Generation of human elongating multi-lineage organized cardiac gastruloids

Human elongating multi-lineage organized (EMLOC) gastruloid technology captures key aspects of trunk neurodevelopment including neural integration with cardiogenesis. We generate multi-chambered, contractile EMLOC gastruloids with integrated central and peripheral neurons using defined culture conditions and signaling factors. hiPSC colonies are primed by activating FGF and Wnt signaling pathways for co-induced lineages. EMLOC gastruloids are then initialized with primed cells in suspension culture using timed exposure to FGF2, HGF, IGF1, and Y-27632. Cardiogenesis is stimulated by FGF2, VEGF, and ascorbic acid. For complete details on the use and execution of this protocol, please refer to Olmsted and Paluh (2022).¹.

The roles of signaling pathways in cardiac regeneration

In recent years, knowledge of cardiac regeneration mechanisms has dramatically expanded. Regeneration can replace lost parts of organs, common among animal species. The heart is commonly considered an organ with terminal development, which has no reparability potential during post-natal life; however, some intrinsic regeneration capacity has been reported for cardiac muscle, which opens novel avenues in cardiovascular disease treatment. Different endogenous mechanisms were studied for cardiac repairing and regeneration in recent decades. Survival, proliferation, inflammation, angiogenesis, cell-cell communication, cardiomyogenesis, and anti-aging pathways are the most important mechanisms that have been studied in this regard. Several in vitro and animal model studies focused on proliferation induction for cardiac regeneration reported promising results. These studies have mainly focused on promoting proliferation signaling pathways and demonstrated various signaling pathways such as Wnt, PI3K/Akt, IGF-1, TGF-β, Hippo, and VEGF signaling cardiac regeneration. Therefore, in this review, we intended to discuss the connection between different critical signaling pathways in cardiac repair and regeneration.

The physiological and pathological functions of VEGFR3 in cardiac and lymphatic development and related diseases

Vascular endothelial growth factor receptors (VEGFRs) are part of the evolutionarily conserved VEGF signalling pathways that regulate the development and maintenance of the body's cardiovascular and lymphovascular systems. VEGFR3, encoded by the FLT4 gene, has an indispensable and well-characterized function in development and establishment of the lymphatic system. Autosomal dominant VEGFR3 mutations, that prevent the receptor functioning as a homodimer, cause one of the major forms of hereditary primary lymphoedema; Milroy disease. Recently, we and others have shown that FLT4 variants, distinct to those observed in Milroy disease cases, predispose individuals to Tetralogy of Fallot, the most common cyanotic congenital heart disease, demonstrating a novel function for VEGFR3 in early cardiac development. Here, we examine the familiar and emerging roles of VEGFR3 in the development of both lymphovascular and cardiovascular systems, respectively, compare how distinct genetic variants in FLT4 lead to two disparate human conditions, and highlight the research still required to fully understand this multifaceted receptor.

VEGF-A in Cardiomyocytes and Heart Diseases

The vascular endothelial growth factor (VEGF), a homodimeric vasoactive glycoprotein, is the key mediator of angiogenesis. Angiogenesis, the formation of new blood vessels, is responsible for a wide variety of physio/pathological processes, including cardiovascular diseases (CVD). Cardiomyocytes (CM), the main cell type present in the heart, are the source and target of VEGF-A and express its receptors, VEGFR1 and VEGFR2, on their cell surface. The relationship between VEGF-A and the heart is double-sided. On the one hand, VEGF-A activates CM, inducing morphogenesis, contractility and wound healing. On the other hand, VEGF-A is produced by CM during inflammation, mechanical stress and cytokine stimulation. Moreover, high concentrations of VEGF-A have been found in patients affected by different CVD, and are often correlated with an unfavorable prognosis and disease severity. In this review, we summarized the current knowledge about the expression and effects of VEGF-A on CM and the role of VEGF-A in CVD, which are the most important cause of disability and premature death worldwide. Based on clinical studies on angiogenesis therapy conducted to date, it is possible to think that the control of angiogenesis and VEGF-A can lead to better quality and span of life of patients with heart disease.

Defective coronary vessel organization and reduction of VEGF-A in mouse embryonic hearts with gestational mild hypoxia

BACKGROUND

Vasculature is formed by responding to homeostatic tissue demands including in developing hearts. Hypoxia generally stimulates vascular formation in which vascular endothelial growth factor A (VEGF-A) plays a critical role. Gestational hypoxia increases the risk of low intrauterine growth and low birth weight, both of which are known to increase the risk of the fetus developing cardiovascular defects. In fact, continuous gestational mild hypoxia (14% O₂ ) from the mid-embryonic stage causes cardiac anomalies accompanied by a thinning compact layer in mice in vivo. Because coronary vasculature formation is necessary for compact layers to thicken, we hypothesized that defective coronary vessel organization is related to the thinning compact layer under gestational hypoxia conditions.

RESULTS

Continuous gestational mild hypoxia (14% O₂ ) applied from embryonic day 10.5 (E10.5) reduced the expression of VEGF-A mRNA and proteins by over 60% in E12.5 hearts relative to control normoxic hearts. Formation of CD31-positive vascular plexus, blood islands, and microvessels in embryonic ventricles were stunted by gestational hypoxia compared to control E12.5 hearts.

CONCLUSIONS

Our results suggest that mild hypoxia (14% O₂ ) does not induce coronary vessel organization or VEGF-A expression in developing mouse hearts, opposing the general effects of hypoxia-triggering vascular organization and VEGF-A expression.

Genome and epigenome analysis of monozygotic twins discordant for congenital heart disease

BACKGROUND

Congenital heart disease (CHD) is the leading non-infectious cause of death in infants. Monozygotic (MZ) twins share nearly all of their genetic variants before and after birth. Nevertheless, MZ twins are sometimes discordant for common complex diseases. The goal of this study is to identify genomic and epigenomic differences between a pair of twins discordant for a form of congenital heart disease, double outlet right ventricle (DORV).

RESULTS

A monoamniotic monozygotic (MZ) twin pair discordant for DORV were subjected to genome-wide sequencing and methylation analysis. We identified few genomic differences but 1566 differentially methylated regions (DMRs) between the MZ twins. Twenty percent (312/1566) of the DMRs are located within 2 kb upstream of transcription start sites (TSS), containing 121 binding sites of transcription factors. Particularly, ZIC3 and NR2F2 are found to have hypermethylated promoters in both the diseased twin and additional patients suffering from DORV.

CONCLUSIONS

The results showed a high correlation between hypermethylated promoters at ZIC3 and NR2F2 and down-regulated gene expression levels of these two genes in patients with DORV compared to normal controls, providing new insight into the potential mechanism of this rare form of CHD.

MicroRNA Profiling of Transgenic Mice with Myocardial Overexpression of Nucleolin

BACKGROUND

Nucleolin (NCL) is the most abundant RNA-binding protein in the cell nucleolus and plays an important role in chromatin stability, ribosome assembly, ribosomal RNA maturation, ribosomal DNA transcription, nucleocytoplasmic transport, and regulation of RNA stability and translation efficiency. In addition to its anti-apoptotic properties, the underlying mechanisms associated with NCL-related roles in different cellular processes remain unclear. In this study, the effect of NCL on microRNA (miRNA) expression was evaluated by generating transgenic mice with myocardial overexpression of NCL and by analyzing microarrays of mature and precursor miRNAs from mice.

METHODS

Using microinjection of alpha-MyHc clone 26-NCL plasmids, we generated transgenic mice with myocardial overexpression of NCL firstly, and then mature and precursor miRNAs expression profiles were analyzed in NCL transgenic mice (n = 3) and wild-type (WT) mice (n = 3) by miRNA microarrays. Statistical Package for the Social Sciences version 16.0 software (SPSS, Inc., Chicago, IL, USA) was used to perform Student's t-test, and statistical significance was determined at P < 0.05.

RESULTS

Several miRNAs were found to be differentially expressed, of which 11 were upregulated and 4 were downregulated in transgenic mice with myocardial overexpression of NCL compared to those in WT mice. Several differentially expressed miRNAs were subsequently confirmed and quantified by real-time quantitative reverse transcription-polymerase chain reaction. Bioinformatics analysis was used for the prediction of miRNA targets. Furthermore, in vitro experiments showed that NCL regulated miR-21 expression following hydrogen peroxide preconditioning.

CONCLUSIONS

Myocardial-protection mechanisms exerted by NCL might be mediated by the miRNAs identified in this study.

VEGFB-VEGFR1 ameliorates Ang II-induced cardiomyocyte hypertrophy through Ca2+ -mediated PKG I pathway

In response to assorted stimuli, the heart will develop into cardiomyocyte hypertrophy, but sustained cardiomyocyte hypertrophy will finally lead to heart failure. This research is aimed to examine the effect of VEGFB on cardiomyocyte hypertrophy by using the cardiomyocyte-derived cell line H9C2 of cultured rates. It turns out that VEGFB can positively prevent the Ang II-induced rising in the size of cardiomyocyte as well as reduce Ang II-induced mRNA and protein levels of β-MHC (β-myosin heavy chain), BNP (brain natriuretic peptide), and ANP (atrial natriuretic peptide). Moreover, VEGFB can regulate the decline of the Ang II-induced rising in Ca²⁺ . After VEGFR1 knockdown, these effects of VEGFB were partially reversed. Moreover, VEGFB attenuated the suppression of PKG I, p-VASP, and RGS2 caused by Ang II; whereas VEGFR1 knockdown partially abolished the indicated effect of VEGFB. In a word, the effect of VEGFB on relevant downstream targets and the pathways of PKG I by VEGFR1 may explain its efficacy on cardiomyocyte hypertrophy. Thus, it can be suggested that it is feasible to apply VEGFB-VEGFR1 for reducing the symptoms of cardiomyocyte hypertrophy.

Anticancer therapy-induced vascular toxicity: VEGF inhibition and beyond

Cardiotoxicity induced by chemotherapeutic agents and radiotherapy is a growing problem. In recent years, an increasing number of new drugs with targeted action have been designed. These molecules, such as monoclonal antibodies and tyrosine kinase inhibitors, can cause different type of toxicities compared to traditional chemotherapy. However, they can also cause cardiac complications such as heart failure, arterial hypertension, QT interval prolongation and arrhythmias. Currently, a field of intense research is the vascular toxicity induced by new biologic drugs, particularly those which inhibit vascular endothelial growth factor (VEGF) and its receptor (VEGF-R) and other tyrosine kinases. In this review, we aim at focusing on the problem of vascular toxicity induced by new targeted therapies, chemotherapy and radiotherapy, and describe the main mechanisms and emphasizing the importance of early diagnosis of vascular damage, in order to prevent clinical complications.

Pregnancy mitigates cardiac pathology in a mouse model of left ventricular pressure overload

In Western countries heart disease is the leading cause of maternal death during pregnancy. The effect of pregnancy on the heart is difficult to study in patients with preexisting heart disease. Since experimental studies are scarce, we investigated the effect of pressure overload, produced by transverse aortic constriction (TAC) in mice, on the ability to conceive, pregnancy outcome, and maternal cardiac structure and function. Four weeks of TAC produced left ventricular (LV) hypertrophy and dysfunction with marked interstitial fibrosis, decreased capillary density, and induced pathological cardiac gene expression. Pregnancy increased relative LV and right ventricular weight without affecting the deterioration of LV function following TAC. Surprisingly, the TAC-induced increase in relative heart and lung weight was mitigated by pregnancy, which was accompanied by a trend towards normalization of capillary density and natriuretic peptide type A expression. Additionally, the combination of pregnancy and TAC increased the cardiac phosphorylation of c-Jun, and STAT1, but reduced phosphoinositide 3-kinase phosphorylation. Finally, TAC did not significantly affect conception rate, pregnancy duration, uterus size, litter size, and pup weight. In conclusion, we found that, rather than exacerbating the changes associated with cardiac pressure overload, pregnancy actually attenuated pathological LV remodeling and mitigated pulmonary congestion, and pathological gene expression produced by TAC, suggesting a positive effect of pregnancy on the pressure-overloaded heart.

The involvement of vimentin in copper-induced regression of cardiomyocyte hypertrophy

Vimentin is critically involved in the VEGFR-1 mediated activation of the PKG-1 signaling pathway, leading to the regression of cardiomyocyte hypertrophy.

Network-based association of hypoxia-responsive genes with cardiovascular diseases

Molecular oxygen is indispensable for cellular viability and function. Hypoxia is a stress condition in which oxygen demand exceeds supply. Low cellular oxygen content induces a number of molecular changes to activate regulatory pathways responsible for increasing the oxygen supply and optimizing cellular metabolism under limited oxygen conditions. Hypoxia plays critical roles in the pathobiology of many diseases, such as cancer, heart failure, myocardial ischemia, stroke, and chronic lung diseases. Although the complicated associations between hypoxia and cardiovascular (and cerebrovascular) diseases (CVD) have been recognized for some time, there are few studies that investigate their biological link from a systems biology perspective. In this study, we integrate hypoxia genes, CVD genes, and the human protein interactome in order to explore the relationship between hypoxia and cardiovascular diseases at a systems level. We show that hypoxia genes are much closer to CVD genes in the human protein interactome than that expected by chance. We also find that hypoxia genes play significant bridging roles in connecting different cardiovascular diseases. We construct an hypoxia-CVD bipartite network and find several interesting hypoxia-CVD modules with significant Gene Ontology (GO) similarity. Finally, we show that hypoxia genes tend to have more CVD interactors in the human interactome than in random networks of matching topology. Based on these observations, we can predict novel genes that may be associated with CVD. This network-based association study gives us a broad view of the relationships between hypoxia and cardiovascular diseases and provides new insights into the role of hypoxia in cardiovascular biology.

In-silico screening and in-vitro validation of Vascular Endothelial Growth Factor Receptor-2 (VEGFR-2) inhibitors

VEGFR-2 tyrosine kinase receptor draws attention of the scientific fraternity in drug discovery for its important role in cancer, cardiopulmonary, cardiovascular diseases etc. Hence there is a need for novel VEGFR-2 inhibitors screening and testing for their biological activities. The 3D-structure was collected from PDB and stability was checked by using WHATIF and PROCHECK programs and subjected for virtual screening on Zinc database. We used virtual screening method to screen new VEGFR-2 blocker molecules based on their binding energies and then docked with active site on the receptor with the help of AUTODOCK software. Based on the results obtained top three molecules (VRB1-3) were selected and tested in Cardiomyocytes H9c2 cells for cell viability under hypoxic condition. The invitro studies showed VRB2 as the best molecule among the selected three molecules as well as with a standard commercial drug Sunitinib.

Toxic cardiomyopathy leading to fatal acute cardiac failure related to vandetanib: a case report with histopathological analysis

CONTEXT

Medullary thyroid carcinoma (MTC) accounts for 3-4% of all malignant thyroid neoplasias. Vandetanib, a tyrosine kinase inhibitor (TKI) targeting vascular endothelial growth factor receptor 2, epidermal growth factor receptor, and RET, has been approved by the FDA for the treatment of locally advanced or metastatic MTC. The heart seems to be particularly susceptible to adverse effects associated with TKI therapy, and virtually all TKIs have been associated with cardiovascular events.

CLINICAL PRESENTATION

We report the case of a patient with metastatic MTC who was enrolled in the Phase III clinical study (NCT00410761) and presented a favorable response to vandetanib therapy, displaying marked decrease in the level of serologic tumor markers and shrinkage of metastatic lesions. After 14 months of therapy, the patient developed a fatal cardiac failure. Myocardial infarction was excluded by serial measurements of specific cardiac markers (serial troponin-T measurements varied from 0.037 to 0.042 ng/ml) and serologic tests for Chaga's disease were negative. Postmortem examination of the heart revealed cardiomyocyte hypertrophy and marked myocyte degeneration in the subendocardial zones and papillary muscles of the myocardium. These pathological changes are similar to those observed in TKI-treated rats and are suggestive of drug-induced cardiotoxicity.

CONCLUSION

This case illustrates a previously unreported serious vandetanib-related adverse effect and highlights the need for close monitoring of patients under TKI therapy in order to identify early signs of congestive heart failure or myocardium damage.

CXCR4 gene transfer prevents pressure overload induced heart failure

Stem cell and gene therapies are being pursued as strategies for repairing damaged cardiac tissue following myocardial infarction in an attempt to prevent heart failure. The chemokine receptor-4 (CXCR4) and its ligand, CXCL12, play a critical role in stem cell recruitment post-acute myocardial infarction. Whereas progenitor cell migration via the CXCL12/CXCR4 axis is well characterized, little is known about the molecular mechanisms of CXCR4 mediated modulation of cardiac hypertrophy and failure. We used gene therapy to test the effects of CXCR4 gene delivery on adverse ventricular remodeling due to pressure overload. We assessed the effect of cardiac overexpression of CXCR4 during trans-aortic constriction (TAC) using a cardiotropic adeno-associated viral vector (AAV9) carrying the CXCR4 gene. Cardiac overexpression of CXCR4 in mice with pressure overload prevented ventricular remodeling, preserved capillary density and maintained function as determined by echocardiography and in vivo hemodynamics. In isolated adult rat cardiac myocytes, CXCL12 treatment prevented isoproterenol induced hypertrophy and interrupted the calcineurin/NFAT pathway. Finally, a complex involving the L-type calcium channel, β2-adrenoceptor, and CXCR4 (Cav1.2/β2AR/CXCR4) was identified in healthy cardiac myocytes and was shown to dissociate as a consequence of heart failure. CXCR4 administered to the heart via gene transfer prevents pressure overload induced heart failure. The identification of CXCR4 participation in a Cav1.2-β2AR regulatory complex provides further insight into the mechanism by which CXCR4 modulates calcium homeostasis and chronic pressure overload responses in the cardiac myocyte. Together these results suggest that AAV9.CXCR4 gene therapy is a potential therapeutic approach for congestive heart failure.

Regression of pathological cardiac hypertrophy: signaling pathways and therapeutic targets

Pathological cardiac hypertrophy is a key risk factor for heart failure. It is associated with increased interstitial fibrosis, cell death and cardiac dysfunction. The progression of pathological cardiac hypertrophy has long been considered as irreversible. However, recent clinical observations and experimental studies have produced evidence showing the reversal of pathological cardiac hypertrophy. Left ventricle assist devices used in heart failure patients for bridging to transplantation not only improve peripheral circulation but also often cause reverse remodeling of the geometry and recovery of the function of the heart. Dietary supplementation with physiologically relevant levels of copper can reverse pathological cardiac hypertrophy in mice. Angiogenesis is essential and vascular endothelial growth factor (VEGF) is a constitutive factor for the regression. The action of VEGF is mediated by VEGF receptor-1, whose activation is linked to cyclic GMP-dependent protein kinase-1 (PKG-1) signaling pathways, and inhibition of cyclic GMP degradation leads to regression of pathological cardiac hypertrophy. Most of these pathways are regulated by hypoxia-inducible factor. Potential therapeutic targets for promoting the regression include: promotion of angiogenesis, selective enhancement of VEGF receptor-1 signaling pathways, stimulation of PKG-1 pathways, and sustention of hypoxia-inducible factor transcriptional activity. More exciting insights into the regression of pathological cardiac hypertrophy are emerging. The time of translating the concept of regression of pathological cardiac hypertrophy to clinical practice is coming.

Copper stimulates growth of human umbilical vein endothelial cells in a vascular endothelial growth factor-independent pathway

Studies in vivo have shown that dietary copper (Cu) supplementation reverses pressure overload-induced cardiac hypertrophy in a mouse model, which is vascular endothelial growth factor (VEGF)-dependent and correlates with enhanced angiogenesis. Because Cu stimulation of endothelial cell growth and differentiation would play a critical role in angiogenesis, the present study was undertaken to examine the effect of Cu on growth of human umbilical vein endothelial cells (HUVECs) in cultures. The HUVECs were treated with CuSO4 at a final concentration of 5 μmol/L Cu element in cultures or with a Cu chelator, tetraethylenepentamine (TEPA), at a final concentration of 25 μmol/L in cultures. Cell growth and Cu effect on cell cycle were determined. In addition, the effect of Cu on VEGF and endothelial nitric oxide synthase (eNOS) mRNA levels was determined, and anti-VEGF antibody and siRNA targeting eNOS were applied to determine the role of VEGF or eNOS in the Cu effect on cell growth. Cu significantly stimulated and TEPA significantly inhibited cell growth, and the TEPA effect was blocked by excess Cu. Cu increased the number of cells in the S phase and correspondingly decreased the number in the G1 phase. Interestingly, Cu did not increase the level of VEGF mRNA, but significantly increased eNOS mRNA. Furthermore, neutralizing VEGF by anti-VEGF antibody did not suppress Cu stimulation of cell growth. However, siRNA targeting eNOS completely blocked Cu reversal of TEPA inhibition of cell growth. The data demonstrate that Cu stimulation of HUVEC cell growth is VEGF-independent, but eNOS-dependent.

Molecular mechanisms of hypertension and heart failure due to antiangiogenic cancer therapies

Targeted antiangiogenic cancer therapies have revolutionized the treatment of highly vascularized cancers such as metastatic renal cell carcinoma and gastrointestinal stromal tumors. Such agents act by inhibiting the actions of proangiogenic growth factors and their receptor tyrosine kinases, which are known to be overexpressed in cancer. However, these factors also play an important role in normal cardiovascular physiology. This article summarizes the incidences of cardiovascular toxicities (namely hypertension and heart failure) associated with the most commonly used antiangiogenic therapies, and then presents data from preclinical and clinical studies to provide some insight into the underlying molecular mechanisms.