Impact of different bone marrow cell preparations on left ventricular remodelling after experimental myocardial infarction

Application of Erythropoietin in Chronic Heart Failure Treatment

Heart Failure (HF) is recognized as an important public health concern worldwide, especially in developed countries, due to its high rate of morbidity and mortality. Although new pharmacological and non-pharmacological agents have improved the clinical sequelae of HF in patients, its mortality remains high, especially among the elderly. Erythropoietin (EPO), a glycoprotein, besides its traditional role in promoting erythropoiesis and production of erythroid progenitors, its beneficial role in reducing infarct area and improving heart function through EPO-induced antiapoptotic and antioxidant effects have been increasingly recognized. This review gathers the evidence to date about the effectiveness of EPO in HF patients. In addition to the growing evidence of EPO in the treatment of HF in the animal studies for improving cardiac function and infarct size, more clinical studies are needed to assess the role of EPO treatment in the management of HF.

Hematopoietic Stem Cells in Regenerative Medicine: Astray or on the Path?

Hematopoietic stem cells (HSCs) are the best characterized adult stem cells and the only stem cell type in routine clinical use. The concept of stem cell transplantation laid the foundations for the development of novel cell therapies within, and even outside, the hematopoietic system. Here, we report on the history of hematopoietic cell transplantation (HCT) and of HSC isolation, we briefly summarize the capabilities of HSCs to reconstitute the entire hemato/lymphoid cell system, and we assess current indications for HCT. We aim to draw the lines between areas where HCT has been firmly established, areas where HCT can in the future be expected to be of clinical benefit using their regenerative functions, and areas where doubts persist. We further review clinical trials for diverse approaches that are based on HCT. Finally, we highlight the advent of genome editing in HSCs and critically view the use of HSCs in non-hematopoietic tissue regeneration.

Cytokine combination therapy with erythropoietin and granulocyte colony stimulating factor in a porcine model of acute myocardial infarction

Purpose

Erythropoietin (EPO) and granulocyte colony stimulating factor (GCSF) have generated interest as novel therapies after myocardial infarction (MI), but the effect of combination therapy has not been studied in the large animal model. We investigated the impact of prolonged combination therapy with EPO and GCSF on cardiac function, infarct size, and vascular density after MI in a porcine model.

Methods

MI was induced in pigs by a 90 min balloon occlusion of the left anterior descending coronary artery. 16 animals were treated with EPO+GCSF, or saline (control group). Cardiac function was assessed by echocardiography and pressure-volume measurements at baseline, 1 and 6 weeks post-MI. Histopathology was performed 6 weeks post-MI.

Results

At week 6, EPO+GCSF therapy stabilized left ventricular ejection fraction, (41 ± 1% vs. 33 ± 1%, p < 0.01) and improved diastolic function compared to the control group. Histopathology revealed increased areas of viable myocardium and vascular density in the EPO+GCSF therapy, compared to the control. Despite these encouraging results, in a historical analysis comparing combination therapy with monotherapy with EPO or GCSF, there were no significant additive benefits in the LVEF and volumes overtime using the combination therapy.

Conclusion

Our findings indicate that EPO+GCSF combination therapy promotes stabilization of cardiac function after acute MI. However, combination therapy does not seem to be superior to monotherapy with either EPO or GCSF.

The current status of engineering myocardial tissue

Myocardial infarction (MI) remains a common fatal disease all over the world. The adult cardiac myocytes regenerative capability is very limited after infarct injury. Heart transplantation would be the best therapeutic option currently but is restricted due to the lack of donor organs and the serious side effects of immune suppression. The emerging of tissue engineering has evolved to provide solutions to tissue repair and replacement. Engineering myocardial tissue is considered to be a new therapeutic approach to repair infarcted myocardium and ameliorate cardiac function after MI. Engineering myocardial tissue is the combination of biodegradable scaffolds with viable cells and has made much progress in the experimental phase. However, the largest challenge of this field is the revascularization of the engineering constructs to provide oxygen and nutrients for cells. This review will give an overview on the current evolution of engineering myocardial tissue and address a new method to improve the vascularization of myocardium tissue in vivo.

Differential effect of myocardial matrix and integrins on cardiac differentiation of human mesenchymal stem cells

Dysregulation of matrix synthesis during myocardial fibrosis in post-infarct ventricular remodeling contributes to ventricular dysfunction. Bone marrow stem cell transplantation prevents functional deterioration following myocardial infarction. However, effect of myocardial extracellular matrix (ECM) on stem cell differentiation is poorly understood. We investigate the role of collagen matrices and integrin system in cardiac differentiation and engraftment of stem cells in infarcted myocardium. Sternum-derived bone marrow mesenchymal stem cells (MSCs) were differentiated into cardiomyocyte-like cells (CLCs). They were characterized using RT-PCR, immunofluorescence, flow cytometry and functional integrin neutralization assays. CLCs were injected into peri-infarct borders of injured myocardium of Wistar rats one week following left anterior descending (LAD) artery ligation. Cardiac function was analyzed via pressure-volume relationships. Cardiac differentiated CLCs displayed collagen V specificity, which was absent in undifferentiated MSCs. Collagen V, but not collagen I matrix, promoted attachment, proliferation and cardiac differentiation of CLCs. In contrast to beta(1), alpha(v) integrin contributed minimally in the attachment of CLCs on collagen matrices. However, inhibition of alpha(v)beta(3,) but not alpha(2)beta(1) integrin, selectively attenuated troponin T, sarcomeric alpha-actin and ryanodine 2 receptor gene expression in CLCs. Both MSC and CLC transplantation prevented chamber dilatation and improved contractile function. However, systolic activity in MSC transplanted animals was accompanied by heightened wall stress as demonstrated by elevated myocardial end-diastolic pressure and prolonged tissue relaxation time. Localization of CLCs in the vicinity of collagen V-expressing myofibers promoted their integration into cardiac syncytium. CLCs may facilitate hemodynamic recovery by preserving tissue elasticity in the peri-infarct borders that sustains contractile efficiency for functional recovery in an actively remodeling infarcted myocardium.

Improving regenerating potential of the heart after myocardial infarction: factor-based approach

The emerging evidence that the heart has the potential to regenerate, albeit not ideally, has stimulated considerable interest in the field of cardiac regenerative medicine. Several lines of research demonstrated that factor-based therapy is feasible and effective, whether it is used independently or as an adjunct to cell therapy. The ultimate goal of the factor-based approach is to improve the regenerating potential of the heart as a means to treat patients with cardiovascular disease. This article reviews recent approaches involving factor-based therapy for cardiac repair and regeneration including some of the advantages of this type of therapy as well as some of the hurdles that must be overcome before this therapeutic approach becomes a standard part of clinical medicine.

Transplantation of mesenchymal stem cells exerts a greater long-term effect than bone marrow mononuclear cells in a chronic myocardial infarction model in rat

The aim of this study is to assess the long-term effect of mesenchymal stem cells (MSC) transplantation in a rat model of chronic myocardial infarction (MI) in comparison with the effect of bone marrow mononuclear cells (BM-MNC) transplant. Five weeks after induction of MI, rats were allocated to receive intramyocardial injection of 10(6) GFP-expressing cells (BM-MNC or MSC) or medium as control. Heart function (echocardiography and (18)F-FDG-microPET) and histological studies were performed 3 months after transplantation and cell fate was analyzed along the experiment (1 and 2 weeks and 1 and 3 months). The main findings of this study were that both BM-derived populations, BM-MNC and MSC, induced a long-lasting (3 months) improvement in LVEF (BM-MNC: 26.61 +/- 2.01% to 46.61 +/- 3.7%, p < 0.05; MSC: 27.5 +/- 1.28% to 38.8 +/- 3.2%, p < 0.05) but remarkably, only MSC improved tissue metabolism quantified by (18)F-FDG uptake (71.15 +/- 1.27 to 76.31 +/- 1.11, p < 0.01), which was thereby associated with a smaller infarct size and scar collagen content and also with a higher revascularization degree. Altogether, results show that MSC provides a long-term superior benefit than whole BM-MNC transplantation in a rat model of chronic MI.