Vascular and Lymphatic Malformations: Perspectives From Human and Vertebrate Studies.

Vascular malformations, affecting ≈1% to 1.5% of the population, comprise a spectrum of developmental patterning defects of capillaries, arteries, veins, and/or lymphatics. The majority of vascular malformations occur sporadically; however, inherited malformations exist as a part of complex congenital diseases. The malformations, ranging from birthmarks to life-threatening conditions, are present at birth, but may reveal signs and symptoms-including pain, bleeding, disfigurement, and functional defects of vital organs-in infancy, childhood, or adulthood. Vascular malformations often exhibit recurrent patterns at affected sites due to the lack of curative treatments. This review series provides a state-of-the-art assessment of vascular malformation research at basic, clinical, genetic, and translational levels.

Novel Mechanisms of Exosome-Mediated Phagocytosis of Dead Cells in Injured Heart.

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Mito-targeted antioxidant prevents cardiovascular remodelling in spontaneously hypertensive rat by modulation of energy metabolism.

Hypertension induced left ventricular hypertrophy (LVH) augments the risk of cardiovascular anomalies. Mitochondrial alterations result in oxidative stress, accompanied by decrease in fatty acid oxidation, leading to the activation of the hypertrophic program. Targeted antioxidants are expected to reduce mitochondrial reactive oxygen species more effectively than general antioxidants. This study was designed to assess whether the mito-targeted antioxidant, Mito-Tempol (Mito-TEMP) is more effective than the general oxidant, Tempol (TEMP) in reduction of hypertension and hypertrophy and prevention of shift in cardiac energy metabolism. Spontaneously hypertensive rats were administered either TEMP (20 mg/kg/day) or Mito-TEMP (2 mg/kg/day) intraperitoneally for 30 days. Post treatment, animals were subjected to 2D-echocardiography. Myocardial lysates were subjected to RPLC - LTQ-Orbitrap-MS analysis. Mid-ventricular sections were probed for markers of energy metabolism and fibrosis. The beneficial effect on cardiovascular structure and function was significantly higher for Mito-TEMP. Increase in mitochondrial antioxidants and stimulation of fatty acid metabolism; with significant improvement in cardiovascular function was apparent in spontaneously hypertensive rats (SHR) treated with Mito-TEMP. The study indicates that Mito-TEMP is superior to its non- targeted isoform in preventing hypertension induced LVH, and the beneficial effects on heart are possibly mediated by reversal of metabolic remodelling.

Extracellular vesicle interplay in cardiovascular pathophysiology.

Extracellular vesicles (EVs) are nanosized lipid bilayer-delimited particles released from cells that mediate intercellular communications and play a pivotal role in various physiological and pathological processes. Subtypes of EVs may include plasma membrane ectosomes or microvesicles and endosomal origin exosomes, although functional distinctions remain unclear. EVs carry cargo proteins, nucleic acids (RNA and DNA), lipids, and metabolites. By presenting or transferring this cargo to recipient cells, EVs can trigger cellular responses. We summarize contemporary understanding of EV biogenesis, composition, and function, with an emphasis on the role of EVs in the cardiovascular system. In addition, we outline the functional relevance of EVs in cardiovascular pathophysiology, further highlighting their potential for diagnostic and therapeutic applications.

Targeting exosome-associated human antigen R attenuates fibrosis and inflammation in diabetic heart.

RNA-binding proteins like human antigen R (HuR) are key regulators in post-transcriptional control of gene expression in several pathophysiological conditions. Diabetes adversely affects monocyte/macrophage biology and function. It is not known whether diabetic milieu affects cellular/exosome-HuR and its implications on cardiac inflammation and fibrosis. Here, we evaluate in vitro and in vivo effects of diabetic milieu on macrophage cellular/exosome-HuR, alterations in intercellular cross talk with fibroblasts, and its impact on cardiac remodeling. Human failing hearts show higher HuR levels. Diabetic milieu activates HuR expression in cardiac- and cultured bone marrow-derived macrophages (BMMØ) and stimulates HuR nuclear-to-cytoplasmic translocation and exosome transfer. Exosomes from macrophages exposed to diabetic milieu (high glucose or db/db mice) significantly increase inflammatory and profibrogenic responses in fibroblast (in vitro) and cardiac fibrosis in mice. Intriguingly, Exo-HuR deficiency (HuR knockdown in macrophage) abrogates the above effects. In diabetic mice, macrophage depletion followed by reconstitution with BMMØ-derived HuR-deficient exosomes inhibits angiotensin II-induced cardiac fibrosis response and preserves left ventricle function as compared to control-exosome administration. To the best of our knowledge, this is the first study to demonstrate that diabetes activates BMMØ HuR expression and its transfer into exosome. The data suggest that HuR might be targeted to alleviate macrophage dysfunction and pathological fibrosis in diabetes.

Multifaceted role of cardiovascular biomarkers.

Cardiovascular diseases, a global health issue, claim the lives of many every year. Lifestyle changes and genetic predisposition are the key drivers for the development of CVDs. In many of the patients, the disease is detected at the end stage making heart transplantation the only treatment option. Hence every attempt should be made to identify the risk at an early stage and initiate preventive measures to improve the quality of their life. Biomarkers are one of the critical factors that aid in the early diagnosis of CVDs. More specific and highly sensitive biomarkers have been discovered lately and have been employed for prognosis and diagnosis of CVDs. The present review briefs about the various categories of cardiovascular biomarkers with emphasis on novel biomarkers and discusses the biomarkers employed for different purposes in CVDs. The biomarkers have also helped in identifying COVID-19 patients with increased risk for developing cardiovascular complications. Being non-invasive makes biomarkers advantageous over other methods for evaluating the pathophysiological status of CVDs.

Histamine 2 receptors in cardiovascular biology: A friend for the heart.

Undermining new mediators involved in the development and progression of cardiovascular diseases (CVDs) is vital for better disease management. Existing studies implicate a crucial role for inflammation and inflammatory cells, particularly mast cells, in cardiac diseases. Interestingly, the mast cell mediator, histamine, and its receptors profoundly impact the pathophysiology of the heart, resulting in hypertension-induced cardiac hypertrophy and other cardiac anomalies. In this review, we provide a detailed description of mast cell activation, mediators, and histamine receptors, with a particular focus on histamine 2 receptors (H2Rs). Preclinical and clinical studies using histamine receptor antagonists report improvement in cardiac function. Insights into the precise function of histamine receptors will aid in developing novel therapies and pave the way for repurposing antihistamines for cardiovascular diseases.

Involvement of Histamine 2 Receptor in Alpha 1 Adrenoceptor Mediated Cardiac Hypertrophy and Oxidative Stress in H9c2 Cardio Myoblasts.

Despite the involvement of ɑ1adrenergic (ɑ1AR) and Histamine 2 receptors (H2R) in cardiac hypertrophy (CH), their relationship is yet to be studied. Our study investigated interrelationship between them using in vitro CH model. H9c2 cardiomyoblasts were exposed to phenylephrine (ɑ1AR agonist-50 µM) in the presence, the absence of famotidine (H2R antagonist-10 µM) and BAY 11-7082 (NF-kB inhibitor-10 µM). The impact of ɑ1AR stimulation on H2R expression and oxidative stress was assessed. Hypertrophic indices were assessed from activities of enzymatic mediators of cardiac hypertrophy, total protein content, BNP levels and cell volume. Additionally, the inverse agonistic property of famotidine and NFkB activity was also studied. ɑ1AR-induced H2R expression, oxidative stress and hypertrophic indices were significantly abolished by famotidine and pharmacological inhibitor of NFkB. Increase in constitutive activity of H2R was noticed correlating with increased receptor population. These results suggest involvement of NFkB-mediated upregulation of H2R in ɑ1AR-mediated CH.

Cardiovascular Changes Associated with Hypertensive Heart Disease and Aging.

Cardiovascular diseases are the leading cause of mortality and morbidity worldwide and account for more than 17.9 million deaths (World Health Organization report). Hypertension and aging are two major risk factors for the development of cardiac structural and functional abnormalities. Hypertension, or elevated blood pressure, if left untreated can result in myocardial hypertrophy leading to heart failure (HF). Left ventricular hypertrophy consequent to pressure overload is recognized as the most important predictor of congestive HF and sudden death. The pathological changes occurring during hypertensive heart disease are very complex and involve many cellular and molecular alterations. In contrast, the cardiac changes that occur with aging are a slow but life-long process and involve all of the structural components in the heart and vasculature. However, these structural changes in the cardiovascular system lead to alterations in overall cardiac physiology and function. The pace at which these pathophysiological changes occur varies between individuals owing to many genetic and environmental risk factors. This review highlights the molecular mechanisms of cardiac structural and functional alterations associated with hypertension and aging.

Nano-Vesicle (Mis)Communication in Senescence-Related Pathologies.

Extracellular vesicles are a heterogeneous group of cell-derived membranous structures comprising of exosomes, apoptotic bodies, and microvesicles. Of the extracellular vesicles, exosomes are the most widely sorted and extensively explored for their contents and function. The size of the nanovesicular structures (exosomes) range from 30 to 140 nm and are present in various biological fluids such as saliva, plasma, urine etc. These cargo-laden extracellular vesicles arise from endosome-derived multivesicular bodies and are known to carry proteins and nucleic acids. Exosomes are involved in multiple physiological and pathological processes, including cellular senescence. Exosomes mediate signaling crosstalk and play a critical role in cell-cell communications. Exosomes have evolved as potential biomarkers for aging-related diseases. Aging, a physiological process, involves a progressive decline of function of organs with a loss of homeostasis and increasing probability of illness and death. The review focuses on the classic view of exosome biogenesis, biology, and age-associated changes. Owing to their ability to transport biological information among cells, the review also discusses the interplay of senescent cell-derived exosomes with the aging process, including the susceptibility of the aging population to COVID-19 infections.

Histone deacetylases 1 and 2 silence cryptic transcription to promote mitochondrial function during cardiogenesis.

Cryptic transcription occurs widely across the eukaryotic genome; however, its regulation during vertebrate development is not understood. Here, we show that two class I histone deacetylases, Hdac1 and Hdac2, silence cryptic transcription to promote mitochondrial function in developing murine hearts. Mice lacking Hdac1 and Hdac2 in heart exhibit defective developmental switch from anaerobic to mitochondrial oxidative phosphorylation (OXPHOS), severe defects in mitochondrial mass, mitochondrial function, and complete embryonic lethality. Hdac1/Hdac2 promotes the transition to OXPHOS by enforcing transcriptional fidelity of metabolic gene programs. Mechanistically, Hdac1/Hdac2 deacetylates histone residues including H3K23, H3K14, and H4K16 to suppress cryptic transcriptional initiation within the coding regions of actively transcribed metabolic genes. Thus, Hdac1/2-mediated epigenetic silencing of cryptic transcription is essential for mitochondrial function during early vertebrate development.

Column-Free Method for Isolation and Culture of C-Kit Positive Stem Cells from Atrial Explants.

Ever since the discovery of stem cells, their isolation from tissues and expansion in culture has been extensively studied due to its potential for therapeutic application. The magnetic-assisted cell sorting (MACS) method is the most widely used technique for the sorting of cells based on their cell surface markers. Though effective, the major drawbacks are high cost and the requirement for the frequent replacement of the columns. In the column-free method, the cells are sorted using the same principle of immune-magnetic isolation but does not require magnetic columns, making it cost-effective. The isolation of c-kit+ stem cells from atrial explants using column-free magnet is found to be efficient and yields homogenous population of stem cells. This method saves time and labor and is economical when working with large sample sizes.

Protective effect of antioxidant Tempol on cardiac stem cells in chronic pressure overload hypertrophy.

AIMS: Cardiac hypertrophy, an independent risk factor for cardiac failure; is associated with oxidative stress. Decline in the proportion of healthy cardiac stem cells (CSCs), possibly mediated by oxidative stress can lead to cardiac failure. The present study was carried out to examine the hypothesis that reduction of oxidative stress restores CSC efficiency and prevents progressive cardiac remodelling. MATERIALS AND METHODS: Six-month old Spontaneously hypertensive rats (SHR) were supplemented with the antioxidant Tempol (20 mg/kg/day) for 14 days. The effect of Tempol on blood pressure and heart were assessed in SHR. Cardiac stem cells were isolated from atrial explants and expanded in culture for assessment of stem cell characteristics. Intracellular reactive oxygen species (ROS), proliferation, migration and senescence were evaluated in cultured atrial CSCs. KEY FINDINGS: Tempol treatment reduced blood pressure, regressed cardiac hypertrophy and reduced oxidative stress in SHR. Compared to Wistar rat, the efficiency of CSCs was significantly compromised in SHR. Tempol reduced intracellular ROS and restored migration potential and proliferative capacity along with reduction of senescent CSCs and expression of senescence proteins p16ink4a and p21. SIGNIFICANCE: Restoration of functional efficiency of CSCs by antioxidants signifies the role of oxidative stress in deterioration of stem cell attributes in the hypertrophic heart. The observations envisage the use of antioxidants as adjuvant medication for maintaining a healthy stem cell population, which can in-turn prevent progressive cardiac remodelling, a major determinant of cardiac failure.

Modulation of cardiac stem cell characteristics by metoprolol in hypertensive heart disease.

Cardiac stem cells (CSCs) play a vital role in cardiac remodeling. Uncontrolled hypertension leads to cardiac hypertrophy, followed by cardiac failure. Pathological remodeling is associated with enhanced oxidative stress. Decreased cardiac stem cell efficiency is speculated in heart diseases. Maintaining a healthy stem cell population is essential for preventing progressive cardiac remodeling. Some anti-hypertensive drugs are cardioprotective. However, the effect of these drugs on CSCs has not been investigated. Metoprolol is a cardioprotective anti-hypertensive agent. To examine whether metoprolol can prevent the deterioration of CSC efficiency, spontaneously hypertensive rats (SHRs) were treated with this drug, and the effects on stem cell function were evaluated. Six-month-old male SHRs were treated with metoprolol (50 mg × kg-1per day) for 2 months. The effectiveness of the treatment at reducing blood pressure and reducing hypertrophy was ensured, and the animals were killed. Cardiac stem cells were isolated from the atrial tissue, and the effect of metoprolol on stem cell migration, proliferation, differentiation, and survival was evaluated by comparing the treated SHRs with untreated SHRs and normotensive Wistar rats. Compared to the Wistar rats, the SHR rats presented with a decrease in stem cell migration and proliferation and an increase in intracellular oxidative stress and senescence. Treating SHRs with metoprolol increased CSC migration and proliferation potential and stemness retention. Cellular senescence and oxidative stress were reduced. The attributes of stem cells from the metoprolol-treated SHRs were comparable to those of the Wistar rats. The restoration of stem cell efficiency is expected to prevent hypertension-induced progressive cardiac remodeling.

Association of histamine with hypertension-induced cardiac remodeling and reduction of hypertrophy with the histamine-2-receptor antagonist famotidine compared with the beta-blocker metoprolol.

The association of histamine with adverse cardiac remodeling in chronic pressure overload has not received much attention. A pilot study in spontaneously hypertensive rats (SHRs) indicated a reduction of left ventricular hypertrophy (LVH) with a histamine-2-receptor (H2R) antagonist (famotidine). This finding prompted a detailed investigation of temporal variation in myocardial histamine and H2R expression and the cardiovascular response to H2R antagonism compared with that of the conventional beta-blocker metoprolol. Reduction of LVH is known to reduce the risk of adverse cardiovascular events. The myocardial histamine content and H2R expression increased with age in SHRs but not in normotensive Wistar rats. The cardiovascular response to famotidine (30 mg kg-1) was compared with that of metoprolol (50 mg kg-1) in 6-month-old male SHRs treated for 60 days. The decrease in diastolic blood pressure and improvement in cardiac function induced by famotidine and metoprolol were comparable. Both treatments caused the regression of LVH as assessed from the hypertrophy index, histomorphometry, B type natriuretic peptide (BNP), pro-collagen 1, and hydroxyproline levels. Calcineurin-A expression (marker of pathological remodeling) decreased, and Peroxiredoxin-3 expression (mitochondrial antioxidant) increased in response to the treatments. The myocardial histamine levels decreased with the treatments. The age-dependent increase in myocardial histamine and H2R in the SHRs signifies their association with progressive cardiac remodeling. The regression of LVH and improvement in cardiac function by famotidine further demonstrates the role of histamine in cardiac remodeling. Hypertrophy of cultured cardiac cells upon exposure to histamine and the H2R agonist amthamine substantiates the role of histamine in cardiac remodeling. The cardiovascular response to famotidine is comparable to that of metoprolol, suggesting repurposing of H2R antagonists for the management of hypertensive heart disease.

Accelerated decline in cardiac stem cell efficiency in Spontaneously hypertensive rat compared to normotensive Wistar rat.

Cardiac hypertrophy is recognized as an independent risk factor for cardiac failure. Efficient management of hypertensive heart disease requires identification of factors that can possibly mediate the transition from hypertrophy to failure. Resident cardiac stem cells have a prominent role in the maintenance of cardiac tissue homeostasis. Decline in the proportion of healthy cardiac stem cells (CSCs) can affect tissue regeneration. In pathological conditions, apart from natural aging, an adverse microenvironment can lead to decrease in efficiency of CSCs. A systematic analysis of cardiac stem cell characteristics in pathological conditions has not been reported so far. Therefore, this study was designed with the objective of examining the age associated variation in stem cell attributes of Spontaneously hypertensive rat (SHR) in comparison with normotensive Wistar rat. Spontaneously hypertensive rat was used as the experimental model since the cardiac remodeling resembles the clinical course of hypertensive heart disease. CSCs were isolated from atrial explants. Stem cell attributes were assessed in 1-week, 6, 12 and 18-month-old male SHR, in comparison with age matched Wistar rats. In 1-week-old pups, stem cell attributes of SHR and Wistar were comparable. Migration potential, proliferative capacity, TERT expression, telomerase activity and the proportion of c-kit+ cells decreased with age, both in SHR and Wistar. DNA damage and the proportion of senescent CSCs increased with age both in SHR and Wistar rats. Age associated increase was observed in the oxidative stress of stem cells, possibly mediated by the enhanced oxidative stress in the microenvironment. The changes were more pronounced in SHR, and as early as six months of age, there was significant decrease in efficiency of CSCs of SHR compared to Wistar. The density of healthy CSCs determined as a fraction of the differentiated cells was remarkably low in 18-month-old SHR. Age associated decrease in functionally efficient CSCs was therefore accelerated in SHR. Considering the vital role of CSCs in the maintenance of a healthy myocardium, decrease in functionally efficient CSCs can be a precipitating factor in pathological cardiac remodeling. Elevated ROS levels in CSCs of SHR lends scope for speculation that decrease in efficiency of CSCs is mediated by oxidative stress; and that modulation of the microenvironment by therapeutic interventions can restore a healthy stem cell population and facilitate maintenance of cardiac homeostasis and prevent cardiac decompensation.

Histamine-2 receptor antagonist famotidine modulates cardiac stem cell characteristics in hypertensive heart disease.

BACKGROUND: Cardiac stem cells (CSCs) play a vital role in cardiac homeostasis. A decrease in the efficiency of cardiac stem cells is speculated in various cardiac abnormalities. The maintenance of a healthy stem cell population is essential for the prevention of adverse cardiac remodeling leading to cardiac failure. Famotidine, a histamine-2 receptor antagonist, is currently used to treat ulcers of the stomach and intestines. In repurposing the use of the drug, reduction of cardiac hypertrophy and improvement in cardiac function of spontaneously hypertensive rats (SHR) was reported by our group. Given that stem cells are affected in cardiac pathologies, the effect of histamine-2 receptor antagonism on CSC characteristics was investigated. METHODS: To examine whether famotidine has a positive effect on CSCs, spontaneously hypertensive rats (SHR) treated with the drug were sacrificed; and CSCs isolated from atrial appendages was evaluated. Six-month-old male SHRs were treated with famotidine (30 mg/kg/day) for two months. The effect of famotidine treatment on migration, proliferation and survival of CSCs was compared with untreated SHRs and normotensive Wistar rats. RESULTS: Functional efficiency of CSCs from SHR was compromised relative to that in Wistar rat. Famotidine increased the migration and proliferation potential, along with retention of stemness of CSCs in treated SHRs. Cellular senescence and oxidative stress were also reduced. The expression of H2R was unaffected by the treatment. DISCUSSION: As anticipated, CSCs from SHRs were functionally impaired. Stem cell attributes of famotidine-treated SHRs was comparable to that of Wistar rats. Therefore, in addition to being cardioprotective, the histamine 2 receptor antagonist modulated cardiac stem cells characteristics. Restoration of stem cell efficiency by famotidine is possibly mediated by reduction of oxidative stress as the expression of H2R was unaffected by the treatment. Maintenance of healthy stem cell population is suggested as a possible mechanism underlying the cardioprotective effect of famotidine.