Autophagy during left ventricular redilation after ventriculoplasty: Insights from a rat model of ischemic cardiomyopathy.

OBJECTIVES: Myocardial autophagy has been recognized as an important factor in heart failure. It is not known whether changes in ventricular geometry by left ventriculoplasty influence autophagy in ischemic cardiomyopathy. We hypothesized that myocardial autophagy plays an important role in left ventricular (LV) redilation after ventriculoplasty. METHODS: Four weeks after ligation of the left anterior descending artery, ventriculoplasty or sham operation was performed. The animals were euthanized at 2 days (early) or 28 days (late) after the second operation. Ventricular autophagy was evaluated by protein expression of microtubule-associated protein light chain 3 II, an autophagosome marker. Cardiomyocyte area was assessed by histologic examination. LV function was evaluated by echocardiography. To examine the implications of autophagy, an autophagy inhibitor (3-methyladenine) was injected intraperitoneally for 3 weeks before sacrifice. RESULTS: The LV was reduced in size early and redilated late after ventriculoplasty. LV systolic function was improved early and later worsened after ventriculoplasty. Light chain 3 II expression decreased early after ventriculoplasty and increased in the late period. Myocyte area increased from the early to late stage after ventriculoplasty. Autophagic inhibition exaggerated the increased myocyte hypertrophy and LV redilation. CONCLUSIONS: In a rat model of myocardial infarction, autophagy decreased early after ventriculoplasty and increased again during LV redilation. These results provide new insights into the mechanism underlying the late failure of ventriculoplasty.

Diagnostic methodology of cardiac dynamics based on the Zipf-Mandelbrot law: evaluation with 50 patients / Metodología diagnóstica de la dinámica cardiaca basada en ley de Zipf-Mandelbrot: evaluación con 50 pacientes

Abstract: Objective: Zipf-Mandelbrot law has been used to assess the complexity of cardiac systems. The objective of this work is to corroborate the clinical applicability of a diagnostic methodology developed from Zipf-Mandelbrot law, in the differentiation of normality and acute cardiac disease. Material and methods: there were taken 50 continuous electrocardiographic Holter monitoring records, 20 normal and 30 with acute alterations of the cardiac dynamics. The frequencies of occurrence of heart rates in ranges of 15 lat/min were organized hierarchically to demonstrate the hyperbolic behavior of dynamics and to apply the Zipf-Mandelbrot law. A linearization was performed and the statistical fractal dimension of each dynamic was obtained, giving rise to the mathematical diagnosis. Sensitivity, specificity and Kappa coefficient were calculated. Results: The values of the statistical fractal dimension of the acute cardiac dynamics were between 0.7123 and 0.9327, whereas for the normal dynamics were found between 0.4253 and 0.6698, evidencing quantitative differences between states of normality and disease. Sensitivity and specificity values of 100% were found and the kappa coefficient was 1. Conclusions: The clinical and diagnostic utility of the mathematical methodology based on Zipf-Mandelbrot law was verified, observing a decrease of dynamics complexity in cases of acute heart disease.(AU)

Resumen: Objetivo: La ley de Zipf-Mandelbrot ha sido utilizada con el fin de evaluar la complejidad de los sistemas cardiacos. El objetivo de este trabajo es corroborar la aplicabilidad clínica de una metodología diagnóstica desarrollada a partir de la ley de Zipf-Mandelbrot, en la diferenciación de normalidad y enfermedad cardiaca aguda. Material y métodos: Se tomaron 50 Holter cardiacos (monitoreo electrocardiográfico continuo ambulatorio), 20 normales y 30 con alteraciones agudas de la dinámica cardiaca. Se organizaron jerárquicamente las frecuencias de aparición de frecuencias cardiacas en rangos de a 15 lat/min, para evidenciar el comportamiento hiperbólico de las dinámicas y aplicar la ley de Zipf-Mandelbrot. Se realizó una linealización y se obtuvo la dimensión fractal estadística de cada dinámica, dando lugar al diagnóstico matemático. Fueron calculadas la sensibilidad, especificidad y el coeficiente Kappa. Resultados: Los valores de la dimensión fractal estadística de las dinámicas cardiacas agudas se encontraron entre 0.7123 y 0.9327, mientras que para las dinámicas normales se hallaron entre 0.4253 y 0.6698, evidenciando diferencias cuantitativas entre estados de normalidad y enfermedad. Se encontraron valores de sensibilidad y especificidad del 100% y el coeficiente kappa fue de 1. Conclusiones: Fue comprobada la utilidad clínica y diagnóstica de la metodología matemática basada en la ley de Zipf-Mandelbrot, observando un decremento de la complejidad de la dinámica en casos de enfermedad cardiaca aguda.(AU)

Cellular cardiomyoplasty into infracted swine's hearts by retrograde infusion through the venous coronary sinus: An experimental study.

OBJECTIVES: The aim was to create a model of myocardial infarction with a borderline myocardial impairment which would enable evaluation of the retrograde cellular cardiomyoplasty through the venous coronary sinus in a large animal model. MATERIALS AND METHODS: Fifteen (study group) and 10 juvenile farm pigs (control group) underwent distal left anterior descending artery ligation. One month later the study group animals underwent sternotomy and a murine myoblastic line C2-C12 was injected at a constant pressure of 30mmHg, into the coronary sinus. Thirty days later all animals that survived from both groups underwent transthoracic echocardiography and 99Tc scintigraphy and were later euthanized and specimens were taken for microscopic evaluation. RESULTS: Cardiac output decreased significantly after ligation (p<0.001) and increased significantly after cardiomyoplasty (p<0.001). In all animals, the surgical induction of myocardial infarction caused a marked decline in the echocardiographic values of cardiac function; however, the cardiac function and dimensions were significantly improved in the study group after cardiomyoplasty versus the control group. All animals undergoing cardiomyoplasty demonstrated a significant reduction of the perfusion deficit in the left anterior descending artery territory, instead such data remained unchanged in the control group. The histological examination demonstrated the engrafted myoblasts could be distinguished from the activated fibroblasts in the scar tissue because they never showed any signs of collagen secretion and fiber buildup. CONCLUSIONS: In conclusion, the venous retrograde delivery route through the coronary sinus is safe and effective, providing a significant improvement in function and viability.

[One-Stage Application of Mitral Valve Correction, Surgical Radiofrequency Ablation and Left Atrial Atrioplasty].

OBJECTIVE: Our aim was to evaluate sinus rhythm restoration and its failure predictors after one-stage application of surgical radiofrequency ablation, left atrial reduction and mitral valve correction. METHODS: This is a prospective longitudinal cohort study with historical controls. Patients were divided into 2 groups according to the performed type of operation--the main group included patients undergone one-stage mitral valve correction, surgical radiofrequency ablation and left atrial atrioplasty (n = 47); and the control group consisted of patients undergone only mitral valve correction (n = 76). Surgical radiofrequency ablation was performed under the scheme Maze-IV. Left atrial atrioplasty procedure was performed according to echocardiography data: if in women LA antero-posterior dimensions were more than 4.7 cm and in men more than 5.2 cm. RESULTS: The study included 123 patients. In the main group (age of the patients 61.0 ± 9.1 years, 55% male) sinus rhythm restoration was observed in 32 (68%) patients during the early postoperative period, but at the time of discharge it reduced to 19 (40%), but in 6 months it increased up to 37 (78%), and in 36 months sinus rhythm already was detected in 40 (85%) patients. At the same time, during the early postoperative period in the control group (patients aged 59.0 ± 11.0 years, 61% male) only 31 (40%) of patients had sinus rhythm, in 6 months it was detected in 11 (14%) cases, and in 36 months sinus rhythm--only in 28 (37%) patients. Predictors of atrial fibrillation recurrence were revealed: valve disease continuance < 4 years (p = 0.017) and atrial fibrillation history < 3 years (p =0.029). CONCLUSION: One-stage peforming of mitral valve correction, surgical radiofrequency ablation and left atrial atrioplasty restores and maintains more regular sinus rhythm, even in presence of atrial fibrillation recurrence predictors.

Cellular cardiomyoplasty for myocardial infarction: a 2014 evidence-based update.

Myocardial infarction is one of the main cause of mortality in many countries. Therefore, an effective therapy for myocardial infarction is required. Reperfusion and other conventional therapy have been the mainstay therapy for myocardial infarction. However, many patients remain refractory to this therapy. Cellular cardiomyoplasty is considered a novel therapy, in which stem cells are used for cardiac repair. Stem cells are potential therapeutic approach that could be the ultimate solution for salvaging damaged cardiomyocyte. Based on current studies, stem cells are a promising therapeutic approach for myocardial infarction. However, some challenges need to be answered by future studies before this novel therapy can be widely applied. As we advance our understanding, all questions behind stem cell therapy would finally be revealed, and eventually provide the ultimate solution for ischaemic cardiac repair. This paper provide an overview of the latest progress in stem cell therapy for myocardial infarction.

[From precursor to reprogrammed cells: evolution of cardiomyoplasty]. / Od komórek prekursorowych do komórek przeprogramowanych: ewolucja kardiomioplastyki.

Myocardial infarction is underoxygenation-driven limited necrosis of heart tissues which results in elimination of ca. 0.5 to 1 billion spontaneously contracting cardiomyocytes (CM). Since the ability of human heart to regenerate is limited, efforts have been undertaken to increase the number of cardiomyocytes in post-infarction myocardium. Theoretically, such proposals might involve transplantation of 1) skeletal myoblasts and cardiomyocytes, or 2) progenitor/stem cells, theoretically capable of differentiating into cardiomyocytes, or 3) pluripotent cells such as embryonal stem cells (ESC) and induced pluripotent stem cells (iPSC) differentiating into cardiomyocytes. The efforts to increase CM could also involve 4) in situ reprogramming of fibroblasts into active cardiomyocyte-like cells, or 5) stimulating in situ proliferation of cardiomyocytes using pharmacological agents. Only three proposals merit closer scrutiny (2, 4 and 5). However, preclinical and clinical data have demonstrated weak ability of progenitor cells to differentiate (proposal 2). Nevertheless, transplanted cell-induced paracrine effects accompanying such therapy do improve functioning of the damaged heart muscle. The proposals that would permit the number of CM to be increased include in situ reprogramming of fibroblasts into active cardiomyocytes (proposal 4), as well as in situ stimulation of quiescent cardiomyocytes' proliferation (proposal 5). It appears that an optimized therapeutic solution (increasing left ventricular ejection fraction and decreasing the post-infarct scar) might combine agents stimulating paracrine effects and reprogramming of fibroblasts.

The use of gadolinium-carbon nanostructures to magnetically enhance stem cell retention for cellular cardiomyoplasty.

In this work, the effectiveness of using Gadonanotubes (GNTs) with an external magnetic field to improve retention of transplanted adult mesenchymal stem cells (MSCs) during cellular cardiomyoplasty was evaluated. As a high-performance T1-weighted magnetic resonance imaging (MRI) cell tracking label, the GNTs are gadolinium-loaded carbon nanotube capsules that render MSCs magnetic when internalized. MSCs were internally labeled with either superparamagnetic GNTs or colloidal diamagnetic lutetium (Lu). In vitro cell rolling assays and ex vivo cardiac perfusion experiments qualitatively demonstrated increased magnetic-assisted retention of GNT-labeled MSCs. Subsequent in vivo epicardial cell injections were performed around a 1.3 T NdFeB ring magnet sutured onto the left ventricle of female juvenile pigs (n = 21). Cell dosage, magnet exposure time, and endpoints were varied to evaluate the safety and efficacy of the proposed therapy. Quantification of retained cells in collected tissues by elemental analysis (Gd or Lu) showed that the external magnet helped retain nearly three times more GNT-labeled MSCs than Lu-labeled cells. The sutured magnet was tolerated for up to 168 h; however, an inflammatory response to the magnet was noted after 48 h. These proof-of-concept studies support the feasibility and value of using GNTs as a magnetic nanoparticle facilitator to improve cell retention during cellular cardiomyoplasty.

Intramuscular delivery of 3D aggregates of HUVECs and cbMSCs for cellular cardiomyoplasty in rats with myocardial infarction.

Cell-based therapeutic neovascularization is a promising method for treating ischemic disorders. In this work, human umbilical vein endothelial cells (HUVECs) were thoroughly premixed with cord-blood mesenchymal stem cells (cbMSCs) and cultivated to form three-dimensional (3D) cell aggregates for cellular cardiomyoplasty. In the in vitro study, tubular networks were formed at day 1 after the co-culturing of dissociated HUVECs and cbMSCs on Matrigel; however, as time progressed, the grown tubular networks regressed severely. Conversely, when 3D cell aggregates were grown on Matrigel, mature and stable tubular networks were observed over time, under the influence of their intensive cell-extracellular matrix (ECM) interactions and cell-cell contacts. 3D cell aggregates were transplanted into the peri-infarct zones of rats with myocardial infarction (MI) via direct intramyocardial injection. Based on our pinhole single photon emission computed tomography (SPECT) myocardial-perfusion observations, echocardiographic heart-function examinations and histological analyses, the engrafted 3D cell aggregates considerably enhanced the vascular densities and the blood flow recovery in the ischemic myocardium over those of their dissociated counterparts, thereby reducing the size of perfusion defects and restoring cardiac function. These results demonstrate that the intramuscular delivery of 3D cell aggregates of HUVECs/cbMSCs can be a valuable cell-based regenerative therapeutic strategy against MI.

Cellular cardiomyoplasty: its past, present, and future.

Cellular cardiomyoplasty is a cell therapy using stem cells or progenitor cells for myocardial regeneration to improve cardiac function and mitigate heart failure. Since we first published cellular cardiomyoplasty in 1989, this procedure became the innovative method to treat damaged myocardium other than heart transplantation. A significant improvement in cardiac function, metabolism, and perfusion is generally observed in experimental and clinical studies, but the improvement is mild and incomplete. Although safety, feasibility, and efficacy have been well documented for the procedure, the beneficial mechanisms remain unclear and optimization of the procedure requires further study. This chapter briefly reviews the stem cells used for cellular cardiomyoplasty and their clinical outcomes with possible improvements in future studies.

Skeletal muscle stem cells.

Skeletal muscle satellite cells (myoblasts) are the primary stem cells of skeletal muscle which contribute to growth, maintenance, and repair of the muscles. Satellite cells are the first stem cells used for cellular cardiomyoplasty more than 20 years ago. The isolation, culture, labeling, and identification of satellite cells are described in detail here. The implantation and outcomes of cellular cardiomyoplasty using satellite cells have been summarized in the previous chapter (Chapter 1).

Route of delivery, cell retention, and efficiency of polymeric microcapsules in cellular cardiomyoplasty.

Stem cell transplantation has been considered as a major breakthrough for treating ischemic heart disease. However, survival and retention of transplanted cells at the site of infarction remains tenuous. This chapter details a method of creating polymeric microcapsules for cell delivery, resulting in increased retention of transplanted cells at the target site, while achieving minimal mechanical trauma and cell loss. Simultaneously biocompatible and biodegradable, polymeric microcapsules have important implications in regenerative cell therapy.

Bio-hybrid tissue engineering for cellular cardiomyoplasty: future directions.

Cardiomyopathy induces geometric alteration of the ventricular cavity, which changes from a natural elliptical (conical) to a spherical shape. Ventricular chamber dilatation and spherical deformation are important causes of morbidity and mortality among patients with congestive heart failure. In addition, diastolic dysfunction is an important clinical problem in these cases because there is no medical or surgical specific treatment. Myocardial tissue engineering associating stem cells represent a new road and fresh hope for this heart failure population.

Embryonic cardiomyocyte, but not autologous stem cell transplantation, restricts infarct expansion, enhances ventricular function, and improves long-term survival.

AIMS: Controversy exists in regard to the beneficial effects of transplanting cardiac or somatic progenitor cells upon myocardial injury. We have therefore investigated the functional short- and long-term consequences after intramyocardial transplantation of these cell types in a murine lesion model. METHODS AND RESULTS: Myocardial infarction (MI) was induced in mice (n = 75), followed by the intramyocardial injection of 1-2×10(5) luciferase- and GFP-expressing embryonic cardiomyocytes (eCMs), skeletal myoblasts (SMs), mesenchymal stem cells (MSCs) or medium into the infarct. Non-treated healthy mice (n = 6) served as controls. Bioluminescence and fluorescence imaging confirmed the engraftment and survival of the cells up to seven weeks postoperatively. After two weeks MRI was performed, which showed that infarct volume was significantly decreased by eCMs only (14.8±2.2% MI+eCM vs. 26.7±1.6% MI). Left ventricular dilation was significantly decreased by transplantation of any cell type, but most efficiently by eCMs. Moreover, eCM treatment increased the ejection fraction and cardiac output significantly to 33.4±2.2% and 22.3±1.2 ml/min. In addition, this cell type exclusively and significantly increased the end-systolic wall thickness in the infarct center and borders and raised the wall thickening in the infarct borders. Repetitive echocardiography examinations at later time points confirmed that these beneficial effects were accompanied by better survival rates. CONCLUSION: Cellular cardiomyoplasty employing contractile and electrically coupling embryonic cardiomyocytes (eCMs) into ischemic myocardium provoked significantly smaller infarcts with less adverse remodeling and improved cardiac function and long-term survival compared to transplantation of somatic cells (SMs and MSCs), thereby proving that a cardiomyocyte phenotype is important to restore myocardial function.

Placental mesenchymal stem cells: a unique source for cellular cardiomyoplasty.

In coronary heart disease, the use of stem cells for regeneration purposes has been broadly studied. Whereas bone marrow mesenchymal stem cells remain the most extensively investigated, other cell sources have been reported. Here we discuss and compare the characteristics of placenta-derived mesenchymal stem cells as a novel alternative cell source for cellular cardiomyoplasty. These cells are isolated from the human term placenta, which is normally discarded post partum. With their lack of ethical conflicts and young age, the readily available placenta-derived mesenchymal stem cells could be more suitable for myocardial regenerative therapy.

A translational approach in using cell sheet fragments of autologous bone marrow-derived mesenchymal stem cells for cellular cardiomyoplasty in a porcine model.

Based on a porcine model with surgically created myocardial infarction (MI) as a pre-clinical scheme, this study investigates the clinical translation of cell sheet fragments of autologous mesenchymal stem cells (MSCs) for cellular cardiomyoplasty. MSC sheet fragments retaining endogenous extracellular matrices are fabricated using a thermo-responsive methylcellulose hydrogel system. Echocardiographic observations indicate that transplantation of MSC sheet fragments in infarcted hearts can markedly attenuate the adverse ventricular dilation and preserve the cardiac function post MI, which is in contrast to the controlled groups receiving saline or dissociated MSCs. Additionally, histological analyses suggest that administering MSC sheet fragments significantly prevents the scar expansion and left ventricle remodeling after MI. Immunohistochemistry results demonstrate that the engrafted MSCs can differentiate into endothelial cells and smooth muscle cells, implying that angiogenesis and the subsequent regional perfusion improvement is a promising mechanism for ameliorating post-infarcted cardiac function. However, according to the data recorded by an implantable loop recorder, the transplanted MSCs may provoke arrhythmia. Nevertheless, the proposed approach may potentially lead to the eventual translation of MSC-based therapy into practical and effective clinical treatments.

Static cardiomyoplasty with synthetic elastic net suppresses ventricular dilatation and dysfunction after myocardial infarction in the rat: a chronic study.

Although static cardiomyoplasty prevents the left ventricle (LV) from dilatation, it may interfere with diastolic relaxation, or cause restriction. We developed a synthetic net with dual elasticity and tested its effect late after myocardial infarction in the rat. LV pressure-volume relationships (PVR) were successively analyzed before, after intravenous volume load, and 10 minutes after occlusion of the left anterior descending artery. Rats were then randomized into groups receiving synthetic net wrapping around the heart (NET+, n = 8) and only partially behind LV (NET-, n = 9), and they underwent the same PVR studies 6 weeks later. End-diastolic and end-systolic PVR were defined, and LV size and function were compared under standardized loading conditions. Although there was no difference in Day 0, increase in LV end-diastolic and end-systolic volumes were significantly attenuated in NET+ rats 6 weeks later when there was a significant correlation between LV volumes by PVR estimation and actual measurements, with significant differences in both measures between the groups: NET+ < NET-. The presence or absence of net did not show restrictive hemodynamics under acute volume load. Static cardiomyoplasty using a synthetic elastic net significantly attenuated LV dilatation and dysfunction without restriction late after myocardial infarction in the rat.

Surgical management of end-stage heart failure.

This review explores the history, methods and evidence surrounding the various surgical therapeutic options which are available for patients with end-stage heart failure.

Cellular retrograde cardiomyoplasty and relaxin therapy for postischemic myocardial repair in a rat model.

We sought to determine whether skeletal myoblasts, wild-type or engineered to express relaxin, might improve myocardial viability and performance in a rat model of chronic myocardial infarction. Our purpose was to investigate a potential new therapy for heart failure. From October 2005 through September 2009, we surgically induced acute myocardial infarction in 80 male Wistar rats. Thirty days after surgery, the rats underwent reoperation for the retrograde coronary venous infusion of skeletal myoblasts, relaxin, or both. The animals were randomly assigned to 4 experimental groups: R1 (the control group, which underwent saline-solution infusion), R2 (systemic relaxin therapy), R3 (myoblast infusion), and R4 (myoblast infusion and systemic relaxin therapy). Echocardiography, positron emission tomography, and cellular and histologic analysis were performed at 4 established time points. Mortality rates were similar among the groups. Postinfarction echocardiographic evaluation revealed similar left ventricular dysfunction. Viable myocardium, evaluated with positron emission tomography, was analogous. After therapy, the echocardiographic values of cardiac function improved significantly (P<0.05) in all groups except R1. Myocardial viability volume increased significantly in groups R3 and R4 (P<0.05) but was unchanged in groups R2 and R1. In group R4, the echocardiographic and positron emission tomographic results improved significantly (P<0.001). Histologic analysis showed that myoblasts settled in regions of ischemic scarring, especially when combined with relaxin. The retrograde venous route is safe, effective, and clinically feasible for cell delivery. Myoblasts and relaxin are better than either alone in terms of myocardial viability and performance improvement.