Male and female hypertrophic rat cardiac myocyte functional responses to ischemic stress and β-adrenergic challenge are different

Female cardiovascular biology and resilience in the setting of physiological and pathological stress

For years, females were thought of as smaller men with complex hormonal cycles; as a result, females have been largely excluded from preclinical and clinical research. However, in the last ten years, with the increased focus on sex as a biological variable, it has become clear that this is not the case, and in fact, male and female cardiovascular biology and cardiac stress responses differ substantially. Premenopausal women are protected from cardiovascular diseases, such as myocardial infarction and resultant heart failure, having preserved cardiac function, reduced adverse remodeling, and increased survival. Many underlying biological processes that contribute to ventricular remodeling differ between the sexes, such as cellular metabolism; immune cell responses; cardiac fibrosis and extracellular matrix remodeling; cardiomyocyte dysfunction; and endothelial biology; however, it is unclear how these changes afford protection to the female heart. Although many of these changes are dependent on protection provided by female sex hormones, several of these changes occur independent of sex hormones, suggesting that the nature of these changes is more complex than initially thought. This may be why studies focused on the cardiovascular benefits of hormone replacement therapy in post-menopausal women have provided mixed results. Some of the complexity likely stems from the fact that the cellular composition of the heart is sexually dimorphic and that in the setting of MI, different subpopulations of these cell types are apparent. Despite the documented sex-differences in cardiovascular (patho)physiology, the underlying mechanisms that contribute are largely unknown due to inconsistent findings amongst investigators and, in some cases, lack of rigor in reporting and consideration of sex-dependent variables. Therefore, this review aims to describe current understanding of the sex-dependent differences in the myocardium in response to physiological and pathological stressors, with a focus on the sex-dependent differences that contribute to post-infarction remodeling and resultant functional decline.

Mechanical Circulatory Support in Myocardial Infarction Complicated by Cardiogenic Shock: Impact of Sex and Timing

Background

Sex differences in presentation, treatment, and outcomes persist in patients with acute myocardial infarction complicated by cardiogenic shock (AMICS). Sex-based outcomes of patients with AMICS undergoing percutaneous coronary intervention (PCI) with percutaneous left ventricular assist device (pLVAD) support are poorly defined.

Methods

From January 2017 to August 2019, consecutive patients undergoing PCI who received Impella support within 48 ​hours of myocardial infarction were enrolled in the prospective RECOVER III postmarket registry. In-hospital survival and predictors of mortality were compared by sex.

Results

A total of 358 patients (276 men and 82 women) were included. Women had lower baseline mean arterial pressure and shorter duration of pLVAD support compared with men. In-hospital adverse events were similar in women and men, including mortality (54% versus 46%, P = .25), major bleeding (11% versus 10%, P = .83), and vascular complications requiring surgery (8.5% versus 4%, P = .10). Women had better survival with pre-PCI versus post-PCI pLVAD implantation (59% versus 34%, P = .03), whereas survival in men was similar regardless of pre- versus post-PCI pLVAD support (56% versus 50%, P = .39). The number of inotrope/vasopressor use pre-pLVAD was the strongest predictor of mortality in women (OR 3.03, P = .01) but not in men (OR 1.18, P = .25).

Conclusions

Survival of patients with AMICS treated with PCI and Impella support was 52% at hospital discharge and was similar for women and men. Women with AMICS may derive greater benefit from early pLVAD support prior to escalation of inotrope/vasopressors and had no evidence of increased risk of access-related complications.

Heart failure in diabetes

Heart failure and cardiovascular disorders represent the leading cause of death in diabetic patients. Here we present a systematic review of the main mechanisms underlying the development of diabetic cardiomyopathy. We also provide an excursus on the relative contribution of cardiomyocytes, fibroblasts, endothelial and smooth muscle cells to the pathophysiology of heart failure in diabetes. After having described the preclinical tools currently available to dissect the mechanisms of this complex disease, we conclude with a section on the most recent updates of the literature on clinical management.

A framework for developing sex-specific engineered heart models

The convergence of tissue engineering and patient-specific stem cell biology has enabled the engineering of in vitro tissue models that allow the study of patient-tailored treatment modalities. However, sex-related disparities in health and disease, from systemic hormonal influences to cellular-level differences, are often overlooked in stem cell biology, tissue engineering and preclinical screening. The cardiovascular system, in particular, shows considerable sex-related differences, which need to be considered in cardiac tissue engineering. In this Review, we analyse sex-related properties of the heart muscle in the context of health and disease, and discuss a framework for including sex-based differences in human cardiac tissue engineering. We highlight how sex-based features can be implemented at the cellular and tissue levels, and how sex-specific cardiac models could advance the study of cardiovascular diseases. Finally, we define design criteria for sex-specific cardiac tissue engineering and provide an outlook to future research possibilities beyond the cardiovascular system.

Improving translational research in sex-specific effects of comorbidities and risk factors in ischaemic heart disease and cardioprotection: position paper and recommendations of the ESC Working Group on Cellular Biology of the Heart

Ischaemic heart disease (IHD) is a complex disorder and a leading cause of death and morbidity in both men and women. Sex, however, affects several aspects of IHD, including pathophysiology, incidence, clinical presentation, diagnosis as well as treatment and outcome. Several diseases or risk factors frequently associated with IHD can modify cellular signalling cascades, thus affecting ischaemia/reperfusion injury as well as responses to cardioprotective interventions. Importantly, the prevalence and impact of risk factors and several comorbidities differ between males and females, and their effects on IHD development and prognosis might differ according to sex. The cellular and molecular mechanisms underlying these differences are still poorly understood, and their identification might have important translational implications in the prediction or prevention of risk of IHD in men and women. Despite this, most experimental studies on IHD are still undertaken in animal models in the absence of risk factors and comorbidities, and assessment of potential sex-specific differences are largely missing. This ESC WG Position Paper will discuss: (i) the importance of sex as a biological variable in cardiovascular research, (ii) major biological mechanisms underlying sex-related differences relevant to IHD risk factors and comorbidities, (iii) prospects and pitfalls of preclinical models to investigate these associations, and finally (iv) will provide recommendations to guide future research. Although gender differences also affect IHD risk in the clinical setting, they will not be discussed in detail here.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Cardiomyocyte functional screening: interrogating comparative electrophysiology of high-throughput model cell systems

Cardiac arrhythmias of both atrial and ventricular origin are an important feature of cardiovascular disease. Novel antiarrhythmic therapies are required to overcome current drug limitations related to effectiveness and pro-arrhythmia risk in some contexts. Cardiomyocyte culture models provide a high-throughput platform for screening antiarrhythmic compounds, but comparative information about electrophysiological properties of commonly used types of cardiomyocyte preparations is lacking. Standardization of cultured cardiomyocyte microelectrode array (MEA) experimentation is required for its application as a high-throughput platform for antiarrhythmic drug development. The aim of this study was to directly compare the electrophysiological properties and responses to isoproterenol of three commonly used cardiac cultures. Neonatal rat ventricular myocytes (NRVMs), immortalized atrial HL-1 cells, and custom-generated human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were cultured on microelectrode arrays for 48-120 h. Extracellular field potentials were recorded, and conduction velocity was mapped in the presence/absence of the β-adrenoceptor agonist isoproterenol (1 µM). Field potential amplitude and conduction velocity were greatest in NRVMs and did not differ in cardiomyocytes isolated from male/female hearts. Both NRVMs and hiPSC-CMs exhibited longer field potential durations with rate dependence and were responsive to isoproterenol. In contrast, HL-1 cells exhibited slower conduction and shorter field potential durations and did not respond to 1 µM isoproterenol. This is the first study to compare the intrinsic electrophysiologic properties of cultured cardiomyocyte preparations commonly used for in vitro electrophysiology assessment. These findings offer important comparative data to inform methodological approaches in the use of MEA and other techniques relating to cardiomyocyte functional screening investigations of particular relevance to arrhythmogenesis.

Gender Differences in Prognostic Markers of All-Cause Death in Patients with Acute Heart Failure: a Prospective 18-Month Follow-Up Study

Acute heart failure (AHF) is a life-threatening condition with poor prognosis. Gender differences have been increasingly recognized in diverse cardiovascular diseases. The present study aimed to evaluate gender-specific prognostic markers of all-cause death in AHF patients based on a prospective 18-month follow-up study. Data were collected from 419 patients with AHF hospitalization who were followed up for 18 months using all-cause death as primary endpoint. The mean age of all patients was 60.9 ± 15.7 years old, 277 were males, and 142 were females. Females had higher rate of valvular heart disease (37.3%) and atrial fibrillation (45.8%) but lower rate of cardiomyopathy (30.3%) than males in this cohort. Based on multiple COX stepwise regression and ROC curve analysis, diastolic blood pressure (DBP), serum sodium, serum creatinine, and pulmonary artery systolic pressure (PASP) were identified as independent predictors of all-cause death in male AHF patients, while systolic blood pressure (SBP), serum aspartate transaminase (AST), serum creatinine, and serum D-dimer as independent predictors in females. Kaplan-Meier analysis showed a higher probability of all-cause death over time in male AHF patients with DBP ≤ 77 mmHg, serum sodium ≤ 138.5 mM, serum creatinine ≥ 126.2 μM, or PASP ≥ 52 mmHg, and in female AHF patients with SBP ≤ 129 mmHg, serum AST > 29.3 U/L, serum creatinine ≥ 102.7 μM, or serum D-dimer ≥ 1.76 mg/L. In conclusion, these data provide novel insights into gender differences in prognostic markers of outcomes of AHF patients.

Estrogen but not testosterone preserves myofilament function from doxorubicin-induced cardiotoxicity by reducing oxidative modifications

Here, we aimed to explore sex differences and the impact of sex hormones on cardiac contractile properties in doxorubicin (DOX)-induced cardiotoxicity. Male and female Sprague-Dawley rats were subjected to sham surgery or gonadectomy and then treated or untreated with DOX (2 mg/kg) every other week for 10 wk. Estrogen preserved maximum active tension (T_max) with DOX exposure, whereas progesterone and testosterone did not. The effects of sex hormones and DOX correlated with both altered myosin heavy chain isoform expression and myofilament protein oxidation, suggesting both as possible mechanisms. However, acute treatment with oxidative stress (H₂O₂) or a reducing agent (DTT) indicated that the effects on T_max were mediated by reversible myofilament oxidative modifications and not only changes in myosin heavy chain isoforms. There were also sex differences in the DOX impact on myofilament Ca²⁺ sensitivity. DOX increased Ca²⁺ sensitivity in male rats only in the absence of testosterone and in female rats only in the presence of estrogen. Conversely, DOX decreased Ca²⁺ sensitivity in female rats in the absence of estrogen. In most instances, this mechanism was through altered phosphorylation of troponin I at Ser²³/Ser²⁴. However, there was an additional DOX-induced, estrogen-dependent, irreversible (by DTT) mechanism that altered Ca²⁺ sensitivity. Our data demonstrate sex differences in cardiac contractile responses to chronic DOX treatment. We conclude that estrogen protects against chronic DOX treatment in the heart, preserving myofilament function. NEW & NOTEWORTHY We identified sex differences in cardiotoxic effects of chronic doxorubicin (DOX) exposure on myofilament function. Estrogen, but not testosterone, decreases DOX-induced oxidative modifications on myofilaments to preserve maximum active tension. In rats, DOX exposure increased Ca²⁺ sensitivity in the presence of estrogen but decreased Ca²⁺ sensitivity in the absence of estrogen. In male rats, the DOX-induced shift in Ca²⁺ sensitivity involved troponin I phosphorylation; in female rats, this was through an estrogen-dependent mechanism.

Biochemical and Ultrastructural Cardiac Changes Induced by High-Fat Diet in Female and Male Prepubertal Rabbits

Early weight gain induced by high-fat diet has been identified as a predictor for cardiac disease, one of the most serious public health problems. Our goal is to study the influence of a HFD on biochemical, oxidant stress parameters, and the cardiac ultrastructure in both male and female prepubertal models. Experiments were carried on 24 prepubertal New Zealand white rabbits, randomly assigned to male and female control (MC and FC, resp.) or HFD (MHFD and FHFD, resp.) groups (n = 6) for 3 months. Body and heart weights and some biochemical and oxidative stress parameters such as lipids, calcium, CKMB, MDA, uric acid, ascorbic acid, and AOA are evaluated in plasma and the left ventricle. Under HFD effect, plasma parameters, such as lipids (TL, PL, and LDL-C), MDA, and CK-MB, increase more significantly in male than in female groups, when AA decreases. Some cardiac parameters such as TG and UA increase, when AA and AOA decrease; these variations are more significant in FHFD. In both male and female rabbits, HFD caused changes in heart ultrastructure, junctional complexes, mitochondria size and form, and so on. Early HFD feeding induced overweight, oxidative stress, and metabolic alterations in plasma and the heart of prepubertal rabbits, whereas lipotoxicity has especially a negative impact on male plasma but affects more the female heart ultrastructure.

Sex Differences in Metabolic Cardiomyopathy

In contrast to ischemic cardiomyopathies which are more common in men, women are over-represented in diabetic cardiomyopathies. Diabetes is a risk factor for cardiovascular disease; however, there is a sexual dimorphism in this risk factor: heart disease is five times more common in diabetic women but only two-times more common in diabetic men. Heart failure with preserved ejection fraction, which is associated with metabolic syndrome, is also more prevalent in women. This review will examine potential mechanisms for the sex differences in metabolic cardiomyopathies. Sex differences in metabolism, calcium handling, nitric oxide, and structural proteins will be evaluated. Nitric oxide synthase and PPARα exhibit sex differences and have also been proposed to mediate the development of hypertrophy and heart failure. We focused on a role for these signalling pathways in regulating sex differences in metabolic cardiomyopathies.