Cell therapy attenuates deleterious ventricular remodeling and improves cardiac performance after myocardial infarction

A nonbiodegradable scaffold-free cell sheet of genome-engineered mesenchymal stem cells inhibits development of acute kidney injury

Cell therapy using genome-engineered stem cells has emerged as a novel strategy for the treatment of kidney diseases. By exploiting genome editing technology, human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) secreting an angiogenic factors or an anti-inflammatory factor were generated for therapeutic application in acute kidney injury. Junction polymerase chain reaction analysis verified zinc finger nucleases-assisted integration of the desired gene into the hUC-MSCs. Flow cytometry and differentiation assays indicated that genome editing did not affect the differentiation potential of these mesenchymal stem cells. Protein measurement in conditioned media with the use of ELISA and immunoblotting revealed the production and secretion of each integrated gene product. For cell therapy in the bilateral ischemia-reperfusion mouse model of acute kidney injury, our innovative scaffold-free cell sheets were established using a non-biodegradable temperature-responsive polymer. One of each type of scaffold-free cell sheets of either the angiogenic factor vascular endothelial grown factor or angiopoietin-1, or the anti-inflammatory factor erythropoietin, or α-melanocyte-stimulating hormone-secreting hUC-MSCs was applied to the decapsulated kidney surface. This resulted in significant amelioration of kidney dysfunction in the mice with acute kidney injury, effects that were superior to intravenous administration of the same genome-engineered hUC-MSCs. Thus, our scaffold-free cell sheets of genome-engineered mesenchymal stem cells provides therapeutic effects by inhibiting acute kidney injury via angiogenesis or anti-inflammation.

Cell-Based Therapies for Cardiac Regeneration: A Comprehensive Review of Past and Ongoing Strategies

Despite considerable improvements in the treatment of cardiovascular diseases, heart failure (HF) still represents one of the leading causes of death worldwide. Poor prognosis is mostly due to the limited regenerative capacity of the adult human heart, which ultimately leads to left ventricular dysfunction. As a consequence, heart transplantation is virtually the only alternative for many patients. Therefore, novel regenerative approaches are extremely needed, and several attempts have been performed to improve HF patients’ clinical conditions by promoting the replacement of the lost cardiomyocytes and by activating cardiac repair. In particular, cell-based therapies have been shown to possess a great potential for cardiac regeneration. Different cell types have been extensively tested in clinical trials, demonstrating consistent safety results. However, heterogeneous efficacy data have been reported, probably because precise end-points still need to be clearly defined. Moreover, the principal mechanism responsible for these beneficial effects seems to be the paracrine release of antiapoptotic and immunomodulatory molecules from the injected cells. This review covers past and state-of-the-art strategies in cell-based heart regeneration, highlighting the advantages, challenges, and limitations of each approach.

Genetic deletion of 12/15 lipoxygenase promotes effective resolution of inflammation following myocardial infarction

12/15 lipoxygenase (LOX) directs inflammation and lipid remodeling. However, the role of 12/15LOX in post-myocardial infarction (MI) left ventricular remodeling is unclear. To determine the role of 12/15LOX, 8-12 week-old C57BL/6 J wild-type (WT; n = 93) and 12/15LOX^-/- (n = 97) mice were subjected to permanent coronary artery ligation and monitored at day (d)1 and d5 post-operatively. Post-MI d28 survival was measured in male and female mice. No-MI surgery mice were maintained as d0 naïve controls. 12/15LOX^-/- mice exhibited higher survival rates with lower cardiac rupture and improved LV function as compared with WT post-MI. Compared to WT, neutrophils and macrophages in 12/15LOX^-/- mice were polarized towards N2 and M2 phenotypes, respectively, with increased of expression mrc-1, ym-1, and arg-1 post-MI. 12/15LOX^-/- mice exhibited lower levels of pro-inflammatory 12-(S)-hydroperoxyeicosatetraenoic acid (12(S)-HETE) and higher CYP2J-derived epoxyeicosatrienoic acids (EETs) levels. CYP2J-derived 5,6-, 8,9-, 11,12-, and 14,15-EETs activated macrophage-specific hemeoxygenase (HO)-1 marked with increases in F4/80⁺/Ly6C^low and F4/80⁺/CD206^high cells at d5 post-MI in 12/15LOX^-/- mice. In contrast, inhibition of HO-1 led to total mortality in 12/15LOX^-/- mice by post-MI d5. 12/15LOX^-/- mice exhibited reduced collagen density and lower α-smooth muscle actin (SMA) expression at d5 post-MI, indicating delayed or limited fibroblast-to-myofibroblast differentiation. In conclusion, genetic deletion of 12/15LOX reduces 12(S)-HETE and activates CYP2J-derived EETs to promote effective resolution of inflammation post-MI leading to reduced cardiac rupture, improved LV function, and better survival.

Safety, feasibility and effectiveness of first in-human administration of muscle-derived stem/progenitor cells modified with connexin-43 gene for treatment of advanced chronic heart failure

AIMS

To assess the safety and efficacy of transendocardial delivery of muscle-derived stem/progenitor cells with connexin-43 overexpression (Cx-43-MDS/PC) in advanced heart failure (HF).

METHODS AND RESULTS

Thirteen subjects with advanced HF, New York Heart Association (NYHA) class II-III were enrolled and treated with targeted injection of Cx-43-MDS/PCs and then monitored for at least 6 months. Overexpression of Cx43 (Cx43+) was significantly higher in all but one subject (Cx43-). Injection of MDS/PCs was associated with significant improvement of exercise capacity: NYHA (3 ± 0 vs. 1.8 ± 0.7, P = 0.003), exercise duration (388.69 ± 141.83 s vs. 462.08 ± 176.69 s, P = 0.025), peak oxygen consumption (14.38 ± 3.97 vs. 15.83 ± 3.74 ml/kg.min, P = 0.022) and oxygen pulse (10.58 ± 2.89 vs. 18.88 ± 22.63 mLO₂ /heart rate, P = 0.012). Levels of BNP, left ventricular (LV) ejection fraction and LV end-diastolic volumes tended to improve. There was a significant improvement of the mean unipolar voltage amplitudes measured for the injected segments and the entire left ventricle (9.62 ± 2.64 vs. 11.62 ± 3.50 mV, P = 0.014 and 8.83 ± 2.80 vs. 10.22 ± 3.41 mV, P = 0.041, respectively). No deaths were documented, Cx43+ (n = 12) subjects presented no significant ventricular arrhythmia; one Cx43- subject suffered from ventricular tachycardia (successfully treated with amiodarone).

CONCLUSIONS

Injection of Cx-43-MDS/PCs in patients with severe HF led to significant improvement in exercise capacity and myocardial viability of the injected segments while inducing no significant ventricular arrhythmia. This may arise from improved electrical coupling of the injected cells and injured myocardium and thus better in-situ mechanical cooperation of both cell types. Therefore, further clinical studies with Cx43+ MDS/PCs are warranted.

Review of the emerging role of optical polarimetry in characterization of pathological myocardium

Myocardial infarction (MI), a cause of significant morbidity and mortality, is typically followed by microstructural alterations where the necrotic myocardium is steadily replaced with a collagen scar. Engineered remodeling of the fibrotic scar via stem cell regeneration has been shown to improve/restore the myocardium function after MI. Nevertheless, the heterogeneous nature of the scar patch may impair the myocardial electrical integrity, leading to the formation of arrhythmogenesis. Radiofrequency ablation (RFA) offers an effective treatment for focal arrhythmias where local heating generated via electric current at specific spots in the myocardium ablate the arrhythmogenic foci. Characterization of these myocardial pathologies (i.e., infarcted, stem cell regenerated, and RFA-ablated myocardial tissues) is of potential clinical importance. Optical polarimetry, the use of light to map and characterize the polarization signatures of a sample, has emerged as a powerful imaging tool for structural characterization of myocardial tissues, exploiting the underlying highly fibrous tissue nature. This study aims to review the recent progress in optical polarimetry pertaining to the characterization of myocardial pathologies while describing the underlying biological rationales that give rise to the optical imaging contrast in various pathologies of the myocardium. Future possibilities of and challenges to optical polarimetry in cardiac imaging clinics are also discussed.

Long-Term Cell Survival and Hemodynamic Improvements after Neonatal Cardiomyocyte and Satellite Cell Transplantation into Healed Myocardial Cryoinfarcted Lesions in Rats

Cell engraftment is a new strategy for the repair of ischemic myocardial lesions. The hemodynamic effectiveness of this strategy, however, is not completely elucidated yet. In a rat model of cryothermia-induced myocardial dysfunction, we investigated whether syngeneic transplantation of neonatal cardiomyocytes or satellite cells is able to improve left ventricular performance. Myocardial infarction was induced in female Lewis rats by a standardized cryolesion to the obtuse margin of the left ventricle. After 4 weeks, 5 × 106 genetically male neonatal cardiomyocytes (n= 16) or satellite cells (n = 16) were engrafted into the myocardial scar. Sham-transplanted animals (n = 15) received injections with cell-free medium. Sham-operated animals (n = 15) served as controls. Left ventricular performance was analyzed 4 months after cell engraftment. Chimerism after this sex-mismatched transplantation was evaluated by detection of PCR-amplified DNA of the Y chromosome. The average heart weight of the infarcted animals significantly exceeded that of controls (p < 0.05). In sham-transplanted animals, mean aortic pressure, left ventricular systolic pressure, aortic flow (indicator of cardiac output), and left ventricular systolic reserve were significantly lower (p < 0.05) compared with sham-operated controls. This was associated with deterioration of ventricular diastolic function (maximal negative dP/dt, time constants of isovolumic relaxation; p < 0.05). Transplantation of satellite cells was found more effective than transplantation of neonatal cardiomyocytes, resulting in i) normalization of mean aortic pressure compared with sham-operated controls, and ii) significantly improved left ventricular systolic pressure and aortic flow (p < 0.05) compared with sham-transplanted animals. Left ventricular systolic reserve and diastolic function, however, were improved by neither satellite cell nor neonatal cardiomyocyte transplantation. Analysis of male genomic DNA revealed 3.98 ± 2.70 ng in hearts after neonatal cardiomyocyte engraftment and 6.16 ± 4.05 ng in hearts after satellite cell engraftment, representing approximately 103 viable engrafted cells per heart. Our study demonstrates i) long-term survival of both neonatal cardiomyocytes and satellite cells after transplantation into cryoinfarcted rat hearts, ii) slight superiority of satellite cells over neonatal cardiomyocytes in improving global left ventricular pump performance, and iii) no effect of both transplant procedures on diastolic dysfunction.

Translational cardiac stem cell therapy: advancing from first-generation to next-generation cell types

Acute myocardial infarction and chronic heart failure rank among the major causes of morbidity and mortality worldwide. Except for heart transplantation, current therapy options only treat the symptoms but do not cure the disease. Stem cell-based therapies represent a possible paradigm shift for cardiac repair. However, most of the first-generation approaches displayed heterogeneous clinical outcomes regarding efficacy. Stemming from the desire to closely match the target organ, second-generation cell types were introduced and rapidly moved from bench to bedside. Unfortunately, debates remain around the benefit of stem cell therapy, optimal trial design parameters, and the ideal cell type. Aiming at highlighting controversies, this article provides a critical overview of the translation of first-generation and second-generation cell types. It further emphasizes the importance of understanding the mechanisms of cardiac repair and the lessons learned from first-generation trials, in order to improve cell-based therapies and to potentially finally implement cell-free therapies.

Smooth muscle cell sheet transplantation preserve cardiac function and minimize cardiac remodeling in a rat myocardial infarction model

BACKGROUND

We examined whether a vascular smooth muscle cell (SMC) sheet is effective in the treatment of a rat myocardial infarction (MI) model.

METHODS

We examined the effect of SMC sheet on the cardiac function and cardiac remodeling in a rat MI model in comparison with their effect of dermal fibroblast (DFB) sheet in vivo. Furthermore, we estimated the apoptosis and secretion of angiogenic factor of SMC under hypoxic condition in comparison with DFB. Seven days after MI, monolayer cell sheets were transplanted on the infarcted area (SMC transplantation group, SMC-Tx; DFB transplantation group, DFB-Tx; no cell sheet transplantation group, Untreated; neither MI nor cell sheet transplantation group, Sham). We evaluated cardiac function by echocardiogram, degree of cardiac remodeling by histological examination, and secretion of angiogenic growth factor by enzyme immunoassay.

RESULTS

Twenty-eight days after transplantation, SMC-Tx showed the following characteristics compared with the other groups: 1) significantly greater fractional area shortening (SMC-Tx, 32.3 ± 2.1 %; DFB-Tx, 23.3 ± 2.1 %; untreated, 25.1 ± 2.6 %), 2) suppressed left ventricular dilation, smaller scar expansion, and preserved wall thickness of the area at risk and the posterior wall, 3) decreased fibrosis, preserved myocardium in the scar area, and greater number of arterioles in border-zone, 4) tight attachment of SMC sheets on the scarred myocardium, and less apoptotic cell death. In in vitro experiments, SMCs secreted higher amounts of basic fibroblast growth factor (SMC, 157.7 ± 6.4 pg/ml; DFB, 3.1 ± 1.0 pg/ml), and showed less apoptotic cell death under hypoxia.

CONCLUSIONS

Our results illustrate that transplantation of SMC sheets inhibited the progression of cardiac remodeling and improve cardiac function. These beneficial effects may be due to superior SMC survival.

Ambient particulate matter exposure and cardiovascular diseases: a focus on progenitor and stem cells

Air pollution is a major challenge to public health. Ambient fine particulate matter (PM) is the key component for air pollution, and associated with significant mortality. The majority of the mortality following PM exposure is related to cardiovascular diseases. However, the mechanisms for the adverse effects of PM exposure on cardiovascular system remain largely unknown and under active investigation. Endothelial dysfunction or injury is considered one of the major factors that contribute to the development of cardiovascular diseases such as atherosclerosis and coronary heart disease. Endothelial progenitor cells (EPCs) play a critical role in maintaining the structural and functional integrity of vasculature. Particulate matter exposure significantly suppressed the number and function of EPCs in animals and humans. However, the mechanisms for the detrimental effects of PM on EPCs remain to be fully defined. One of the important mechanisms might be related to increased level of reactive oxygen species (ROS) and inflammation. Bone marrow (BM) is a major source of EPCs. Thus, the number and function of EPCs could be intimately associated with the population and functional status of stem cells (SCs) in the BM. Bone marrow stem cells and other SCs have the potential for cardiovascular regeneration and repair. The present review is focused on summarizing the detrimental effects of PM exposure on EPCs and SCs, and potential mechanisms including ROS formation as well as clinical implications.

Chronic High-Fat Feeding Affects the Mesenchymal Cell Population Expanded From Adipose Tissue but Not Cardiac Atria

Mesenchymal stem cells offer a promising approach to the treatment of myocardial infarction and prevention of heart failure. However, in the clinic, cells will be isolated from patients who may be suffering from comorbidities such as obesity and diabetes, which are known to adversely affect progenitor cells. Here we determined the effect of a high-fat diet (HFD) on mesenchymal stem cells from cardiac and adipose tissues. Mice were fed a HFD for 4 months, after which cardiosphere-derived cells (CDCs) were cultured from atrial tissue and adipose-derived mesenchymal cells (ADMSCs) were isolated from epididymal fat depots. HFD raised body weight, fasted plasma glucose, lactate, and insulin. Ventricle and liver tissue of HFD-fed mice showed protein changes associated with an early type 2 diabetic phenotype. At early passages, more ADMSCs were obtained from HFD-fed mice than from chow-fed mice, whereas CDC number was not affected by HFD. Migratory and clonogenic capacity and release of vascular endothelial growth factor did not differ between cells from HFD- and chow-fed animals. CDCs from chow-fed and HFD-fed mice showed no differences in surface marker expression, whereas ADMSCs from HFD-fed mice contained more cells positive for CD105, DDR2, and CD45, suggesting a high component of endothelial, fibroblast, and hematopoietic cells. Both Noggin and transforming growth factor β-supplemented medium induced an early stage of differentiation in CDCs toward the cardiomyocyte phenotype. Thus, although chronic high-fat feeding increased the number of fibroblasts and hematopoietic cells within the ADMSC population, it left cardiac progenitor cells largely unaffected.

SIGNIFICANCE

Mesenchymal cells are a promising candidate cell source for restoring lost tissue and thereby preventing heart failure. In the clinic, cells are isolated from patients who may be suffering from comorbidities such as obesity and diabetes. This study examined the effect of a high-fat diet on mesenchymal cells from cardiac and adipose tissues. It was demonstrated that a high-fat diet did not affect cardiac progenitor cells but increased the number of fibroblasts and hematopoietic cells within the adipose-derived mesenchymal cell population.

On-chip monitoring of skeletal myoblast transplantation for the treatment of hypoxia-induced myocardial injury

A comprehensive elucidation of the unexpected adverse events that occur in skeletal myoblast transplantation is fundamental for the optimization of myocardial therapeutic effects. However, a well-defined method to study the interactions between skeletal myoblasts and cardiomyocytes during the healing process is out of reach. Here, we describe a microfluidic method for monitoring the interactions between skeletal myoblasts and hypoxia-injured cardiomyocytes in a spatiotemporally-controlled manner, mimicking the in vivo cell transplantation process. A myocardial hypoxia environment was created using an oxygen consumption blocking reagent, carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone. Meanwhile, the interactions between the skeletal L6 myoblasts and hypoxia-injured myocardium H9c2 cells were investigated, and the effects of a L6 conditional medium on H9c2 cells were comparatively analyzed by quantitatively measuring the morphological and pathophysiological dynamics of H9c2 cells. The results showed that skeletal myoblasts could repair hypoxia-injured H9c2 cells mainly through direct cell-to-cell interactions. This simple on-chip assay for investigating myocardial repair processes may provide avenues for the in vitro screening of drug-induced cardiotoxicity.

Drug and cell delivery for cardiac regeneration

The spectrum of ischaemic cardiomyopathy, encompassing acute myocardial infarction to congestive heart failure is a significant clinical issue in the modern era. This group of diseases is an enormous source of morbidity and mortality and underlies significant healthcare costs worldwide. Cardiac regenerative therapy, whereby pro-regenerative cells, drugs or growth factors are administered to damaged and ischaemic myocardium has demonstrated significant potential, especially preclinically. While some of these strategies have demonstrated a measure of success in clinical trials, tangible clinical translation has been slow. To date, the majority of clinical studies and a significant number of preclinical studies have utilised relatively simple delivery methods for regenerative therapeutics, such as simple systemic administration or local injection in saline carrier vehicles. Here, we review cardiac regenerative strategies with a particular focus on advanced delivery concepts as a potential means to enhance treatment efficacy and tolerability and ultimately, clinical translation. These include (i) delivery of therapeutic agents in biomaterial carriers, (ii) nanoparticulate encapsulation, (iii) multimodal therapeutic strategies and (iv) localised, minimally invasive delivery via percutaneous transcatheter systems.

Non-invasive technology that improves cardiac function after experimental myocardial infarction: Whole Body Periodic Acceleration (pGz)

Myocardial infarction (MI) may produce significant inflammatory changes and adverse ventricular remodeling leading to heart failure and premature death. Pharmacologic, stem cell transplantation, and exercise have not halted the inexorable rise in the prevalence and great economic costs of heart failure despite extensive investigations of such treatments. New therapeutic modalities are needed. Whole Body Periodic Acceleration (pGz) is a non-invasive technology that increases pulsatile shear stress to the endothelium thereby producing several beneficial cardiovascular effects as demonstrated in animal models, normal humans and patients with heart disease. pGz upregulates endothelial derived nitric oxide synthase (eNOS) and its phosphorylation (p-eNOS) to improve myocardial function in models of myocardial stunning and preconditioning. Here we test whether pGz applied chronically after focal myocardial infarction in rats improves functional outcomes from MI. Focal MI was produced by left coronary artery ligation. One day after ligation animals were randomized to receive daily treatments of pGz for four weeks (MI-pGz) or serve as controls (MI-CONT), with an additional group as non-infarction controls (Sham). Echocardiograms and invasive pressure volume loop analysis were carried out. Infarct transmurality, myocardial fibrosis, and markers of inflammatory and anti-inflammatory cytokines were determined along with protein analysis of eNOS, p-eNOS and inducible nitric oxide synthase (iNOS).At four weeks, survival was 80% in MI-pGz vs 50% in MI-CONT (p< 0.01). Ejection fraction and fractional shortening and invasive pressure volume relation indices of afterload and contractility were significantly better in MI-pGz. The latter where associated with decreased infarct transmurality and decreased fibrosis along with increased eNOS, p-eNOS. Additionally, MI-pGz had significantly lower levels of iNOS, inflammatory cytokines (IL-6, TNF-α), and higher level of anti-inflammatory cytokine (IL-10). pGz improved survival and contractile performance, associated with improved myocardial remodeling. pGz may serve as a simple, safe, non-invasive therapeutic modality to improve myocardial function after MI.

The duality of chemokines in heart failure

The failing human heart is a bustling network of intra- and inter-cellular signals and related processes attempting to coordinate a repair mechanism for the injured or diseased myocardium. While our understanding of signaling by mode of cytokines is well understood on a systemic level, we are only now coming to elucidate the role of cytokines in cardiac self-regulation. An increasing number of studies are showing now that cardiomyocytes themselves have not only the ability but also the mandate to produce signals, and play direct roles in how these signals are interpreted. One of the families of cytokines employed by distressed cardiac tissue are chemokines. By regulating the movement of pro-inflammatory cell types to sites of injury, we see now how the myocardium responds to stress. Herein we review the participation of these inflammatory mediators and explore the delicate balance between their protective roles and damaging functions.

Mesenchymal stem cell insights: prospects in cardiovascular therapy

Ischemic heart damage usually triggers cardiomyopathological remodeling and fibrosis, thus promoting the development of heart functional failure. Mesenchymal stem cells (MSCs) are a heterogeneous group of cells in culture, with multipotent and hypoimmunogenic characters to aid tissue repair and avoid immune responses, respectively. Numerous experimental findings have proven the feasibility, safety, and efficiency of MSC therapy for cardiac regeneration. Despite that the exact mechanism remains unclear, the therapeutic ability of MSCs to treat ischemia heart diseases has been tested in phase I/II clinical trials. Based on encouraging preliminary findings, MSCs might become a potentially efficacious tool in the therapeutic options available to treat ischemic and nonischemic cardiovascular disorders. The molecular mechanism behind the efficacy of MSCs on promoting engraftment and accelerating the speed of heart functional recovery is still waiting for clarification. It is hypothesized that cardiomyocyte regeneration, paracrine mechanisms for cardiac repair, optimization of the niche for cell survival, and cardiac remodeling by inflammatory control are involved in the interaction between MSCs and the damaged myocardial environment. This review focuses on recent experimental and clinical findings related to cellular cardiomyoplasticity. We focus on MSCs, highlighting their roles in cardiac tissue repair, transdifferentiation, the MSC niche in myocardial tissues, discuss their therapeutic efficacy that has been tested for cardiac therapy, and the current bottleneck of MSC-based cardiac therapies.

Stem cell therapy for cardiovascular disease: the demise of alchemy and rise of pharmacology

Regenerative medicine holds great promise as a way of addressing the limitations of current treatments of ischaemic disease. In preclinical models, transplantation of different types of stem cells or progenitor cells results in improved recovery from ischaemia. Furthermore, experimental studies indicate that cell therapy influences a spectrum of processes, including neovascularization and cardiomyogenesis as well as inflammation, apoptosis and interstitial fibrosis. Thus, distinct strategies might be required for specific regenerative needs. Nonetheless, clinical studies have so far investigated a relatively small number of options, focusing mainly on the use of bone marrow-derived cells. Rapid clinical translation resulted in a number of small clinical trials that do not have sufficient power to address the therapeutic potential of the new approach. Moreover, full exploitation has been hindered so far by the absence of a solid theoretical framework and inadequate development plans. This article reviews the current knowledge on cell therapy and proposes a model theory for interpretation of experimental and clinical outcomes from a pharmacological perspective. Eventually, with an increased association between cell therapy and traditional pharmacotherapy, we will soon need to adopt a unified theory for understanding how the two practices additively interact for a patient's benefit.

Effect of exogenous Oct4 overexpression on cardiomyocyte differentiation of human amniotic mesenchymal cells

Regenerative therapy is a new strategy for the end-stage heart failure; however, the ideal cell source has not yet been established for this therapy. We expected that the amnion might be an ideal cell source for cardiac regenerative therapy and that the differentiation potency of the human amnion mesenchymal cells (hAMCs) could be improved by overexpression of Oct4, a key factor that maintains the undifferentiated state. A plasmid vector was made by insertion of the Oct4 open reading frame (ORF) under control of a cytomegalovirus (CMV) promoter (pCMV-hOct4) and transfected into hAMCs by electroporation. The optimum induction time was investigated by comparing the quantity of stem cell-specific mRNAs, cardiac-specific mRNAs, and cardiac-specific proteins with time. hAMCs already expressed cardiac-specific proteins such as Nkx2.5 and Connexin43. After pCMV-hOct4 transfection, endogenous Oct4 mRNA and other stem cell markers showed a transient increase. With 5-azacytidine treatment, quantities of the cardiac-specific mRNAs, such as GATA4 and myosin light-chain-2v (Mlc-2v), were increased significantly. After Oct4 overexpression, the highest expression of cardiac-specific mRNAs and stem cell makers was seen at almost the same time. Furthermore, more mature myocardial contraction proteins were observed when hAMCs were induced at specific optimal times after gene transfection. In conclusion, hAMCs were activated to an undifferentiated state by overexpression of Oct4, and their cardiac differentiation potency was improved. Thus, the single-time transfection of the Oct4 expression vector may be a useful strategy for effective cell therapy. The use of cryopreserved hAMCs in cell therapy still requires more investigation.

Expression of CD80 on cultured neonatal mice cardiomyocytes and attenuation of cytotoxic T lymphocyte-mediated lysis

Transplantation of cultured heterogeneous proliferating cardiomyocytes is a promising therapeutic approach for the treatment of the damage cardiac area resulting from myocardial infarction. However, the chances of recipient rejection are high. How to reduce the immunogenicity of heterogeneous cardiomyocytes and attenuate immune rejection is one of the key stumbling blocks in the application of these cells. In this study, we determined that cultured neonatal cardiomyocytes from mice can express CD80 after culture. CD80 is one of the key costimulatory molecules. Most scholars believe that the main function of CD80 is to activate and boost immune rejection. However, recent studies have shown that CD80 may primarily bind with CTLA-4 and inhibit the immune response. To further study how CD80 worked on these cells, a cytotoxic T-lymphocyte (CTL) assay was performed. The results showed that activated allogenic CTLs lysed cultured cardiomyocytes lacking CD80 expression, but they did not efficiently lyse cardiomyocytes expressing CD80. If we blocked the CD80 with anti-CD80 monoclonal antibody (mAb), the percentages of cardiomyocytes lysis were significantly increased. CD80 can bind CD28, CTLA-4, PD-L1, and even B7-H1, but the main ligands are CD28 and CTLA-4. Thus, we blocked the two ligands separately. When anti-CTLA-4 mAb was applied, the percentages of cardiomyocytes lysis were significantly increased, but when anti-CD28 mAb was applied, the percentages of cell lysis were the same as the intact control. The results indicated that CD80 and CTLA-4 played an important role on the attenuation of CTL-mediated lysis. To our knowledge, this study, for the first time, proves that cardiomyocytes can express CD80 and this expression pattern can resist CTL-mediated lysis through CTLA-4 pathway. The results could have implications in efforts to improve therapeutic strategies for cardiomyocyte transplantation.

Left-ventricular aneurysms: from disease to repair

Myocardial infarction may be complicated by the formation of a left-ventricular aneurysm that distorts the normal elliptical geometry of the ventricle to produce a dilated spherical ventricle with limited contractile and filling capacities. One of the consequences is congestive heart failure, which may be refractory to medical therapy and require surgical treatment. Surgical methods to restore the volume and shape of the left ventricle have evolved over the years. Nevertheless, although surgery for left-ventricular aneurysms has been performed for almost 50 years, the most appropriate approach is still controversial. This review gives an overview of the postinfarction left-ventricular aneurysm, tackling issues from the disease itself to surgical and other techniques of ventricular remodeling.

Adult stem cells and heart regeneration

Cardiovascular disease remains the single greatest cause of death in the Western world, claiming more lives in the USA than the next four leading causes combined. Among these diseases, the incidence of heart failure continues to rise at a staggering rate. Recent advances in medical and device therapies have dramatically improved both the survival and quality of life of many of these patients; however, limited strategies are available to address the central pathophysiology underlying the development of heart failure, namely, the loss of functional cardiomyocytes. Therefore, one recent strategy has been the development of cell-based therapies, aiming towards the replacement of injured or lost cardiomyocytes and thereby improved cardiac function. In this review, we will examine the cell types undergoing investigation as potential cell-based therapies and provide an overview of current clinical trials utilizing cell-based therapeutic approaches in patients with heart disease.

Cardiac tissue engineering: renewing the arsenal for the battle against heart disease

The development of therapies that lead to the regeneration or functional repair of compromised cardiac tissue is the most important challenge facing translational cardiovascular research today.

Identification of apolipoprotein D as a cardioprotective gene using a mouse model of lethal atherosclerotic coronary artery disease

Mice with homozygous null mutations in the HDL receptor (scavenger receptor class B, type I, or SR-BI) and apolipoprotein E (apoE) genes [SR-BI/apoE double KO (SR-BI(-/-)/apoE(-/-) or dKO) mice] spontaneously develop occlusive, atherosclerotic coronary artery disease (CAD) and die prematurely (50% mortality at 42 d of age). Using microarray mRNA expression profiling, we identified genes whose expression in the hearts of dKO mice changed substantially during disease progression [at 21 d of age (no CAD), 31 d of age (small myocardial infarctions), and 43 d of age (extensive myocardial infarctions) vs. CAD-free SR-BI(+/-)/apoE(-/-) controls]. Expression of most genes that increased >sixfold in dKO hearts at 43 d also increased after coronary artery ligation. We examined the influence and potential mechanism of action of apolipoprotein D (apoD) whose expression in dKO hearts increased 80-fold by 43 d. Analysis of ischemia/reperfusion-induced myocardial infarction in both apoD KO mice and wild-type mice with abnormally high plasma levels of apoD (adenovirus-mediated hepatic overexpression) established that apoD reduces myocardial infarction. There was a correlation of apoD's ability to protect primary cultured rat cardiomyocytes from hypoxia/reoxygenation injury with its potent ability to inhibit oxidation in a standard antioxidation assay in vitro. We conclude that dKO mice represent a useful mouse model of CAD and apoD may be part of an intrinsic cardioprotective system, possibly as a consequence of its antioxidation activity.

Recent advancements in tissue engineering for stem cell-based cardiac therapies

Advances in cardiac tissue engineering have recently focused on utilizing stem cells to regenerate infarcted and scarred myocardium. Due to their proliferative nature and tremendous potential for differentiation, stem cells are presently being investigated for clinical applications. Unfortunately, limiting factors such as massive cell death and poor retention have hampered clinical outcomes. Consequently, the development of an efficient delivery system for stem cells to the target site is essential. The use of innovative tissue engineering techniques has opened up new horizons within the field of cellular cardiomyoplasty. This paper will present a comprehensive overview of the recent advancements in stem cell technology destined for myocardial tissue repair. In addition, the multidisciplinary approach to tissue engineering presented here will provide the reader with insight into the clinical realization of cellular cardiomyoplasty.

Intramyocardial autologous cell engraftment in patients with ischaemic heart failure: a meta-analysis of randomised controlled trials

BACKGROUND

Intramyocardial cellular delivery provides a promising therapeutic strategy for ischaemic cardiac dysfunction. However, individual studies have reported controversial results.

METHODS

Relevant trials were identified by systematic search of MEDLINE, EMBASE, the Cochrane database, and CINAH database. Studies, which applied randomised design and compared intramyocardial cell injection with placebo or optimal medical therapy in patients with chronic ischaemic heart failure, were eligible.

RESULTS

A total of 210 participants in five randomised controlled trials were included. The pooled analyses showed that cell therapy did not significantly improve left ventricular ejection fraction compared with the control (95% CI -0.35 to 0.31, p=0.91). Nevertheless, cell therapy provided a benefit in increasing 6-min walk distance (95% CI 21.09 m-142.62 m, p=0.008), improving MLHF score (95% CI -25.21 to -3.55, p=0.009), and lowering the incidence of NYHA functional class deterioration (95% CI 0.05-0.76, p=0.02). However, the novel procedure did not result in a significant reduction in all-cause mortality. Conversely, cell therapy did not significantly increase the risk of ventricular tachycardia or acute heart failure, however we were underpowered to evaluate these endpoints.

CONCLUSIONS

Intramyocardial cell therapy was feasible in treating patients with ischaemic heart failure.

The effect of bone marrow- and adipose tissue-derived mesenchymal stem cell transplantation on myocardial remodelling in the rat model of ischaemic heart failure

This study aimed to investigate the effect of bone marrow- and adipose tissue-derived mesenchymal stem cell (BM-MSC and AD-MSC respectively) transplantation on left ventricular function and infarct area (IA) in the rat model of ischaemic heart failure. In anaesthetized Wistar rats, the left coronary artery (LCA) was occluded for 40 min with subsequent reperfusion for 7 days. Seven days following surgery, the animals with LCA occlusion/reperfusion were randomized into three groups: (i) Controls received intramyocardial injection of vehicle at three different locations within the peri-infarct zone, (ii) BM-MSC: cells were injected in the same way as in previous group (10(6) ), (iii) AD-MSC: using the same protocol as used in the BM-MSC group. In addition there was also a sham-treated group that had no injection. Two weeks following MSC transplantation, the hearts were isolated and perfused according to the Langendorff method followed by 30-min global ischaemia and 90-min reperfusion. After this IA was determined histologically. During Langendorff perfusion initial and postischaemic LV functions were the same in all groups although LV pressure at the 10th minute of reperfusion was higher in the AD-MSC group compared to controls. However, LV pressure during 30-min global ischaemia was significantly higher in BM-MSC as compared to controls and AD-MSC. The sham treated animals showed the same results as those seen with BM-MSC. Thus, BM-MSC transplantation, in contrast to transplantation of AD-MSC, resulted in better preservation of the LV ability to contract during ischaemia. Furthermore, IA was significantly smaller in BM-MSC group as compared to the controls and the AD-MSC groups. Thus this study has demonstrated that treatment with BM-MSC both ameliorates LV function and reduces histological scar size.

Update: Innovation in cardiology (IV). Cardiac tissue engineering and the bioartificial heart

Heart failure is the end-stage of many cardiovascular diseases-such as acute myocardial infarction-and remains one of the most appealing challenges for regenerative medicine because of its high incidence and prevalence. Over the last 20 years, cardiomyoplasty, based on the isolated administration of cells with regenerative capacity, has been the focal point of most studies aimed at regenerating the heart. Although this therapy has proved feasible in the clinical setting, the degree of infarcted myocardium regenerated and of improved cardiac function are at best modest. Hence, tissue engineering has emerged as a novel technology using cells with regenerative capacity, biological and/or synthetic materials, growth, proangiogenic and differentiation factors, and online registry systems, to induce the regeneration of whole organs or locally damaged tissue. The next step, seen recently in pioneering animal studies, is de novo generation of bioartificial hearts by decellularization and preservation of supporting structures for their subsequent repopulation with new contractile, vascular muscle tissue. Ultimately, this new approach would entail transplantation of the "rebuilt" heart, reestablishing cardiac function in the recipient.

Adult cardiac progenitor cell aggregates exhibit survival benefit both in vitro and in vivo

Background

A major hurdle in the use of exogenous stems cells for therapeutic regeneration of injured myocardium remains the poor survival of implanted cells. To date, the delivery of stem cells into myocardium has largely focused on implantation of cell suspensions.

Methodology and Principal Findings

We hypothesize that delivering progenitor cells in an aggregate form would serve to mimic the endogenous state with proper cell-cell contact, and may aid the survival of implanted cells. Microwell methodologies allow for the culture of homogenous 3D cell aggregates, thereby allowing cell-cell contact. In this study, we find that the culture of cardiac progenitor cells in a 3D cell aggregate augments cell survival and protects against cellular toxins and stressors, including hydrogen peroxide and anoxia/reoxygenation induced cell death. Moreover, using a murine model of cardiac ischemia-reperfusion injury, we find that delivery of cardiac progenitor cells in the form of 3D aggregates improved in vivo survival of implanted cells.

Conclusion

Collectively, our data support the notion that growth in 3D cellular systems and maintenance of cell-cell contact improves exogenous cell survival following delivery into myocardium. These approaches may serve as a strategy to improve cardiovascular cell-based therapies.

Stem cell-based therapy for ischemic heart disease

Despite great advances in therapy over the past decades, ischemic heart disease (IHD) remains the leading cause of death worldwide because the decrease in mortality after acute myocardial infarction (AMI) leads to a longer life span in patients with chronic postinfarct heart failure (HF). There are no existing medical treatments that can cure chronic HF and the only currently available therapeutic option for end-stage HF is heart transplantation. However, transplantation is limited by the shortage of donor organs and patients require lifelong immunosuppression. In the past 10 years, stem cell-based cardiac therapy has been proposed as a promising approach for the treatment of IHD. There is a variety of potential stem cell types for cardiac repair and regeneration, including bone marrow cells (BMCs), resident cardiac stem cells (CSCs) and induced pluripotent stem cells (iPSCs). Stem cell-based therapy may comprise cell transplantation or cardiac tissue engineering (CTE), which might be an attractive alternative to solve the problems of low retention and poor survival of transplanted cells. This review focuses on the characteristics of stem cells from various sources and discusses the strategies of stem cell-based therapy for the treatment of IHD.

Myocardial cell sheet therapy and cardiac function

Heart failure (HF) is the leading cause of death in developed countries. Regenerative medicine has the potential to drastically improve treatment for advanced HF. Stem cell-based medicine has received attention as a promising candidate therapy over the past decade; however, it has not yet realized this potential in terms of reliability. The cell sheet is an innovative technology for constructing aligned graft cells, and several cell sources have been investigated for making a feasible cell sheet. The most representative thus far is skeletal myoblast, although such cells raise the issue of arrhythmogenicity. Regenerative cardiomyocytes (CMs) derived from pluripotent stem cells (PSCs), such as embryonic stem cells or induced PSCs, are the most promising, because a myocardial cell sheet (MCS) constructed with regenerative CMs can potentially enable contraction recovery and electromechanical coupling with host CMs. The functional outcomes of experimental MCS are reduction of ventricular wall stress and paracrine effects rather than contraction recovery. Several technical obstacles still hamper the clinical application of MCSs, with graft survival the most pivotal issue. Ischemia, apoptosis, inflammation, and immune response can all cause graft cell death, and a stable blood supply to the MCS is critical for successful engraftment. Ventricular tachycardia must also be considered in any myocardial cell therapy, and multiple layering of MCS (>3 layers) is necessary to reconstruct human myocardium. Innervation is also a potential issue. The future application of myocardial cell therapy with MCS for advanced HF depends on resolving these difficulties.

Replacement of dynamic cultured biograft improves damaged heart function-comparative study of static cultured biografts-

PURPOSE

To determine whether a dynamic cultured biograft can positively affect the function of the damaged heart.

METHODS

We ligated the coronary artery (LAD) of rats to generate a model of myocardial infarction (MI) and then implanted them with the following grafts comprising vascular smooth muscle cells (VSMCs) derived from the rat aorta and seeded onto biodegradable patches (patch replacement therapy; (PRTx)): control without PRTx, PRTx without seeded cells, PRTx with static cultured VSMCs, PRTx with dynamic cultured VSMCs and sham-operated. Cultured VSMCs were labeled with PKH26 for identification after implantation, and the centre of the MI site was excised and replaced with an implanted biograft. Cardiac performance was monitored for 12 weeks thereafter and followed by a histological study.

RESULTS

Although the ejection fraction of the damaged heart improved in all groups that were transplanted with grafts, remodeling was prevented only in groups with a dynamic or static cultured patch. More cells were α-SMA-positive in the group with the dynamic, rather than the static cultured patch. Cells were positive for PKH26 in the biograft and in the infarcted myocardium.

CONCLUSIONS

Dynamic cultured biografts improved the function of the infarcted myocardium more than statically cultured biografts or those without cells.

Increased angiogenesis and improved left ventricular function after transplantation of myoblasts lacking the MyoD gene into infarcted myocardium

Skeletal myoblast transplantation has therapeutic potential for repairing damaged heart. However, the optimal conditions for this transplantation are still unclear. Recently, we demonstrated that satellite cell-derived myoblasts lacking the MyoD gene (MyoD(-/-)), a master transcription factor for skeletal muscle myogenesis, display increased survival and engraftment compared to wild-type controls following transplantation into murine skeletal muscle. In this study, we compare cell survival between wild-type and MyoD(-/-) myoblasts after transplantation into infarcted heart. We demonstrate that MyoD(-/-) myoblasts display greater resistance to hypoxia, engraft with higher efficacy, and show a larger improvement in ejection fraction than wild-type controls. Following transplantation, the majority of MyoD(-/-) and wild-type myoblasts form skeletal muscle fibers while cardiomyocytes do not. Importantly, the transplantation of MyoD(-/-) myoblasts induces a high degree of angiogenesis in the area of injury. DNA microarray data demonstrate that paracrine angiogenic factors, such as stromal cell-derived factor-1 (SDF-1) and placental growth factor (PlGF), are up-regulated in MyoD(-/-) myoblasts. In addition, over-expression and gene knockdown experiments demonstrate that MyoD negatively regulates gene expression of these angiogenic factors. These results indicate that MyoD(-/-) myoblasts impart beneficial effects after transplantation into an infarcted heart, potentially due to the secretion of paracrine angiogenic factors and enhanced angiogenesis in the area of injury. Therefore, our data provide evidence that a genetically engineered myoblast cell type with suppressed MyoD function is useful for therapeutic stem cell transplantation.

Cardiac side population cells: moving toward the center stage in cardiac regeneration

Over the past decade, extensive work in animal models and humans has identified the presence of adult cardiac progenitor cells, capable of cardiomyogenic differentiation and likely contributors to cardiomyocyte turnover during normal development and disease. Among cardiac progenitor cells, there is a distinct subpopulation, termed "side population" (SP) progenitor cells, identified by their unique ability to efflux DNA binding dyes through an ATP-binding cassette transporter. This review highlights the literature on the isolation, characterization, and functional relevance of cardiac SP cells. We review the initial discovery of cardiac SP cells in adult myocardium as well as their capacity for functional cardiomyogenic differentiation and role in cardiac regeneration after myocardial injury. Finally, we discuss recent advances in understanding the molecular regulators of cardiac SP cell proliferation and differentiation, as well as likely future areas of investigation required to realize the goal of effective cardiac regeneration.

Myocardial restoration: is it the cell or the architecture or both?

Myocardial infarction is the leading cause of death in developed countries. Cardiac cell therapy has been introduced to clinical trials for more than ten years but its results are still controversial. Tissue engineering has addressed some limitations of cell therapy and appears to be a promising solution for cardiac regeneration. In this review, we would like to summarize the current understanding about the therapeutic effect of cell therapy and tissue engineering under purview of functional and structural aspects, highlighting actual roles of each therapy towards clinical application.

What does it take to make a heart?

Ever increasing advances are being made in our quest to understand what it takes to direct pluripotent precursor cells to adopt a specific developmental fate. Eventually, the obvious goal is that targeted manipulation of these precursor cells will result in an efficient and reliable production of tissue-specific cells, which can be safely employed for therapeutic purposes. We have gained an incredible insight as to which molecular pathways are involved in governing neural, skeletal and cardiac muscle fate decisions. However, we still face the challenge of how to direct, for example, a cardiac fate in stem cells in the amounts needed to be employed for regenerative means. Equally importantly, we need to resolve critical questions such as: can the in vitro generated cardiomyocytes actually functionally replace damaged heart tissue? Here I will provide an overview of the molecules and signalling pathways that have first been demonstrated in embryological studies to function in cardiogenesis, and summarize how this knowledge is being applied to differentiate mouse and human embryonic stem cells into cardiomyocytes.

Wnt signaling exerts an antiproliferative effect on adult cardiac progenitor cells through IGFBP3

RATIONALE

Recent work in animal models and humans has demonstrated the presence of organ-specific progenitor cells required for the regenerative capacity of the adult heart. In response to tissue injury, progenitor cells differentiate into specialized cells, while their numbers are maintained through mechanisms of self-renewal. The molecular cues that dictate the self-renewal of adult progenitor cells in the heart, however, remain unclear.

OBJECTIVE

We investigate the role of canonical Wnt signaling on adult cardiac side population (CSP) cells under physiological and disease conditions.

METHODS AND RESULTS

CSP cells isolated from C57BL/6J mice were used to study the effects of canonical Wnt signaling on their proliferative capacity. The proliferative capacity of CSP cells was also tested after injection of recombinant Wnt3a protein (r-Wnt3a) in the left ventricular free wall. Wnt signaling was found to decrease the proliferation of adult CSP cells, both in vitro and in vivo, through suppression of cell cycle progression. Wnt stimulation exerted its antiproliferative effects through a previously unappreciated activation of insulin-like growth factor binding protein 3 (IGFBP3), which requires intact IGF binding site for its action. Moreover, injection of r-Wnt3a after myocardial infarction in mice showed that Wnt signaling limits CSP cell renewal, blocks endogenous cardiac regeneration and impairs cardiac performance, highlighting the importance of progenitor cells in maintaining tissue function after injury.

CONCLUSIONS

Our study identifies canonical Wnt signaling and the novel downstream mediator, IGFBP3, as key regulators of adult cardiac progenitor self-renewal in physiological and pathological states.

Synthetic matrices to serve as niches for muscle cell transplantation

Poor cell retention and limited cell survival after grafting are major limitations of cell therapy. Recent studies showed that the use of matrices as vehicles at the time of cell injection can significantly improve cell engraftment by providing an appropriate structure and physical support for the injected cells. Properly designed matrices can also promote the organization of the cells into a functioning cardiac-like tissue and enhance integration between the host and the engrafted tissue. Furthermore, the use of an injectable biomaterial provides an opportunity to release in situ bioactive molecules that can further enhance the beneficial effects of cell transplantation. In this article we review a large variety of biologically derived synthetic and hybrid materials that have been tested as matrices for cardiac repair. We summarize the optimal parameters required for an ideal matrix including biocompatibility, injectability, degradation rate, and mechanical properties. Using an in vivo subcutaneous grafting model, we also provide novel data involving a side-by-side comparison of six synthetic matrices derived from maltodextrin. By systematically varying polymer molecular weight, cross-link density, and availability of cell adhesion motifs, a synthetic matrix was identified that supported skeletal myotube formation similar to Matrigel™. Our results emphasize not only the need to have a range of tunable matrices for cardiac cell therapy but also the importance of further characterizing the physical properties required for an ideal injectable matrix.

Efficient non-viral reprogramming of myoblasts to stemness with a single small molecule to generate cardiac progenitor cells

The current protocols for generation of induced pluripotent stem (iPS) cells involve genome integrating viral vectors which may induce tumorgenesis. The aim of this study was to develop and optimize a non-viral method without genetic manipulation for reprogramming of skeletal myoblasts (SMs) using small molecules.

Advances in cell transplantation therapy for diseased myocardium

The overall objective of cell transplantation is to repopulate postinfarction scar with contractile cells, thus improving systolic function, and to prevent or to regress the remodeling process. Direct implantation of isolated myoblasts, cardiomyocytes, and bone-marrow-derived cells has shown prospect for improved cardiac performance in several animal models and patients suffering from heart failure. However, direct implantation of cultured cells can lead to major cell loss by leakage and cell death, inappropriate integration and proliferation, and cardiac arrhythmia. To resolve these problems an approach using 3-dimensional tissue-engineered cell constructs has been investigated. Cell engineering technology has enabled scaffold-free sheet development including generation of communication between cell graft and host tissue, creation of organized microvascular network, and relatively long-term survival after in vivo transplantation.

Improvement of cardiac function in the failing rat heart after transfer of skeletal myoblasts engineered to overexpress placental growth factor

BACKGROUND

Transplant of skeletal myoblasts is an attractive alternative to repair irreversibly damaged myocardium in ischemic heart failure. We investigated whether transplant of myoblasts overexpressing placental growth factor would stimulate angiogenesis and enhance myoblast survival in a rat heart failure model.

METHODS

Three weeks after myocardial infarction, Sprague-Dawley rats in heart failure received intramyocardial injections of Ringer solution (control) or autologous myoblasts, unmodified or transfected with placental growth factor expression plasmid. Sham-operated animals served as noninfarct controls. Cardiac function was assessed by echocardiography to 86 days after engraftment. Immunocytochemistry and fluorescence imaging were used to investigate vessel formation, grafted myoblast survival, infarct wall thickness, and infarct size. Quantitative real-time reverse transcriptase polymerase chain reaction and Western blotting measured tissue messenger RNA and protein expressions.

RESULTS

Left ventricular function significantly improved with time, and fractional shortening on day 86 was significantly enhanced in transfected myoblast group relative to control (P < .01) and unmodified myoblast (P < .05) groups. Vascular density (P < .01) and myoblast survival (P < .05) were enhanced in rats treated with transfected myoblasts relative to other groups (P < .05). Mean fraction of fibrotic scar tissue was decreased in unmodified and transfected myoblast groups relative to controls on day 86 (P < .05), and left ventricular wall thickness was significantly increased in transfected myoblast group relative to other groups (P < .05).

CONCLUSIONS

Intramyocardial injections of autologous myoblasts overexpressing placental growth factor improved cardiac function, attenuated adverse cardiac remodeling, induced angiogenesis, and probably enhanced survival of grafted myoblasts.

Cardiac cell therapy: where we've been, where we are, and where we should be headed

INTRODUCTION

Stem cell therapy has emerged as a promising strategy for the treatment of ischemic cardiomyopathy.

SOURCES OF DATA

Multiple candidate cell types have been used in preclinical animal models and in clinical trials to repair or regenerate the injured heart either directly (through formation of new transplanted tissue) or indirectly (through paracrine effects activating endogenous regeneration).

AREAS OF AGREEMENT

(i) Clinical trials examining the safety and efficacy of bone marrow derived cells in patients with heart disease are promising, but results leave much room for improvement. (ii) The safety profile has been quite favorable. (iii) Efficacy has been inconsistent and, overall, modest. (iv) Tissue retention of cells after delivery into the heart is disappointingly low. (v) The beneficial effects of adult stem cell therapy are predominantly mediated by indirect paracrine mechanisms.

AREAS OF CONTROVERSY

The cardiogenic potential of bone marrow-derived cells, the mechanism whereby small numbers of poorly-retained cells translate to measurable clinical benefit, and the overall impact on clinical outcomes are hotly debated. GROWING POINTS/AREAS TIMELY FOR DEVELOPING RESEARCH: This overview of the field leaves us with cautious optimism, while motivating a search for more effective delivery methods, better strategies to boost cell engraftment, more apt patient populations, safe and effective 'off the shelf' cell products and more potent cell types.

Stem cell therapy for ischemic heart disease

Stem cell transplantation has emerged as a novel treatment option for ischemic heart disease. Different cell types have been utilized and the recent development of induced pluripotent stem cells has generated tremendous excitement in the regenerative field. Bone marrow-derived multipotent progenitor cell transplantation in preclinical large animal models of postinfarction left ventricular remodeling has demonstrated long-term functional and bioenergetic improvement. These beneficial effects are observed despite no significant engraftment of bone marrow cells in the myocardium and even lower differentiation of these cells into cardiomyocytes. It is thought to be related to the paracrine effect of these stem cells, which secrete factors that lead to long-term gene expression changes in the host myocardium, thereby promoting neovascularization, inhibiting apoptosis, and stimulating resident cardiac progenitor cells. Future studies are warranted to examine the changes in the recipient myocardium after stem cell transplantation and to investigate the signaling pathways involved in these effects.

Animal models of cardiac disease and stem cell therapy

Animal models that mimic cardiovascular diseases are indispensable tools for understanding the mechanisms underlying the diseases at the cellular and molecular level. This review focuses on various methods in preclinical research to create small animal models of cardiac diseases, such as myocardial infarction, dilated cardiomyopathy, heart failure, myocarditis and cardiac hypertrophy, and the related stem cell treatment for these diseases.

One-year follow-up of feasibility and safety of the first U.S., randomized, controlled study using 3-dimensional guided catheter-based delivery of autologous skeletal myoblasts for ischemic cardiomyopathy (CAuSMIC study)

OBJECTIVES

The aim of this study was to test safety and feasibility of myoblast transplantation with the Biosense-NOGA (Diamond Bar, California) 3-dimensional-guided endomyocardial delivery system.

BACKGROUND

Previous Phase-1 trials showed feasibility of epicardial injection of myoblasts. However, catheter-based delivery has several advantages: it can be applied on high-risk patients, the procedure can be repeated, and it is associated with less morbidity and mortality.

METHODS

Twenty-three subjects, with previous myocardial infarction and heart failure, New York Heart Association (NYHA) functional class II to IV, were enrolled, 11 control and 12 treatment subjects. To assess safety, physical exam, electrocardiogram, continuous rhythm monitoring, quality of life assessments, and heart function were evaluated at baseline and follow-up until 1 year.

RESULTS

There was favorable safety: no difference between groups in arrhythmias, and no deaths. Treated subjects showed sustained improvements in NYHA and Minnesota Living with Heart Failure Questionnaire (MLHFQ) compared with control subjects (NYHA, -1.0 point in treatment vs. +0.3 point in control group, p < 0.0004; MLHFQ, -14 point in treatment vs. +1 point in the control group, p = 0.004). Blinded core laboratory echocardiography evaluations showed sustained reductions in the treatment versus control in end diastolic diameter (-0.03 cm vs. +0.05 cm, p = 0.07) and end systolic diameter (-0.05 cm vs. +0.1 cm, p = 0.07). Finally, NOGA voltage mapping demonstrated improved voltage measurements (+1.0 mV, p = 0.008).

CONCLUSIONS

This trial of myoblast transplantation via catheter into heart failure patients demonstrated safety and feasibility. Treated patients showed improvement in NYHA, MLHFQ, ventricular viability, and evidence of reverse ventricular remodeling. These data demonstrate positive safety outcomes and warrant initiation of larger phase 2, double-blind, placebo-controlled clinical trials.