Cardiac stem cells: biology and clinical applications

Healing the Broken Hearts: A Glimpse on Next Generation Therapeutics

Cardiovascular diseases are the leading cause of death worldwide, accounting for 32% of deaths globally and thus representing almost 18 million people according to WHO. Myocardial infarction, the most prevalent adult cardiovascular pathology, affects over half a million people in the USA according to the last records of the AHA. However, not only adult cardiovascular diseases are the most frequent diseases in adulthood, but congenital heart diseases also affect 0.8–1.2% of all births, accounting for mild developmental defects such as atrial septal defects to life-threatening pathologies such as tetralogy of Fallot or permanent common trunk that, if not surgically corrected in early postnatal days, they are incompatible with life. Therefore, both congenital and adult cardiovascular diseases represent an enormous social and economic burden that invariably demands continuous efforts to understand the causes of such cardiovascular defects and develop innovative strategies to correct and/or palliate them. In the next paragraphs, we aim to briefly account for our current understanding of the cellular bases of both congenital and adult cardiovascular diseases, providing a perspective of the plausible lines of action that might eventually result in increasing our understanding of cardiovascular diseases. This analysis will come out with the building blocks for designing novel and innovative therapeutic approaches to healing the broken hearts.

Telomere Length and Regulatory Genes as Novel Stress Biomarkers and Their Diversities in Broiler Chickens (Gallus gallus domesticus) Subjected to Corticosterone Feeding

Simple Summary

Assessment of poultry welfare is very crucial for sustainable production in the tropics. There is a demand for alternatives to plasma corticosterone levels as they have received much criticism as an unsuitable predictor of animal welfare due to inconsistency. In this study, we noticed no effect of age on plasma corticosterone (CORT) although it was altered by CORT treatment. However, growth performances and organ weight were affected by CORT treatment and age. The broad sense evaluation of telomere length in this study revealed that telomere length in the blood, muscle, liver and heart was shortened by chronic stress induced by corticosterone administration. The expression profile of the telomere regulatory genes was altered by chronic stress. This study informed us of the potential of telomere length and its regulatory genes in the assessment of animal welfare in the poultry sector for sustainable production.

Abstract

This study was designed to characterize telomere length and its regulatory genes and to evaluate their potential as well-being biomarkers. Chickens were fed a diet containing corticosterone (CORT) for 4 weeks and performances, organ weight, plasma CORT levels, telomere lengths and regulatory genes were measured and recorded. Body weights of CORT-fed chickens were significantly suppressed (p < 0.05), and organ weights and circulating CORT plasma levels (p < 0.05) were altered. Interaction effect of CORT and duration was significant (p < 0.05) on heart and liver telomere length. CORT significantly (p < 0.05) shortened the telomere length of the whole blood, muscle, liver and heart. The TRF1, chTERT, TELO2 and HSF1 were significantly (p < 0.05) upregulated in the liver and heart at week 4 although these genes and TERRA were downregulated in the muscles at weeks 2 and 4. Therefore, telomere lengths and their regulators are associated and diverse, so they can be used as novel biomarkers of stress in broiler chickens fed with CORT.

Cellular Senescence Affects Cardiac Regeneration and Repair in Ischemic Heart Disease

Ischemic heart disease (IHD) is defined as a syndrome of ischemic cardiomyopathy. Myogenesis and angiogenesis in the ischemic myocardium are important for cardiomyocyte (CM) survival, improving cardiac function and decreasing the progression of heart failure after IHD. Cellular senescence is a state of permanent irreversible cell cycle arrest caused by stress that results in a decline in cellular functions, such as proliferation, migration, homing, and differentiation. In addition, senescent cells produce the senescence-associated secretory phenotype (SASP), which affects the tissue microenvironment and surrounding cells by secreting proinflammatory cytokines, chemokines, growth factors, and extracellular matrix degradation proteins. The accumulation of cardiovascular-related senescent cells, including vascular endothelial cells (VECs), vascular smooth muscle cells (VSMCs), CMs and progenitor cells, is an important risk factor of cardiovascular diseases, such as vascular aging, atherosclerotic plaque formation, myocardial infarction (MI) and ventricular remodeling. This review summarizes the processes of angiogenesis, myogenesis and cellular senescence after IHD. In addition, this review focuses on the relationship between cellular senescence and cardiovascular disease and the mechanism of cellular senescence. Finally, we discuss a potential therapeutic strategy for MI targeting senescent cells.

Serum Levels of Bone Morphogenetic Proteins 2 and 4 in Patients with Acute Myocardial Infarction

Background: Bone morphogenetic proteins-2 and -4 (BMPs) have been implicated in left ventricular remodeling (LVR) processes such as an inflammation and fibrogenesis. We hypothesized that this knowledge could be translated into clinics. Methods: We studied the dynamics of serum levels of BMPs, its correlation with markers of LVR and with parameters of echocardiography in patients (n = 31) during the six-month follow-up period after myocardial infarction (MI). Results: Elevated serum levels of BMPs decreased by the six-month follow-up period. BMP-2 decreased from the first day after MI, and BMP-4 decreased from the Day 14. The elevated level of BMP-2 at Day 1 was associated with a lower level of troponin I, reperfusion time and better left ventricular ejection fraction (LV EF) at the six-month follow-up. Elevated serum level of BMP-4 at Day 1 was associated with a lower level of a soluble isoform of suppression of tumorigenicity 2 (sST2), age and reperfusion time. An elevated level of BMP-2 at the six-month follow-up was associated with higher levels of BMP-4, high-sensitivity C-reactive protein (hCRP) and sST2. High serum level of BMP-2 correlated with high levels of hCRP and matrix metalloproteinase (MMP)-9 on Day 7. High serum level of BMP-4 correlated with low levels of hCRP, MMP-9 at Day 3, sST2 at Day 1 and with decreased LV EF on Day 7. The findings of multivariate analysis support the involvement of BMP-2 in the development of post-infarction LVR. Conclusions: Our research translates experimental data about the BMPs in the development of adverse LVR into the clinic. Elevated serum levels of BMPs decreased by the end of the six-month period after MI. BMP-2 decreased from the first day and BMP-4 decreased from Day 14. BMP-2 and BMP-4 were associated with the development of LVR. Their correlations with markers of inflammation, degradation of the extracellular matrix, hemodynamic stress and markers of myocardial damage further support our hypothesis. Diagnostic and predictive values of these BMPs at the development of post-infarction LVR in vivo should be investigated further.

Stem cells as therapy for heart disease: iPSCs, ESCs, CSCs, and skeletal myoblasts

Heart Diseases are serious and global public health concern. In spite of remarkable therapeutic developments, the prediction of patients with Heart Failure (HF) is weak, and present therapeutic attitudes do not report the fundamental problem of the cardiac tissue loss. Innovative therapies are required to reduce mortality and limit or abolish the necessity for cardiac transplantation. Stem cell-based therapies applied to the treatment of heart disease is according to the understanding that natural self-renewing procedures are inherent to the myocardium, nonetheless may not be adequate to recover the infarcted heart muscle. Following the first account of cell therapy in heart diseases, examination has kept up to rapidity; besides, several animals and human clinical trials have been conducted to preserve the capacity of numerous stem cell population in advance cardiac function and decrease infarct size. The purpose of this study was to censoriously evaluate the works performed regarding the usage of four major subgroups of stem cells, including induced Pluripotent Stem Cells (iPSC), Embryonic Stem Cells (ESCs), Cardiac Stem Cells (CDC), and Skeletal Myoblasts, in heart diseases, at the preclinical and clinical studies. Moreover, it is aimed to argue the existing disagreements, unsolved problems, and prospect directions.

Vascular endothelial growth factor association with angiopoietin 1 promotes improvement in ventricular function after ischemic cardiomyopathy induced in mini pigs

PURPOSE

To investigate the safety and clinical, hemodynamic and tissue improvement ability in mini pigs undergoing cell and gene therapy for the treatment of acute myocardial infarction.

METHODS

Thirty-two mini pigs Br1 lineage, 12 months old, undergoing induction of acute myocardial infarction by occlusion of the diagonal branch of the paraconal coronary. They were divided into 4 groups: one control group and 3 treatment groups (cell therapy and gene cell therapy). Echocardiography reviews were performed on three occasions and histopathological analysis was performed after 4 weeks. Analysis of variance (ANOVA), Tukey and Wilcoxon tests, were performed.

RESULTS

Association of vascular endothelial growth factor (VEGF) with angiopoietin1 (Ang1) presented satisfactory results in the improvement of ventricular function following ischemic cardiomyopathy in mini pigs when compared to the results of the other treated groups.

CONCLUSION

The therapy with VEGF and the combination of VEGF with Ang1, promoted recovered function of the myocardium, characterized by reduced akinetic area and induction of neovascularization.

Supramolecular surface functionalization via catechols for the improvement of cell-material interactions

Optimization of cell-material interactions is crucial for the success of synthetic biomaterials in guiding tissue regeneration. To do so, catechol chemistry is often used to introduce adhesiveness into biomaterials. Here, a supramolecular approach based on ureido-pyrimidinone (UPy) modified polymers is combined with catechol chemistry in order to achieve improved cellular adhesion onto supramolecular biomaterials. UPy-modified hydrophobic polymers with non-cell adhesive properties are developed that can be bioactivated via a modular approach using UPy-modified catechols. It is shown that successful formulation of the UPy-catechol additive with the UPy-polymer results in surfaces that induce cardiomyocyte progenitor cell adhesion, cell spreading, and preservation of cardiac specific extracellular matrix production. Hence, by functionalizing supramolecular surfaces with catechol functionalities, an adhesive supramolecular biomaterial is developed that allows for the possibility to contribute to biomaterial-based regeneration.

p53 Modulates the Fate of Cardiac Progenitor Cells Ex Vivo and in the Diabetic Heart In Vivo

p53 is an important modulator of stem cell fate, but its role in cardiac progenitor cells (CPCs) is unknown. Here, we tested the effects of a single extra-copy of p53 on the function of CPCs in the presence of oxidative stress mediated by doxorubicin in vitro and type-1 diabetes in vivo. CPCs were obtained from super-p53 transgenic mice (p53-tg), in which the additional allele is regulated in a manner similar to the endogenous protein. Old CPCs with increased p53 dosage showed a superior ability to sustain oxidative stress, repair DNA damage and restore cell division. With doxorubicin, a larger fraction of CPCs carrying an extra-copy of the p53 allele recruited γH2A.X reestablishing DNA integrity. Enhanced p53 expression resulted in a superior tolerance to oxidative stress in vivo by providing CPCs with defense mechanisms necessary to survive in the milieu of the diabetic heart; they engrafted in regions of tissue injury and in three days acquired the cardiomyocyte phenotype. The biological advantage provided by the increased dosage of p53 in CPCs suggests that this genetic strategy may be translated to humans to increase cellular engraftment and growth, critical determinants of successful cell therapy for the failing heart.

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p53 improves the ability of CPCs to sustain oxidative stress.

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p53 promotes the restoration of DNA integrity and cell division.

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p53 enhances the engraftment of CPCs in the diabetic heart.

Ongoing clinical trials with autologous cardiac stem cells (CSCs) are faced with a critical limitation which is related to the modest amount of retained cells within the damaged myocardium. We have developed a strategy that overcomes in part this problem enhancing the number of CSCs able to engraft within the pathologic organ. Additionally, these genetically modified CSCs can be generated in large number, raising the possibility that multiple temporally distinct deliveries of cells can be introduced to restore the structural and functional integrity of the decompensated heart.

A Novel Class of Human Cardiac Stem Cells

Following the recognition that hematopoietic stem cells improve the outcome of myocardial infarction in animal models, bone marrow mononuclear cells, CD34-positive cells, and mesenchymal stromal cells have been introduced clinically. The intracoronary or intramyocardial injection of these cell classes has been shown to be safe and to produce a modest but significant enhancement in systolic function. However, the identification of resident cardiac stem cells in the human heart (hCSCs) has created great expectation concerning the potential implementation of this category of autologous cells for the management of the human disease. Although phase 1 clinical trials have been conducted with encouraging results, the search for the most powerful hCSC for myocardial regeneration is in its infancy. This manuscript discusses the efforts performed in our laboratory to characterize the critical biological variables that define the growth reserve of hCSCs. Based on the theory of the immortal DNA template, we propose that stem cells retaining the old DNA represent 1 of the most powerful cells for myocardial regeneration. Similarly, the expression of insulin-like growth factor-1 receptors in hCSCs recognizes a cell phenotype with superior replicating reserve. However, the impressive recovery in ventricular hemodynamics and anatomy mediated by clonal hCSCs carrying the "mother" DNA underscores the clinical relevance of this hCSC class for the treatment of human heart failure.

Are Endothelial Progenitor Cells the Real Solution for Cardiovascular Diseases? Focus on Controversies and Perspectives

Advanced knowledge in the field of stem cell biology and their ability to provide a cue for counteracting several diseases are leading numerous researchers to focus their attention on “regenerative medicine” as possible solutions for cardiovascular diseases (CVDs). However, the lack of consistent evidence in this arena has hampered the clinical application. The same condition affects the research on endothelial progenitor cells (EPCs), creating more confusion than comprehension. In this review, this aspect is discussed with particular emphasis. In particular, we describe biology and physiology of EPCs, outline their clinical relevance as both new predictive, diagnostic, and prognostic CVD biomarkers and therapeutic agents, discuss advantages, disadvantages, and conflicting data about their use as possible solutions for vascular impairment and clinical applications, and finally underline a very crucial aspect of EPCs “characterization and definition,” which seems to be the real cause of large heterogeneity existing in literature data on this topic.

Inhibiting the mobilization of Ly6C(high) monocytes after acute myocardial infarction enhances the efficiency of mesenchymal stromal cell transplantation and curbs myocardial remodeling

BACKGROUND

Ischemia related inflammation is the most critical factor for the survival of transplanted mesenchymal stem cells (MSCs), and strategies for controlling excessive inflammation after acute myocardial infarction (AMI) are essential and necessary for cell transplantation therapy. Our present study tested the effect of decreased Ly6C(high) monocytes on mouse MSCs transplantation after AMI.

METHODS

BALB/c AMI mice were treated systemically with a CCR2 antagonist (RS 504393, 2 mg/kg, subcutaneously) or normal saline (control group). Next, 10(5) EdU-labeled MSCs were administered by intramyocardial injection to the mice in each group. TUNEL kits were used to identify the apoptotic cardiomyocytes in the infarct. The slides of the infarct border zone were stained with wheat germ agglutinin to measure the vessel density, and anti-myosin heavy chain eFluor 660 was used to measure the cardiac myosin-positive area. A transwell chamber was used to examine the interactions between Ly6C(high) monocytes and MSCs. The inflammatory cytokines expressed by Ly6C(high) monocytes and the SDF-1 expressed by MSCs were detected using ELISA kits. MSC viability was further examined by MTT and mitochondrial membrane potential assays by flow cytometry using JC-1 kits.

RESULTS

We first observed the increased survival of transplanted MSCs (11.2 ± 3.4/mm(2) vs. 3.5 ± 1.6/mm(2), p < 0.001), and the decreased apoptosis of cardiomyocytes (11.20% ± 3.55% vs. 20.51% ± 8.17%, p < 0.001) in the infarcts at 3 days in the CCR2 antagonist group. An increased number of capillaries and small arterioles (139.6 ± 21.7/mm(2) vs. 95.4 ± 17.6/mm(2), p < 0.001) and an increased cardiac myosin-positive area (17.9% ± 6.6% vs. 11.8% ± 3.5%, p < 0.001) were also observed in the infarct zone at 21 days post MSC infusion in the CCR2 antagonist group. In addition, a significantly increased LvEF% (50.17 ± 10.06 vs. 45.44 ± 9.45, p < 0.001) was detected at the same time compared to the control mice. We further demonstrated that both the mitochondrial membrane potential of the MSCs (0.45 ± 0.11 vs. 3.4 ± 0.3, p < 0.001) and stromal cell-derived factor-1 (SDF-1) secreted by the MSCs significantly decreased (80.77 ± 39.02 pg/ml vs. 435.5 ± 77.41 pg/ml, p < 0.001) when co-cultured with Ly6C(high) monocytes. This is possibly mediated by the over-expressed cytokines secreted by the Ly6C(high) monocytes compared to the Ly6C(low) monocytes, including IL-1 (139.45 ± 30.44 vs. 80.05 ± 19.33, p < 0.001), IL-6 (187.82 ± 40.43 vs. 135.5 ± 22.09, p < 0.001), TNF-α (121.77 ± 31.65 vs. 75.3 ± 22.14, p < 0.001) and IFN-γ (142.46 ± 27.55 vs. 88.25 ± 19.91, p < 0.001).

New redox-related arrows in the arsenal of cardiac disease treatment

While great strides have been made to improve the poor prognosis with cardiac disease, heart failure in particular, cardiac affections still remain the most prevalent, difficult-to-treat, and costly human pathologies in the western world. At rest, the heart produces a significant oxidative environment inside diverse cell compartments, due to its high-energy demand. Cardiac cells have an exquisite control system to deal with this constant redox stress. However, persistent hemodynamic alterations can compromise these mechanisms, fueling further myocardial redox imbalance and dysfunction. Still, this would be a one-sided and incomplete view, because the physiological role of reactive oxygen species (ROS) should be considered as well. Indeed, ROS are multipurpose agents, serving signaling and cell defense tasks too, and, similar to antioxidants, these functions can be highly compartmentalized within the cell. The present Forum was designed to collect cutting-edge research concerning when and how to effectively counter excessive oxidative burden to preserve cardiac structure and/or to improve function, under conditions of ordinary or extraordinary stress. Another major objective was to unravel old and new intersections between different myocardial processes by which ROS may act as "on" or "off" switches, and in doing so, dictating function, always with an eye on possible, immediate therapeutic applications, as suggested by the title of the Forum itself, that is, Cardiac Therapeutics.