cell immunity and suppress tumor growth. Therefore, DLL4 may provide a strong platform as an immuno-therapeutic target in LFS and cancer patients.

Increased Levels of Interferon-Inducible Protein 10 (IP-10) in 22q11.2 Deletion Syndrome

The 22q11.2 deletion syndrome (22q11.2 DS), also known as DiGeorge syndrome, is a genetic disorder with an estimated incidence of 1:4000 births. These patients may suffer from affection of many organ systems with cardiac malformations, thymic hypoplasia or aplasia, hypoparathyroidism, palate anomalies and psychiatric disorders being the most frequent. The incidence of autoimmune diseases is increased in older patients. The aim of the present study was to examine a cytokine profile in patients with 22q11.2 DS by measuring a broad spectrum of serum cytokines. Patients with a proven deletion of chromosome 22q11.2 (n = 55) and healthy individuals (n = 54) recruited from an age- and sex-comparable group were included in the study. Serum levels of 27 cytokines, including chemokines and growth factors, were analysed using multiplex technology. Interferon-inducible protein 10 (IP-10) was also measured by ELISA to confirm the multiplex results. The 22q11.2 DS patients had distinctly and significantly raised levels of pro-inflammatory and angiostatic chemokine IP-10 (P < 0.001) compared to controls. The patients with congenital heart defects (n = 31) had significantly (P = 0.018) raised serum levels of IP-10 compared to patients born without heart defects (n = 24). The other cytokines investigated were either not detectable or did not differ between patients and controls.

Nanoparticles combined with growth factors: recent progress and applications

Increasing attention has been focused on the applications of nanoparticles combined with growth factors (NPs/GFs) due to the substantial functions of GFs in regenerative medicine and disease treatments.

Endocardial Notch Signaling in Cardiac Development and Disease

The Notch signaling pathway is an ancient and highly conserved signaling pathway that controls cell fate specification and tissue patterning in the embryo and in the adult. Region-specific endocardial Notch activity regulates heart morphogenesis through the interaction with multiple myocardial-, epicardial-, and neural crest-derived signals. Mutations in NOTCH signaling elements cause congenital heart disease in humans and mice, demonstrating its essential role in cardiac development. Studies in model systems have provided mechanistic understanding of Notch function in cardiac development, congenital heart disease, and heart regeneration. Notch patterns the embryonic endocardium into prospective territories for valve and chamber formation, and later regulates the signaling processes leading to outflow tract and valve morphogenesis and ventricular trabeculae compaction. Alterations in NOTCH signaling in the endocardium result in congenital structural malformations that can lead to disease in the neonate and adult heart.

Genetic variations of VEGF gene were associated with tetralogy of fallot risk in a Chinese Han population

OBJECTIVES

Tetralogy of Fallot (TOF) is one of the most common forms of congenital heart disease. In this study, we aimed at investigating the associations between genetic variations of vascular endothelial growth factor (VEGF) gene and the risk of TOF in a Chinese Han population. Our findings may contribute to a deeper understanding of TOF pathogenesis and better diagnostic and therapeutic suggestions.

METHODS

A total of 165 TOF patients and 240 controls from a Chinese Han population in Shenyang and Harbin were recruited in the current study. Nine single-nucleotide polymorphisms (SNPs) (-2578C/A, -460T/C, -1154G/A, -634G/C, 534C/T, +398G/A, +963C/T, 752C/T, 913G/A) were genotyped by the MALDI-TOF MassARRAY system. Individual SNPs as well as their haplotypes were analyzed for their associations with TOF risk, using odds ratios and the 95% confidence interval under codominant and dominant models.

RESULTS

In the single SNP analyses, the mutant homozygous genotypes of -2578C/A (rs699947) and +963C/T (rs3025039) were related with an increased risk of TOF. In addition, carriers with the mutant A allele of -1154G/A (rs1570360) were supposed to have a significantly elevated TOF risk. Similarly, compared with the wild homozygote GG carriers, the GC carrier of -634G/C (rs2010963) revealed a significant relationship with susceptibility of TOF, but not for the mutant homozygote CC carriers. However, no significant association was found for the other five SNPs. Meanwhile, haplotype analysis revealed that CCA and ATA in block 1 (-2578C/A, -460T/C, and -1154G/A) and TTG and TCA in block 3 (+963C/T, 752C/T, and 913G/A) were significantly related with an increased TOF risk compared with the most common haplotypes.

CONCLUSION

In summary, our results suggested that VEGF variants (-2578C/A, -1154G/A, -634G/C, +963G/A) were involved in the susceptibility of TOF. However, validation of our study needs further study in various ethnics to reveal the functional relationship between VEGF polymorphisms and TOF risk, which may contribute to diagnosis and therapy of TOF.

Cellular origin and developmental program of coronary angiogenesis

Coronary artery disease causes acute myocardial infarction and heart failure. Identifying coronary vascular progenitors and their developmental program could inspire novel regenerative treatments for cardiac diseases. The developmental origins of the coronary vessels have been shrouded in mystery and debated for several decades. Recent identification of progenitors for coronary vessels within the endocardium, epicardium, and sinus venosus provides new insights into this question. In addition, significant progress has been achieved in elucidating the cellular and molecular programs that orchestrate coronary artery development. Establishing adequate vascular supply will be an essential component of cardiac regenerative strategies, and these findings raise exciting new strategies for therapeutic cardiac revascularization.

Abnormal sinoatrial node development resulting from disturbed vascular endothelial growth factor signaling

BACKGROUND

Sinus node dysfunction is frequently observed in patients with congenital heart disease (CHD). Variants in the Vascular Endothelial Growth Factor-A (VEGF) pathway are associated with CHD. In Vegf(120/120) mice, over-expressing VEGF120, a reduced sinoatrial node (SAN) volume was suggested. Aim of the study is to assess the effect of VEGF over-expression on SAN development and function.

METHODS

Heart rate was measured in Vegf(120/120) and wildtype (WT) embryos during high frequency ultrasound studies at embryonic day (E)12.5, 14.5 and 17.5 and by optical mapping at E12.5. Morphology was studied with several antibodies. SAN volume estimations were performed, and qualitative-PCR was used to quantify expression of genes in SAN tissues of WT and Vegf(120/120) embryos.

RESULTS

Heart rate was reduced in Vegf(120/120) compared with WT embryos during embryonic echocardiography (52 ± 17 versus 125 ± 31 beats per minute (bpm) at E12.5, p<0.001; 123 ± 37 vs 160 ± 29 bmp at E14.5, p=0.024; and 177 ± 30 vs 217 ± 34 bmp, at E17.5 p=0.017) and optical mapping (81 ± 5 vs 116 ± 8 bpm at E12.5; p=0.003). The SAN of mutant embryos was smaller and more vascularized, and showed increased expression of the fast conducting gap junction protein, Connexin43.

CONCLUSIONS

Over-expression of VEGF120 results in reduced heart rate and a smaller, less compact and hypervascularized SAN with increased expression of Connexin43. This indicates that VEGF is necessary for normal SAN development and function.

Coronary anomalies in mice with congenital heart defects

BACKGROUND

Coronary anomalies are frequently associated with congenital cardiac defects. Accordingly, we tested the hypothesis that the development of the tunica media of coronary arteries/arterioles is compromised in mice with cardiac defects of the outflow tract (persistent truncus arteriosus, double outlet right ventricle and transposition of the great arteries) by studying hearts of G7-9 generation mice bred from mutagenized mice caused by N-ethyl-N-nitrosourea. Mice were studied at embryonic days E16.5, E17.5, and postnatal days 1 and 11. Data were based on immunohistochemistry of serial sections.

RESULTS

In 21 of 24 mice with outflow tract defects, the development of smooth muscle in arteries and arterioles was retarded; most commonly arterioles had an incomplete layer of smooth muscle or in a few instances, lacked a tunica media. In this model, an absence of a coronary ostium occurred in only 2 mice, indicating that the mechanisms underlying the formation of coronary ostia and the recruitment and differentiation of vascular smooth muscle differ. Coronary fistulas were present in 20% and dilated vessels in 30% of the hearts with cardiac defects.

CONCLUSIONS

The data suggest that vascular smooth muscle recruitment and differentiation are not necessarily linked to other coronary anomalies, such as absence of a main coronary artery or branching patterns.

microRNA expression profiling of heart tissue during fetal development

microRNAs (miRNAs) are important both in early cardiogenesis and in the process of heart maturation. The aim of this study was to determine the stage-specific expression of miRNAs in human fetal heart in order to identify valuable targets for further study of heart defects. Affymetrix microarrays were used to obtain miRNA expression profiles from human fetal heart tissue at 5, 7, 9 and 23 weeks of gestation. To identify differentially expressed miRNAs at each time-point, linear regression analysis by the R limma algorithm was employed. Hierarchical clustering analysis was conducted with Cluster 3.0 software. Gene Ontology analysis was carried out for miRNAs from different clusters. Commonalities in miRNA families and genomic localization were identified, and the differential expression of selected miRNAs from different clusters was verified by quantitative polymerase chain reaction (qPCR). A total of 703 miRNAs were expressed in human fetal heart. Of these, 288 differentially expressed miRNAs represented 5 clusters with different expression trends. Several clustered miRNAs also shared classification within miRNA families or proximal genomic localization. qPCR confirmed the expression patterns of selected miRNAs. miRNAs within the 5 clusters were predicted to target genes vital for heart development and to be involved in cellular signaling pathways that affect heart structure formation and heart-associated cellular events. In conclusion, to the best of our knowledge, this is the first miRNA expression profiling study of human fetal heart tissue. The stage-specific expression of specific miRNAs suggests potential roles at distinct time-points during fetal heart development.

An unusual case of anomalous origin of the right coronary artery and hepatic focal nodular hyperplasia

Anomalous origin of the right coronary artery (ARCA) and focal nodular hyperplasia (FNH) are frequently reported in association with congenital heart abnormalities but not with each other. We propose that both conditions may share common origins in a maladative hyperplastic response to differential vascular flow due to developmental arterial malformations or aberrant Notch signalling during simultaneous gut and cardiac vasculorigenesis.

TGFβ and BMP signaling in cardiac cushion formation: lessons from mice and chicken

Cardiac cushion formation is crucial for both valvular and septal development. Disruption in this process can lead to valvular and septal malformations, which constitute the largest part of congenital heart defects. One of the signaling pathways that is important for cushion formation is the TGFβ superfamily. The involvement of TGFβ and BMP signaling pathways in cardiac cushion formation has been intensively studied using chicken in vitro explant assays and in genetically modified mice. In this review, we will summarize and discuss the role of TGFβ and BMP signaling components in cardiac cushion formation.

The arterial and cardiac epicardium in development, disease and repair

The importance of the epicardium covering the heart and the intrapericardial part of the great arteries has reached a new summit. It has evolved as a major cellular component with impact both in development, disease and more recently also repair potential. The role of the epicardium in development, its differentiation from a proepicardial organ at the venous pole (vPEO) and the differentiation capacities of the vPEO initiating cardiac epicardium (cEP) into epicardium derived cells (EPDCs) have been extensively described in recent reviews on growth and transcription factor pathways. In short, the epicardium is the source of the interstitial, the annulus fibrosus and the adventitial fibroblasts, and differentiates into the coronary arterial smooth muscle cells. Furthermore, EPDCs induce growth of the compact myocardium and differentiation of the Purkinje fibers. This review includes an arterial pole located PEO (aPEO) that provides the epicardium covering the intrapericardial great vessels. In avian and mouse models disturbance of epicardial outgrowth and maturation leads to a broad spectrum of cardiac anomalies with main focus on non-compaction of the myocardium, deficient annulus fibrosis, valve malformations and coronary artery abnormalities. The discovery that in disease both arterial and cardiac epicardium can again differentiate into EPDCs and thus reactivate its embryonic program and potential has highly broadened the scope of research interest. This reactivation is seen after myocardial infarction and also in aneurysm formation of the ascending aorta. Use of EPDCs for cell therapy show their positive function in paracrine mediated repair processes which can be additive when combined with the cardiac progenitor stem cells that probably share the same embryonic origin with EPDCs. Research into the many cell-autonomous and cell-cell-based capacities of the adult epicardium will open up new realistic therapeutic avenues.

NOing the heart: role of nitric oxide synthase-3 in heart development

Congenital heart disease is the most common birth defect in humans. Identifying factors that are critical to embryonic heart development could further our understanding of the disease and lead to new strategies of its prevention and treatment. Nitric oxide synthase-3 (NOS3) or endothelial nitric oxide synthase (eNOS) is known for many important biological functions including vasodilation, vascular homeostasis and angiogenesis. Over the past decade, studies from our lab and others have shown that NOS3 is required during heart development. More specifically, deficiency in NOS3 results in congenital septal defects, cardiac hypertrophy and postnatal heart failure. In addition, NOS3 is pivotal to the morphogenesis of major coronary arteries and myocardial capillary development. Interestingly, these effects of NOS3 are mediated through induction of transcription and growth factors that are crucial in the formation of coronary arteries. Finally, deficiency in NOS3 results in high incidences of bicuspid aortic valves, a disease in humans that often leads to complications with age including aortic valve stenosis or regurgitation, endocarditis, aortic aneurysm formation, and aortic dissection. In summary, these data suggest NOS3 plays a critical role in embryonic heart development and morphogenesis of coronary arteries and aortic valves.