Stem cell therapies in patients with single ventricle physiology

Recent advances and challenges on application of tissue engineering for treatment of congenital heart disease

Congenital heart disease (CHD) affects a considerable number of children and adults worldwide. This implicates not only developmental disorders, high mortality, and reduced quality of life but also, high costs for the healthcare systems. CHD refers to a variety of heart and vascular malformations which could be very challenging to reconstruct the malformed region surgically, especially when the patient is an infant or a child. Advanced technology and research have offered a better mechanistic insight on the impact of CHD in the heart and vascular system of infants, children, and adults and identified potential therapeutic solutions. Many artificial materials and devices have been used for cardiovascular surgery. Surgeons and the medical industry created and evolved the ball valves to the carbon-based leaflet valves and introduced bioprosthesis as an alternative. However, with research further progressing, contracting tissue has been developed in laboratories and tissue engineering (TE) could represent a revolutionary answer for CHD surgery. Development of engineered tissue for cardiac and aortic reconstruction for developing bodies of infants and children can be very challenging. Nevertheless, using acellular scaffolds, allograft, xenografts, and autografts is already very common. Seeding of cells on surface and within scaffold is a key challenging factor for use of the above. The use of different types of stem cells has been investigated and proven to be suitable for tissue engineering. They are the most promising source of cells for heart reconstruction in a developing body, even for adults. Some stem cell types are more effective than others, with some disadvantages which may be eliminated in the future.

A review of application of stem cell therapy in the management of congenital heart disease

Research on stem cells has been rapidly growing with impressive breakthroughs. Although merely a few of the laboratory researches have successfully transited to the clinical trial phase, the application of stem cells as a therapeutic option for some currently incapacitating diseases hold fascinating potentials. This review emphasis the various opportunities for the application of stem cell in the treatment of fetal diseases. First, we provide a brief commentary on the common stem cell strategy used in the treatment of congenital anomalies, thereafter we discuss how stem cell is being used in the management of some fetal disorders.

Stem Cell Therapy for Congenital Heart Disease: A Systematic Review

BACKGROUND

Congenital heart disease (CHD) constitutes the most prevalent and heterogeneous group of congenital anomalies. Although surgery remains the gold standard treatment modality, stem cell therapy has been gaining ground as a complimentary or alternative treatment option in certain types of CHD. The aim of this study was to present the existing published evidence and ongoing research efforts on the implementation of stem cell-based therapeutic strategies in CHD.

METHODS

A systematic review was conducted by searching Medline, ClinicalTrials.gov, and the Cochrane library, along with reference lists of the included studies through April 23, 2017.

RESULTS

Nineteen studies were included in this review (8 preclinical, 6 clinical, and 5 ongoing trials). Various routes of cardiac stem cell delivery have been reported, including intracoronary, intramyocardial, intravenous, and epicardial. Depending on their origin and level of differentiation at which they are harvested, stem cells may exhibit different properties. Preclinical studies have mostly focused on modeling right ventricle dysfunction or failure and pulmonary artery hypertension by using pressure or volume overload in vitro or in vivo. Only a limited number of clinical trials on patients with CHD exist, and these primarily focus on hypoplastic left heart syndrome. Cell-based tissue engineering has recently been introduced, and research currently is focusing on developing cell-seeded grafts and patches that could potentially grow in parallel with whole body growth once implanted in the heart.

CONCLUSIONS

It seems that stem cell delivery to the diseased heart as an adjunct to surgical palliation may provide some benefits over surgery alone in terms of cardiac function, somatic growth, and quality of life. Despite encouraging preliminary results, stem cell therapies for patients with CHD should only be considered in the setting of well-designed clinical trials. More wet laboratory research experience is needed, and translation of promising findings to large clinical studies is warranted to clearly define the efficacy and safety profile of this alternative and potentially groundbreaking therapeutic approach.

Stem cell therapy for the systemic right ventricle

INTRODUCTION

In specific forms of congenital heart defects and pulmonary hypertension, the right ventricle (RV) is exposed to systemic levels of pressure overload. The RV is prone to failure in these patients because of its vulnerability to chronic pressure overload. As patients with a systemic RV reach adulthood, an emerging epidemic of RV failure has become evident. Medical therapies proven for LV failure are ineffective in treating RV failure. Areas covered: In this review, the pathophysiology of the failing RV under pressure overload is discussed, with specific emphasis on the pivotal roles of angiogenesis and oxidative stress. Studies investigating the ability of stem cell therapy to improve angiogenesis and mitigate oxidative stress in the setting of pressure overload are then reviewed. Finally, clinical trials utilizing stem cell therapy to prevent RV failure under pressure overload in congenital heart disease will be discussed. Expert commentary: Although considerable hurdles remain before their mainstream clinical implementation, stem cell therapy possesses revolutionary potential in the treatment of patients with failing systemic RVs who currently have very limited long-term treatment options. Rigorous clinical trials of stem cell therapy for RV failure that target well-defined mechanisms will ensure success adoption of this therapeutic strategy.

Cardiac Progenitor Cells Enhance Neonatal Right Ventricular Function After Pulmonary Artery Banding

BACKGROUND

C-kit⁺ cardiac progenitor cells (CPCs) have been shown to be safe and effective in large-animal models and in an early-phase clinical trial for adult patients with ischemic heart disease. However, CPCs have not yet been evaluated in a preclinical model of right ventricular (RV) dysfunction, which is a salient feature of many forms of congenital heart disease.

METHODS

Human c-kit⁺ CPCs were generated from right atrial appendage biopsy specimens obtained during routine congenital cardiac operations. Immunosuppressed Yorkshire swine (6 to 9 kg) underwent pulmonary artery banding to induce RV dysfunction. Thirty minutes after banding, pigs received intramyocardial injection into the RV free wall with c-kit⁺ CPCs (1 million cells, n = 5) or control (phosphate-buffered saline, n = 5). Pigs were euthanized at 30 days postbanding.

RESULTS

Banding was calibrated to a consistent rise in the RV-to-systemic pressure ratio across both groups (postbanding: CPCs = 0.76 ± 0.06, control = 0.75 ± 0.03). At 30 days postbanding, the CPCs group demonstrated less RV dilatation and a significantly greater RV fractional area of change than the control group (p = 0.002). In addition, measures of RV myocardial strain, including global longitudinal strain and strain rate, were significantly greater in the CPCs group at 4 weeks relative to control (p = 0.004 and p = 0.01, respectively). The RV free wall in the CPCs group demonstrated increased arteriole formation (p < 0.0001) and less myocardial fibrosis compared with the control group (p = 0.02).

CONCLUSIONS

Intramyocardial injection of c-kit⁺ CPCs results in enhanced RV performance relative to control at 30 days postbanding in neonatal pigs. This model is important for further evaluation of c-kit⁺ CPCs, including long-term efficacy.

Cell Therapy Trials in Congenital Heart Disease

Dramatic evolution in medical and catheter interventions and complex surgeries to treat children with congenital heart disease (CHD) has led to a growing number of patients with a multitude of long-term complications associated with morbidity and mortality. Heart failure in patients with hypoplastic left heart syndrome predicated by functional single ventricle lesions is associated with an increase in CHD prevalence and remains a significant challenge. Pathophysiological mechanisms contributing to the progression of CHD, including single ventricle lesions and dilated cardiomyopathy, and adult heart disease may inevitably differ. Although therapeutic options for advanced cardiac failure are restricted to heart transplantation or mechanical circulatory support, there is a strong impetus to develop novel therapeutic strategies. As lower vertebrates, such as the newt and zebrafish, have a remarkable ability to replace lost cardiac tissue, this intrinsic self-repair machinery at the early postnatal stage in mice was confirmed by partial ventricular resection. Although the underlying mechanistic insights might differ among the species, mammalian heart regeneration occurs even in humans, with the highest degree occurring in early childhood and gradually declining with age in adulthood, suggesting the advantage of stem cell therapy to ameliorate ventricular dysfunction in patients with CHD. Although effective clinical translation by a variety of stem cells in adult heart disease remains inconclusive with respect to the improvement of cardiac function, case reports and clinical trials based on stem cell therapies in patients with CHD may be invaluable for the next stage of therapeutic development. Dissecting the differential mechanisms underlying progressive ventricular dysfunction in children and adults may lead us to identify a novel regenerative therapy. Future regenerative technologies to treat patients with CHD are exciting prospects for heart regeneration in general practice.

Intracoronary Stem Cell Delivery to the Right Ventricle: A Preclinical Study

Clinical protocols for stem cell-based therapies are currently under development for patients with hypoplastic left heart syndrome. An ideal cell delivery method should have minimal safety risks and provide a wide distribution of cells to the nonischemic right ventricle (RV). However, the optimal strategy for stem cell delivery to the RV has yet to be explored in a preclinical model, necessary for a hypoplastic left heart syndrome trial. Human c-kit⁺ cardiac stem cells (CSCs) were delivered to healthy Yorkshire swine through the proximal right coronary artery with a stop and reflow technique. The effect of premedication with antiarrhythmic (AA) medications in this model was retrospectively reviewed, with the primary outcome of survival 2 hours after infusion. A group underwent CSC delivery to the RV without prophylactic AA medication (no AA, n = 7), whereas the second group was premedicated with a loading dose and intravenous infusion of amiodarone and lidocaine (AA, n = 13). Cardiac biopsies were obtained from each chamber to ascertain the biodistribution of CSCs. Survival was significantly greater in the prophylactic AA group compared with the group without AA (13/13 [100%] vs 1/7 [14.3%], P < 0.0001). Cardiac arrest during balloon inflation was the cause of death in each of the nonmedicated animals. In the premedicated group, 9 (69.2%) pigs experienced transient ST segment changes in the precordial leads during CSC delivery, which resolved spontaneously. Most c-kit⁺ CSCs were distributed to lateral segments of the RV free wall, consistent with the anatomical course of the right coronary artery (lateral RV, 19.2 ± 1.5 CSCs/field of view vs medial RV, 10.4 ± 1.3 CSCs/field of view, P < 0.0001). Few c-kit⁺ CSCs were identified in the right atrium, septum, or left ventricle. Prophylactic infusion of AA enhances survival in swine undergoing intracoronary delivery of human c-kit⁺ CSCs to the RV. Additionally, intracoronary delivery results in a limited biodistribution of c-kit⁺ CSCs within the RV. Human clinical protocols can be optimized by requiring infusion of AA medications before cell delivery.

Regenerative Medicine Strategies for Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS), the most severe and common form of single ventricle congenital heart lesions, is characterized by hypoplasia of the mitral valve, left ventricle (LV), and all LV outflow structures. While advances in surgical technique and medical management have allowed survival into adulthood, HLHS patients have severe morbidities, decreased quality of life, and a shortened lifespan. The single right ventricle (RV) is especially prone to early failure because of its vulnerability to chronic pressure overload, a mode of failure distinct from ischemic cardiomyopathy encountered in acquired heart disease. As these patients enter early adulthood, an emerging epidemic of RV failure has become evident. Regenerative medicine strategies may help preserve or boost RV function in children and adults with HLHS by promoting angiogenesis and mitigating oxidative stress. Rescuing a RV in decompensated failure may also require the creation of new, functional myocardium. Although considerable hurdles remain before their clinical translation, stem cell therapy and cardiac tissue engineering possess revolutionary potential in the treatment of pediatric and adult patients with HLHS who currently have very limited long-term treatment options.

Myoblast cell sheet transplantation enhances the endogenous regenerative abilities of infant hearts in rats with myocardial infarction

The shortage of heart transplantation donors for infants is severe. Regenerative cell therapy has been expected to offer new methods of treatment, and this study was about regenerative cell therapy for infant hearts. The aims of the present study were to clarify the effects of regenerative cell therapy on the infant heart. The heart impairment model and tissue-engineered myoblast cell sheets were used for regenerative cell therapy. Infant rats (n = 54) aged 2 weeks and adult rats aged 12 weeks (n = 35) were used. Myocardial infarction (MI) was induced as the heart impairment model and triple-layer myoblast cell sheets were used for transplantation to MI lesions. Infant rats after MI had better self-regenerative ability in wall thickness, fibrosis and cardiac function and we observed greater numbers of proliferating cardiomyocytes than in adults. Moreover, infant MI rats treated with myoblast cell sheets showed better results in wall thickness, fibrosis and cardiac function than infant MI rats without myoblast cell sheets, because of the positive effect that myoblast cell sheets had on proliferating cardiomyocytes, increasing vascular networks and accumulating c-kit-positive cells. We clarified that regenerative cell therapy enhances the endogenous regenerative ability of infant hearts in rats with MI; moreover, it has a greater therapeutic effect on infant hearts than on adult hearts, because of the ability of infant hearts for cardiomyocyte proliferation. The present paper provides essential new data for clinical therapy in infant patients. Copyright © 2015 John Wiley & Sons, Ltd.

Stem cell therapy for CHD: towards translation

Stem cell therapy has the optimistic goal of regenerating the myocardium as defined by re-growth of lost or destroyed myocardium. As applied to patients with heart failure, many confuse or limit the regenerative definition to just improving myocardial function and/or decreasing myocardial scar formation, which may not be the most important clinical outcome to achieve in this promising field of molecular medicine. Many different stem cell-based therapies have been tested and have demonstrated a safe and feasible profile in adult patients with heart failure, but with varied efficacious end points reported. Although not achieved as of yet, the encompassing goal to regenerate the heart is still believed to be within reach using these cell-based therapies in adult patients with heart failure, as the first-generation therapies are now being tested in different phases of clinical trials. Similar efforts to foster the translation of stem cell therapy to children with heart failure have, however, been limited. In this review, we aim to summarise the findings from pre-clinical models and clinical experiences to date that have focussed on the evaluation of stem cell therapy in children with heart failure. Finally, we present methodological considerations pertinent to the design of a stem cell-based trial for children with heart failure, as they represent a population of patients with very different sets of issues when compared with adult patients. As has been taught by many learned clinicians, children are not small adults!

Transcoronary infusion of cardiac progenitor cells in hypoplastic left heart syndrome: Three-year follow-up of the Transcoronary Infusion of Cardiac Progenitor Cells in Patients With Single-Ventricle Physiology (TICAP) trial

OBJECTIVES

Our aim was to assess midterm safety and clinical outcomes of intracoronary infusion of cardiosphere-derived cells (CDCs) after staged palliation in patients with hypoplastic left heart syndrome (HLHS).

METHODS

In this prospective, controlled study, 14 consecutive patients with HLHS who were undergoing 2- or 3-stage surgical palliations were assigned to receive intracoronary CDC infusion 1 month after cardiac surgery (n = 7), followed by 7 patients allocated to a control group with standard care alone. The primary end point was to assess procedural feasibility and safety; the secondary end point was to evaluate cardiac function and heart failure status through 36-month follow-up.

RESULTS

No complications, including tumor formation, were reported within 36 months after CDC infusion. Echocardiography showed significantly greater improvement in right ventricular ejection fraction (RVEF) in infants receiving CDCs than in controls at 36 months (+8.0% ± 4.7% vs +2.2% ± 4.3%; P = .03). These cardiac function improvements resulted in reduced brain natriuretic peptide levels (P = .04), lower incidence of unplanned catheter interventions (P = .04), and higher weight-for-age z score (P = .02) at 36 months relative to controls. As independent predictors of treatment responsiveness, absolute changes in RVEF at 36 months were negatively correlated with age, weight-for-age z score, and RVEF at CDC infusion.

CONCLUSIONS

Intracoronary CDC infusion after staged procedure in patients with HLHS is safe and improves RVEF, which persists during 36-month follow-up. This therapeutic strategy may enhance somatic growth and reduce incidence of heart failure.

Stem cell therapy and tissue engineering for correction of congenital heart disease

This review article reports on the new field of stem cell therapy and tissue engineering and its potential on the management of congenital heart disease. To date, stem cell therapy has mainly focused on treatment of ischemic heart disease and heart failure, with initial indication of safety and mild-to-moderate efficacy. Preclinical studies and initial clinical trials suggest that the approach could be uniquely suited for the correction of congenital defects of the heart. The basic concept is to create living material made by cellularized grafts that, once implanted into the heart, grows and remodels in parallel with the recipient organ. This would make a substantial improvement in current clinical management, which often requires repeated surgical corrections for failure of implanted grafts. Different types of stem cells have been considered and the identification of specific cardiac stem cells within the heterogeneous population of mesenchymal and stromal cells offers opportunities for de novo cardiomyogenesis. In addition, endothelial cells and vascular progenitors, including cells with pericyte characteristics, may be necessary to generate efficiently perfused grafts. The implementation of current surgical grafts by stem cell engineering could address the unmet clinical needs of patients with congenital heart defects.

Bioengineering and Stem Cell Technology in the Treatment of Congenital Heart Disease

Congenital heart disease places a significant burden on the individual, family and community despite significant advances in our understanding of aetiology and treatment. Early research in ischaemic heart disease has paved the way for stem cell technology and bioengineering, which promises to improve both structural and functional aspects of disease. Stem cell therapy has demonstrated significant improvements in cardiac function in adults with ischaemic heart disease. This finding, together with promising case studies in the paediatric setting, demonstrates the potential for this treatment in congenital heart disease. Furthermore, induced pluripotent stems cell technology, provides a unique opportunity to address aetiological, as well as therapeutic, aspects of disease.

Managing heart failure in adults with congenital heart disease

OPINION STATEMENT

The current era of cardiology has seen a significant increase in the number of adults living with congenital heart disease (CHD). Although advances in medical and surgical management have resulted in approximately 90 % of children with CHD living into adulthood, many suffer from late complications, with myocardial dysfunction as the leading cause of morbidity and mortality. The heterogeneity of the adult congenital heart disease (ACHD) population has presented a challenge, as there are only limited data regarding appropriate treatment modalities. Given the growing ACHD population and the high morbidity and mortality related to myocardial dysfunction, a comprehensive approach to heart failure (HF) care is recommended in conjunction with ACHD and HF specialty care. The field must focus on developing research strategies to leverage existing and future medical and surgical treatment options in order to improve outcomes in this diverse population.

The Year in Review

Congenital cardiac anesthesiology is a rapidly expanding field at both ends of the life spectrum. The care of the unborn child with congenital heart disease is becoming highly specialized in regional centers that offer advanced imaging techniques, coordinated specialist care, and potentially fetal interventions. As more children with congenital heart disease survive to adulthood, patients and their health care providers are facing new challenges. The growing volume of publications reflects this expanding field of congenital cardiac anesthesiology. This year in review article highlights some developing trends in the literature.

Hypoplastic left heart syndrome - unresolved issues

Hypoplastic left heart syndrome (HLHS) is one of the most challenging congenital heart defects. At present, it is expected that - at best - 70% of newborns with HLHS will reach adulthood. This review addresses the problems of right ventricular (RV) failure and insufficient growth of pulmonary vasculature in these patients. In order to further improve long-term prognosis translational research to control RV function, growth of pulmonary arteries and progress in chronic circulatory support are clearly needed to provide a further improvement for adults with HLHS.