Germán Esteban González

When blood flow to a part of the myocardial muscle is reduced or blocked, it leads to tissue ischemia in that region. Myocardial infarction (MI) occurs when the ischemic insult is of sufficient duration in time to induce cardiomyocyte death and subsequent activation of the innate immune response. MI initiates a complex cascade of cellular and molecular events within the left ventricle. Inflammatory cells rapidly infiltrate the infarcted area to remove necrotic tissue, setting the stage for reparative wound healing processes. Over the ensuing days, various cell populations—including leukocytes, fibroblasts, and endothelial cells—are attracted to the infarcted site by inflammatory cytokines and chemokines. The activated cells at the site of injury contribute to tissue remodeling and scar formation through the deposition of extracellular matrix components, particularly collagen. While scar formation is essential for structural stabilization of the infarct region to replace the loss of cardiomyocytes, scar tissue also increases myocardial stiffness and impairs cardiac contractile function. This review summarizes our knowledge regarding cellular dynamics, inflammatory signaling, and cardiac remodeling that govern MI healing. We identify the current gaps in the field and provide a foundational resource for those seeking to understand the biological underpinnings of cardiac repair following MI.

Cardiometabolic syndrome (CMS) encompasses a cluster of metabolic abnormalities, including obesity, insulin resistance, dyslipidemia, and hypertension, that collectively increase the risk of cardiovascular disease and type 2 diabetes. Animal models are widely used to study CMS, with diet-induced models being the most physiologically relevant. A lack of reporting standards and variability in dietary composition, feeding duration, and macronutrient content across studies hinder reproducibility assessment and translational impact evaluation. We provide standardized guidelines for the consideration, preparation, and use of diets in experimental models of CMS. Advantages and limitations of different diet-induced models are compared with genetic and pharmacological approaches, emphasizing replicability to human metabolic dysregulation. Key components include macronutrient composition, fat source selection, feeding duration, strain susceptibility, and sex differences. In addition, we outline husbandry practices, including environmental factors, bedding material, and enrichment conditions, which can affect metabolic outcomes. Standardization is essential for enhancing experimental reproducibility and facilitating cross-study comparisons. These guidelines serve as a framework for researchers to optimize dietary interventions in CMS models, improving the predictive value of preclinical findings for translational applications to aid in the development of targeted therapeutic strategies.

High salt (NaCl) intake has been associated with visceral adipose tissue (VAT) dysfunction independently of its impact on blood pressure. Liraglutide (LGT), a GLP-1 agonist, could be a potential therapeutic option. We investigated the impact of a chronic high-salt diet (HSD) on VAT homeostasis and evaluated the potential protective effects of LGT, a GLP-1 receptor agonist. Male C57BL/6 mice were fed a standard diet (Control, C) or 8% NaCl (HSD) for 15 weeks and subsequently treated with LGT or vehicle for 5 weeks. In VAT, histological characteristics, collagen deposition, vascular density, mitochondrial dynamics, oxidative stress, and adipokine expression were evaluated. The HSD significantly decreased body weight, VAT mass, and adipocyte size (p < 0.05). Moreover, it impaired vascular density and induced interstitial fibrosis (p < 0.01). LGT treatment improved vascularization and VEGF expression and reduced fibrosis (p < 0.05 vs. the HSD). The HSD induced oxidative stress and mitochondrial fragmentation, which were attenuated by LGT (p < 0.001). Leptin levels were elevated by the HSD (p < 0.05) and normalized with LGT, while adiponectin levels increased. In conclusion, excessive salt consumption induces structural and metabolic dysfunction in VAT. LGT therapy mitigates several of these adverse effects, supporting its potential as a novel strategy for managing salt-sensitive adipose tissue dysfunction.

Galectin-3 (Gal-3) is a carbohydrate-binding protein with multiple functions. Gal-3 regulates cell growth, proliferation, and apoptosis by orchestrating cell-cell and cell-matrix interactions. It is implicated in the development and progression of cardiovascular disease, and its expression is increased in patients with heart failure. In atherosclerosis, Gal-3 promotes monocyte recruitment to the arterial wall boosting inflammation and atheroma. In acute myocardial infarction (AMI), the expression of Gal-3 increases in infarcted and remote zones from the beginning of AMI, and plays a critical role in macrophage infiltration, differentiation to M1 phenotype, inflammation and interstitial fibrosis through collagen synthesis. Genetic deficiency of Gal-3 delays wound healing, impairs cardiac remodeling and function after AMI. On the contrary, Gal-3 deficiency shows opposite results with improved remodeling and function in other cardiomyopathies and in hypertension. Pharmacologic inhibition with non-selective inhibitors is also protective in cardiac disease. Finally, we recently showed that Gal-3 participates in normal aging. However, genetic absence of Gal-3 in aged mice exacerbates pathological hypertrophy and increases fibrosis, as opposed to reduced fibrosis shown in cardiac disease. Despite some gaps in understanding its precise mechanisms of action, Gal-3 represents a potential therapeutic target for the treatment of cardiovascular diseases and the management of cardiac aging. In this review, we summarize the current knowledge regarding the role of Gal-3 in the pathophysiology of heart failure, atherosclerosis, hypertension, myocarditis, and ischemic heart disease. Furthermore, we describe the physiological role of Gal-3 in cardiac aging.

Cardiovascular disease is the most prevalent cause of death in Western countries, with acute myocardial infarction (MI) being the most prevalent form. This paper describes a protocol for studying the role of galectin 3 (Gal-3) in the temporal evolution of cardiac healing and remodeling in an experimental animal model of MI. The procedures described include an experimental model of MI with a permanent coronary ligature in male C57BL/6J (control) and Gal-3 knockout (KO) mice, an echocardiography procedure to study cardiac remodeling and systolic function in vivo, a histological evaluation of interstitial myocardial fibrosis with picrosirius red-stained and rhodamine-conjugated lectin-stained sections for studying myocyte hypertrophy by the cross-sectional area (MCSA), and the quantification of infarct size and cardiac remodeling (scar thinning, septum thickness, and expansion index) by planimetry in slices stained with Masson's trichrome and triphenyl tetrazolium chloride. Gal-3 KO mice with MI showed disrupted cardiac remodeling and an increase in the scar thinning ratio and the expansion index. At the onset of MI, myocardial function and cardiac remodeling were also severely affected. At 4 weeks post MI, the natural evolution of fibrosis in infarcted Gal-3 KO mice was also affected. In summary, the experimental model of MI is a suitable model for studying the temporal evolution of cardiac repair and remodeling in mice with the genetic deletion of Gal-3 and other animal models. The lack of Gal-3 affects the dynamics of cardiac repair and disrupts the evolution of cardiac remodeling and function after MI.

Background/Aims: Aging is accompanied by progressive and adverse cardiac remodeling characterized by myocardial hypertrophy, fibrosis, and dysfunction. We previously reported that galectin-3 (Gal-3) is a critical regulator of inflammation and fibrosis associated with hypertensive heart disease and myocardial infarction. Nevertheless, the role and mechanism of Gal-3 in age-related cardiac remodeling have not been previously investigated. We hypothesized that Gal-3 plays a critical role in cardiac aging and that its deficiency exacerbates the underlying mechanisms of myocardial hypertrophy and fibrosis. Methods: Male C57BL/6 (control) (n=24) and Gal-3 knockout (KO) (n=29) mice were studied at 24 months of age to evaluate the role of Gal-3 in cardiac aging. We assessed 1) survival rate; 2) systolic blood pressure (SBP) by plethysmography; 3) myocardial hypertrophy, apoptosis, and fibrosis by quantification of histological and immunohistochemical analysis; 4) cardiac expression of angiotensin (Ang) II, Ang (1–7) by Radioimmunoassay; 5) transforming growth factor-β (TGF-β), sirtuin (SIRT) 1, SIRT 7 and metalloproteinase 9 (MMP-9) by RT-qPCR and 6) ventricular remodeling and function by echocardiography. Results: We found that aged Gal-3 KO mice had a lower survival rate and exhibited exacerbated myocardial hypertrophy and fibrosis without changes in SBP. Similarly, myocardial apoptosis and MMP-9 mRNA expression was significantly increased in the hearts of Gal-3 KO mice compared to controls. Additionally, cardiac Ang II and TGF-β expression were higher in aged Gal-3 KO mice while SIRT1 and SIRT7 expression were reduced. Conclusion: Our findings strongly suggest that Gal-3 is involved in age-related cardiac remodeling by regulating critical mechanisms associated with the development of pathological hypertrophy. The gene deletion of Gal-3 reduced the lifespan and markedly increased age-dependent mechanisms of myocardial hypertrophy, apoptosis, and fibrosis, including Ang-II, TGF-β, and MMP-9. At the same time, there was diminished cardiac-specific expression of SIRT1 and SIRT7, which are extensively implicated in delaying age-dependent cardiomyopathies.