Cardiotoxic Agent Research Articles

Efficacy and Bioavailability of silymarin on Plasma S100B Level in Cardiotoxicity-induced Rats

Cardiotoxicity is a cause of death by drug overdose. Silymarin, a cytoprotective agent used in this research to protect against induced-cardiotoxic effects in Albino Wister rats; exhibited signs of heart damage, such as elevated levels of S100B, troponin I, and CK-MB. Seventy albino Wister rats of both genders were divided randomly with each group having 10 rats. Silymarin-treated, cardiotoxic-induced, and control groups were treated for ten days. The bioavailability of silymarin was assessed, and evaluation of the efficacy of silymarin on the biomarker S100B and cardiac biomarkers (Troponin I, and CK-MB), also the histopathological assessments of the heart, liver, and kidney, in addition to the coefficient correlation of the studied biomarkers were analyzed. Research’s outcome indicated that the sets subjected to silymarin presented substantial differences in rat weight and food consumption, compared to a decrease in cardiotoxic clusters. S100B plasma level was increased in cardiotoxic groups, reduced in those subjected to silymarin, and eliminated by pretreatment with silymarin. Troponin I & CK-MB expressively elevated significantly in cardiotoxic prompted rats, which declined with silymarin treatment and were prohibited in pretreatment by silymarin. The shielding characteristic of silymarin detected in end organs, like the liver, kidneys, and hearts when exposed to the cardiotoxic agent clozapine was extremely significant. The consequences of the histopathological examination of this study illustrated silymarin’s cardioprotective effects. A significant positive coefficient correlation of S100B with troponin I & CK-MB was recorded. In conclusion, silymarin reduces and prevents to a larger extent the cardiotoxicity brought about by clozapine and averts heart injury. The cardioprotective efficacy of silymarin is explained by its new mechanism of action as decreasing S100B, troponin I & CK-MB levels with a strong significant correlation to each other. The cardioprotective efficacy of silymarin gives promise for monitoring the cardiotoxicity adverse drug reaction induced by drugs.

In silico ADMET and anti-inflammatory profiles of the stigmast-4-en-3-one and isolation of isovanillin as the antioxidant principle of Imperata cylindrica (L.) P. Beauv

Imperata cylindrica (L.) P. Beauv. is an invasive species widely used in treatment of several diseases associated with pain and inflammation in different countries including Madagascar. This work aims to report the isolation of the antioxidant, analgesic and anti-nflammatory compounds from the methanol extract of I. cylindrica. The bio-guided method was used to isolate its bioactive compounds by combining chromatographic methods, writhing test in mice and antioxidant assays. Stigmast-4-en-3-one was isolated as one among the compounds responsible for the analgesic and anti-inflammatory properties and isovanillin as one among the antioxidant compounds from the extract. Stigmast-4-en-3-one showed a good oral pharmacokinetic profile and good binding affinities with some pro-inflammatory targets. It did not show any mutagenic effect, nor a carcinogenic one and had a low risk to be a cardiotoxic agent. All of our results provide scientific justification for its traditional medicinal use in the management of pain and inflammatory related diseases.

Cardiotoxicity of Agents Used in Patients With Breast Cancer.

Cancer and cardiovascular diseases are the two major causes of mortality, morbidity, and disability worldwide. The improvement in effective therapeutic options for the management of breast cancer (BC) has led to an increased number of BC survivors, who can experience long-term toxicities from cancer treatments. Adverse events including cardiovascular toxicities must be considered in light of effectiveness of recently approved drugs for BC treatment, including elacestrant, tucatinib, neratinib, olaparib, the immune checkpoint inhibitors, trastuzumab deruxtecan, or sacituzumab govitecan. Many cancer drugs affect the cardiovascular system with a range of clinical manifestations. Prompt diagnosis and treatment as well as a multidisciplinary approach involving a cardio-oncologist is optimal for management of these cardiovascular events.

Gallic acid and sesame oil exert cardioprotection via mitochondrial protection and antioxidant properties on Ketamine-Induced cardiotoxicity model in rats

Ketamine is a cardiotoxic agent and can deplete ATP in cardiomyocytes through mitochondrial dysfunction. We investigated the effects of gallic acid and sesame oil in ketamine-induced cardiotoxicity in rats. Male Wistar rats were randomly divided into six groups including control; ketamine; ketamine + gallic acid; ketamine + sesame oil; gallic acid and sesame oil. Serum cardiac marker, cardiac tissue oxidative stress markers, histopathological analysis and mitochondrial toxicity parameters (succinate dehydrogenase activity, mitochondrial swelling, reactive oxygen species (ROS) production and collapse of mitochondria membrane potential) were measured on the fifteen days of the study. The results showed that ketamine administration increased serum cardiac markers, oxidative stress parameters, histopathological alterations and mitochondrial dysfunction in cardiac tissue. Gallic acid and sesame oil administration in presence of ketamine was observed to decrease serum cardiac markers, oxidative stress parameters, histopathological alterations and mitochondrial dysfunction in cardiac tissue. The results suggest that gallic acid and sesame oil exert cardioprotection via mitochondrial protection, antioxidant properties and ultimately improving mitochondrial function and cardiac function.

Ponatinib Drives Cardiotoxicity by S100A8/A9-NLRP3-IL-1β Mediated Inflammation.

The tyrosine kinase inhibitor ponatinib is the only treatment option for chronic myelogenous leukemia patients with T315I (gatekeeper) mutation. Pharmacovigilance analysis of Food and Drug Administration and World Health Organization datasets has revealed that ponatinib is the most cardiotoxic agent among all Food and Drug Administration-approved tyrosine kinase inhibitors in a real-world scenario. However, the mechanism of ponatinib-induced cardiotoxicity is unknown. The lack of well-optimized mouse models has hampered the in vivo cardio-oncology studies. Here, we show that cardiovascular comorbidity mouse models evidence a robust cardiac pathological phenotype upon ponatinib treatment. A combination of multiple in vitro and in vivo models was employed to delineate the underlying molecular mechanisms. An unbiased RNA sequencing analysis identified the enrichment of dysregulated inflammatory genes, including a multifold upregulation of alarmins S100A8/A9, as a top hit in ponatinib-treated hearts. Mechanistically, we demonstrate that ponatinib activates the S100A8/A9-TLR4 (Toll-like receptor 4)-NLRP3 (NLR family pyrin domain-containing 3)-IL (interleukin)-1β signaling pathway in cardiac and systemic myeloid cells, in vitro and in vivo, thereby leading to excessive myocardial and systemic inflammation. Excessive inflammation was central to the cardiac pathology because interventions with broad-spectrum immunosuppressive glucocorticoid dexamethasone or specific inhibitors of NLRP3 (CY-09) or S100A9 (paquinimod) nearly abolished the ponatinib-induced cardiac dysfunction. Taken together, these findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. From a translational perspective, our results provide critical preclinical data and rationale for a clinical investigation into immunosuppressive interventions for managing ponatinib-induced cardiotoxicity.

The Chemotherapeutic Efficacy of Hyaluronic Acid Coated Polymeric Nanoparticles against Breast Cancer Metastasis in Female NCr-Nu/Nu Nude Mice.

Polyethylene glycol (PEG) coated Poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) for cancer treatment are biocompatible, nonimmunogenic and accumulate in tumour sites due to the enhanced permeability and retention (EPR). Doxorubicin (DOX) is a potent but cardiotoxic anticancer agent. Hyaluronic acid (HA) occurs naturally in the extra-cellar matrix and binds to CD44 receptors which are overexpressed in cancer metastasis, proven to be characteristic of cancer stem cells and responsible for multidrug resistance. In this study, an athymic mice model of breast cancer metastasis was developed using red fluorescent protein (RFP)-labelled triple negative cancer cells. The animals were divided into four treatment groups (Control, HA-PEG-PLGA nanoparticles, PEG-PLGA nanoparticles, and Free DOX). The tumour size growth was assessed until day 25 when animals were sacrificed. Mice treated with HA-PEG-PLGA NPs inhibited tumour growth. The tumour growth at day 25 (118% ± 13.0) was significantly (p < 0.05) less than PEG-PLGA NPs (376% ± 590 and control (826% ± 970). Fluorescent microscopy revealed that HA-PEG-PLGA NPs had significantly (p < 0.05) less metastasis in liver, spleen, colon, and lungs as compared to control and to Free DOX groups. The efficacy of HA-PEG-PLGA NPs was proven in vivo. Further pharmacokinetic and toxicity studies are required for this formulation to be ready for clinical research.

Role of Scl39a13/ZIP13 in cardiovascular homeostasis.

Zinc plays a critical role in many physiological processes, and disruption of zinc homeostasis induces various disorders, such as growth retardation, osteopenia, immune deficiency, and inflammation. However, how the imbalance in zinc homeostasis leads to heart disease is not yet fully understood. Cardiovascular diseases are a major cause of death worldwide, and the development of novel therapeutic targets to treat it is urgently needed. We report that a zinc transporter, ZIP13, regulates cardiovascular homeostasis. We found that the expression level of Zip13 mRNA was diminished in both primary neonatal cardiomyocytes and mouse heart tissues treated with the cardiotoxic agent doxycycline. Primary neonatal cardiomyocytes from Zip13 gene-knockout (KO) mice exhibited abnormal irregular arrhythmic beating. RNA-seq analysis identified 606 differentially expressed genes in Zip13-KO mouse-derived primary neonatal cardiomyocytes and Gene ontology (GO) analysis revealed that both inflammation- and cell adhesion-related genes were significantly enriched. In addition, telemetry echocardiography analysis suggested that arrhythmias were likely to occur in Zip13-KO mice, in which elevated levels of the cardiac fibrosis marker Col1a1, vascular inflammation-related gene eNOS, and Golgi-related molecule GM130 were observed. These results indicate the physiological importance of ZIP13—it maintains cardiovascular homeostasis by resolving inflammation and stress response. Our findings suggest that optimizing ZIP13 expression and/or function may improve cardiovascular disease management.

Abstract GS109: Ponatinib-induced Cardiotoxicity Is Driven By S100A8/A9-NLRP3-IL1β Signaling Mediated Excessive Inflammation

Background: The tyrosine kinase inhibitor (TKI) ponatinib is the oral drug for the treatment of chronic myelogenous leukemia (CML) patients with T315I (gatekeeper) mutation. Pharmacovigilance analysis of FDA and WHO datasets have revealed that ponatinib is the most cardiotoxic agent among all FDA-approved TKIs in a real-world scenario. However, the mechanism of ponatinib-induced cardiotoxicity is unknown. The cardiotoxic effects of ponatinib remained hidden in preclinical studies and were only revealed in phase 2 clinical studies and by the subsequent meta-analysis. The lack of well-optimized mouse models has hampered the in vivo cardio-oncology studies. To this end, here we aimed to investigate the hidden cardiotoxic mechanism of ponatinib and strategies to prevent the cardiotoxic manifestations. Methods: We employed wild-type C57BL/6, cardiovascular (CV) comorbidity models e.g., transverse aortic constriction (TAC)-pressure overload (cardiac comorbidity) and high-fat diet-fed ApoE -/- (vascular comorbidity), to investigate the cardiotoxic mechanism of ponatinib. Echocardiography was performed to assess cardiac function. Comprehensive immune profiling was performed to identify ponatinib-induced immune activation using flow cytometry analysis and cytokine assay. Results: Echocardiographic assessment of ponatinib treated high-fat diet-fed ApoE -/- and pressure overload (PO) murine model showed a significant decline in cardiac function, suggesting the key role of CV-comorbidities in ponatinib-induced cardiomyopathy. A combination of multiple in vitro and in vivo models was employed to delineate the underlying molecular mechanisms. An unbiased RNA-Seq analysis identified the enrichment of dysregulated inflammatory genes, including a multi-fold upregulation of alarmins S100A8/A9 as a top hit in ponatinib-treated hearts. Mechanistically, we demonstrate that ponatinib activates the S100A8/9-TLR4-NLRP3-IL-1β signaling pathway in cardiac and systemic myeloid cells (monocytes and neutrophils), in vitro and in vivo , thereby leading to excessive myocardial and systemic inflammation. Excessive inflammation was central to the cardiac pathology because interventions with broad-spectrum immunosuppressive glucocorticoid dexamethasone or direct NLRP3 inhibitor Cy-09 nearly abolished the ponatinib-induced cardiac dysfunction. Taken together, these findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. Conclusions: These findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. Our results provide critical preclinical data and rationale for a clinical investigation into immunosuppressive interventions to mitigate ponatinib-induced cardiotoxicity.

A Case Series of Indian Red Scorpion Bite and Rare Clinical Presentation of Central Nervous System

Indian red scorpion (Hottentotta tamulus) is a very dangerous venomous animal found in Indian Territory; its venom contains various toxins which causes direct effect on the central nervous system (CNS). We report a case series of 12 patients who were bitten and had atypical clinical presentation affecting CNS. We evaluated 12 patients of Indian red scorpion sting by taking history, routine blood investigations, CT scan of brain, and CNS examination at a tertiary care hospital in Gujarat. We observed that if patient takes longer time after sting to visit hospital, there are more chances of development of CNS signs and symptoms and indicates poor prognosis. Indian red scorpion venom is a potent sympathetic stimulant and cardio-toxic agent. It can also cause haemorrhagic and thrombotic stroke, cerebellar stroke and cerebellitis. Prazosin is the treatment of sting as there is no availability of anti-venom for sting. Prognosis is directly related to duration between scorpion sting and initiation of treatment. Keywords: 5’nucleotidase, roving eye movements, acute cerebellitis.

Abstract 204: Evaluation Of Impact Of Cardio-oncology Department On Cardiovascular Outcomes And Oncology Treatment: A Single Center Cross -sectional Retrospective Chart Review

Introduction: Cardiotoxicity secondary to cancer therapy can lead to alterations or discontinuation of therapy regimens and potentially impact patient outcomes. We examined overall cardiovascular and oncology treatment outcomes among cancer patients in an urban center with an established cardio-oncology department. Hypothesis: We hypothesized that in adult cancer patients receiving cardiotoxic treatments, the rates of occurrences of major adverse cardiovascular events (MACE) and the rates of emergency room (ER) visits due to cardiovascular (CV) complications would differ when managed by a cardio-oncologist compared with a general cardiologist. Method: We performed a retrospective chart review of 127 patients managed by a general cardiologist and 254 patients managed by a cardio-oncologist for MACE, CV-related ER visits and oncology treatment modifications. Inclusion criteria included ≥18 years of age, a diagnosis of breast cancer (36.48%, 139 of 381), lung cancer (23.1%, 88 of 381), multiple myeloma (13.65%, 52 of 381) or lymphoma (26.77%, 102 of 381); and history of treatment with a known cardiotoxic agent or chest radiation therapy. A two-tailed chi-square analysis was used to compare differences. Welch’s T test analysis was used to compare the rate of ER visits. Result: There was significantly higher MACE among patients managed by a general cardiologist (46.46%, 59 of 127) compared with a cardio-oncologist (22.83%, 58 of 254). The rate of ER visits due to cardiovascular complications was significantly lower among those managed by a cardio-oncologist (21.26%, 54 of 254) compared with a general cardiologist (59.84%, 76 of 127). Less patients had treatment modifications, delays and discontinuations in patients managed by a cardio-oncologist (with p<0.01 for all). Conclusion: We found lower occurrences of MACE and CV-related ER visits in patients on cardiotoxic cancer therapy managed by a cardio-oncologist compared with a general cardiologist.

Protective Effects of Sauropus Androgynus Leaf Extract against Isoproterenol Induced Cardiotoxicity.

The identification of cardioprotective effects of the ethanolic extract of Sauropus androgynus (EESA) leaves was performed using in vitro and in vivo models. The cell culture studies were performed using cardio myoblast cells (H9C2) and in vivo cardioprotective effects of EESA was assessed in albino wistar rats employing isoproterenol (ISO) as cardiotoxic agent. The animals were divided into six treatment groups and myocardial infraction was induced at 14th day followed by the treatment with therapeutic doses of EESA (100, 200 and 400mg/kg) for next two days. Various biochemical and histopathological parameters were evaluated in animals kept under control and treatment groups. The in vitro cell line studies revealed a positive impact on H9C2 cells. The ethanolic extract of Sauropus androgynus depicted low toxicity on cardiomyoblast cells and significant proliferation was observed after treatment. The results from animal studies have shown 1.7 times reduction in serum LDH (151.9 ± 1.302) and CPK (237.6 ± 5.781) levels with EESA treated groups compared to toxic control. EESA also significantly increased the antioxidant enzyme levels, which are responsible for cardioprotective effects in animals. This research study reveals that EESA possess antioxidant activity and also provides a protective role against myocardial infarction induced by ISO. We conclude that EESA could be a potential candidate to prevent and treat cardiotoxic consequences of high catecholamine levels.

Angiotensin receptor-neprilysin inhibition by sacubitril/valsartan attenuates doxorubicin-induced cardiotoxicity in a pretreatment mice model by interfering with oxidative stress, inflammation, and Caspase 3 apoptotic pathway.

Doxorubicin (DOX) is a well-known cardiotoxic agent, whereas sacubitril/valsartan (Sac/Val) is an effective treatment option in heart failure. In this study, we aimed to evaluate the effect of Sac/Val on DOX-induced cardiotoxicity in pretreatment mice model. A total of 24 mice were equally classified into 4 groups; control group, DOX (20 mg/kg; fifth day), Sac/Val (80 mg/kg), and Sac/Val+DOX (Sac/Val was given from day one of the study before doxorubicin administration). Electrocardiography parameters, including durations of QRS, ST, QT, PP segment, and QT/PQ index were measured. Total antioxidant status (TAS), total oxidant status (TOS), tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), IL-6, NT-proBNP concentrations, and Caspase 3 activity were evaluated. At the end of the 9-day study duration, QRS, ST, QT intervals, QT/PQ index and TAS, TOS, TNF-α, IL-1β, IL-6 levels were significantly higher in the DOX group than in the control group (p<0.001). Moreover, there were significant differences only in the PP interval when comparing the Sac/Val+DOX and control groups (p<0.001). QRS, ST, QT intervals, and QT/PQ index, TAS, TOS, TNF-α, IL-1β, IL-6 levels were significantly lower in the Sac/Val+ DOX group compared with the DOX group (p<0.001). Furthermore, NT-proBNP levels were lower in the Sac/Val+DOX group compared with the DOX group along with less Caspase 3 apoptosis. Sac/Val seems to be cardioprotective against DOX-induced cardiotoxicity in pretreatment mice model. These findings can be attributed to the antiarrhythmic, anti-inflammatory, antioxidant, and antiapoptotic effects of Sac/Val as shown in this study.

Metformin Modulates Doxorubicin‐induced Senescence Phenotype in Endothelial Cells

Background Doxorubicin (DOX) is a cardiotoxic chemotherapeutic agent. In addition to cardiotoxicity, DOX treatment is associated with endothelial dysfunction and increased markers of vascular aging in cancer survivors, contributing to DOX-induced cardiovascular complications. Metformin, an anti-diabetic drug, has been shown to have anti-aging effects in different models of aging. Therefore, in our current work, we first established an in vitro model of DOX-induced senescence in EA.hy926 human endothelial-derived cells and Human Umbilical Vein Endothelial Cells (HUVECs). Then, we identified the effects of metformin on DOX-induced senescence phenotype. Methods Both HUVECs and EA.hy926 human endothelial-derived cells were treated with increasing DOX concentrations for 24 hours. Thereafter, DOX was removed and cells were incubated in DOX free media for another 72-120 hours. Protein expression of senescence markers were measured using Western blot analysis. Cell cycle analysis was assessed using flow cytometry. Senescence-associated beta-galactosidase (SA-beta GAL) activity was measured by SA-beta GAL assay. Next, cells were incubated with DOX +/- increasing metformin concentrations. Effects of metformin on DOX-induced senescence markers and cell cycle were assessed. To delineate the molecular mechanisms, the effects of metformin on major signaling pathways were determined. Results DOX significantly induced expression of senescence markers in endothelial cells in a concentration-dependent manner. Moreover, DOX caused cell cycle arrest in the G2/M phase and increased SA-beta GAL staining. Metformin corrected DOX-induced upregulation of senescence markers, which was associated with a significant inhibition of the JNK pathway. Intriguingly, metformin had no effect on DOX-induced cell cycle arrest and slightly corrected the increased expression of SA-beta GAL. Conclusions Our current work shows that metformin modulates DOX-induced senescence phenotype in endothelial cells, suggesting it may protect against DOX-induced vascular aging and endothelial dysfunction.

EXERCISE TRAINING PROTECTED CARDIAC DAMAGE FROM DOXORUBICIN-INDUCED HEART FAILURE IN SPRAGUE-DAWLEY RATS

Objective: Heart failure is a complex end stage result of various cardiovascular diseases, and has a poor prognosis. Exercise training according to oxidative stress, myocardial fibrosis, inflammation pathways improve cardiac function. The aim of this study was to investigate the possible protective effects of exercise training against cardiac damage in doxorubicin (DOX)-induced heart failure in Sprague-Dawley Rats. Design and method: This study used 45 male Sprague-Dawley (SD) rats weighing 150 ± 20 g that were randomly divided into a control group (normal saline), doxorubicin (DOX) group and DOX plus exercise (DOX + E) group. Heart failure was induced experimentally by intraperitoneal injections of the cardiotoxic agent DOX. All groups received different treatment for 8 weeks. Blood samples were obtained from the inferior vena cava and collected in serum tubes; the blood samples were stored at minus 80°C until use. Heart tissues were fixed in 10% formalin and then embedded in paraffin for histological evaluation. The heart was stored in liquid nitrogen for immunoblotting or mRNA analysis. Results: Left ventricular fractional shortening and ejection fraction were higher in DOX + E group rats than in DOX group rats on an echocardiographic examination (Figure 1 and Table 1). Significant cardiac tissue damage (haematoxylin and eosin, Masson's trichrome staining) was seen in rats of the DOX group compared to those of the DOX + E group (Figure2). Exercise inhibited DOX-induced cardiac fibrosis (transforming growth factor, smooth muscle actin, collagen I, and collagen III) and oxidative stress (Nox4, p53) in an immunoblotting analysis (Figure 3 and 4). Conclusions: These results indicate that exercise training may be a potential therapeutic target for cardiac damage caused by DOX-induced heart failure.

Segmental analysis by speckle-tracking echocardiography of the left ventricle response to isoproterenol in male and female mice

We studied by conventional and speckle-tracking echocardiography, the response of the left ventricle (LV) to a three-week continuous infusion of isoproterenol (Iso), a non-specific beta-adrenergic receptor agonist in male and female C57Bl6/J mice. Before and after Iso (30 mg/kg/day), we characterized LV morphology and function as well as global and segmental strain. We observed that Iso reduced LV ejection in both male (−8.7%) and female (−14.7%) mice. Several diastolic function parameters were negatively regulated in males and females such as E/A, E/E′, isovolumetric relaxation time. Global longitudinal (GLS) and circumferential (GCS) strains were reduced by Iso in both sexes, GLS by 31% and GCS by about 20%. For the segmental LV analysis, we measured strain, strain rate, reverse strain rate, peak speckle displacement and peak speckle velocity in the parasternal long axis. We observed that radial strain of the LV posterior segments were more severely modulated by Iso than those of the anterior wall in males. In females, on the other hand, both posterior and anterior wall segments were negatively impacted by Iso. Longitudinal strain showed similar results to the radial strain for both sexes. Strain rate, on the other hand, was only moderately changed by Iso. Reverse strain rate measurements (an index of diastolic function) showed that posterior LV segments were negatively regulated by Iso. We then studied the animals 5 and 17 weeks after Iso treatment. Compared to control mice, LV dilation was still present in males. Ejection fraction was decreased in mice of both sex compared to control animals. Diastolic function parameters, on the other hand, were back to normal. Taken together, our study indicates that segmental strain analysis can identify LV regions that are more negatively affected by a cardiotoxic agent such as Iso. In addition, cessation of Iso was not accompanied with a complete restoration of cardiac function after four months.

Cardiac efficacy and toxicity of aconitine: A new frontier for the ancient poison.

Aconitine (AC) is well-known as the main toxic ingredient and active compound of Aconitum species, of which several aconites are essential herbal medicines of Traditional Chinese Medicine (TCM) and widely applied to treat diverse diseases for their excellent anti-inflammatory, analgesic, and cardiotonic effects. However, the cardiotoxicity and neurotoxicity of AC attracted a lot of attention and made it a favorite botanic poison in history. Nowadays, the narrow therapeutic window of AC limits the clinical application of AC-containing herbal medicines; overdosing on AC always induces ventricular tachyarrhythmia and heart arrest, both of which are potentially lethal. But the underlying cardiotoxic mechanisms remained chaos. Recently, beyond its cardiotoxic effects, emerging evidence shows that low doses of AC or its metabolites could generate cardioprotective effects and are necessary to aconite's clinical efficacy. Consistent with TCM's theory that even toxic substances are powerful medicines, AC thus could not be simply identified as a toxicant or a drug. To prevent cardiotoxicity while digging the unique value of AC in cardiac pharmacology, there exists a huge urge to better know the characteristic of AC being a cardiotoxic agent or a potential heart drug. Here, this article reviews the advances of AC metabolism and focuses on the latest mechanistic findings of cardiac efficacy and toxicity of this aconite alkaloid or its metabolites. We also discuss how to prevent AC-related cardiotoxicity, as well as the issues before the development of AC-based medicines that should be solved, to provide new insight into the paradoxical nature of this ancient poison.

Cardiac Spheroids as in vitro Bioengineered Heart Tissues to Study Human Heart Pathophysiology

Despite several advances in cardiac tissue engineering, one of the major challenges to overcome remains the generation of a fully functional vascular network comprising several levels of complexity to provide oxygen and nutrients within bioengineered heart tissues. Our laboratory has developed a three-dimensional in vitro model of the human heart, known as the "cardiac spheroid" or "CS". This presents biochemical, physiological, and pharmacological features typical of the human heart and is generated by co-culturing its three major cell types, such as cardiac myocytes, endothelial cells, and fibroblasts. Human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs or iCMs) are co-cultured at ratios approximating the ones found in vivo with human cardiac fibroblasts (HCFs) and human coronary artery endothelial cells (HCAECs) in hanging drop culture plates for three to four days. The confocal analysis of CSs stained with antibodies against cardiac Troponin T, CD31 and vimentin (markers for cardiac myocytes, endothelial cells and fibroblasts, respectively) shows that CSs present a complex endothelial cell network, resembling the native one found in the human heart. This is confirmed by the 3D rendering analysis of these confocal images. CSs also present extracellular matrix (ECM) proteins typical of the human heart, such as collagen type IV, laminin and fibronectin. Finally, CSs present a contractile activity measured as syncytial contractility closer to the one typical of the human heart compared to CSs that contain iCMs only. When treated with a cardiotoxic anti-cancer agent, such as doxorubicin (DOX, used to treat leukemia, lymphoma and breast cancer), the viability of DOX-treated CSs is significantly reduced at 10 µM genetic and chemical inhibition of endothelial nitric oxide synthase, a downstream target of DOX in HCFs and HCAECs, reduced its toxicity in CSs. Given these unique features, CSs are currently used as in vitro models to study heart biochemistry, pathophysiology, and pharmacology.

Cardiac Spheroids as in vitro Bioengineered Heart Tissues to Study Human Heart Pathophysiology.

Despite several advances in cardiac tissue engineering, one of the major challenges to overcome remains the generation of a fully functional vascular network comprising several levels of complexity to provide oxygen and nutrients within bioengineered heart tissues. Our laboratory has developed a three-dimensional in vitro model of the human heart, known as the "cardiac spheroid" or "CS". This presents biochemical, physiological, and pharmacological features typical of the human heart and is generated by co-culturing its three major cell types, such as cardiac myocytes, endothelial cells, and fibroblasts. Human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs or iCMs) are co-cultured at ratios approximating the ones found in vivo with human cardiac fibroblasts (HCFs) and human coronary artery endothelial cells (HCAECs) in hanging drop culture plates for three to four days. The confocal analysis of CSs stained with antibodies against cardiac Troponin T, CD31 and vimentin (markers for cardiac myocytes, endothelial cells and fibroblasts, respectively) shows that CSs present a complex endothelial cell network, resembling the native one found in the human heart. This is confirmed by the 3D rendering analysis of these confocal images. CSs also present extracellular matrix (ECM) proteins typical of the human heart, such as collagen type IV, laminin and fibronectin. Finally, CSs present a contractile activity measured as syncytial contractility closer to the one typical of the human heart compared to CSs that contain iCMs only. When treated with a cardiotoxic anti-cancer agent, such as doxorubicin (DOX, used to treat leukemia, lymphoma and breast cancer), the viability of DOX-treated CSs is significantly reduced at 10 µM genetic and chemical inhibition of endothelial nitric oxide synthase, a downstream target of DOX in HCFs and HCAECs, reduced its toxicity in CSs. Given these unique features, CSs are currently used as in vitro models to study heart biochemistry, pathophysiology, and pharmacology.

Measuring the systolic and the diastolic properties of single human pluripotent stem-cell cardiomyocyte for drug testing and disease modeling

Abstract Background The advent of human pluripotent stem cell–derived cardiomyocytes (hPSC-CMs) provided exciting tools for cardiovascular physiological studies, disease modeling and drug testing applications. Current platforms for studying the mechanical properties of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) as single-cells do not measure forces directly, require numerous assumptions, and cannot study cell mechanics at different loading conditions. Objective To establish a novel platform to assess the active and passive mechanical properties of single-cell hPSC-CMs at different loading conditions and to demonstrate the potential of this approach for drug testing and disease modeling applications. Methods and results To allow morphological maturation, hPSC-CMs were treated with Tri-iodo-thyronine hormone, dexamethasone and Insulin-like growth factor-1. The hPSC-CM were then lifted and attached to a highly sensitive optical-force transducer and a piezoelectric length controller and electrically-stimulated. The attached hPSC-CM remained intact and contractile allowing evaluation of their passive and active mechanical properties. Utilizing this technique, single-cell hPSC-CMs exhibited positive length-tension (Frank-Starling) relationships, and appropriate inotropic, klinotropic, and lusitropic changes in response to treatment with isoproterenol. The unique potential of the approach for drug testing and disease modeling was exemplified by treating the cells with doxorubicin (a potential cardiotoxic anti-cancer agent) and omecamtiv mecarbil (a positive ionotropic drug currently in stage 3 clinical trial). The results of these studies recapitulated the drugs' known actions to suppress (doxorubicin) and augment (omecamtiv mecarbil at low dose) cardiomyocyte contractility. Finally, novel insights were gained regarding the cellular effects of these drugs as doxorubicin treatment led to cellular mechanical alternans and high doses of omecamtiv mecarbil suppressed contractility and worsened the cellular diastolic properties. Conclusion A novel method that allows direct active and passive force measurements from single hPSC-CMs at different loading conditions for the first time was established and validated. Our results highlight the potential implications of this novel approach for pharmacological studies and disease modeling studies. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): European Research Council

A Rat Model of Pressure Overload Induced Moderate Remodeling and Systolic Dysfunction as Opposed to Overt Systolic Heart Failure.

In response to an injury, such as myocardial infarction, prolonged hypertension or a cardiotoxic agent, the heart initially adapts through the activation of signal transduction pathways, to counteract, in the short-term, for the cardiac myocyte loss and or the increase in wall stress. However, prolonged activation of these pathways becomes detrimental leading to the initiation and propagation of cardiac remodeling leading to changes in left ventricular geometry and increases in left ventricular volumes; a phenotype seen in patients with systolic heart failure (HF). Here, we describe the creation of a rat model of pressure overload induced moderate remodeling and early systolic dysfunction (MOD) by ascending aortic banding (AAB) via a vascular clip with an internal area of 2 mm2. The surgery is performed in 200 g Sprague-Dawley rats. The MOD HF phenotype develops at 8-12 weeks after AAB and is characterized noninvasively by means of echocardiography. Previous work suggests the activation of signal transduction pathways and altered gene expression and post-translational modification of proteins in the MOD HF phenotype that mimic those seen in human systolic HF; therefore, making the MOD HF phenotype a suitable model for translational research to identify and test potential therapeutic anti-remodeling targets in HF. The advantages of the MOD HF phenotype compared to the overt systolic HF phenotype is that it allows for the identification of molecular targets involved in the early remodeling process and the early application of therapeutic interventions. The limitation of the MOD HF phenotype is that it may not mimic the spectrum of diseases leading to systolic HF in human. Moreover, it is a challenging phenotype to create, as the AAB surgery is associated with high mortality and failure rates with only 20% of operated rats developing the desired HF phenotype.