Cardiomyocyte death and renewal in the normal and diseased heart. Cardiovasc Pathol. 2008;17:349-374. [PMID: 18402842 DOI: 10.1016/j.carpath.2008.02.004]

Loss of Snord116 protects cardiomyocyte kinetics during ischemic stress

Loss of Snord116, a non-coding RNA, causes Prader Willi Syndrome (PWS), a complex disorder with circadian, metabolic, neurologic, and cardiovascular phenotypes. The Snord116 paternal knockout (Snord116p-) mouse, a model of PWS, demonstrated differential methylation of thousands of genes involved in regulation of metabolism, epigenetics, and ion homeostasis. To determine if Snord116 expression influences the cardiomyocyte response to acute ischemia, we developed a model of ischemia and reperfusion using living myocardial slices and monitored cardiomyocyte function in slices derived from Snord116p- mice and wildtype littermates (WT LM) of both sexes. We found that Snord116 loss reduced ischemia-induced systolic prolongation and delayed diastolic elongation in slices from both males and females. Furthermore, when compared with slices from males, slices from females experienced a greater increase in end-diastolic force after ischemia. We conclude that female myocardium responds more dramatically and quickly to ischemic injury in this model and that loss of Snord116 is cardioprotective; this allows for a more complete myocardial recovery following reperfusion.

Enhanced FGF21 Delivery via Neutrophil-Membrane-Coated Nanoparticles Improves Therapeutic Efficacy for Myocardial Ischemia-Reperfusion Injury

Acute myocardial infarction, a leading cause of death globally, is often associated with cardiometabolic disorders such as atherosclerosis and metabolic syndrome. Metabolic treatment of these disorders can improve cardiac outcomes, as exemplified by the GLP-1 agonist semaglutide. Fibroblast growth factor 21 (FGF21), a novel metabolic regulator, plays pivotal roles in lipid mobilization and energy conversion, reducing lipotoxicity, inflammation, mitochondrial health, and subsequent tissue damage in organs such as the liver, pancreas, and heart. Here, we test the therapeutic efficacy of FGF21 in mice with ischemia-reperfusion (I/R) injury, a model of acute myocardial infarction. We employed the strategic method of coating the FGF21-encapsulating liposomal nanoparticles with a neutrophil membrane designed to camouflage FGF21 from macrophage-mediated efferocytotic clearance and promote its targeted accumulation at I/R foci due to the inherent neutrophilic attraction to the inflammatory site. Our findings revealed that the coated FGF21 nanoparticles markedly accumulated within the lesions with a prolonged half-life, in additional to the liver, leading to substantial improvements in cardiac performance by enhancing mitochondrial energetic function and reducing oxidative stress, inflammation, and cell death. Therefore, our research highlights a viable strategy for the enhanced delivery of therapeutical FGF21 analogs to lesions beyond the liver following myocardial infarction.

Pathobiology of myocardial and cardiomyocyte injury in ischemic heart disease: Perspective from seventy years of cell injury research

This review presents a perspective on the pathobiology of acute myocardial infarction, a major manifestation of ischemic heart disease, and related mechanisms of ischemic and toxic cardiomyocyte injury, based on advances and insights that have accrued over the last seventy years, including my sixty years of involvement in the field as a physician-scientist-pathologist. This analysis is based on integration of my research within the broader context of research in the field. A particular focus has been on direct measurements in cardiomyocytes of electrolyte content by electron probe X-ray microanalysis (EPXMA) and Ca2+ fluxes by fura-2 microspectrofluorometry. These studies established that increased intracellular Ca2+ develops at a transitional stage in the progression of cardiomyocyte injury in association with ATP depletion, other electrolyte alterations, altered cell volume regulation, and altered membrane phospholipid composition. Subsequent increase in total calcium with mitochondrial calcium accumulation can occur. These alterations are characteristic of oncosis, which is an initial pre-lethal state of cell injury with cell swelling due to cell membrane dysfunction in ATP depleted cells; oncosis rapidly progresses to necrosis/necroptosis with physical disruption of the cell membrane, unless the adverse stimulus is rapidly reversed. The observed sequential changes fit a three-stage model of membrane injury leading to irreversible cell injury. The data establish oncosis as the primary mode of cardiomyocyte injury in evolving myocardial infarcts. Oncosis also has been documented to be the typical form of non-ischemic cell injury due to toxins. Cardiomyocytes with less energy impairment have the capability of undergoing apoptosis and autophagic death as well as oncosis, as is seen in pathological remodeling in chronic heart failure. Work is ongoing to apply the insights from experimental studies to better understand and ameliorate myocardial ischemia and reperfusion injury in patients. The perspective and insights in this review are derived from basic principles of pathology, an integrative discipline focused on mechanisms of disease affecting the cell, the organizing unit of living organisms.

Overexpression of zinc-finger protein 418 inhibits pathological cardiac remodelling after acute myocardial infarction

AIMS

Zinc-finger protein 418 (ZNF418) has been confirmed to be expressed in myocardial tissue. However, the role and mechanism of ZNF418 in pathological myocardial remodelling after myocardial infarction (MI) have not been reported. This study was to elucidate the effect and mechanism of ZNF418 on ventricular remodelling after MI in mice.

METHODS AND RESULTS

MI mice and H9c2 cardiomyocytes were used to conduct in vivo and in vitro experiments, respectively. ZNF418 expression was regulated by adeno-associated virus 9 and adenovirus vectors. Pathological analysis, echocardiography, and molecular analysis were performed. ZNF418 was down-regulated in the left ventricular tissues of post-MI mice. In contrast, ZNF418 overexpression decreased mortality and improved cardiac function in MI mice. The MI mice exhibited a significantly increased cross-sectional area of myocardial cells and elevated protein expression levels of myocardial hypertrophy markers ANP, BNP, and β-MHC (all P < 0.05). Moreover, a significantly increased area of myocardial fibrosis and protein expression levels of myocardial fibrosis markers collagen I, collagen III, and CTGF were observed in MI mice (all P < 0.05) in MI mice. All of the above negative effects in MI mice were ameliorated in ZNF418 overexpressed mice (all P < 0.05). Mechanistically, ZNF418 overexpression inhibited the activation of the MAPK signalling pathway, as evidenced by the in vivo and in vitro experiments.

CONCLUSIONS

Overexpression of ZNF418 could improve cardiac function and inhibit pathological cardiac remodelling by inhibiting the MAPK signalling pathway in post-MI mice.

Unravelling oncosis: morphological and molecular insights into a unique cell death pathway

Programmed cell death (PCD) is a fundamental biological process for maintaining cellular equilibrium and regulating development, health, and disease across all living organisms. Among the various types of PCD, apoptosis plays a pivotal role in numerous diseases, notably cancer. Cancer cells frequently develop mechanisms to evade apoptosis, increasing resistance to standard chemotherapy treatments. This resistance has prompted extensive research into alternative mechanisms of programmed cell death. One such pathway is oncosis, characterized by significant energy consumption, cell swelling, dilation of the endoplasmic reticulum, mitochondrial swelling, and nuclear chromatin aggregation. Recent research suggests that oncosis can impact conditions such as chemotherapeutic cardiotoxicity, myocardial ischemic injury, stroke, and cancer, mediated by specific oncosis-related proteins. In this review, we provide a detailed examination of the morphological and molecular features of oncosis and discuss various natural or small molecule compounds that can induce this type of cell death. Additionally, we summarize the current understanding of the molecular mechanisms underlying oncosis and its role in both normal physiology and pathological conditions. These insights aim to illuminate future research directions and propose innovative strategies for leveraging oncosis as a therapeutic tool against human diseases and cancer resistance.

Cardiovascular risk evaluation in pregnancy: focus on cardiac specific biomarkers

Despite the evidence demonstrating the clinical utility of cardiac specific biomarkers in improving cardiovascular risk evaluation in several clinical conditions, even the most recent reviews and guidelines fail to consider their measurement in order to enhance the accuracy of the evaluation of cardiovascular risk in pregnant women. The aim of this review article was to examine whether the assay of cardiac specific biomarkers can enhance cardiovascular risk evaluation in pregnant women, first by reviewing the relationships between the physiological state of pregnancy and cardiac specific biomarkers. The clinical relevance of brain natriuretic peptide (BNP)/NT-proBNP and high-sensitivity cardiac troponin I/high-sensitivity cardiac troponin T (hs-cTnI/hs-cTnT) assay in improving cardiovascular risk evaluation is examined based on the results of clinical studies on subjects with normal and those with complicated pregnancy. Finally, the analytical approaches and clinical objectives related to cardio specific biomarkers are advocated in order to allow an early and more accurate evaluation of cardiovascular risk in pregnant women.

Recent Advances of Using Exosomes as Diagnostic Markers and Targeting Carriers for Cardiovascular Disease

Cardiovascular diseases (CVDs) are the leading cause of human death worldwide. Exosomes act as endogenous biological vectors; they possess advantages of low immunogenicity and low safety risks, also providing tissue selectivity, including the inherent targeting the to heart. Therefore, exosomes not only have been applied as biomarkers for diagnosis and therapeutic outcome confirmation but also showed potential as drug carriers for cardiovascular targeting delivery. This review aims to summarize the progress and challenges of exosomes as novel biomarkers, especially many novel exosomal noncoding RNAs (ncRNAs), and also provides an overview of the improved targeting functions of exosomes by unique engineered approaches, the latest developed administration methods, and the therapeutic effects of exosomes used as the biocarriers of medications for cardiovascular disease treatment. Also, the possible therapeutic mechanisms and the potentials for transferring exosomes to the clinic for CVD treatment are discussed. The advances, in vivo and in vitro applications, modifications, mechanisms, and challenges summarized in this review will provide a general understanding of this promising strategy for CVD treatment.

Variability of cardiac troponin levels in normal subjects and in patients with cardiovascular diseases: analytical considerations and clinical relevance

In accordance with all the most recent international guidelines, the variation of circulating levels of cardiac troponins I and T, measured with high-sensitivity methods (hs-cTnI and hs-cTnT), should be used for the detection of acute myocardial injury. Recent experimental and clinical evidences have demonstrated that the evaluation of hs-cTnI and hs-cTnT variations is particularly relevant: a) for the differential diagnosis of Acute Coronary Syndromes (ACS) in patients admitted to the Emergency Department (ED); b) for the evaluation of cardiovascular risk in patients undergoing major cardiac or non-cardiac surgery, and in asymptomatic subjects of the general population aged >55 years and with co-morbidities; c) for the evaluation of cardiotoxicity caused by administration of some chemotherapy drugs in patients with malignant tumors. The aim of this document is to discuss the fundamental statistical and biological considerations on the intraindividual variability of hs-cTnI and hs-cTnT over time in the same individual. Firstly, it will be discussed in detail as the variations of circulating levels strictly depend not only on the analytical error of the method used but also on the intra-individual variability of the biomarker. Afterwards, the pathophysiological interpretation and the clinical relevance of the determination of the variability of the hs-cTnI and hs-cTnT values ​​ in patients with specific clinical conditions are discussed. Finally, the evaluation over time of the variation in circulating levels of hs-cTnI and hs-cTnT is proposed for a more accurate estimation of cardiovascular risk in asymptomatic subjects from the general population.

The Na+/K+-ATPase: A potential therapeutic target in cardiometabolic diseases

Cardiometabolic diseases (CMD) are a direct consequence of modern living and contribute to the development of multisystem diseases such as cardiovascular diseases and diabetes mellitus (DM). CMD has reached epidemic proportions worldwide. A sodium pump (Na+/K+-ATPase) is found in most eukaryotic cells' membrane and controls many essential cellular functions directly or indirectly. This ion transporter and its isoforms are important in the pathogenesis of some pathological processes, including CMD. The structure and function of Na+/K+-ATPase, its expression and distribution in tissues, and its interactions with known ligands such as cardiotonic steroids and other suspected endogenous regulators are discussed in this review. In addition, we reviewed recent literature data related to the involvement of Na+/K+-ATPase activity dysfunction in CMD, focusing on the Na+/K+-ATPase as a potential therapeutic target in CMD.

Current knowledge of pyroptosis in heart diseases

Pyroptosis is a form of pro-inflammatory, necrotic cell death mediated by proteins of the gasdermin family. Various heart diseases, including myocardial ischemia/reperfusion injury, myocardial infarction, and heart failure, involve cardiomyocyte and non-myocyte pyroptosis. Cardiomyocyte pyroptosis also causes the release of pro-inflammatory cytokines. Recent studies have confirmed that pyroptosis is predominantly triggered by both the canonical and non-canonical inflammasome pathways, which independently facilitate caspase-1 or caspase-11/4/5 activation and gasdermin D (GSDMD) cleavage. Cardiac fibroblast and myeloid cell pyroptosis also contributes to the pathogenesis and development of heart diseases. This review summarizes the recent studies on pyroptosis in heart diseases and discusses the associated therapeutic targets.

UCHL1 protects against ischemic heart injury via activating HIF-1α signal pathway

Ubiquitin carboxyl-terminal esterase L1 (UCHL1) has been thought to be a neuron specific protein and shown to play critical roles in Parkinson's Disease and stroke via de-ubiquiting and stabilizing key pathological proteins, such as α-synuclein. In the present study, we found that UCHL1 was significantly increased in both mouse and human cardiomyocytes following myocardial infarction (MI). When LDN-57444, a pharmacological inhibitor of UCHL1, was used to treat mice subjected to MI surgery, we found that administration of LDN-57444 compromised cardiac function when compared with vehicle treated hearts, suggesting a potential protective role of UCHL1 in response to MI. When UCHL1 was knockout by CRISPR/Cas 9 gene editing technique in human induced pluripotent stem cells (hiPSCs), we found that cardiomyocytes derived from UCHL1−/− hiPSCs were more susceptible to hypoxia/re-oxygenation induced injury as compared to wild type cardiomyocytes. To study the potential targets of UCHL1, a BioID based proximity labeling approach followed by mass spectrum analysis was performed. The result suggested that UCHL1 could bind to and stabilize HIF-1α following MI. Indeed, expression of HIF-1α was lower in UCHL1−/− cells as determined by Western blotting and HIF-1α target genes were also suppressed in UCHL1−/− cells as quantified by real time RT-PCR. Recombinant UCHL1 (rUCHL1) protein was purified by E. Coli fermentation and intraperitoneally (I.P.) delivered to mice. We found that administration of rUCHL1 could significantly preserve cardiac function following MI as compared to control group. Finally, adeno associated virus mediated cardiac specific UCHL1 delivery (AAV9-cTNT-m-UCHL1) was performed in neonatal mice. UCHL1 overexpressing hearts were more resistant to MI injury as compare to the hearts infected with control virus. In summary, our data revealed a novel protective role of UCHL1 on MI via stabilizing HIF-1α and promoting HIF-1α signaling.

Emerging roles of circRNAs in the pathological process of myocardial infarction

Myocardial infarction (MI) is defined as cardiomyocyte death in a clinical context consistent with ischemic insult. MI remains one of the leading causes of morbidity and mortality worldwide. Although there are a number of effective clinical methods for the diagnosis and treatment of MI, further investigation of novel biomarkers and molecular therapeutic targets is required. Circular RNAs (circRNAs), novel non-coding RNAs, have been reported to function mainly by acting as microRNA (miRNA) sponges or binding to RNA-binding proteins (RBPs). The circRNA-miRNA-mRNA (protein) regulatory pathway regulates gene expression and affects the pathological mechanisms of various diseases. Undoubtedly, a more comprehensive understanding of the relationship between MI and circRNA will lay the foundation for the development of circRNA-based diagnostic and therapeutic strategies for MI. Therefore, this review summarizes the pathophysiological process of MI and various approaches to measure circRNA levels in MI patients, tissues, and cells; highlights the significance of circRNAs in the regulation MI pathogenesis and development; and provides potential clinical insight for the diagnosis, prognosis, and treatment of MI.

Diagnostic algorithms for non-ST-segment elevation myocardial infarction: open issues

The use of serial measurement of cardiac troponin (cTn) is recommended by international guidelines for the diagnosis of myocardial infarction (MI) since 2000. This article focuses on factors influencing temporal changes in high-sensitive cTn (hs)-cTn and the impact of these factors on the diagnosis of non-ST-segment elevation MI (NSTEMI). The recommendations proposed by three different international guidelines published in 2020-2021 for the management of acute coronary syndromes (ACS) in patients presenting without persistent ST-segment elevation (NSTE) show some discrepancies. In particular, there is no agreement among these guidelines about cut-off or absolute change values to be used for the rule-in, especially regarding the use of sex-specific cut-off values. Furthermore, there are no sufficient evidences on the diagnostic accuracy and cost effectiveness related to cut-off values suggested for algorithms to be used by some hs-cTnI methods.

Cell Death and Exosomes Regulation After Myocardial Infarction and Ischemia-Reperfusion

Cardiovascular disease (CVD) is the leading cause of death in the global population, accounting for about one-third of all deaths each year. Notably, with CVDs, myocardial damages result from myocardial infarction (MI) or cardiac arrhythmias caused by interrupted blood flow. Significantly, in the process of MI or myocardial ischemic-reperfusion (I/R) injury, both regulated and non-regulated cell death methods are involved. The critical factor for patients' prognosis is the infarct area's size, which determines the myocardial cells' survival. Cell therapy for MI has been a research hotspot in recent years; however, exosomes secreted by cells have attracted much attention following shortcomings concerning immunogens. Exosomes are extracellular vesicles containing several biologically active substances such as lipids, nucleic acids, and proteins. New evidence suggests that exosomes play a crucial role in regulating cell death after MI as exosomes of various stem cells can participate in the cell damage process after MI. Hence, in the review herein, we focused on introducing various cell-derived exosomes to reduce cell death after MI by regulating the cell death pathway to understand myocardial repair mechanisms better and provide a reference for clinical treatment.

The cell theory and cellular pathology: Discovery, refinements and applications fundamental to advances in biology and medicine

This review explores the developments leading up to the establishment of the cell theory and cellular pathology and their subsequent refinements and applications while focusing on the individuals who have made seminal advances in the field. The links between cell biology, cell pathology and cell injury research are emphasized. Recognition also is given to the importance of technological advances in microscopy, histology, biochemical and molecular methods for discovery in cell biology and cell pathology. Particular attention is focused on the work of Rudolph Virchow and his former students in the formulation of the cell theory in biology and pathology and John F. R. Kerr and colleagues who identified and developed a comprehensive characterization of apoptosis, thereby giving impetus to the contemporary field of cell injury research. Cell injury research remains an important and fruitful field of ongoing inquiry and discovery.

Exercise promotes heart regeneration in aged rats by increasing regenerative factors in myocardial tissue

Exercise-induced stem cell activation is implicated in cardiovascular regeneration. However, ageing limits the capacity of cellular and molecular remodelling of the heart. It has been shown that exercise improves structure regeneration and function in the process of ageing. Aged male Wistar rats (n = 24) were divided into three groups: Control (CO), High-intensity interval training (HIIT) (80-100% of the maximum speed), and continuous endurance training (CET) (60-70% of the maximum speed) groups. Training groups were trained for 6 weeks. The expression of the Nkx2.5 gene was determined by real-time (RT-PCRs) analysis. Immunohistochemical staining was performed to assess the C-kit positive cardiac progenitor and Ki67 positive cells. The mRNA level of Nkx2.5 was significantly increased in the CET and HIIT groups (P < 0.05). Also, cardiac progenitor cells positive for C-kit were increased in both the CET and HIIT groups (P < 0.05). Exercise training improved the ejection fraction and fractional shortening in both training groups (P < 0.05). This study indicated that training initiates the activation of cardiac progenitor cells, leading to the generation of new myocardial cells (R = 0.737, P = 0.001). It seems that C-kit positive cells in training groups showed an increase in the expression of some transcription factors (Nkx2.5 gene), representing an increased regenerative capacity of cardiomyocytes during the training period. These findings suggest that the endogenous regenerative capacity of the adult heart, mediated by cardiac stem cells, would be increased in response to exercise.

High-sensitivity methods for cardiac troponins: The mission is not over yet

The measurement of cardiac troponin (cTn) is recommended by all guidelines as the gold standard for the differential diagnosis of Acute Coronary Syndromes. The aim of this review is to discuss in details some key issues regarding both analytical and clinical characteristics of the high-sensitivity methods for cTn (hs-cTn), which are still considered controversial or unresolved. In particular, the major clinical concern regarding hs-cTn methods is the difficulty to differentiate the pathophysiological mechanism responsible for biomarker release from cardiomyocytes after reversible or irreversible injury, respectively. Indeed, recent experimental and clinical studies have demonstrated that different circulating forms of cTnI and cTnT can be respectively measured in plasma samples of patients with reversible or irreversible myocardial injury. Accordingly, a new generation of hs-Tn methods should be set up, based on immunometric immunoassays or chromatographic techniques, specific for circulating peptide forms more characteristics for reversible or irreversible myocardial injury. It is conceivable that this new generation of hs-cTn methods will complete the mission regarding the laboratory tests for specific cardiac biomarkers, started more than 20 years ago, which has already revolutionized the diagnosis, prognosis and management of patients with cardiac diseases.

Role of PARP-1 in mitochondrial homeostasis

BACKGROUND

Nuclear poly(ADP-ribose) polymerase-1 (PARP-1) is a well characterised protein that accounts for the majority of PARylation reactions using NAD⁺ as a substrate, regulating diverse cellular functions. In addition to its nuclear functions, several recent studies have identified localization of PARP-1 in mitochondria and emphasized its possible role in maintaining mitochondrial homeostasis. Various reports suggest that nuclear PARP-1 has been implicated in diverse mitochondria-specific communication processes.

SCOPE OF REVIEW

The present review emphasizes on the potential role of PARP-1 in mitochondrial processes such as bioenergetics, mtDNA maintenance, cell death and mitophagy.

MAJOR CONCLUSIONS

The origin of mitochondrial PARP-1 is still an enigma; however researchers are trying to establish the cross-talk between nuclear and mitochondrial PARP-1 and how these PARP-1 pools modulate mitochondrial activity.

GENERAL SIGNIFICANCE

A better understanding of the possible role of PARP-1 in mitochondrial homeostasis helps us to explore the potential therapeutic targets to protect mitochondrial dysfunctions.

Prevention of heart failure with preserved ejection fraction (HFpEF): reexamining microRNA-21 inhibition in the era of oligonucleotide-based therapeutics

Heart failure with preserved ejection fraction (HFpEF) accounts for 50% of cases of heart failure, which is the most common cause of hospitalization in US patients over the age of 65. HFpEF pathogenesis is increasingly believed to be due to pathological hypertrophy and fibrosis of the myocardium that may be a result of systemic inflammation from comorbid conditions such as hypertension, diabetes mellitus, chronic obstructive pulmonary disease, anemia, chronic kidney disease and others. It is believed that oxidative stress triggers a process of pathological hypertrophy and fibrosis in cardiac endothelial cells, which leads to increased left ventricle filling pressures and, eventually, symptoms of heart failure. Numerous recent major clinical trials that have examined various therapies aimed at improving mortality in HFpEF have emerged empty-handed and thus the search for effective management strategies continues. Over the last several years, there have been many new developments in the field of antisense oligonucleotide-based therapeutics, which involves using noncoding nucleic acid particles such as microRNA and small interfering RNA to repress the expression of specific messenger RNA. In this article, we review the concept of using oligonucleotide-based therapeutics to prevent or treat HFpEF by targeting a specific microRNA that has been implicated in the pathogenesis of myocardial fibrosis and hypertrophy, microRNA-21 (miR-21). We review the various evidence that implicates miR-21 in the process of myocardial fibrosis and discuss recent attempts to use antimiR-21 compounds to prevent fibrosis. We also discuss proposed methods for screening patients at high risk for HFpEF for diastolic dysfunction in order to determine which patients.

The Role of Bone Morphogenetic Protein 7 (BMP-7) in Inflammation in Heart Diseases

Bone morphogenetic protein-7 is (BMP-7) is a potent anti-inflammatory growth factor belonging to the Transforming Growth Factor Beta (TGF-β) superfamily. It plays an important role in various biological processes, including embryogenesis, hematopoiesis, neurogenesis and skeletal morphogenesis. BMP-7 stimulates the target cells by binding to specific membrane-bound receptor BMPR 2 and transduces signals through mothers against decapentaplegic (Smads) and mitogen activated protein kinase (MAPK) pathways. To date, rhBMP-7 has been used clinically to induce the differentiation of mesenchymal stem cells bordering the bone fracture site into chondrocytes, osteoclasts, the formation of new bone via calcium deposition and to stimulate the repair of bone fracture. However, its use in cardiovascular diseases, such as atherosclerosis, myocardial infarction, and diabetic cardiomyopathy is currently being explored. More importantly, these cardiovascular diseases are associated with inflammation and infiltrated monocytes where BMP-7 has been demonstrated to be a key player in the differentiation of pro-inflammatory monocytes, or M1 macrophages, into anti-inflammatory M2 macrophages, which reduces developed cardiac dysfunction. Therefore, this review focuses on the molecular mechanisms of BMP-7 treatment in cardiovascular disease and its role as an anti-fibrotic, anti-apoptotic and anti-inflammatory growth factor, which emphasizes its potential therapeutic significance in heart diseases.

Head-to-head comparison of plasma cTnI concentration values measured with three high-sensitivity methods in a large Italian population of healthy volunteers and patients admitted to emergency department with acute coronary syndrome: A multi-center study

BACKGROUND

The study aim is to compare cTnI values measured with three high-sensitivity (hs) methods in apparently healthy volunteers and patients admitted to emergency department (ED) with acute coronary syndrome enrolled in a large multicentre study.

METHODS

Heparinized plasma samples were collected from 1511 apparently healthy subjects from 8 Italian clinical institutions (mean age: 51.5 years, SD: 14.1 years, range: 18-65 years, F/M ratio:0.95). All volunteers denied chronic or acute diseases and had normal values of routine laboratory tests. Moreover, 1322 heparinized plasma sample were also collected by 9 Italian clinical institutions from patients admitted to ED with clinical symptoms typical of acute coronary syndrome. The reference study laboratory assayed all plasma samples with three hs-methods: Architect hs-cTnI, Access hs-cTnI and ADVIA Centaur XPT methods. Principal Component Analysis (PCA) was also used to analyze the between-method differences among hs-cTnI assays.

RESULTS

On average, a between-method difference of 31.2% CV was found among the results of hs-cTnI immunoassays. ADVIA Centaur XPT method measured higher cTnI values than Architect and Access methods. Moreover, 99th percentile URL values depended not only on age and sex of reference population, but also on the statistical approach used for calculation (robust non-parametric vs bootstrap).

CONCLUSIONS

Due to differences in concentrations and reference values, clinicians should be advised that plasma samples of the same patient should be measured for cTnI assay in the same laboratory. Specific clinical studies are needed to establish the most appropriate statistical approach to calculate the 99th percentile URL values for hs-cTnI methods.

Pathobiology of cardiovascular diseases: an update

This article introduces the Second Special Issue of Cardiovascular Pathology (CVP), the official journal of the Society for Cardiovascular Pathology (SCVP). This CVP Special Issue showcases a series of commemorative review articles in celebration of the 25th anniversary of CVP originally published in 2016 and now compiled into a virtual collection with online access for the cardiovascular pathology community. This overview also provides updates on the major categories of cardiovascular diseases from the perspective of cardiovascular pathologists, highlighting publications from CVP, as well as additional important review articles and clinicopathologic references.

Cardioprotective microRNAs: Lessons from stem cell-derived exosomal microRNAs to treat cardiovascular disease

The stem cell-based therapy has emerged as a promising therapeutic strategy for treating cardiovascular ischemic diseases (CVIDs), such as myocardial infarction (MI). However, some important functional shortcomings of stem cell transplantation, such as immune rejection, tumorigenicity and infusional toxicity, have overshadowed stem cell therapy in the setting of cardiovascular diseases (CVDs). Accumulating evidence suggests that the therapeutic effects of transplanted stem cells are predominately mediated by secreting paracrine factors, importantly, microRNAs (miRs) present in the secreted exosomes. Therefore, novel cell-free therapy based on the stem cell-secreted exosomal miRs can be considered as a safe and effective alternative tool to stem cell therapy for the treatment of CVDs. Stem cell-derived miRs have recently been found to transfer, via exosomes, from a transplanted stem cell into a recipient cardiac cell, where they regulate various cellular process, such as proliferation, apoptosis, stress responses, as well as differentiation and angiogenesis. The present review aimed to summarize cardioprotective exosomal miRs secreted by transplanted stem cells from various sources, including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), and cardiac stem/progenitor cells, which showed beneficial modulatory effects on the myocardial infracted heart. In summary, stem cell-exosomal miRs, including miR-19a, mirR-21, miR-21-5p, miR-21-a5p, miR-22 miR-24, miR-26a, miR-29, miR-125b-5p, miR-126, miR-201, miR-210, and miR-294, have been shown to have cardioprotective effects by enhancing cardiomyocyte survival and function and attenuating cardiac fibrosis. Additionally, MCS-exosomal miRs, including miR-126, miR-210, miR-21, miR-23a-3p and miR-130a-3p, are found to exert cardioprotective effects through induction of angiogenesis in ischemic heart after MI.

Rat Left Ventricular Cardiomyocytes Characterization in the Process of Postinfarction Myocardial Remodeling

Ischemic lesions of the heart, including myocardial infarction, are the most common pathologies of human cardiovascular system. Despite all the research and achievements of medicine in this field, the mortality from this disease remains heavy. Therefore, studying of processes occurring in the myocardium in the early and late postinfarction periods remains important. Rat left ventricular cardiomyocyte (CMC) ploidy, hypertrophy, hyperplasia, and ultrastructure were investigated in 2, 6, and 26 weeks after experimental myocardial infarction, caused by permanent ligation of left coronary artery. Cytofluorimetric study of CMC ploidy revealed no difference between normal, sham-operated, and infarcted animals for all the tested stages. However, interference microscopy indicated significant changes in cells size. CMC dry mass of infarcted rats in 2 weeks after surgery was 1.5 times lower than in control and sham operated groups. Electron microscopy analysis of CMC revealed disruption of sarcomere structure. However, in 6 weeks after surgery CMC dry mass was 1.6 times higher than in control. In 26 weeks after myocardial infarction CMC dry mass exceeded control only in peri-infarction zone. Cell counting showed that the number of left ventricular CMC, reduced as a result of myocardial infarction, was not restored during myocardial remodeling. © 2019 International Society for Advancement of Cytometry.

A Thin Layer of Decellularized Porcine Myocardium for Cell Delivery

Decellularized porcine myocardium has shown many benefits as a cell delivery scaffold for cardiac therapy. However, using full thickness decellularized myocardium as cardiac patch may lead to poor viability and inhomogeneous distribution of delivered cells, due to perfusion limitations. In this study, we explored the feasibility of decellularized porcine myocardial slice (dPMS) to construct a vascularized cardiac patch for cell delivery. Decellularized porcine myocardium was sliced into thin layers (thickness~300 µm). Adipose-derived Stem cells (ASCs) obtained from rat and pig were seeded on dPMS. The viability, infiltration, and differentiation of seeded ASCs were examined. The mechanical properties of dPMSs of various thickness and native myocardium were tested. We noticed dPMS supported attachment and growth of rat and pig ASCs. Both rat and pig ASCs showed high viability, similar patterns of proliferation and infiltration within dPMS. Rat ASCs showed expression of early-endothelial markers followed by mature-endothelial marker without any additional inducers on dPMS. Using rat myocardial infarction model, we delivered ASCs using dPMS patched to the infarcted myocardium. After 1 week, a higher number of transplanted cells were present in the infarcted area when cells were delivered using dPMS versus direct injection. Compared with MI group, increased vascular formation was also observed.

Estrogen and/or Estrogen Receptor α Inhibits BNIP3-Induced Apoptosis and Autophagy in H9c2 Cardiomyoblast Cells

The process of autophagy in heart cells maintains homeostasis during cellular stress such as hypoxia by removing aggregated proteins and damaged organelles and thereby protects the heart during the times of starvation and ischemia. However, autophagy can lead to substantial cell death under certain circumstances. BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), a hypoxia-induced marker, has been shown to induce both autophagy and apoptosis. A BNIP3-docked organelle, e.g., mitochondria, also determines whether autophagy or apoptosis will take place. Estrogen (E2) and estrogen receptor (ER) alpha (ERα) have been shown to protect the heart against mitochondria-dependent apoptosis. The aim of the present study is to investigate the mechanisms by which ERα regulates BNIP3-induced apoptosis and autophagy, which is associated with hypoxic injury, in cardiomyoblast cells. An in vitro model to mimic hypoxic injury in the heart by engineering H9c2 cardiomyoblast cells to overexpress BNIP3 was established. Further, the effects of E2 and ERα in BNIP3-induced apoptosis and autophagy were determined in BNIP3 expressing H9c2 cells. Results from TUNEL assay and Immunoflourecense assay for LC3 puncta formation, respectively, revealed that ERα/E2 suppresses BNIP3-induced apoptosis and autophagy. The Western blot analysis showed ERα/E2 decreases the protein levels of caspase 3 (apoptotic marker), Atg5, and LC3-II (autophagic markers). Co-immunoprecipitation of BNIP3 and immunoblotting of Bcl-2 and Rheb showed that ERα reduced the interaction between BNIP3 and Bcl-2 or Rheb. The results confirm that ERα binds to BNIP3 causing a reduction in the levels of functional BNIP3 and thereby inhibits cellular apoptosis and autophagy. In addition, ERα attenuated the activity of the BNIP3 promoter by binding to SP-1 or NFκB sites.

Senescent cells: a therapeutic target for cardiovascular disease

Cellular senescence, a major tumor-suppressive cell fate, has emerged from humble beginnings as an in vitro phenomenon into recognition as a fundamental mechanism of aging. In the process, senescent cells have attracted attention as a therapeutic target for age-related diseases, including cardiovascular disease (CVD), the leading cause of morbidity and mortality in the elderly. Given the aging global population and the inadequacy of current medical management, attenuating the health care burden of CVD would be transformative to clinical practice. Here, we review the evidence that cellular senescence drives CVD in a bimodal fashion by both priming the aged cardiovascular system for disease and driving established disease forward. Hence, the growing field of senotherapy (neutralizing senescent cells for therapeutic benefit) is poised to contribute to both prevention and treatment of CVD.

Regulation of BECN1-mediated autophagy by HSPB6: Insights from a human HSPB6S10F mutant

HSPB6/Hsp20 (heat shock protein family B [small] member 6) has emerged as a novel cardioprotector against stress-induced injury. We identified a human mutant of HSPB6 (HSPB6^S10F) exclusively present in dilated cardiomyopathy (DCM) patients. Cardiac expression of this mutant in mouse hearts resulted in remodeling and dysfunction, which progressed to heart failure and early death. These detrimental effects were associated with reduced interaction of mutant HSPB6^S10F with BECN1/Beclin 1, leading to BECN1 ubiquitination and its proteosomal degradation. As a result, autophagy flux was substantially inhibited and apoptosis was increased in HSPB6^S10F-mutant hearts. In contrast, overexpression of wild-type HSPB6 (HSPB6 WT) not only increased BECN1 levels, but also competitively suppressed binding of BECN1 to BCL2, resulting in stimulated autophagy. Indeed, preinhibition of autophagy attenuated the cardioprotective effects of HSPB6 WT. Taken together, these findings reveal a new regulatory mechanism of HSPB6 in cell survival through its interaction with BECN1. Furthermore, Ser10 appears to be crucial for the protective effects of HSPB6 and transversion of this amino acid to Phe contributes to cardiomyopathy.

Possible Muscle Repair in the Human Cardiovascular System

The regenerative potential of tissues and organs could promote survival, extended lifespan and healthy life in multicellular organisms. Niches of adult stemness are widely distributed and lead to the anatomical and functional regeneration of the damaged organ. Conversely, muscular regeneration in mammals, and humans in particular, is very limited and not a single piece of muscle can fully regrow after a severe injury. Therefore, muscle repair after myocardial infarction is still a chimera. Recently, it has been recognized that epigenetics could play a role in tissue regrowth since it guarantees the maintenance of cellular identity in differentiated cells and, therefore, the stability of organs and tissues. The removal of these locks can shift a specific cell identity back to the stem-like one. Given the gradual loss of tissue renewal potential in the course of evolution, in the last few years many different attempts to retrieve such potential by means of cell therapy approaches have been performed in experimental models. Here we review pathways and mechanisms involved in the in vivo repair of cardiovascular muscle tissues in humans. Moreover, we address the ongoing research on mammalian cardiac muscle repair based on adult stem cell transplantation and pro-regenerative factor delivery. This latter issue, involving genetic manipulations of adult cells, paves the way for developing possible therapeutic strategies in the field of cardiovascular muscle repair.

Roles and Mechanisms of Herbal Medicine for Diabetic Cardiomyopathy: Current Status and Perspective

Diabetic cardiomyopathy is one of the major complications among patients with diabetes mellitus. Diabetic cardiomyopathy (DCM) is featured by left ventricular hypertrophy, myocardial fibrosis, and damaged left ventricular systolic and diastolic functions. The pathophysiological mechanisms include metabolic-altered substrate metabolism, dysfunction of microvascular, renin-angiotensin-aldosterone system (RAAS) activation, oxidative stress, cardiomyocyte apoptosis, mitochondrial dysfunction, and impaired Ca²⁺ handling. An array of molecules and signaling pathways such as p38 mitogen-activated protein kinase (p38 MAPK), c-Jun N-terminal kinase (JNK), and extracellular-regulated protein kinases (ERK) take roles in the pathogenesis of DCM. Currently, there was no remarkable effect in the treatment of DCM with application of single Western medicine. The myocardial protection actions of herbs have been gearing much attention. We present a review of the progress research of herbal medicine as a potential therapy for diabetic cardiomyopathy and the underlying mechanisms.

Thrombospondins: A Role in Cardiovascular Disease

Thrombospondins (TSPs) represent extracellular matrix (ECM) proteins belonging to the TSP family that comprises five members. All TSPs have a complex multidomain structure that permits the interaction with various partners including other ECM proteins, cytokines, receptors, growth factors, etc. Among TSPs, TSP1, TSP2, and TSP4 are the most studied and functionally tested. TSP1 possesses anti-angiogenic activity and is able to activate transforming growth factor (TGF)-β, a potent profibrotic and anti-inflammatory factor. Both TSP2 and TSP4 are implicated in the control of ECM composition in hypertrophic hearts. TSP1, TSP2, and TSP4 also influence cardiac remodeling by affecting collagen production, activity of matrix metalloproteinases and TGF-β signaling, myofibroblast differentiation, cardiomyocyte apoptosis, and stretch-mediated enhancement of myocardial contraction. The development and evaluation of TSP-deficient animal models provided an option to assess the contribution of TSPs to cardiovascular pathology such as (myocardial infarction) MI, cardiac hypertrophy, heart failure, atherosclerosis, and aortic valve stenosis. Targeting of TSPs has a significant therapeutic value for treatment of cardiovascular disease. The activation of cardiac TSP signaling in stress and pressure overload may be therefore beneficial.

The 99th percentile of reference population for cTnI and cTnT assay: methodology, pathophysiology and clinical implications

According to recent international guidelines, including the 2012 Third Universal Definiton of Myocardial Infarction by the Joint ESC/ACCF/AHA/WHF Task Force, an increase in cardiac troponin (cTn) levels over the 99th percentile upper reference limit (99th URL) should be considered clinically relevant, this cut-off being measured with an imprecision ≤10 CV%. In theory 99th URL values strongly depend not only on demographic and physiological variables (i.e. criteria for considering the reference population “healthy”), but also on the analytical performance of cTn methods and mathematical algorithms used for the calculation. The aim of the present article was therefore to review the methodological and pathophysiological factors affecting the evaluation and calculation of the 99th URL for cTn assay. The critical analysis made showed that no uniform procedure is followed, and nor have experts or regulatory bodies provided uniform guidelines for researchers or cTn assays manufacturers as an aid in “their quest to define normality”. In particular, little attention has been paid to the way in which a healthy reference population is to be selected, or the criteria for calculating the 99th URL value for cTn assays, thus highlighting the need for international recommendations not only for demographic and physiological variables criteria for defining a healthy reference population, but also for calculating mathematical algorithms for establishing/calculating clinical decision values. An expert consensus group, comprising laboratory and clinical scientists, biomedical statisticians, industrial and regulatory representatives, should be responsible for drawing up these guidelines.

Mitochondria in Ischemic Heart Disease

A core feature of ischemic heart disease is injury to cardiomyocytes (CMC). Ischemic CMC manifest the molecular mechanisms to undergo the major forms of cell injury and death, namely, oncotic necrosis, necroptosis, apoptosis and unregulated autophagy. Important modulators of ischemic injury are reperfusion and conditioning. Mitochondria have a major role in mediating the injury to CMC through membrane protein complexes referred to as death channels. Apoptosis is mediated by activation of a channel regulated by the Bcl-2 protein family leading to mitochondrial outer membrane permeabilization (MOMP). Oncotic type injury is mediated by opening of the mitochondrial permeability transition pore (mPTP). Mitochondria also have a reperfusion salvage kinase pathway (RISK). With cyclosporine A serving as a prototype, ongoing research is aimed at developing pharmacological approaches to condition and preserve mitochondrial integrity in order to promote CMC survival during episodes of myocardial ischemia.

Circulating Exosomes in Cardiovascular Diseases

Circulating exosomes could arrive in distant tissues via blood circulation, thus directly communicating with target cells and rapidly regulating intracellular signalings. Circulating exosomes and exosomal cargos are critically involved in cardiovascular pathophysiology, such as cardiomyocyte hypertrophy, apoptosis, and angiogenesis. Circulating exosomes enriched with various types of biological molecules can be changed not only in the number but also in the composite cargos upon cardiac injury, such as myocardial infarction, myocardial ischemia reperfusion injury, atherosclerosis, hypertension, and sepsis cardiomyopathy, which may further influence cardiomyocyte function and contribute to the pathogenesis of cardiovascular diseases. Thus, exosome-based therapeutic strategy may be used to attenuate myocardial injury and promote cardiac regeneration and repair. Also, more preclinical and clinical studies would be needed to investigate the potential of circulating exosomes as biomarkers for the diagnosis, risk stratification, and prognosis of cardiovascular diseases.

Therapeutic targeting of autophagy in myocardial infarction and heart failure

INTRODUCTION

Myocardial infarction (MI) is the leading cause of death. When MI is not lethal, heart failure (HF) is a major consequence with high prevalence and poor prognosis. The targeting of autophagy represents a potentially therapeutic approach for the treatment of both pathologies.

AREAS COVERED

PubMed searches were performed to discuss the current state of the art regarding the role of autophagy in MI and HF. We review available and potential approaches to modulate autophagy from a pharmacological and genetic perspective. We also discuss the targeting of autophagy in myocardial regeneration. Expert commentary: The targeting of autophagy has potential for the treatment of MI and HF. Autophagy is a process that takes place in virtually all cells of the body and thus, in order to evaluate this therapeutic approach in clinical trials, strategies that specifically target this process in the myocardium is required to avoid unwanted effects in other organs.

Nuquantus: Machine learning software for the characterization and quantification of cell nuclei in complex immunofluorescent tissue images

Determination of fundamental mechanisms of disease often hinges on histopathology visualization and quantitative image analysis. Currently, the analysis of multi-channel fluorescence tissue images is primarily achieved by manual measurements of tissue cellular content and sub-cellular compartments. Since the current manual methodology for image analysis is a tedious and subjective approach, there is clearly a need for an automated analytical technique to process large-scale image datasets. Here, we introduce Nuquantus (Nuclei quantification utility software) - a novel machine learning-based analytical method, which identifies, quantifies and classifies nuclei based on cells of interest in composite fluorescent tissue images, in which cell borders are not visible. Nuquantus is an adaptive framework that learns the morphological attributes of intact tissue in the presence of anatomical variability and pathological processes. Nuquantus allowed us to robustly perform quantitative image analysis on remodeling cardiac tissue after myocardial infarction. Nuquantus reliably classifies cardiomyocyte versus non-cardiomyocyte nuclei and detects cell proliferation, as well as cell death in different cell classes. Broadly, Nuquantus provides innovative computerized methodology to analyze complex tissue images that significantly facilitates image analysis and minimizes human bias.

Cardiomyocyte loss is not required for the progression of left ventricular hypertrophy induced by pressure overload in female mice

Left ventricular (LV) hypertrophy in response to hypertension and increased afterload frequently progresses to heart failure. It is under debate whether the loss of cardiomyocytes contributes to this transition. To address this question, female C57BL/6 wild-type mice were subjected to transverse aortic constriction (TAC) and developed compensated LV hypertrophy after 1 week, which progressed to heart failure characterized by reduced ejection fraction and pulmonary congestion 4 weeks post-TAC. Quantitative, design-based stereology methods were used to estimate number and mean volume of LV cardiomyocytes. DNA strand breaks were visualized using the TUNEL method 6 weeks post-TAC to quantify the number of apoptotic cell nuclei. The volume of the LV myocardium as well as the cardiomyocyte mean volume increased progressively after TAC. In contrast, the number of LV cardiomyocytes remained constant 1 and 4 weeks post-TAC in comparison to sham-operated mice. Moreover, there was no significant difference in the number of cardiomyocyte nuclei stained for DNA strand breaks at 6 weeks post-TAC. It was concluded that the loss of cardiomyocytes is not required for the transition from compensated hypertrophy to heart failure induced by TAC in the female murine heart.

Pathobiology of Ischemic Heart Disease: Past, Present and Future

This review provides a perspective on knowledge of ischemic heart disease (IHD) obtained from the contemporary era of research which began in the 1960s and has continued to the present day. Important discoveries have been made by basic and translational scientists and clinicians. Pathologists have contributed significantly to insights obtained from experimental studies and clinicopathological studies in humans. The review also provides a perspective for future directions in research in IHD aimed at increasing basic knowledge and developing additional therapeutic options for patients with IHD.

C-kit(+) resident cardiac stem cells improve left ventricular fibrosis in pressure overload

To investigate the effect of resident cardiac stem cells (RCSC) on myocardial remodeling, c-kit(+) RCSC were isolated from hearts of C57Bl/6-Tg (ACTb-EGFP)1Osb/J mice expressing green fluorescent protein and expanded in vitro. C57/Bl6N wildtype mice were subjected to transverse aortic constriction (TAC, 360 μm) or sham-operation. 5 × 10(5) c-kit(+) RCSC or c-kit(-) cardiac cells or cell buffer were infused intravenously 24 h post-surgery (n = 11-24 per group). Hypoxia-inducible factor-1α-mRNA in left ventricles of TAC mice was enhanced 24 h after transplantation. 35 days post-TAC, the density of c-kit(+) RCSC in the myocardium was increased by two-fold. Infusion of c-kit(+) resident cardiac stem cells post-TAC markedly reduced myocardial fibrosis and the expression of collagen Iα2 and connective tissue growth factor. Infusion of c-kit(-) cardiac cells did not ameliorate cardiac fibrosis. In parallel, expression of pro-angiogenic mediators (FGFb, IL-4, IL-6, TGFß, leptin) and the density of CD31(+) and CD31(+) GFP(+) endothelial cells were increased. Transplantation reduced brain- and atrial natriuretic peptides and the cardiomyocyte cross-sectional area. Infusion of c-kit(+) resident cardiac stem reduced the rate of apoptosis and oxidative stress in cardiomyocytes and in non-cardiomyocyte cells.

The number of cardiac myocytes in the hypertrophic and hypotrophic left ventricle of the obese and calorie-restricted mouse heart

Changes in body mass due to varying amounts of calorie intake occur frequently with obesity and anorexia/cachexia being at opposite sides of the scale. Here, we tested whether a high-fat diet or calorie restriction (CR) decreases the number of cardiac myocytes and affects their volume. Ten 6-8-week-old mice were randomly assigned to a normal (control group, n = 5) or high-fat diet (obesity group, n = 5) for 28 weeks. Ten 8-week-old mice were randomly assigned to a normal (control group, n = 5) or CR diet (CR group, n = 5) for 7 days. The left ventricles of the hearts were prepared for light and electron microscopy, and analysed by design-based stereology. In CR, neither the number of cardiac myocytes, the relationship between one- and multinucleate myocytes nor their mean volume were significantly different between the groups. In contrast, in the obese mice we observed a significant increase in cell size combined with a lower number of cardiomyocytes (P < 0.05 in the one-sided U-test) and an increase in the mean number of nuclei per myocyte. The mean volume of myofibrils and mitochondria per cardiac myocyte reflected the hypertrophic and hypotrophic remodelling in obesity and CR, respectively, but were only significant in the obese mice, indicating a more profound effect of the obesity protocol than in the CR experiments. Taken together, our data indicate that long-lasting obesity is associated with a loss of cardiomyocytes of the left ventricle, but that short-term CR does not alter the number of cardiomyocytes.