Background : ATPase inhibitor factor-1 (IF1) preserves cellular ATP under conditions of respiratory collapse, yet the function of IF1 under normal respiring conditions is unresolved. We tested the hypothesis that IF1 promotes mitochondrial dysfunction and pathological cardiomyocyte hypertrophy in the context of heart failure (HF). Methods and results Cardiac expression of IF1 was increased in mice and in humans with HF, downstream of neurohumoral signaling pathways and in patterns that resembled the fetal-like gene program. Adenoviral expression of wild type IF1 in primary cardiomyocytes resulted in pathological hypertrophy and metabolic remodeling as evidenced by enhanced mitochondrial oxidative stress, reduced mitochondrial respiratory capacity, and the augmentation of extra-mitochondrial glycolysis. Similar perturbations were observed with an IF1 mutant incapable of binding to ATP-synthase (E55A mutation), indication that these effects occurred independent of binding to ATP synthase. Instead, IF1 promoted mitochondrial fragmentation and compromised mitochondrial Ca2+ handling, which resulted in sarcoplasmic reticulum Ca2+ overloading. The effects of IF1 on Ca2+ handling were associated with the cytosolic activation of CaMKII and inhibition of CaMKII or co-expression of catalytically dead CaMKIIδC was sufficient to prevent IF-1 induced pathological hypertrophy. Conclusions IF1 represents a novel member of the fetal-like gene program that contributes to mitochondrial dysfunction and pathological cardiac remodeling in HF. Furthermore, we present evidence for a novel, ATP-synthase independent, role for IF1 in mitochondrial Ca2+ handling and mitochondrial- to nuclear crosstalk involving CaMKII.

Right ventricular remodeling and its function are closely related to the symptom severity and survival of hypoxia pulmonary hypertension, but molecular mechanisms of cardiomyocyte hypertrophy and myocardial injury remain unclear. It evaluated the cardiac function (by right cardiac catheterization to measure right ventricular systolic pressure and mean pulmonary artery pressure), myocardial tissue morphology（Haematoxylin and Eosin）, myocardial hypertrophy (Wheat Germ Agglutinin Staining), then RNA sequencing was applied to explore the mechanism, which results were verified by western blot in final. Hypoxia developed pulmonary hypertension, right ventricular diastolic and systolic functions were enhanced in rats, such as the mean pulmonary artery pressure, systolic pressure of pulmonary artery, the max pressure of right ventricular, the mean right ventricular pressure, and the heart rate was significantly higher than that in control. We found that Hif-1 signaling pathway and p38-MAPK signaling pathway have been activated by hypoxia, and cardiomyocyte apoptosis also aggravated in the right ventricular, which might be one cause of cardiomyocyte hypertrophy and myocardial injury, and targeted intervention might be one potential prevention for cardiomyocyte hypertrophy and myocardial injury induced by hypoxia.

Darier disease (DD) is an autosomal dominant disorder due to mutation of ATP2A2 gene causing an isolated skin manifestation based on keratinocyte disconnection and apoptosis. Systemic manifestations of DD have not been demonstrated so far although a high incidence of neuropsychiatric syndromes suggest an involvement of central nervous system. A Novel ATP2A2 Gene Mutation c.118G>A, causing keratinocyte and cardiomyocyte disconnection in Darier disease, is reported. Their common pathologic pathway, still unreported, was documented by both skin and left ventricular endomyocardial biopsy because of cardiac dilatation and dysfunction appeared several decades after skin manifestations.Keratinocyte disconnection was paralleled by cardiomyocyte separation at lateral junction. Cardiomyocyte separation was associated to cell disarray, sarcoplasmic reticulum dilatation and increased myocyte apoptosis. Clinically, hyperkeratotic skin papules were associated to chest pain, severe muscle exhaustion and ventricular arrhythmias that improved following administration of aminophylline, a phosphodiesterase inhibitor enhancing SERCA2 protein phosphorylation.Specific mutations of ATP2A2 gene may cause cardiac involvement in patients with DD. Cardiac pathologic changes are similar to those documented in the skin including cardiomyocyte disconnection that promotes precordial pain and cardiac arrhythmias. Phosphodiesterase inhibitors, enhancing SERCA2 protein phosphorylation may substantially attenuate the symptoms.

Cardiovascular disease (CVD), a group of disorders affecting the heart or blood vessels, are the primary cause of death worldwide, with an immense impact on patient quality of life and disa-bility. According to the World Health Organization, CVD takes an estimated 17.9 million lives each year, where more than four out of five CVD deaths are due to heart attacks and strokes. In the decades to come, increased prevalence of age-related CVD, such as atherosclerosis, coronary artery stenosis, myocardial infarction (MI), valvular heart disease, and heart failure (HF) will contribute to even greater health and economic burden as the global average life expectancy increases and consequently the world’s population continues to age. Considering this, it is important to focus our research efforts on understanding the fundamental mechanisms underlying CVD. In this review, we focus on cellular senescence and mitochondrial dysfunction, which have long been established to contribute to CVD. We also assess the recent advances in targeting mitochondrial dysfunction and senescence with a focus on therapies that influence both and therefore perhaps represent strategies with the most clinical potential, range, and utility.

Heart failure (HF) has become a public health problem, but exact pathophysiology is still unknown. Western diet characterised with high sugar, high fat, red meat and processed meat, eggs, fried foods and sweetened beverages, may cause oxidative stress and inflammation, leading to oxidative dysfunction and adverse effects on cardiac-ultra-structure. However, only little is known about oxidative function of the of the myocardium and how oxidative dysfunction predispose Ca-overloading resulting in to physio-pathological remodelling leading to HF. Antioxidants such as flavonoids and polyphenolics, omega-3 fatty acids, vitamins, minerals as well as essential and nonessential amino acids that are rich in Indo-Mediterranean type of diets, may have protective roles in maintaining oxidative functions of the heart. The cardiac cells use fatty acids and glucose for the metabolic functions depending upon physiological and metabolic requirements. Apart from glucotoxicity, lipotoxicity is also damaging to cardiac cells which worsen in presence of deficiency of endogenous antioxidants and lower exogenous antioxidants in the diet. There is increased production of ceramide, advanced glycation end products (AGE) and triamino-methyl-N-oxide (TMAO) due to high sugar and high fat diets, leading to oxidative dysfunction and Ca-overloading. The biological changes may begin with physiological remodelling to pathological remodelling due to oxidative damages. High fat diet in combination with inducible nitric oxide synthase (NOSi) via N-arginine methyl ester has been found to preserve ejection fraction in a mouse model of HF. It is possible that increased supplementation of High Exogenous Antioxidant Restorative Treatment (HEART) diet; polyphenolics and flavonoids, vitamins, minerals, arginine, with omega-3 fatty acids, and cessation of red meat and egg may further improve the oxidative function of cardiac cells, resulting in the prevention and improvement in the earliest of the Six Stages of HF. Cohort studies and randomised, controlled trials would be necessary for demonstration of the role of HEART diet in the management of HF.

Calcineurin plays a key role in cardiovascular pathogenesis by exerting pro-apoptotic effects in cardiomyocytes; however, its involvement in the regulation of cardiomyocyte autophagy under chronic intermittent hypoxia (CIH) remains largely unknown. Here we showed that CIH induced calcineurin activity in H9C2 cells, resulting in the attenuation of adenosine monophos-phate-activated protein kinase (AMPK) signaling and inhibition of H9C2 cell autophagy. Au-tophagy, LC3-II levels, and AMPK phosphorylation were significantly elevated in response to CIH in H9C2 cells by day 3; however, these effects were reversed, and calcineurin activity and apoptosis were significantly increased by day 5. The calcineurin inhibitor, FK506, restored AMPK activation and LC3 protein levels, and reduced CIH-induced H9C2 cell apoptosis, while calcineurin overexpression significantly attenuated the increase in LC3 levels and enhanced H9C2 cell apop-tosis. Calcineurin inhibition failed to induce autophagy or alleviate apoptosis in H9C2 cells ex-pressing a dominant negative K45R AMPK mutant. Autophagy downregulation abrogated the protective effects of FK506-mediated calcineurin inhibition. These results indicated that calcineurin suppressed adaptive autophagy during CIH by downregulating AMPK activation. Our findings showed the underlying mechanisms of calcineurin and autophagy regulation during H9C2 cell survival in response to CIH, and suggested a new strategy for preventing CIH-induced cardiomyocyte damage.

Long non-coding RNAs (lncRNAs) have been found to be involved in many biological processes, including the regulation of cell differentiation, but a complete characterization of lncRNA is still lacking. Additionally, there is evidence that lncRNAs interact with ribosomes, raising questions about their functions in cells. Here, we used a developmentally staged protocol to induce cardiogenic commitment of hESCs and then investigated the differential association of lncRNAs with polysomes. Our results identified lncRNAs in both the ribosome-free and polysome-bound fractions during cardiogenesis and showed a very well-defined temporal lncRNA association with polysomes. Clustering of lncRNAs was performed according to the gene expression patterns during the five timepoints analyzed. In addition, differential lncRNA recruitment to polysomes was observed when comparing the differentially expressed lncRNAs in the ribosome-free and polysome-bound fractions or when calculating the polysome-bound vs ribosome-free ratio. The association of lncRNAs with polysomes could represent an additional cytoplasmic role of lncRNAs, e.g., in translational regulation of mRNA expression.

The cross-kingdom stress hormone abscisic acid (ABA) and its mammalian receptors LANCL1 and LANCL2 regulate cardiomyocyte response to hypoxia by activating NO generation. Over-expression of LANCL1/2 increases transcription, phosphorylation and activity of eNOS and im-proves cell vitality after hypoxia/reoxygenation via the AMPK/PGC-1α axis. The aim of this study was to investigate whether the ABA/LANCL system also affects mitochondrial oxidative metab-olism and structural proteins. The effect of ABA and of the silencing or overexpression of LANCL1 and LANCL2 were investigated in H9c2 rat cardiomyoblasts on mitochondrial function, cell cycle and expression of cytoskeletal, contractile and ion channel proteins. Overexpression or silencing of LANCL1/2 significantly increased, or conversely decreased, mitochondrial number, oxphos complex I, proton gradient, glucose and palmitate-dependent respiration, transcription of uncoupling proteins, expression of proteins involved in cytoskeletal, contractile and electrical functions. These effects, and LANCL1/2-dependent NO generation, are mediated by the tran-scription factor ERRα, upstream of the AMPK/PGC1-α axis and transcriptionally controlled by the LANCL1/2-ABA system. The ABA-LANCL1/2 hormone-receptors system controls fundamental aspects of cardiomyocyte physiology via an ERRα/AMPK/PGC-1α signaling axis and ABA-mediated targeting of this axis could improve cardiac function and resilience to hypoxic and dysmetabolic conditions.

It has been proposed that procedures which up-regulate mitochondrial biogenesis and autophagy by replacing damaged mitochondria with healthy ones, may prevent the development of several heart diseases. A member of serine and threonine kinases, AMPK, could play essential roles in the autophagy and/or mitophagy. AMPK is widely distributed in various cells, which might play diverse regulatory roles in different tissues and/or organs. In fact, changes in the kinase function of AMPK due to alteration of activity have been linked with diverse pathologies including cardiac disorders. AMPK can regulate mitochondrial biogenesis via PGC1α signaling and also improve oxidative mitochondrial metabolism through inhibition of mTOR pathway, which may also modulate the autophagy/mitophagy through ULK1 and/or TGF-β signaling. Therefore, the modulation of AMPK in autophagy/mitophagy pathway might be considered as a therapeutic tactic for several cardiac disorders. As kinases are amongst the most controllable proteins, in general, the design of small molecules targeting kinases might be an eye-catching avenue to modulate the cardiac function. Some analyses of the molecular biology underlying mitophagy suggests that nutraceuticals and/or drugs including specific AMPK modulator as well as physical exercise and/or dietary restriction that could modulate AMPK may be useful against several heart diseases. In particular, some nutraceutical regimens may have encouraging potential for controlling some of cardiac disorders.

Direct cardiac reprogramming of fibroblasts into induced cardiomyocytes (iCMs) is a promising approach but remains a challenging technology of regenerative medicine for damaged myocardium. Efforts have been focused on improving the efficiency by understanding fundamental mechanisms. One of the major challenges is that the plasticity of cultured fibroblast varies batch to batch with unknown mechanisms. Here, we noticed that a portion of in vitro cultured fibroblasts have been activated to differentiate into myofibroblasts, marked by the expression of αSMA, even in the primary cell culture of tissues. Both forskolin, which activates adenylyl cyclase and increases cAMP concentration, and TGFbeta inhibitor SB431542 can efficiently suppress myofibroblast differentiation of cultured fibroblasts. However, SB431542 improved but forskolin blocked iCM reprogramming of fibroblasts that were infected with retroviruses of Gata4, Mef2c and Tbx5 (GMT). Moreover, inhibitors of cAMP downstream signaling pathways, PKA or CREB-CBP, significantly improved the efficiency of iCM reprogramming. Consistently, inhibition of p38/MAPK, another upstream regulator of CREB-CBP, also improved reprogramming efficiency. We then investigated if inhibition of these signaling pathways in primary cultured fibroblast could improve their plasticity for reprogramming, and found that preconditioning of cultured fibroblasts with CREB-CBP inhibitor significantly improved the cellular plasticity of fibroblasts to be reprogrammed, yielding ~2-fold amount of reprogrammed iCMs compared to that of untreated control cells. In conclusion, suppression of cAMP/PKA/CREB signaling axis improves fibroblast plasticity for direct cardiac reprogramming.

Direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs) holds a great promise for regenerative medicine and has been studied in several major directions. However, cell-cycle regulation, a fundamental biological process, has not been investigated during iCM-reprogramming. Here, our time-lapse imaging on iCMs, reprogrammed by Gata4, Mef2c, and Tbx5 (GMT) monocistronic retroviruses, revealed that iCM-reprogramming was majorly initiated at late-G1- or S-phase and nearly half of GMT-reprogrammed iCMs divided soon after reprogramming. iCMs exited cell cycle along the process of reprogramming with decreased percentage of EdU⁺/αMHC-GFP⁺ cells. S-phase synchronization post-GMT-infection could enhance cell-cycle exit of reprogrammed iCMs and yield more GFP^high iCMs, which achieved an advanced reprogramming with more expression of cardiac genes than GFP^low cells; however, S-phase synchronization didn’t enhance the polycistronic-MGT reprogramming, in which cell-cycle exit had been accelerated. In conclusion, post-infection synchronization of S-phase facilitated the early progression of GMT-reprogramming through a mechanism of enhanced cell-cycle exit.

Myocardial heterogeneity is an attribute of the normal heart. We have developed integrative models of cardiomyocytes from the subendocardial (ENDO) and subepicardial (EPI) ventricular regions that take into account experimental data on specific features of intracellular electromechanical coupling in the guinea pig heart. The models adequately simulate experimental data on the action potential and contraction of the ENDO and EPI cells. The modeling results predict that heterogeneity in the parameters of calcium handling and myofilament mechanics in isolated ENDO and EPI cardiomyocytes via cooperative mechanisms of mechano-calcium-electric feedback are essential to produce the differences in Ca²⁺ transients and contraction profiles and may further enhance transmural differences in the electrical properties between the cells. Simulation results predict that ENDO cells have greater sensitivity to changes in afterload than EPI cells. These data are important for understanding the behavior of cardiomyocytes in the intact heart.

Hemodynamics is the eternal theme of the circulatory system. Abnormal hemodynamics and cardiac and pulmonary development intertwine to form the most important features of children with congenital heart diseases (CHDs), thus determining these children’s long-term quality of life. However, due to the lack of neonatal rodent models of CHDs, it is unclear how CHD-associated hemodynamics shape postnatal cardiac and pulmonary development. Here, we review the varieties of hemodynamic abnormalities that exist in children with CHDs, the recently developed neonatal rodent models of CHDs, and the inspirations these models have brought us in the areas of cardiomyocyte proliferation and maturation, and in alveolar development. Furthermore, current limitations, future directions, and clinical decision-making based on these inspirations are highlighted. Understanding how CHD-associated hemodynamic scenarios shape postnatal heart and lung development may provide a novel path to improving the long-term quality of life of children with CHDs, transplantation of stem cell–derived cardiomyocytes, and cardiac regeneration.

Despite great strides in diagnosis and treatment, cardiac diseases remain the number one cause of mortality in the developed world, with rates catching up at an alarming rate in the developing world. Targeted delivery of therapeutics, specifically to cardiomyocytes, would open up new frontiers. Our prior work using a combinatorial in vitro and in vivo phage display methodology identified a 12-amino acid long peptide that targets cardiomyocytes selectively after an intravenous injection in as little as 5 mins, and hence was termed cardiac targeting peptide (CTP: APHLSSQYSRT). CTP has been used to deliver imaging agents, small drug molecules, photosensitizing nanoparticles, exosomes, and even miRNA to cardiomyocytes. As a natural extension for development of CTP as a clinically viable cardiac vector, we now present toxicity studies performed on the peptide. In vitro viability studies were performed in a human left ventricular myocyte cell line with 10µM of Cyanine-5.5 labeled CTP (CTP-Cy5.5). In vitro ion channel profiles were completed for CTP followed by more extensive studies performed by Eurofins in stably transfected cell lines for an extensive list of GPCR-coupled receptors. Positive data for GPCR-coupled receptors was interrogated further with RT-qPCRs performed on mouse heart tissue. In vivo studies consisted of pre- and post-blood pressure monitoring acutely after a single CTP (10 mg/Kg) injection. Further in vivo toxicity studies consisted of injecting 60, 6-week-old, wild-type CD1, male/female mice (1:1) injected with CTP (150 µg/Kg) intravenously. Mice were weighed immediately before injections and daily thereafter. Cohorts of mice were euthanized on day 0, 1, 2, 7 and 14 with inhalational CO2, followed by opening of the chest cavity, collection of blood via cardiac puncture, complete blood count analysis, metabolic profiling, and finally, liver, renal and thyroid studies. Lastly, mouse cardiac MRI was performed immediately before and after injections of CTP (150 µg/Kg) to assess changes in cardiac size or function. Human left ventricular cardiomyocytes showed no decrease in viability after a 30 min incubation with CTP-Cy5.5. In the Eurofins Cardiac Profiler Qube, no significant activation or inhibition of any of seventy-eight protein channels was observed other than OPRM1 and COX2 at the highest tested concentration, neither of which were expressed in mouse heart tissue as assessed by RT-qPCR. There was no change in blood pressures before and after injections with CTP at 10 mg/Kg. Blood counts and chemistries showed no evidence of significant hematological, hepatic or renal toxicities. Lastly, there was no significant difference in cardiac function, size or mass before and after CTP injections. Our studies with CTP showed no activation or inhibition of GPCR-associated receptors in vitro. We found no signals indicative of toxicity in vivo. Most importantly, cardiac functions remained unchanged acutely in response to CTP uptake. Further studies, in good laboratory practices fashion, are needed with more prolonged, chronic administration of CTP conjugated to a specific cargo of choice before human studies can be contemplated.

Aerobic exercise training (AET) has been used in the management of heart disease. AET may, totally or partially, restore the activity and/or expression of proteins that regulate calcium (Ca2+) handling, optimize intracellular Ca2+ flow, and attenuate cardiac functional impairment in failing hearts. However, the literature presents conflicting data regarding the effects of AET on Ca2+ transit and cardiac function in rats with heart failure resulting from aortic stenosis. The objective of this study was to evaluate the effects of AET on calcium handling and cardiac function in rats with heart failure due to aortic stenosis. Wistar rats were distributed into two groups: control (Sham; n= 61) and aortic stenosis (AoS; n= 44). After 18 weeks, the groups were redistributed into: non-exposed to exercise training (Sham, n = 28 and AoS, n = 22) and trained (Sham-ET, n = 33 and AoS-ET, n = 22) for 10 weeks. Treadmill exercise training was performed with a velocity equivalent to the lactate threshold. Echocardiogram, isolated papillary muscle, and isolated cardiomyocyte analyzed cardiac function. During isolated papillary muscle assay and isolated cardimyocyte was evaluated Ca2+. The expression of regulatory proteins of diastolic Ca2+ was analyzed via Western Blot. AET attenuated the diastolic dysfunction and benefited the systolic function. AoS-ET animals presented better response to post-rest contraction, and SERCA2a and L-type Ca2+ channels blocked than the AoS. Furthermore, AET was able to improve aspects of the mechanical function and the responsiveness of the myofilaments to the Ca2+ of the AoS-ET animals. AoS animals presented alteration in the protein expression of the SERCA2a and NCX, and AET restored SERCA2a and NCX levels near normal values. Therefore, AET increased SERCA2a activity, improved the cellular Ca2+ influx mechanism, and increased myofilament responsiveness to Ca2+, attenuating cardiac dysfunction at cellular, tissue, and chamber levels in animals with aortic stenosis and heart failure.

Background: Obtaining adipose-derived stem cells is limited by its capacity to differentiate. Stimulation by platelet-rich fibrin appears to have the beneficial effects to accelerate differentiation. Objective: To obtain immunohistochemistry evidence of platelet-rich fibrin to accelerate differentiation of adipose-derived stem cells. Methods: We used post-test only controlled-group design. Adipose-derived stem cells were isolated and cultured until 4 passages in α-MEM culture medium. Results: GATA-4 expression increased in platelet-rich fibrin group compared with control group (68.20±6.82 vs 58.15±1.23 counts; p<0.05; 68.20±6.82 vs 52.96±2.02 counts; p<0.05). Troponin expression also increased in platelet-rich fibrin group (50.66±7.2 vs 10.73±2.39 counts; p<0.05; 50.66±7.2 vs 26.00±0.4 counts; p<0.05). Conclusion: There is an immunohistochemistry benefit of platelet-rich fibrin to accelerate differentiation of adipose-derived stem cells into cardiomyocyte-like cells.

Background: There is several challenges to solve irreversible loss of cardiomyocytes due to myocardial infarction. Cell therapy is believed as an ideal treatment for cardiac regeneration in the infarct area. Obtaining adipose-derived stem cells increases seems to be promising, however it is limited by the capacity to differentiate. Stimulation by injectable platelet-rich fibrin appears to have the beneficial effects to accelerate cardiomyocyte-like cells differentiation. Objective: To analyse the benefit of injectable platelet-rich fibrin to accelerate differentiation of adipose-derived mesenchymal stem cells into cardiomyocyte-like cells. Methods: This study is a true experimental randomized post-test design study. Adipose-derived mesenchymal stem cells were isolated from adipose tissues and cultured until 4 passages. The characteristics of adipose-derived mesenchymal stem cells were measured by the expression of CD 34-, CD 45-, and CD 105+ using flowcytometry. The samples were divided into 3 groups, i.e. negative control (α-MEM), positive control (differentiation medium) and treatment group (platelet-rich fibrin). The assessment of GATA-4 marker expression was conducted using flowcytometry on the fifth day and troponin was conducted using immunocytochemistry on the tenth day to determine the differentiation to cardiomyocyte. Data analysis was conducted using T-test and One-Way ANOVA on normally distributed data determined through Shapiro-Wilk test. Results: Flowcytometry on GATA-4 expression revealed significant difference on addition of platelet-rich fibrin compared with negative and positive controls (68.20 ± 6.82 vs 58.15 ± 1.23; p<0.05; 68.20 ± 6.82 vs 52.96 ± 2.02; p<0.05). This was supported by the results of immunocytochemistry on troponin expression which revealed significant difference between platelet-rich fibrin group compared with negative and positive controls (50.66 ± 7.2 vs 10.73 ± 2.39; p<0.05; 50.66 ± 7.2 vs 26.00 ± 0.4; p<0.05). Conclusion: Injectable platelet-rich fibrin has beneficial effect to accelerate differentiation of adipose-derived mesenchymal stem cells into cardiomyocyte-like cells.