Stem Cell Therapy: Promising Treatment in Heart Failure?

Direct differentiation of rat skin fibroblasts into cardiomyocytes

Myocardial infarction (MI) is one of the major cardiovascular diseases caused by diminished supply of nutrients and oxygen to the heart due to obstruction of the coronary artery. Different treatment options are available for cardiac diseases, however, they do not completely repair the damage. Therefore, reprogramming terminally differentiated fibroblasts using transcription factors is a promising strategy to differentiate them into cardiac like cells in vitro and to increase functional cardiomyocytes and reduce fibrotic scar in vivo. In this study, skin fibroblasts were selected for reprogramming because they serve as a convenient source for the autologous cell therapy. Fibroblasts were isolated from skin of rat pups, propagated, and directly reprogrammed towards cardiac lineage. For reprogramming, two different approaches were adopted, i.e., cells were transfected with: (1) combination of cardiac transcription factors; GATA4, MEF2c, Nkx2.5 (GMN), and (2) combination of cardiac transcription factors; GATA4, MEF2c, Nkx2.5, and iPSC factors; Oct4, Klf4, Sox2 and cMyc (GMNO). After 72 h of transfection, cells were analyzed for the expression of cardiac markers at the mRNA and protein levels. For in vivo study, rat MI models were developed by ligating the left anterior descending coronary artery and the reprogrammed cells were transplanted in the infarcted heart. qPCR results showed that the reprogrammed cells exhibited significant upregulation of cardiac genes. Immunocytochemistry analysis further confirmed cardiomyogenic differentiation of the reprogrammed cells. For the assessment of cardiac function, animals were analyzed via echocardiography after 2 and 4 weeks of cell transplantation. Echocardiographic results showed that the hearts transplanted with the reprogrammed cells improved ejection fraction, fractional shortening, left ventricular internal systolic and diastolic dimensions, and end systolic and diastolic volumes. After 4 weeks of cell transplantation, heart tissues were harvested and processed for histology. The histological analysis showed that the reprogrammed cells improved wall thickness of left ventricle and reduced fibrosis significantly as compared to the control. It is concluded from the study that novel combination of cardiac transcription factors directly reprogrammed skin fibroblasts and differentiated them into cardiomyocytes. These differentiated cells showed cardiomyogenic characters in vitro, and reduced fibrosis and improved cardiac function in vivo. Furthermore, direct reprogramming of fibroblasts transfected with cardiac transcription factors showed better regeneration of the injured myocardium and improved cardiac function as compared to the indirect approach in which combination of cardiac and iPSC factors were used. The study after further optimization could be used as a better strategy for cell-based therapeutic approaches for cardiovascular diseases.

Hesperetin attenuates LPS-induced the inflammatory response and apoptosis of H9c2 by activating the AMPK/P53 signaling pathway

INTRODUCTION

Hesperetin (HES), whose main pharmacological effects are anti-inflammatory and cardioprotective properties. In our study, we investigated the role of HES in lipopolysaccharide (LPS)-induced inflammation and apoptosis in H9c2 cells.

METHODS

Cell viability was assessed through MTT assay. Tumor necrosis factor (TNF)-α and interleukin (IL)-β expression were quantified through RT-qPCR assay. Secondly, the apoptosis rate was assessed by Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. Finally, B-cell lymphoma 2 (Bcl-2)- associated X protein (Bax), adenosine monophosphate-activated protein kinase (AMPK), and P53 expression were quantified through western blot assay.

RESULTS

Our results demonstrated that LPS stimulation decreased the cell viability, increased IL-1β and TNF-α expression in H9c2 cells. However, HES treatment significantly increased the cell viability, decreased IL-1β and TNF-α expression in LPS-induced H9c2 cells. In addition, HES significantly increased the phosphorylation level of AMPK. Meanwhile, HES prevented against LPS-mediated the P53 and Bax protein upregulation, and Bcl-2 protein downregulation in H9c2 cells. More interestingly, compound C (an AMPK inhibitor) treatment eliminated the protective effects of HES.

CONCLUSION

Our findings revealed that HES attenuated the LPS-mediated inflammation and apoptosis of H9c2 cells by activating the AMPK/P53 signaling pathway, suggesting that HES may be a potential cardioprotective agent.

Cortical Bone Derived Stem Cells for Cardiac Wound Healing

Ischemic heart disease can lead to myocardial infarction (MI), a major cause of morbidity and mortality worldwide. Adoptive transfer of multiple stem cell types into failing human hearts has demonstrated safety however the beneficial effects in patients with cardiovascular disorders have been modest. Modest improvement in patients with cardiac complications warrants identification of a novel stem cell population that possesses effective reparative properties and improves cardiac function after injury. Recently we have shown in a mouse model and a porcine pre-clinical animal model, that cortical bone derived stem cells (CBSCs) enhance cardiac function after MI and/or ischemia-reperfusion injury. These beneficial effects of allogeneic cell delivery appear to be mediated by paracrine mechanisms rather than by transdifferentiation of injected cells into vessels and/or immature myocytes. This review will discuss role of CBSCs in cardiac wound healing. After having modest beneficial improvement in most of the clinical trials, a critical need is to understand the interaction of the transplanted stem cells with the ischemic cardiac environment. Transplanted stem cells are exposed to pro-inflammatory factors and activated immune cells and fibroblasts, but their interactions remain unknown. We have shown that CBSCs modulate different processes including modulation of the immune response, angiogenesis, and restriction of infarct sizes after cardiac injury. This review will provide information on unique protective signature of CBSCs in rodent/swine animal models for heart repair that should provide basis for developing novel therapies for treating heart failure patients.

Myocardial Reparative Properties of Cardiac Mesenchymal Cells Isolated on the Basis of Adherence

BACKGROUND

The authors previously reported that the c-kit-positive (c-kit^POS) cells isolated from slowly adhering (SA) but not from rapidly adhering (RA) fractions of cardiac mesenchymal cells (CMCs) are effective in preserving left ventricular (LV) function after myocardial infarction (MI).

OBJECTIVES

This study evaluated whether adherence to plastic alone, without c-kit sorting, was sufficient to isolate reparative CMCs.

METHODS

RA and SA CMCs were isolated from mouse hearts, expanded in vitro, characterized, and evaluated for therapeutic efficacy in mice subjected to MI.

RESULTS

Morphological and phenotypic analysis revealed that murine RA and SA CMCs are indistinguishable; nevertheless, transcriptome analysis showed that they possess fundamentally different gene expression profiles related to factors that regulate post-MI LV remodeling and repair. A similar population of SA CMCs was isolated from porcine endomyocardial biopsy samples. In mice given CMCs 2 days after MI, LV ejection fraction 28 days later was significantly increased in the SA CMC group (31.2 ± 1.0% vs. 24.7 ± 2.2% in vehicle-treated mice; p < 0.05) but not in the RA CMC group (24.1 ± 1.2%). Histological analysis showed reduced collagen deposition in the noninfarcted region in mice given SA CMCs (7.6 ± 1.5% vs. 14.5 ± 2.8% in vehicle-treated mice; p < 0.05) but not RA CMCs (11.7 ± 1.7%), which was associated with reduced infiltration of inflammatory cells (14.1 ± 1.6% vs. 21.3 ± 1.5% of total cells in vehicle and 19.3 ± 1.8% in RA CMCs; p < 0.05). Engraftment of SA CMCs was negligible, which implies a paracrine mechanism of action.

CONCLUSIONS

We identified a novel population of c-kit-negative reparative cardiac cells (SA CMCs) that can be isolated with a simple method based on adherence to plastic. SA CMCs exhibited robust reparative properties and offered numerous advantages, appearing to be more suitable than c-kit^POS cardiac progenitor cells for widespread clinical therapeutic application.

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.

Rationally engineered Troponin C modulates in vivo cardiac function and performance in health and disease

Treatment for heart disease, the leading cause of death in the world, has progressed little for several decades. Here we develop a protein engineering approach to directly tune in vivo cardiac contractility by tailoring the ability of the heart to respond to the Ca(2+) signal. Promisingly, our smartly formulated Ca(2+)-sensitizing TnC (L48Q) enhances heart function without any adverse effects that are commonly observed with positive inotropes. In a myocardial infarction (MI) model of heart failure, expression of TnC L48Q before the MI preserves cardiac function and performance. Moreover, expression of TnC L48Q after the MI therapeutically enhances cardiac function and performance, without compromising survival. We demonstrate engineering TnC can specifically and precisely modulate cardiac contractility that when combined with gene therapy can be employed as a therapeutic strategy for heart disease.

Similar effect of autologous and allogeneic cell therapy for ischemic heart disease: systematic review and meta-analysis of large animal studies

RATIONALE

In regenerative therapy for ischemic heart disease, use of both autologous and allogeneic stem cells has been investigated. Autologous cell can be applied without immunosuppression, but availability is restricted, and cells have been exposed to risk factors and aging. Allogeneic cell therapy enables preoperative production of potent cell lines and immediate availability of cell products, allowing off-the-shelf therapy. It is unknown which cell source is preferred with regard to improving cardiac function.

OBJECTIVE

We performed a meta-analysis of preclinical data of cell therapy for ischemic heart disease.

METHODS AND RESULTS

We conducted a systematic literature search to identify publications describing controlled preclinical trials of unmodified stem cell therapy in large animal models of myocardial ischemia. Data from 82 studies involving 1415 animals showed a significant improvement in mean left ventricular ejection fraction in treated compared with control animals (8.3%, 95% confidence interval, 7.1-9.5; P<0.001). Meta-regression revealed a similar difference in left ventricular ejection fraction in autologous (8.8%, 95% confidence interval, 7.3-10.3; n=981) and allogeneic (7.3%, 95% confidence interval, 4.4-10.2, n=331; P=0.3) cell therapies.

CONCLUSIONS

Autologous and allogeneic cell therapy for ischemic heart disease show a similar improvement in left ventricular ejection fraction in large animal models of myocardial ischemia, compared with placebo. These results are important for the design of future clinical trials.

Mesenchymal stem cell therapy for cardiac repair

OPINION STATEMENT

Owing to the prevalence of heart disease and the lack of effective long-term solutions for managing cardiac injury, research has turned to cell therapy as a potential mechanism for myocardial repair. Mesenchymal stem cells (MSC) in particular have become popular because their differentiative ability and their angiogenic and immunomodulatory properties make them attractive candidates for transplantation. However, there is still debate regarding the optimal strategy for the delivery of these cells. Recent clinical studies have isolated MSCs from a variety of tissue origins and have also tested the benefits of pretreatment with cardiogenic growth factors. Meanwhile, a newer school of thought instead supports the utilization of cardiomyocytes generated from MSC-derived induced pluripotent stem cells. This review will examine the promise of MSC therapy, discuss the results of past work, and propose steps that must be taken in the future.

Hesperetin attenuates mitochondria-dependent apoptosis in lipopolysaccharide-induced H9C2 cardiomyocytes

Apoptosis is closely associated with the occurrence and development of cardiovascular diseases and is considered as one of the crucial pathological processes of cardiomyopathy, sepsis, ischemia/reperfusion injury, myocardial infarction and heart failure. Hesperetin (HES), a flavanone glycoside found in citrus fruit peels, has been known to exhibit several key biological and pharmacological properties. Previous studies have demonstrated the anti-inflammatory, anti-oxidant and anti-tumor functions of HES. However, with regards to the pro- or anti-apoptotic functions of HES, there are several disagreements within the literature. To examine whether HES has protective effects in cardiac apoptosis, the present study examined the role of HES in lipopolysaccharide (LPS)-stimulated H9C2 cardiomyocytes, aiming to clarify the possible mechanisms underlying its effects. In the present study, HES reduced the percentage of viable apoptotic (VA) cells in a flow cytometry analysis. It had an anti-apoptosis function in LPS-stimulated H9C2 cells. To clarify whether HES alleviated LPS-stimulated apoptosis through the mitochondria-dependent intrinsic apoptotic pathway, certain indicators of this pathway were detected, including members of the caspase family. The data revealed that HES attenuated the activation of capase-3 and caspase-9. These results indicated HES has a mitochondria-dependent anti-apoptosis effect in LPS-stimulated H9C2 cells. To explore the possible mechanisms, the protein expression levels of certain markers in the possible signaling pathway were detected, including JNK and Bcl-2 family. As a result, HES downregulated the protein expression of Bax, upregulated the expression of Bcl-2 and attenuated the phosphorylation level of JNK. Therefore, the anti-apoptosis effects of HES were possibly mediated by the JNK/Bax signaling pathway. In conclusion, HES has a mitochondria-dependent anti-apoptosis effect in LPS-induced H9C2 cells via the JNK/Bax signaling pathway.

Anti-remodeling effects of rapamycin in experimental heart failure: dose response and interaction with angiotensin receptor blockade

While neurohumoral antagonists improve outcomes in heart failure (HF), cardiac remodeling and dysfunction progress and outcomes remain poor. Therapies superior or additive to standard HF therapy are needed. Pharmacologic mTOR inhibition by rapamycin attenuated adverse cardiac remodeling and dysfunction in experimental heart failure (HF). However, these studies used rapamycin doses that produced blood drug levels targeted for primary immunosuppression in human transplantation and therefore the immunosuppressive effects may limit clinical translation. Further, the relative or incremental effect of rapamycin combined with standard HF therapies targeting upstream regulators of cardiac remodeling (neurohumoral antagonists) has not been defined. Our objectives were to determine if anti-remodeling effects of rapamycin were preserved at lower doses and whether rapamycin effects were similar or additive to a standard HF therapy (angiotensin receptor blocker (losartan)). Experimental murine HF was produced by transverse aortic constriction (TAC). At three weeks post-TAC, male mice with established HF were treated with placebo, rapamycin at a dose producing immunosuppressive drug levels (target dose), low dose (50% target dose) rapamycin, losartan or rapamycin + losartan for six weeks. Cardiac structure and function (echocardiography, catheterization, pathology, hypertrophic and fibrotic gene expression profiles) were assessed. Downstream mTOR signaling pathways regulating protein synthesis (S6K1 and S6) and autophagy (LC3B-II) were characterized. TAC-HF mice displayed eccentric hypertrophy, systolic dysfunction and pulmonary congestion. These perturbations were attenuated to a similar degree by oral rapamycin doses achieving target (13.3±2.1 ng/dL) or low (6.7±2.5 ng/dL) blood levels. Rapamycin treatment decreased mTOR mediated regulators of protein synthesis and increased mTOR mediated regulators of autophagy. Losartan monotherapy did not attenuate remodeling, whereas Losartan added to rapamycin provided no incremental benefit over rapamycin alone. These data lend support to investigation of low dose rapamycin as a novel therapy in human HF.