Transplanted cardiomyocytes survive in scar tissue and improve heart function

Engineering Stem Cells for Biomedical Applications

Stem cells are characterized by a number of useful properties, including their ability to migrate, differentiate, and secrete a variety of therapeutic molecules such as immunomodulatory factors. As such, numerous pre-clinical and clinical studies have utilized stem cell-based therapies and demonstrated their tremendous potential for the treatment of various human diseases and disorders. Recently, efforts have focused on engineering stem cells in order to further enhance their innate abilities as well as to confer them with new functionalities, which can then be used in various biomedical applications. These engineered stem cells can take on a number of forms. For instance, engineered stem cells encompass the genetic modification of stem cells as well as the use of stem cells for gene delivery, nanoparticle loading and delivery, and even small molecule drug delivery. The present Review gives an in-depth account of the current status of engineered stem cells, including potential cell sources, the most common methods used to engineer stem cells, and the utilization of engineered stem cells in various biomedical applications, with a particular focus on tissue regeneration, the treatment of immunodeficiency diseases, and cancer.

Cell origin of human mesenchymal stem cells determines a different healing performance in cardiac regeneration

The possible different therapeutic efficacy of human mesenchymal stem cells (hMSC) derived from umbilical cord blood (CB), adipose tissue (AT) or bone marrow (BM) for the treatment of myocardial infarction (MI) remains unexplored. This study was to assess the regenerative potential of hMSC from different origins and to evaluate the role of CD105 in cardiac regeneration. Male SCID mice underwent LAD-ligation and received the respective cell type (400.000/per animal) intramyocardially. Six weeks post infarction, cardiac catheterization showed significant preservation of left ventricular functions in BM and CD105(+)-CB treated groups compared to CB and nontreated MI group (MI-C). Cell survival analyzed by quantitative real time PCR for human GAPDH and capillary density measured by immunostaining showed consistent results. Furthermore, cardiac remodeling can be significantly attenuated by BM-hMSC compared to MI-C. Under hypoxic conditions in vitro, remarkably increased extracellular acidification and apoptosis has been detected from CB-hMSC compared to BM and CD105 purified CB-derived hMSC. Our findings suggests that hMSC originating from different sources showed a different healing performance in cardiac regeneration and CD105(+) hMSC exhibited a favorable survival pattern in infarcted hearts, which translates into a more robust preservation of cardiac function.

Bone marrow stem cell derived paracrine factors for regenerative medicine: current perspectives and therapeutic potential

During the past several years, there has been intense research in the field of bone marrow-derived stem cell (BMSC) therapy to facilitate its translation into clinical setting. Although a lot has been accomplished, plenty of challenges lie ahead. Furthermore, there is a growing body of evidence showing that administration of BMSC-derived conditioned media (BMSC-CM) can recapitulate the beneficial effects observed after stem cell therapy. BMSCs produce a wide range of cytokines and chemokines that have, until now, shown extensive therapeutic potential. These paracrine mechanisms could be as diverse as stimulating receptor-mediated survival pathways, inducing stem cell homing and differentiation or regulating the anti-inflammatory effects in wounded areas. The current review reflects the rapid shift of interest from BMSC to BMSC-CM to alleviate many logistical and technical issues regarding cell therapy and evaluates its future potential as an effective regenerative therapy.

Bcl-2 engineered MSCs inhibited apoptosis and improved heart function

Engraftment of mesenchymal stem cells (MSCs) derived from adult bone marrow has been proposed as a potential therapeutic approach for postinfarction left ventricular dysfunction. However, limited cell viability after transplantation into the myocardium has restricted its regenerative capacity. In this study, we genetically modified MSCs with an antiapoptotic Bcl-2 gene and evaluated cell survival, engraftment, revascularization, and functional improvement in a rat left anterior descending ligation model via intracardiac injection. Rat MSCs were manipulated to overexpress the Bcl-2 gene. In vitro, the antiapoptotic and paracrine effects were assessed under hypoxic conditions. In vivo, the Bcl-2 gene-modified MSCs (Bcl-2-MSCs) were injected after myocardial infarction. The surviving cells were tracked after transplantation. Capillary density was quantified after 3 weeks. The left ventricular function was evaluated by pressure-volume loops. The Bcl-2 gene protected MSCs against apoptosis. In vitro, Bcl-2 overexpression reduced MSC apoptosis by 32% and enhanced vascular endothelial growth factor secretion by more than 60% under hypoxic conditions. Transplantation with Bcl-2-MSCs increased 2.2-fold, 1.9-fold, and 1.2-fold of the cellular survival at 4 days, 3 weeks, and 6 weeks, respectively, compared with the vector-MSC group. Capillary density in the infarct border zone was 15% higher in Bcl-2-MSC transplanted animals than in vector-MSC treated animals. Furthermore, Bcl-2-MSC transplanted animals had 17% smaller infarct size than vector-MSC treated animals and exhibited functional recovery remarkably. Our current findings support the premise that transplantation of antiapoptotic gene-modified MSCs may have values for mediating substantial functional recovery after acute myocardial infarction.

Donor cell transplantation for myocardial disease: does it complement current pharmacological therapies?This paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum

Heart failure secondary to ischemic heart disease, hypertension, and myocardial infarction is a common cause of death in developed countries. Although pharmacological therapies are very effective, poor prognosis and shorter life expectancy of heart disease patients clearly indicate the need for alternative interventions to complement the present therapies. Since the progression of heart disease is associated with the loss of myocardial cells, the concept of donor cell transplantation into host myocardium is emerging as an attractive strategy to repopulate the damaged tissue. To this end, a number of donor cell types have been tested for their ability to increase the systolic function of diseased hearts in both experimental and clinical settings. Although initial clinical trials with bone marrow stem cells are encouraging, long-term consequences of such interventions are yet to be rigorously examined. While additional laboratory studies are required to address several issues in this field, there is also a clear need for further characterization of drug interactions with donor cells in these interventions. Here, we provide a brief summary of current pharmacological and cell-based therapies for heart disease. Further, we discuss the potential of various donor cell types in myocardial repair, mechanisms underlying functional improvement in cell-based therapies, as well as potential interactions between pharmacological and cell-based therapies.

Realizing the cardiac stem cell promise: a case for trophism

Recent advances in stem cell biology have given rise the new field of cardiac regenerative medicine. Specifically, the development of cardiac stem cell science now offers the promise of novel cardiovascular therapies based on a dynamic body of basic and translational research. Importantly, the potential wide-spread clinical application of this technology will require that therapies be optimized for individuals with potential impairments in cardiac stem cell function. To this end, the previous experience of hematopoietic stem cell therapies can provide important guidance in the development and maturation of the young cardiac stem cell field. Parallel to the impact that exogenous growth factors have made in the field of hematopoietic therapies, the discovery and potential application of the factor(s) that govern cardiac regeneration may speed the progression of cardiac stem cell technology into an assessable and potent clinical therapy.

Xenogeneic embryonic stem cell-derived cardiomyocyte transplantation

PURPOSE

The purpose of this study was to investigate the survival of xenogeneic embryonic stem cell (ES cell)-derived cardiomyocytes transplanted into the normal myocardium.

MATERIAL AND METHODS

Undifferentiated mouse ES cells carrying the enhanced green fluorescent protein (EGFP) were cultured in hanging drops and then plated onto dishes. These cells were identified as cardiomyocytes by the expression of cardiac-specific genes, recording of action potential, and immunostaining with anti-sarcomeric myosin antibody. Donor cells were injected into the normal myocardium, with cyclosporine administered daily. One week after the transplantation, we investigated donor cell survival by examining EGFP expression, hematoxylin and eosin staining, and immunostaining with anti-sarcomeric myosin antibody.

RESULTS

In vitro donor cells derived from ES cells expressed myosin light chain-2v and alpha-myosin heavy chain genes, had action potentials of a ventricular myocyte type, and were stained by anti-sarcomeric myosin antibody. In vivo 1 week after transplantation, EGFP-expressed cells were detected in the cell transplanted area. No lymphocytic infiltration was observed around these cells.

CONCLUSIONS

ES cell-derived cardiomyocytes survived in the normal myocardium after the transplantation, even in a discordant xenogeneic transplantation model. These results indicate that cell transplantation using cardiomyocytes derived from ES cells, even if xenogeneic represents an attractive strategy for treating heart disease.

Skeletal myoblast transplant in heart failure

Despite recent advances in the prevention and treatment of ischemic heart disease (IHD), treatment of patients with heart failure secondary to myocardial infarction remains a therapeutic challenge. Heart transplantation has emerged as a viable option but is fraught with problems of supply. Mechanical assist devices are extremely expensive and dynamic cardiomyoplasty has shown only limited success in the clinical setting. Recent insights into the pathogenesis of myocardial diseases and the progress made in the field of molecular biology have resulted in the development of new strategies at molecular as well as cellular levels for cardiac muscle repair. One such strategy is to augment ventricular function by means of cellular cardiomyoplasty through intracardiac cell grafting using adult and fetal cardiomyocytes, stem cells, and autologous skeletal myoblasts.

Cardiomyocyte transplantation into the failing heart-new therapeutic approach for heart failure?

Heart failure, frequently the consequence of irreversible myocardial damage with subsequent formation of akinetic scar tissue, is a highly prevalent disease, and in its advanced stages associated with high mortality. The transplantation of exogenous cells with the inherent ability to contract has been put forward as one potential treatment strategy to increase contractility and cardiac performance. Besides skeletal myoblasts or stem cells from various sources, immature cardiomyocytes, such as fetal or neonatal cardiomyocytes, have been transplanted into normal, cryoinjured, infarcted myocardium, as well as into models of global heart failure. Survival of transplanted immature cardiomyocytes has been demonstrated up to 6-7 months, accompanied by vascularization of the grafted tissue. Transplants developed sarcomeric structures and other morphological features of differentiation. The principal possibility of cell-to-cell coupling between graft and host cells was demonstrated after cardiomyocyte transplantation into normal hearts and in some studies in damaged myocardium. But most long-term follow-up investigations in models of myocardial infarction reported that optimal integration of the engrafted cells appeared to be hindered by scar tissue, separating the transplant from the host. Nonetheless, in several studies, improved parameters of cardiac performance were demonstrated ex-vivo and in vivo. Potential mechanisms might involve beneficial effects on the remodeling process. In this review, we critically evaluate the potential value of cardiomyocyte transplantation as a new approach in the treatment of the syndrome of "heart failure".

Cellular cardiomyoplasty--a novel approach to treat heart disease

Cell transplantation is a novel experimental strategy to treat heart disease, such as myocardial infarction and heart failure. Its beneficial effects may include active contribution of transplanted cells to contractile function, passive improvement of the mechanics of the heart, induction of neoangiogenesis or other indirect influences on the biology of the heart. Several cell types have been used for cardiac cell transplantation including cardiac cells from fetal or newborn animals and cardiac muscle cell lines, skeletal myoblasts and skeletal muscle cell lines, smooth muscle cells, and a variety of stem cells, either adult or embryonic. With many of these cells, encouraging results in experimental ischemic and nonischemic heart disease have been obtained including successful cell survival after transplantation, integration into the host myocardium, and improvement of the function of diseased hearts. Most of these studies found cardiac contractility improved and some found enhanced angiogenesis. However, the mechanisms of these effects remain obscure, and the impact of dosage (cell number) on functional response is completely unclear. In addition, not enough comparative studies were performed to allow preference of one cell type over the other. The current data suggest that whatever cell species is used, the best survival and integration may be accomplished if immature and undifferentiated cells are used. Any kind of stem cell has obvious advantages in terms of endless reproducibility and plasticity, but the complete differentiation and maturation into cardiac myocytes still needs to be proven. At present several clinical studies are exploring the therapeutic benefits of cellular cardiomyoplasty in patients with ischemic heart disease, but it has to be noted that there are many issues that need to be addressed before this strategy will add to the therapeutic options for patients with heart disease.

Cell transplantation as future therapy for cardiovascular disease?: A workshop of the National Heart, Lung, and Blood Institute

Despite the development of improved therapies and the significant advances in the understanding of the basis of disease pathogenesis, millions of Americans continue to live with life-threatening cardiovascular diseases. Recent breakthroughs suggest exciting directions that are likely to produce more effective therapies for the treatment of cardiovascular disease. One such area, cell transplantation (grafting of healthy cells into the diseased heart), holds enormous potential as an approach to cardiovascular pathophysiology. Once thought to be a scientific long shot, cell transplantation is becoming recognized as a viable strategy to strengthen weak hearts and limit infarct growth. The technology could also be used for the long-term delivery of beneficial recombinant proteins to the heart, which is a strategy to complement molecular biology advances and provide an alternative strategy for gene therapy. On August 24, 1998, the National Heart, Lung, and Blood Institute convened a workshop to discuss the current status of this fast-moving line of research and to explore its promise for treating cardiovascular disease. The participants included basic and clinical researchers, with representatives from academic and commercial research settings. The workshop was designed to establish the state-of-the-art and to equate current research with practical clinical application. The group recommended short- and long-term goals to assist in realizing, in the most expedient manner, the potential utility of cell transplantation for the treatment of cardiovascular disease. A summary of the meeting discussions and recommendations for future areas of research is presented.