Transplantation of embryonic stem cell-derived cardiomyocytes improves cardiac function in infarcted rat hearts

Bisphosphonate of Zoledronate Has Antiapoptotic Effect on Hypoxia/Reoxygenation Injury in Human Embryonic Stem Cell-Derived Cardiomyocytes Through Trk Signaling Pathway

In this work, we investigated the in vitro and in vivo functions of bisphosphonate of zoledronate (Zd) in hypoxia/reoxygenation (H/R) injured human embryonic stem cell-derived cardiomyocytes (hES-CMs). In the in vitro setting, the effects of Zd on hES-CM survival and differentiation were examined. We found that low and medium concentrations (<2 µm) of Zd did not induce cell death of hES-CMs. 0.5 µm Zd protected H/R-induced hES-CM apoptosis but did not affect key differentiation proteins, including hcTnl, PECM-1 Cnx43 and Pan-Cadherin. In addition, Zd-induced TrkA/B phosphorylation and promoted VEGF to counter the apoptotic effect of H/R injury. In the in vivo animal model of myocardial infarction, Zd treatment promoted the survival of hES-CMs by inducing PECAM1 and hcTnl. Thus, we concluded that Zd protected H/R-induced hES-CM apoptosis in vitro and promoted hES-CM survival in vivo. These data may facilitate the development of human embryonic stem cells into clinical applications for patients with ischemic heart disease.

Re-Defining Stem Cell-Cardiomyocyte Interactions: Focusing on the Paracrine Effector Approach

Stem cell research for treating or curing ischemic heart disease has, till date, culminated in three basic approaches: the use of induced pluripotent stem cell (iPSC) technology; reprogramming cardiac fibroblasts; and cardiovascular progenitor cell regeneration. As each approach has been shown to have its advantages and disadvantages, exploiting the advantages while minimizing the disadvantages has been a challenge. Using human germline pluripotent stem cells (hgPSCs) along with a modified version of a relatively novel cell-expansion culture methodology to induce quick, indefinite expansion of normally slow growing hgPSCs, it was possible to emphasize the advantages of all three approaches. We consistently found that unipotent germline stem cells, when removed from their niche and cultured in the correct medium, expressed endogenously, pluripotency genes, which induced them to become hgPSCs. These cells are then capable of producing cell types from all three germ layers. Upon differentiation into cardiac lineages, our data consistently showed that they not only expressed cardiac genes, but also expressed cardiac-promoting paracrine factors. Taking these data a step further, we found that hgPSC-derived cardiac cells could integrate into cardiac tissue in vivo. Note, while the work presented here was based on testes-derived hgPSCs, data from other laboratories have shown that ovaries contain very similar types of stem cells that can give rise to hgPSCs. As a result, hgPSCs should be considered a viable option for eventual use in patients, male or female, with ischemic heart disease

Stem Cell Therapy: A New Therapeutic Option for Cardiovascular Diseases

Cardiovascular diseases are known as one of major causes of morbidity and mortality worldwide. Despite the many advancement in therapies are associated with cardiovascular diseases, it seems that finding of new therapeutic option is necessary. Cell therapy is one of attractive therapeutic platforms for treatment of a variety of diseases such as cardiovascular diseases. Among of various types of cell therapy, stem cell therapy has been emerged as an effective therapeutic approach in this area. Stem cells divided into multipotent stem cells and pluripotent stem cells. A large number studies indicated that utilization of each of them are associated with a variety of advantages and disadvantages. Multiple lines evidence indicated that stem cell therapy could be used as suitable therapeutic approach for treatment of cardiovascular diseases. Many clinical trials have been performed for assessing efficiency of stem cell therapies in human. However, stem cell therapy are associated with some challenges, but, it seems resolving of them could contribute to using of them as effective therapeutic approach for patients who suffering from cardiovascular diseases. In the current review, we summarized current therapeutic strategies based on stem cells for cardiovascular diseases. J. Cell. Biochem. 119: 95-104, 2018. © 2017 Wiley Periodicals, Inc.

Cellular Therapy for Heart Failure

The pathogenesis of cardiomyopathy and heart failure (HF) is underpinned by complex changes at subcellular, cellular and extracellular levels in the ventricular myocardium. For all of the gains that conventional treatments for HF have brought to mortality and morbidity, they do not adequately address the loss of cardiomyocyte numbers in the remodeling ventricle. Originally conceived to address this problem, cellular transplantation for HF has already gone through several stages of evolution over the past two decades. Various cell types and delivery routes have been implemented to positive effect in preclinical models of ischemic and nonischemic cardiomyopathy, with pleiotropic benefits observed in terms of myocardial remodeling, systolic and diastolic performance, perfusion, fibrosis, inflammation, metabolism and electrophysiology. To a large extent, these salubrious effects are now attributed to the indirect, paracrine capacity of transplanted stem cells to facilitate endogenous cardiac repair processes. Promising results have also followed in early phase human studies, although these have been relatively modest and somewhat inconsistent. This review details the preclinical and clinical evidence currently available regarding the use of pluripotent stem cells and adult-derived progenitor cells for cardiomyopathy and HF. It outlines the important lessons that have been learned to this point in time, and balances the promise of this exciting field against the key challenges and questions that still need to be addressed at all levels of research, to ensure that cell therapy realizes its full potential by adding to the armamentarium of HF management.

Infarcted cardiac microenvironment may hinder cardiac lineage differentiation of human embryonic stem cells

Microenvironment regulates cell fate and function. In this study, we investigated the effects of the infarcted cardiac microenvironment on cardiac differentiation of human embryonic stem cells (hESCs). hESCs were intramyocardially transplanted into infarcted or uninjured rat hearts. After 4 weeks, mesodermal and cardiac lineage markers were detected by immunofluorescence. Cardiac function was assessed by echocardiography. hESCs were differentiated in vitro under hypoxic (5% O₂ ), low-nutrient (5% FBS), or control condition. The numbers of beating clusters, proportions of cardiac troponin T (cTnT)-positive cells, and relative levels of cardiac-specific markers were determined. Results showed that in both uninjured and infarcted hearts, hESCs survived, underwent development, and formed intracardiac grafts, with a higher proportion in the uninjured hearts. However, cells that were double positive for human fetal liver kinase 1 (Flk1), a marker of cardiac progenitors, and human β-tubulin, a marker for labeling human cells, were found in the uninjured hearts but not in the infarcted hearts. hESC transplantation did not restore the cardiac function of acutely infarcted rats. In vitro, low FBS treatment was associated with fewer beating clusters, a lower proportion of cTnT-positive cells and lower levels of cardiac troponin I (cTnI) and α-myosin heavy chain (α-MHC) expression than those in the control. Conversely, hypoxia treatment was associated with a higher proportion of cTnT-positive cells and higher levels of cTnI expression. In conclusion, transplanted hESCs differentiate toward Flk1-positive cardiac progenitors in the uninjured but not infarcted hearts. The infarcted cardiac microenvironment recapitulated is unsuitable for cardiac differentiation of hESCs, likely due to nutrient deprivation.

Insight on stem cell preconditioning and instructive biomaterials to enhance cell adhesion, retention, and engraftment for tissue repair

Stem cells are a promising solution for the treatment of a variety of diseases. However, the limited survival and engraftment of transplanted cells due to a hostile ischemic environment is a bottleneck for effective utilization and commercialization. Within this environment, the majority of transplanted cells undergo apoptosis prior to participating in lineage differentiation and cellular integration. Therefore, in order to maximize the clinical utility of stem/progenitor cells, strategies must be employed to increase their adhesion, retention, and engraftment in vivo. Here, we reviewed key strategies that are being adopted to enhance the survival, retention, and engraftment of transplanted stem cells through the manipulation of both the stem cells and the surrounding environment. We describe how preconditioning of cells or cell manipulations strategies can enhance stem cell survival and engraftment after transplantation. We also discuss how biomaterials can enhance the function of stem cells for effective tissue regeneration. Biomaterials can incorporate or mimic extracellular function (ECM) function and enhance survival or differentiation of transplanted cells in vivo. Biomaterials can also promote angiogenesis, enhance engraftment and differentiation, and accelerate electromechanical integration of transplanted stem cells. Insight gained from this review may direct the development of future investigations and clinical trials.

Reprogramming for cardiac regeneration

Treatment of cardiovascular diseases remains challenging considering the limited regeneration capacity of the heart muscle. Developments of reprogramming strategies to create in vitro and in vivo cardiomyocytes have been the focus point of a considerable amount of research in the past decades. The choice of cells to employ, the state-of-the-art methods for different reprogramming strategies, and their promises and future challenges before clinical entry, are all discussed here.

Cell therapy for heart failure: a comprehensive overview of experimental and clinical studies, current challenges, and future directions

Despite significant therapeutic advances, the prognosis of patients with heart failure (HF) remains poor, and current therapeutic approaches are palliative in the sense that they do not address the underlying problem of the loss of cardiac tissue. Stem cell-based therapies have the potential to fundamentally transform the treatment of HF by achieving what would have been unthinkable only a few years ago-myocardial regeneration. For the first time since cardiac transplantation, a therapy is being developed to eliminate the underlying cause of HF, not just to achieve damage control. Since the initial report of cell therapy (skeletal myoblasts) in HF in 1998, research has proceeded at lightning speed, and numerous preclinical and clinical studies have been performed that support the ability of various stem cell populations to improve cardiac function and reduce infarct size in both ischemic and nonischemic cardiomyopathy. Nevertheless, we are still at the dawn of this therapeutic revolution. Many important issues (eg, mechanism(s) of action of stem cells, long-term engraftment, optimal cell type(s), and dose, route, and frequency of cell administration) remain to be resolved, and no cell therapy has been conclusively shown to be effective. The purpose of this article is to critically review the large body of work performed with respect to the use of stem/progenitor cells in HF, both at the experimental and clinical levels, and to discuss current controversies, unresolved issues, challenges, and future directions. The review focuses specifically on chronic HF; other settings (eg, acute myocardial infarction, refractory angina) are not discussed.

Stem cells for cardiac repair in acute myocardial infarction

Despite recent advances in medical therapy, reperfusion strategies, implantable cardioverter-defibrillators and cardiac assist devices, ischemic heart disease is a frequent cause of morbidity and mortality worldwide. Cell therapy has been introduced as a new treatment modality to regenerate lost cardiomyocytes. At present, several cell types seem to improve left ventricular function in animal models as well as in humans, but evidence for true generation of new myocardium is confined to the experimental models. In the clinical perspective, myocardial regeneration has been replaced by myocardial repair, as other mechanisms seem to be involved. Clinical studies on adult stem cells suggest, at best, moderate beneficial effects on surrogate end points, but some applications may qualify for evaluation in larger trials. Complete regeneration of the myocardium by cell therapy after a large myocardial infarction is still visionary, but pluripotent stem cells and tissue engineering are important tools to solve the puzzle.

Human embryonic stem cell-derived mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) originally isolated from marrow have multipotent differentiation potential and favorable immunomodulatory and anti-inflammatory properties that make them very attractive for regenerative cellular therapy. Cells with similar phenotypic characteristics have now been derived from almost all fetal, neonatal, and adult tissues; furthermore, more recently similar cells have also been generated from human embryonic stem cells (ESCs). Generation of MSCs from human ESCs provides an opportunity to study the developmental biology of human mesenchymal lineage generation in vitro. Generation of bone and cartilage from human ESC-derived MSCs and their functional characterization, both in vitro and in vivo, is also an active area of investigation as ESCs could provide an unlimited source of MSCs for potential repair of bone and cartilage defects. MSCs from adult sources are being investigated in numerous Phase I-III clinical trials for a wide variety of indications, mainly based on their immunomodulatory properties. Our group and others have shown MSCs derived from human ESCs possess immunomodulatory properties similar to marrow-derived MSCs. Immunomodulatory properties of ESC-derived MSCs could prove to be highly valuable for their potential clinical applications in the future as derivatives of human ESCs have already entered clinical arena in the context of Phase I clinical trials.

Mitogen-activated protein kinase in endothelin-1-induced cardiac differentiation of mouse embryonic stem cells

Endothelin-1(ET-1) is a potent vasoconstrictor involved in the development of cardiovascular diseases and is an important regulator of heart development. However, the role of ET-1 in cardiac differentiation of mouse embryonic stem cells (mESCs) and the underlying molecular mechanisms remain poorly understood. In the present study, we showed that ET-1 significantly up-regulated gene expression of the cardiac specific transcriptional factors Nkx2.5, GATA4, and conduction system specific marker CX40, with no affect on the gene expression of α-MHC and β-MHC in cardiac differentiation of mESCs. The percentage of beating embryoid bodies (EB) and the Troponin T (TnT) positive area in total EBs was unchanged following ET-1 treatment, while the percentage of spindle cells that stained positively with TnT was increased in the presence of ET-1. Further investigation indicated that the percentage of beating EBs and the TnT positive area were decreased by the extracellular signal-related kinases (ERK)-1/2 inhibitor U0126 and the p38 inhibitor SB203580, but not by the Jun amino-terminal kinases (JNK) inhibitor SP600125. Inhibition of ERK1/2, p38, and JNK pathways also blocked the up-regulation of Nkx2.5 and GATA4 by ET-1, however only inhibition of the ERK1/2 pathway had negatively effects on the increase in CX40 expression in response to ET-1. ET-1 induced an increase in the percentage of spindle cells was also inhibited by U0126. Our results suggest that ET-1 plays a significant role in the cardiac differentiation of mESCs, especially in those cells committed to the conduction system, with the ERK1/2 pathway playing a critical role in this process.

Human embryonic stem cell-derived mesenchymal progenitors: an overview

Mesenchymal stromal/stem cells (MSCs) were originally isolated from bone marrow (BM), but are now known to be present in all fetal and adult tissues. These multipotent cells can be differentiated into at least three downstream mesenchymal lineages that include bone, cartilage, and fat. However, under some experimental conditions, these cells can differentiate into nonmesenchymal cell types and/or participate in regeneration of damaged tissues through a variety of mechanisms. Most recently, MSCs have been derived from human embryonic stem cells (hESCs) through several different methodologies. Human MSCs derived from hESCs have been shown to possess characteristics very similar to BM-derived MSCs. Thus, the generation of MSCs from hESCs provides an opportunity to study the developmental biology of cells of mesenchymal lineages in an appropriate in vitro model. Furthermore, MSCs from different adult tissue sources are being actively investigated in a multitude of clinical trials; therefore, hESCs could provide an unlimited source of MSCs for potential clinical applications in the future. Such MSCs could be used without further differentiation for regeneration of tissues, or they could be directed towards specific lineage pathways, such as bone and cartilage, for reconstruction of tissues. Finally, immunomodulatory properties of hESC-derived MSCs are likely to prove valuable for inducing immune tolerance toward other cells or tissues derived from the same hESC lines.

Very small embryonic-like stem cells (VSELs)-a new promising candidate for use in cardiac regeneration

In recent years, stem cell-based therapy has been given increased attention in terms of its potential contribution to cardiac regeneration and repair, after acute myocardial infarction (AMI). The published studies have identified many kinds of stem cells with the ability to regenerate and repair damaged myocardium after AMI. These include embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), multipotent adult progenitor cells, unrestricted somatic stem cells, etc. More recently, very small embryonic-like stem cells (VSELs) were identified from murine, as a population of very small CXCR4(+) Lin(-) CD45(-) cells and from human, as a population of very small CD34(+) CD133(+) CXCR4(+) Lin(-) CD45(-) cells. These cells exhibit beneficial effects on improving cardiac function and attenuating cardiac remodeling after AMI. However, the mechanisms underlying the benefits associated with VSELs therapy, in cardiac regeneration and repair, remain poorly understood. This review summarizes the current studies on cardiac repair with VSELs after AMI, and discusses the potential mechanisms and implications of these cells in cardiac repair.

Cardiomyocyte enrichment from human embryonic stem cell cultures by selection of ALCAM surface expression

AIMS

The production of a homogenous population of human cardiomyocytes that can be expanded in vitro may facilitate development of replacement tissue lost as a result of cardiac disease and injury.

MATERIALS AND METHODS

We evaluated the utility of activated leukocyte cell-adhesion molecule, CD166 (ALCAM) expression as a marker for isolating cardiomyocytes from differentiating cultures of human embryonic stem cells (hESCs). Using RT-qPCR, immunohistochemistry and DNA methylation studies, we evaluated the developmental age of hESC-derived cardiomyocytes.

RESULTS AND CONCLUSIONS

We demonstrate that cardiomyocytes derived from hESC cultures express ALCAM and that this surface antigen can be used to select a population of differentiated cells that are enriched for cardiomyocytes. Expression of contractile proteins and ion channels, and DNA methylation patterns, suggest that ALCAM-enriched cardiomyocytes have an embryonic phenotype. Selected cardiomyocyte populations survive sorting, adhere to collagen-coated tissue culture plastic and proliferate in short-term culture. Long-term in vitro survival of cardiomyocytes was achieved by culturing cells in 3D aggregates.

Teratoma formation by human embryonic stem cells: evaluation of essential parameters for future safety studies

Transplantation of human embryonic stem cells (hESC) into immune-deficient mice leads to the formation of differentiated tumors comprising all three germ layers, resembling spontaneous human teratomas. Teratoma assays are considered the gold standard for demonstrating differentiation potential of pluripotent hESC and hold promise as a standard for assessing safety among hESC-derived cell populations intended for therapeutic applications. We tested the potency of teratoma formation in seven anatomical transplantation locations (kidney capsule, muscle, subcutaneous space, peritoneal cavity, testis, liver, epididymal fat pad) in SCID mice with and without addition of Matrigel, and found that intramuscular teratoma formation was the most experimentally convenient, reproducible, and quantifiable. In the same experimental setting, we compared undifferentiated hESC and differentiated populations enriched for either beating cardiomyocytes or definitive endoderm derivatives (insulin-secreting beta cells), and showed that all cell preparations rapidly formed teratomas with varying percentages of mesoderm, ectoderm, and endoderm. In limiting dilution experiments, we found that as little as two hESC colonies spiked into feeder fibroblasts produced a teratoma, while a more rigorous single-cell titration achieved a detection limit of 1/4000. In summary, we established core parameters essential for facilitating safety profiling of hESC-derived products for future therapeutic applications.

Resveratrol attenuates ventricular arrhythmias and improves the long-term survival in rats with myocardial infarction

OBJECTIVE

The effects of resveratrol treatment on ventricular arrhythmia, survival, and late cardiac remodeling were evaluated in rats with myocardial infarction (MI).

METHODS

Three groups of rats (S: ham-operated, MI, and MI pre-treated with resveratrol) were treated in an in vivo MI model by ligation of left anterior descending coronary artery. The electrocardiogram signals were monitored and recorded for 24 h using an implanted telemetry transmitter. The incidence of ventricular arrhythmias during the first 24-h after MI was also evaluated. Meanwhile, invasive in vivo electrophysiology with pacing in the right ventricle was performed in each group to assess the inducibility of ventricular arrhythmias.

RESULTS

Administration of resveratrol significantly suppressed the MI-induced ventricular tachycardia and ventricular fibrillation (0.4 +/- 0.2 in Resv group vs. 7.1 +/- 2.2 in MI group episodes per hour per rat, P < 0.01). Data also showed that the incidence of inducible ventricular tachycardia was lower in the Resv group than the MI group (46% vs. 81%, P < 0.01). The infarct size and mortality in the Resv group at 14 weeks were reduced by 20% and 33%, respectively, compared with the MI groups. Results from patch clamp recording revealed that resveratrol inhibited L-type calcium current (I (Ca-L)), and selectively enhanced ATP-sensitive K(+) current (I (K,ATP)) in a concentration-dependent manner.

CONCLUSION

These results suggested that the emerging anti-arrhythmic character induced by resveratrol treatment in rat hearts could be mainly accounted for by inhibition of I (Ca-L) and enhancement of I (K,ATP). Administration of resveratrol also improved the long-term survival by suppressing left ventricular remodeling.

Embryonic Stem Cells as a Model for Cardiac Development and Disease

This review highlights recent progress in the use of embryonic stem cell (ESC) systems for studying and treating cardiovascular disease. Although ESCs represent an in vitro system, they can provide a rich source of progenitor cells, and this has been exploited recently to identify novel precursors and to investigate the lineage relationships among various cell types that comprise the developing heart, including cardiac muscle, endothelium, and smooth muscle. ESCs grown in aggregates (embryoid bodies) recapitulate normal developmental programs. Since they can be grown under defined culture conditions, they have been used to systematically identify specific genes and signaling pathways that promote cardiogenesis. A major goal is to optimize the production of cardiac progenitors and differentiated cell types, and to test their ability to promote healing in transplant assays, for example post-infarction. While many challenges remain, the development of iPS technology provides a means to generate cells for autologous transplant and for investigating patient-specific disease mechanisms. The development of new techniques to derive cardiac derivatives in vitro from ESC or iPS sources, coupled with novel tissue-engineering approaches and a better understanding of how explanted cells can survive and integrate in host tissue, should have a significant impact on the development of both cell-based and pharmacological therapies for cardiovascular disease.

Differentiation of embryonic stem cells to clinically relevant populations: lessons from embryonic development

The potential to generate virtually any differentiated cell type from embryonic stem cells (ESCs) offers the possibility to establish new models of mammalian development and to create new sources of cells for regenerative medicine. To realize this potential, it is essential to be able to control ESC differentiation and to direct the development of these cells along specific pathways. Embryology has offered important insights into key pathways regulating ESC differentiation, resulting in advances in modeling gastrulation in culture and in the efficient induction of endoderm, mesoderm, and ectoderm and many of their downstream derivatives. This has led to the identification of new multipotential progenitors for the hematopoietic, neural, and cardiovascular lineages and to the development of protocols for the efficient generation of a broad spectrum of cell types including hematopoietic cells, cardiomyocytes, oligodendrocytes, dopamine neurons, and immature pancreatic beta cells. The next challenge will be to demonstrate the functional utility of these cells, both in vitro and in preclinical models of human disease.