Search Results (1,087)

L-type Ca²⁺ channels, particularly Ca_V1.2, play a crucial role in cardiac excitation-contraction coupling and are known to exhibit mechanosensitivity. However, the mechanisms regulating their response to mechanical stress remain poorly understood. To investigate the mechanosensitivity and nitric oxide (NO)-dependent regulation of L-type Ca²⁺ channels in rat ventricular cardiomyocytes, we used RNA sequencing to assess isoform expression and whole-cell patch-clamp recordings to measure L-type Ca²⁺ current (I_Ca,L) under controlled mechanical and pharmacological conditions. RNA sequencing revealed predominant expression of Ca_V1.2 (TPM: 0.1170 ± 0.0075) compared to Ca_V1.3 (0.0021 ± 0.0002) and Ca_V1.1 (0.0002 ± 0.0002). Local axial stretch (6–10 μm) consistently reduced I_Ca,L in proportion to stretch magnitude. The NO donor SNAP (200 μM) had variable effects on basal I_Ca,L in unstretched cells (stimulatory, inhibitory, or biphasic) but consistently restored stretch-reduced I_Ca,L to control levels. Ascorbic acid (10 μM), which reduces S-nitrosylation, increased basal I_Ca,L and partially restored the reduction caused by stretch, implicating S-nitrosylation in channel regulation. The sGC inhibitor ODQ (5 μM) decreased I_Ca,L in both stretched and unstretched cells, indicating involvement of the NO–cGMP pathway. Mechanical stress modulates L-type Ca²⁺ channels through a complex interplay between S-nitrosylation and NO–cGMP signaling, with S-nitrosylation playing a predominant role in stretch-induced effects. This mechanism may represent a key component of cardiac mechanotransduction and could be relevant for therapeutic targeting in cardiac pathologies involving mechanically induced dysfunction. Full article

Hibiscus syriacus L. (HS), native to Eastern and Southern Asia, has been traditionally used in Asian herbal medicine for its anticancer, antimicrobial, and anti-inflammatory properties. Despite these recognized bioactivities, its potential cardioprotective effects, particularly in the setting of heart failure (HF), remain largely unexplored. This study aimed to investigate the effects of HS extracts and its bioactive constituents on angiotensin II (Ang II)-induced cardiac injury using an in vitro model with H9c2 rat cardiomyocytes. Cells exposed to Ang II were pretreated with HS extracts, and assays were performed to assess cell viability, reactive oxygen species (ROS) generation, protein synthesis, and secretion of inflammatory mediators, including tumor necrosis factor-alpha, interleukin 1β (IL-1β), and interleukin 6 (IL-6), as well as chemokine (CCL20) and HF-related biomarkers, such as brain natriuretic peptide (BNP) and endothelin-1. The results demonstrated that HS extracts significantly and dose-dependently attenuated Ang II-induced ROS accumulation and suppressed the secretion of pro-inflammatory cytokines, chemokines, BNP, and endothelin-1. Additionally, HS and its purified components inhibited Ang II-induced protein synthesis, indicating anti-hypertrophic effects. Collectively, these findings highlight the antioxidative, anti-inflammatory, and antihypertrophic properties of HS in the context of Ang II-induced cardiac injury, suggesting that HS may represent a promising adjunctive therapeutic candidate for HF management. Further in vivo studies and mechanistic investigations are warranted to validate its clinical potential. Full article

Diabetes mellitus, both type 1 (T1D) and type 2 (T2D), has become the epidemic of the century and a major public health concern given its rising prevalence and the increasing adoption of a sedentary lifestyle globally. This multifaceted disease is characterized by impaired pancreatic beta cell function and insulin resistance (IR) in peripheral organs, namely the liver, skeletal muscle, and adipose tissue. Additional insulin target tissues, including cardiomyocytes and neuronal cells, are also affected. The advent of stem cell research has opened new avenues for tackling this disease, particularly through the regeneration of insulin target cells and the establishment of disease models for further investigation. Human-induced pluripotent stem cells (iPSCs) have emerged as a valuable resource for generating specialized cell types, such as hepatocytes, myocytes, adipocytes, cardiomyocytes, and neuronal cells, with diverse applications ranging from drug screening to disease modeling and, importantly, treating IR in T2D. This review aims to elucidate the significant applications of iPSC-derived insulin target cells in studying the pathogenesis of insulin resistance and T2D. Furthermore, recent differentiation strategies, protocols, signaling pathways, growth factors, and advancements in this field of therapeutic research for each specific iPSC-derived cell type are discussed. Full article

Background: Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) hold transformative potential for cardiovascular regenerative medicine, yet their clinical application is hindered by suboptimal mitochondrial maturation and metabolic inefficiencies. This systematic review evaluates targeted strategies for optimizing mitochondrial function, integrating metabolic preconditioning, substrate selection, and pathway modulation to enhance energy production and cellular resilience. Additionally, we examine the role of extracellular matrix stiffness and mechanical stimulation in mitochondrial adaptation, given their influence on metabolism and maturation. Methods: A comprehensive analysis of recent advancements in iPSC-CM maturation was conducted, focusing on metabolic interventions that enhance mitochondrial structure and function. Studies employing metabolic preconditioning, lipid and amino acid supplementation, and modulation of key signaling pathways, including PGC-1α, AMPK, and mTOR, were reviewed. Computational modeling approaches predicting optimal metabolic shifts were assessed, alongside insights into reactive oxygen species (ROS) signaling, calcium handling, and the impact of electrical pacing on energy metabolism. Results: Evidence indicates that metabolic preconditioning with fatty acids and oxidative phosphorylation enhancers improves mitochondrial architecture, cristae density, and ATP production. Substrate manipulation fosters a shift toward adult-like metabolism, while pathway modulation refines mitochondrial biogenesis. Computational models enhance precision, predicting interventions that best align iPSC-CM metabolism with native cardiomyocytes. The synergy between metabolic and biomechanical cues offers new avenues for accelerating maturation, bridging the gap between in vitro models and functional cardiac tissues. Conclusions: Strategic metabolic optimization is essential for overcoming mitochondrial immaturity in iPSC-CMs. By integrating biochemical engineering, predictive modeling, and biomechanical conditioning, a robust framework emerges for advancing iPSC-CM applications in regenerative therapy and disease modeling. These findings pave the way for more physiologically relevant cell models, addressing key translational challenges in cardiovascular medicine. Full article

Doxorubicin-induced cardiotoxicity (DIC) significantly constrains the clinical efficacy of anthracycline chemotherapy, primarily through the induction of ferroptosis, an iron-dependent, regulated cell death driven by oxidative stress and lipid peroxidation. However, the upstream regulators of ferroptosis in DIC remain incompletely defined. Cold-inducible RNA-binding protein (CIRBP) exhibits cardioprotective effects in various pathological contexts, but its precise role in ferroptosis-related cardiotoxicity is unknown. This study investigated whether CIRBP mitigates DIC by modulating the ferroptosis pathway via the SLC7A11 (Solute carrier family 7 member 11)/GPX4 (Glutathione peroxidase 4) axis. We observed marked downregulation of CIRBP in cardiac tissues and cardiomyocytes following doxorubicin exposure. CIRBP knockout significantly exacerbated cardiac dysfunction, mitochondrial damage, oxidative stress, and lipid peroxidation, accompanied by increased mortality rates. Conversely, CIRBP overexpression alleviated these pathological changes. Molecular docking and dynamics simulations, supported by transcriptomic analyses, revealed direct binding of CIRBP to the 3′-UTR of Slc7a11 mRNA, enhancing its stability and promoting translation. Correspondingly, CIRBP deficiency markedly suppressed SLC7A11 and GPX4 expression, impairing cystine uptake, glutathione synthesis, and antioxidant defenses, thus amplifying ferroptosis. These ferroptotic alterations were partially reversed by ferroptosis inhibitor ferrostatin-1 (Fer-1). Collectively, this study identifies CIRBP as a critical regulator of ferroptosis in DIC, elucidating a novel post-transcriptional mechanism involving Slc7a11 mRNA stabilization. These findings offer new insights into ferroptosis regulation and highlight CIRBP as a potential therapeutic target for preventing anthracycline-associated cardiac injury. Full article

Human induced pluripotent stem cells (hiPSCs) are widely used in basic research because of their versatility and ability to differentiate into multiple cell types. In particular, differentiating hiPSCs into cardiac cells (hiPSC-CMs) has been an important milestone in cardiac pathophysiology studies. Although hiPSC-CMs offer a model for human cardiomyocytes, they still exhibit characteristics linked to the fetal cardiac cell phenotype. One important feature that prevents hiPSC-CMs from being identified as adult cells relates to their metabolism, which is a key factor in defining a mature phenotype capable of sustaining the workload requirements characteristic of fully differentiated cardiomyocytes. This review aims to present the most relevant strategies in terms of culture medium composition, culture times, and 3D culture methods that have been developed to promote the metabolic maturation of hiPSC-CMs, which are now widely used. Defining a standardized and universally accepted protocol would enable the creation of a cellular model for studies of cardiac pathophysiology from a patient-specific perspective and for drug screening. Full article

Background/Objectives: Doxorubicin is a chemotherapeutic agent whose clinical use is limited by side effects (SEs). The most common SE is doxorubicin-induced cardiotoxicity (DIC), for which there is still no prevention. The hypothesis arises that active substances of natural origin could influence DIC prevention by affecting several pathways of DIC occurrence. Methods: Thirty Wistar rats were divided into six groups (control, NADES (C8:C10) solvent, pumpkin pulp extract, doxorubicin, NADES (C8:C10) solvent–doxorubicin, and pumpkin pulp extract–doxorubicin). During the experiment, parameters of general condition, body, and heart weight were observed. Heart function parameters were monitored by measuring the levels of serum NT-pro-BNP, CK-MB, and hsTnT. Tissue damage was evaluated by determining the doxorubicin damage score and the expression of anti-cardiac troponin I, anti-Nrf2, anti-Bcl-2, anti-caspase-3, anti-COX2, and anti-Ki67 antibodies. Results: Doxorubicin administration led to impaired general condition of animals and increased the levels of NT-proBNP, CK-MB, hsTnT, and myocardium tissue damage of medium grade. Its administration induced apoptosis (as evidenced by elevated Casp3), reduced antiapoptotic Bcl-2 and troponin I expression in cardiomyocytes. Reduced Nrf2 expression due to doxorubicin administration was restored when pumpkin pulp extract containing carotenoids was coadministered, which led to the normalization of Casp3, Bcl-2, and troponin I expression. Consequently, the general condition and body weight were better in animals treated with both doxorubicin and the other treatment compared to those treated with doxorubicin alone. Conclusions: The results of this study strongly suggest that pumpkin pulp extract containing carotenoids has a cardioprotective effect, possibly by regulating the Nrf2 pathway. Full article

New approach methodologies (NAMs), including microphysiological systems (MPSs), can recapitulate structural and functional complexities of organs. Vanoxerine was reported to induce cardiac adverse events, including torsade de points (TdP), in a Phase III clinical trial. Despite earlier nonclinical animal models and Phase I–II clinical trials, events of QT prolongation or proarrhythmia were not observed. Here, we utilized cardiac NAMs to evaluate the functional consequences of vanoxerine treatment on human cardiac excitation–contraction coupling. The cardiac MPS used in this study was a microfabricated fluidic culture platform with human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) capable of evaluating voltage, intracellular calcium handling, and contractility. Likewise, the hiPSC-CM comprehensive in vitro proarrhythmia assay (CiPA) was employed based on multielectrode array (MEA). Vanoxerine treatment delayed repolarization in a concentration-dependent manner and induced proarrhythmic events in both NAM platforms. The complex cardiac MPS displayed a frequency-dependent vanoxerine response such that EADs were eliminated at a faster pacing rate (1.5 Hz). Moreover, exposure analysis revealed a 99% vanoxerine loss in the cardiac MPS. TdP risk analysis demonstrated high to intermediate TdP risk at clinically relevant concentrations of vanoxerine and frequency-independent EAD events in the hiPSC-CM CiPA model. These findings demonstrate that nonclinical cardiac NAMs can recapitulate clinical outcomes, including detection of vanoxerine-induced delayed repolarization and proarrhythmic effects. Moreover, this work provides a foundation to evaluate the safety and efficacy of novel compounds to reduce the dependence on animal studies. Full article

Human induced pluripotent stem cell-derived cardiomyocytes (iCMs) provide a powerful platform for investigating cardiac biology. However, structural, metabolic, and electrophysiological immaturity of iCMs limits their capacity to model adult cardiomyocytes. Currently, no universally accepted criteria or protocols for effective iCMs maturation exist. This study aimed to identify practical culture conditions that promote iCMs maturation, thereby generating more physiologically relevant in vitro cardiac models. We evaluated the effects of short- and long-term culture in media supplemented with various stimulatory compounds under 2D conditions, focusing on intracellular content and localization of slow skeletal troponin I (ssTnI) and cardiac troponin I (cTnI) isoforms. Our findings demonstrate that the multicomponent metabolic maturation medium (MM-1) effectively enhances the transition toward a more mature iCM phenotype, as evidenced by increased cTnI expression and formation of cross-striated myofibrils. iCMs cultured in MM-1 more closely resemble adult cardiomyocytes and are compatible with high-resolution single-cell techniques such as electron microscopy and patch-clamp electrophysiology. This work provides a practical and scalable approach for advancing the maturation of iPSC-derived cardiac models, with applications in disease modeling and drug screening. Full article

Pulmonary arterial hypertension (PAH) is a rare, progressive, and incurable disease characterized by an elevated pulmonary blood pressure, extensive remodeling of the pulmonary vasculature, increased pulmonary vascular resistance, and culminating in right ventricular failure. Mitochondrial dysfunction has a major role in the pathogenesis of PAH and secondary right ventricular failure, and its targeting may offer therapeutic benefit. In this study, we provide proof-of-concept for the use of the mitochondrially active drug SUL-150 to treat PAH. PAH was induced in rats by monocrotaline, followed by the placement of an aortocaval shunt one week later. The mitoprotective compound SUL-150 (~6 mg·kg⁻¹·day⁻¹) or vehicle was administered intraperitoneally via osmotic minipump for 28 days, implanted at the time of aortocaval shunt placement. Vehicle-treated PAH rats had dyspnea and showed pulmonary artery remodeling with increased responsiveness to phenylephrine, in addition to remodeling of the intrapulmonary arterioles. SUL-150 administration mitigated the dyspnea and the remodeling responses. Vehicle-treated PAH rats developed right ventricular hypertrophy, fibrosis, and failure. SUL-150 administration precluded cardiomyocyte hypertrophy and inhibited ventricular fibrogenesis. Right ventricular failure in vehicle-treated PAH rats induced mitochondrial loss and dysfunction associated with a decrease in mitophagy. SUL-150 was unable to prevent the mitochondrial loss but improved mitochondrial health in the right ventricle, which culminated in the preservation of right ventricular function. We conclude that SUL-150 improves PAH-associated morbidity by the amelioration of pulmonary vascular remodeling and right ventricular failure and may be considered a promising therapeutic candidate to slow disease progression in pulmonary arterial hypertension and secondary right ventricular failure. Full article

Background: Methylene blue (MB), a versatile redox agent, is emerging as a promising therapeutic in diseases associated with mitochondrial dysfunction. Its ability to optimize the electron transport chain increases ATP synthesis (30–40%) and reduces oxidative stress, protecting cellular components such as mitochondrial DNA. The protective role of this compound has been described in several neurodegenerative disease such as Alzheimer’s and Parkinson’s diseases. However, its role in cardiovascular disease has been poorly explored. Methods: In this study, we explored the impact of MB on murine (HL1) and human (AC16) cardiomyocyte redox signaling and cellular survival using RT-Qpcr analysis and immunochemistry assays. Results: Our results revealed that MB increased functional mitochondria, reversed H₂O₂-induced oxidative damage, and modulated antioxidant gene expression. Furthermore, it regulated the microRNA16–UPR signaling axis, reducing CHOP expression and promoting cell survival. Conclusions: These findings underscore its potential in cardioprotective therapy; however, its putative use as a drug requires in vivo validation in preclinical animal models. Full article

Background/Objectives: Doxorubicin (DOX), a widely used anthracycline chemotherapeutic agent, is recognized for its efficacy in treating various malignancies. However, its clinical application is critically limited due to dose-dependent cardiotoxicity, predominantly induced by oxidative stress and compromised antioxidant defenses. Photobiomodulation (PBM), a non-invasive intervention that utilizes low-intensity light, has emerged as a promising therapeutic modality in regenerative medicine, demonstrating benefits such as enhanced tissue repair, reduced inflammation, and protection against oxidative damage. This investigation sought to evaluate the cardioprotective effects of PBM preconditioning in human-induced pluripotent stem cell-derived ventricular cardiomyocytes (hiPSC-vCMs) subjected to DOX-induced toxicity. Methods: Human iPSC-vCMs were allocated into three experimental groups: control cells (untreated), DOX-treated cells (exposed to 2 μM DOX for 24 h), and PBM+DOX-treated cells (preconditioned with PBM, utilizing 660 nm ±10 nm LED light at an intensity of 10 mW/cm² for 500 s, delivering an energy dose of 5 J/cm², followed by DOX exposure). Cell viability assessments were conducted in conjunction with evaluations of oxidative stress markers, including antioxidant enzyme activities and malondialdehyde (MDA) levels. Furthermore, transcriptional profiling of 40 genes implicated in cardiac dysfunction was performed using TaqMan quantitative polymerase chain reaction (qPCR), complemented by analyses of protein expression for markers of cardiac stress, inflammation, and apoptosis. Results: Exposure to DOX markedly reduced the viability of hiPSC-vCMs. The cells exhibited significant alterations in the expression of 32 out of 40 genes (80%) after DOX exposure, reflecting the upregulation of markers associated with apoptosis, inflammation, and adverse cardiac remodeling. PBM preconditioning partially restored the cell viability, modulating the expression of 20 genes (50%), effectively counteracting a substantial proportion of the dysregulation induced by DOX. Notably, PBM enhanced the expression of genes responsible for antioxidant defense, augmented antioxidant enzyme activity, and reduced oxidative stress indicators such as MDA levels. Additional benefits included downregulating stress-related mRNA markers (HSP1A1 and TNC) and apoptotic markers (BAX and TP53). PBM also demonstrated gene reprogramming effects in ventricular cells, encompassing regulatory changes in NPPA, NPPB, and MYH6. PBM reduced the protein expression levels of IL-6, TNF, and apoptotic markers in alignment with their corresponding mRNA expression profiles. Notably, PBM preconditioning showed a diminished expression of BNP, emphasizing its positive impact on mitigating cardiac stress. Conclusions: This study demonstrates that PBM preconditioning is an effective strategy for reducing DOX-induced chemotherapy-related cardiotoxicity by enhancing cell viability and modulating signaling pathways associated with oxidative stress, as well as inflammatory and hypertrophic markers. Full article

A sudden increase in ambient oxygen concentration after birth forces the metabolic switch from anaerobic glycolysis to oxidative phosphorylation, which contributes to the rapid decline of cardiomyocyte proliferation. Lactate dehydrogenase A (LDHA), a metabolic enzyme normally localized in the cytoplasm, has been reported to regulate cardiomyocyte proliferation via inducing metabolic reprogramming. Nuclear LDHA has been observed in multiple proliferative cells, whereas the role of LDHA nuclear translocation in cardiomyocyte proliferation remains unresolved. Here we found that the expression of nuclear LDHA was induced both in the infarct area of myocardial infarction (MI) in mice and hypoxic cardiomyocytes in vitro. Mechanically, mild hypoxia prompted metabolic reprogramming which motivated cardiomyocyte proliferation by alleviating reactive oxygen species (ROS), while severe hypoxia coincided with oxidative stress that induced cardiomyocyte cell cycle arrest. Interestingly, LDHA nuclear translocation in cardiomyocytes occurred in response to oxidative stress, and blocking of nuclear LDHA resulted in elevated ROS generation. Collectively, our findings uncover a non-canonical role of nuclear LDHA in maintaining redox balance and resisting cardiomyocyte cell cycle arrest. Full article

The recently identified proton-activated chloride (PAC) channel is ubiquitously expressed, and it regulates several proton-sensitive physiological and pathophysiological processes. While the PAC channel is activated by strong acids due to the binding of protons to extracellular binding sites, here, we describe the way in which weak acids inhibit the PAC channel by a mechanism involving a distinct extracellular binding site. Whole-cell patch clamp was performed on wildtype HEK293T cells, PAC-knockout HEK293 cells expressing human (h)PAC mutant constructs, and on hiPSC-derived cardiomyocytes. Proton-induced cytotoxicity was examined in HEK293T cells. Acetic acid inhibited endogenous PAC channels in HEK 293T cells in a reversible, concentration-dependent, and pH-dependent manner. The inhibition of PAC channels was also induced by lactic acid, propionic acid, itaconic acid, and β-hydroxybutyrate. Weak acids also inhibited recombinant wildtype hPAC channels and PAC-like currents in hiPSC-derived cardiomyocytes. Replacement of the extracellular arginine 93 by an alanine (hPAC–Arg93Ala) strongly reduced the inhibition by some weak acids, including arachidonic acid. Although lactic acid inhibited PAC, it did not reduce the proton-induced cytotoxicity examined in wildtype HEK 293 cells. To conclude, weak acids inhibit PAC via an extracellular mechanism involving Arg93. These data warrant further investigations into the regulation of the PAC channel by endogenous weak acids. Full article

Background: Left ventricular non-compaction cardiomyopathy (LVNC) is a congenital heart disease characterized by abnormal prenatal development of the left ventricle that has an aberrantly thick trabecular layer and a thinner compacted myocardial layer. However, the underlying molecular mechanisms of LVNC regulated by mitochondrial phosphatase genes remain largely unresolved. Methods: We generated a mouse model with cardiac-specific deletion (CKO) of Ptpmt1, a type of mitochondrial phosphatase gene, using the αMHC-Cre, and investigated the effects of cardiac-specific Ptpmt1 deficiency on cardiac development. Morphological, histological, and immunofluorescent analyses were conducted in Ptpmt1 CKO and littermate controls. A transcriptional atlas was identified by RNA sequencing (RNA-seq) analysis. Results: We found that CKO mice were born at the Mendelian ratio with normal body weights. However, most of the CKO mice died within 24 h after birth, developing spontaneous ventricular tachycardia. Morphological and histological analysis further revealed that newborn CKO mice developed an LVNC phenotype, evidenced by a thicker trabecular layer and a thinner myocardium layer, when compared with the littermate control. We then examined the embryonic hearts and found that such an LVNC phenotype could also be observed in CKO hearts at E15.5 but not at E13.5. We also performed the EdU incorporation assay and demonstrated that cardiac cell proliferation in both myocardium and trabecular layers was significantly reduced in CKO hearts at E15.5, which is also consistent with the dysregulation of genes associated with heart development and cardiomyocyte proliferation in CKO hearts at the same stage, as revealed by both the transcriptome analysis and the quantitative real-time PCR. Deletion of Ptpmt1 in mouse cardiomyocytes also induced an increase in phosphorylated eIF2α and ATF4 levels, indicating a mitochondrial stress response in CKO hearts. Conclusions: Our results demonstrated that Ptpmt1 may play an essential role in regulating left ventricular compaction during mouse heart development. Full article