Transcoronary bone marrow-derived progenitor cells in a child with myocardial infarction: first pediatric experience

An overview of stem cell therapy for paediatric heart failure

Significant achievements in paediatric cardiology, surgical treatment and intensive care of congenital heart disease have drastically changed clinical outcomes for paediatric patients. Nevertheless, late-onset heart failure in children after staged surgeries still remains a serious concern in the medical community. Heart transplantation is an option for treatment; however, the shortage of available organs is a persistent problem in many developed countries. In order to resolve these issues, advanced technologies, such as innovative mechanical circulatory support devices and regenerative therapies, are strongly desired. Accumulated evidence regarding cell-based cardiac regenerative therapies has suggested their safety and efficacy in treating adult heart failure. Given that young children seem to have a higher regenerative capacity than adults, stem cell-based therapies appear a promising treatment option for paediatric heart failure as well. Based on the findings from past trials and studies, we present the potential of various different types of stem cells, ranging from bone marrow mononuclear cells to cardiosphere-derived stem cells for use in paediatric cell-based therapies. Here, we assess both the current challenges associated with cell-based therapies and novel strategies that may be implemented in the future to advance stem cell therapy in the paediatric population.

Stem cells: will they cure pediatric heart failure?

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of the state of cardiac regenerative medicine, including the unique opportunities and challenges in its application to pediatric patients.

RECENT FINDINGS

There has been a rapid proliferation of clinical studies using stem cells in adults with heart failure, yet little convincing evidence of clinically significant improvement. Readers will develop an understanding of the current limitations of stem cell treatments and the challenges to be overcome before they can achieve successful clinical translation.

SUMMARY

Clinical trials in cardiac regeneration using stem cells are advancing rapidly despite clear knowledge of mechanism and rigorous evidence in animal models. The potential for cardiac regeneration in children may be greater than in adults, given the smaller degree of scar present in nonischemic heart disease and the greater potential of the younger heart for repair. However, similar to adult trials, there has yet to be convincing evidence of a positive effect in pediatric patients, and rigorous controlled studies are still lacking. There is still much biology to be learned in cardiac regeneration; future clinical trials in children should be based on solid evidence in animal models of both efficacy and safety.

Regenerative therapies in young hearts with structural or congenital heart disease

Pediatric heart failure (HF) is rare. The prognosis is generally poor. HF is most frequently related to cardiomyopathy or congenital heart disease (CHD). Associated phenotypes are HF with preserved (HFpEF) or reduced ejection fraction (HFrEF); both in children with biventricular or univentricular circulation. Cardiac growth, differentiation, proliferation and consecutively regenerative and repair mechanisms are inversely related to the patient's age; edaphic and circulating cardiac progenitor cells as well; in sum, there are enormous endogenous potentials repairing a diseased heart in particular in young children. Efforts supporting pediatric cardiac regeneration are clearly justified; cell-based therapies have been addressed in small series of children with end-stage HF of either the left or right ventricle, more recently in randomized clinical trials. Different cell populations like autologous bone marrow mononuclear cells, progenitor cells or cardiac derived cells have been injected into coronaries or directly into the myocardium. Beneficial at least transient improvement of cardiac function was observed in patients with dilative cardiomyopathy and CHD, mainly hypoplastic left heart syndrome (HLHS). Cellular repopulation and possibly more crucial, paracrine effects contributed in slowing down progression of pediatric end-stage HF. Our review summarizes the current knowledge in different scenarios of HF by cell-based cardiac therapies in critically ill children. Based on the actual clinical experience future work to distinguish responders from non-responders among other refinements will lead to individualized precision treatment of HF in children, what means a lot to a child on a long list waiting for heart transplantation (HTX).

Transcoronary cell infusion with the stop-flow technique in children with single-ventricle physiology

BACKGROUND

Almost all reports on cardiac regeneration therapy have referred to adults, and only a few have focused on transcoronary infusion of cardiac progenitor cells using the stop-flow technique in children.

METHODS

Intracoronary autologous cardiosphere-derived cell (CDC) transfer was conducted at Okayama University as a phase 1 clinical trial for seven patients with hypoplastic left heart syndrome between January 2011 and December 2012, and as a phase 2 clinical trial for 34 patients with single-ventricle physiology between July 2013 and March 2015.

RESULTS

A total of 41 patients with single-ventricle physiology underwent transcoronary infusion of CDC with the stop-flow technique. The median age was 33 months (range, 5-70 months) and the median weight was 10.1 kg (range, 4.1-16.0 kg). Transient adverse events occurred during the procedure, including ST-segment elevation or depression, hypotension, bradycardia, and coronary artery vasospasm. All patients completely recovered. There were no major procedure-related adverse events. In this study, transcoronary infusion of CDC using the stop-flow technique was successfully completed in all patients.

CONCLUSION

Transcoronary infusion of CDC using the stop-flow technique in children is a feasible and safe procedure.

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.

Clinical cardiac regenerative studies in children

Although the incidence of pediatric heart failure is low, the mortality is relatively high, with severe clinical symptoms requiring repeated hospitalization or intensive care treatment in the surviving patients. Cardiac biopsy specimens have revealed a higher number of resident human cardiac progenitor cells, with greater proliferation and differentiation capacity, in the neonatal period as compared with adults, demonstrating the regeneration potential of the young heart, with rising interest in cardiac regeneration therapy in critically ill pediatric patients. We review here the available literature data, searching the MEDLINE, Google Scholar and EMBASE database for completed, and www.clinicaltrials.gov homepage for ongoing studies involving pediatric cardiac regeneration reports. Because of difficulties conducting randomized blinded clinical trials in pediatric patients, mostly case reports or cohort studies with a limited number of individuals have been published in the field of pediatric regenerative cardiology. The majority of pediatric autologous cell transplantations into the cardiac tissue have been performed in critically ill children with severe or terminal heart failure. Congenital heart disease, myocarditis, and idiopathic hypertrophic or dilated cardiomyopathy leading to congestive heart failure are some possible areas of interest for pediatric cardiac regeneration therapy. Autologous bone marrow mononuclear cells, progenitor cells, or cardiospheres have been applied either intracoronary or percutaneously intramyocardially in severely ill children, leading to a reported clinical benefit of cell-based cardiac therapies. In conclusion, compassionate use of autologous stem cell administration has led to at least short-term improvement in heart function and clinical stability in the majority of the critically ill pediatric patients.

Stem cell therapies for congenital heart disease

Congenital heart disease (CHD) is the most prevalent congenital anomaly in newborn babies. Cardiac malformations have been induced in different animal model experiments, by perturbing some molecules that take part in the developmental pathways associated with myocyte differentiation, specification, or cardiac morphogenesis. The exact epigenetic, environmental, or genetic, basis for these molecules perturbations is yet to be understood. But, scientist have bridged this gap by introducing autologous stem cell into the defective hearts to treat CHD. The choice of stem cells to use has also raised an issue. In this review, we explore different stem cells that have been recently used, as an update into the pool of this knowledge and we suggested the future perspective into the choice of stem cells to control this disease. We propose that isolating mesenchymal stem cells from neonate will give a robust heart regeneration as compared to adults. This source are easily isolated. To unveil stem cell therapy beyond its possibility and safety, further study is required, including largescale randomized, and clinical trials to certify the efficacy of stem cell therapy.

Stem Cell Therapy and Congenital Heart Disease

For more than a decade, stem cell therapy has been the focus of intensive efforts for the treatment of adult heart disease, and now has promise for treating the pediatric population. On the basis of encouraging results in the adult field, the application of stem cell-based strategies in children with congenital heart disease (CHD) opens a new therapy paradigm. To date, the safety and efficacy of stem cell-based products to promote cardiac repair and recovery in dilated cardiomyopathy and structural heart disease in infants have been primarily demonstrated in scattered clinical case reports, and supported by a few relevant pre-clinical models. Recently the TICAP trial has shown the safety and feasibility of intracoronary infusion of autologous cardiosphere-derived cells in children with hypoplastic left heart syndrome. A focus on preemptive cardiac regeneration in the pediatric setting may offer new insights as to the timing of surgery, location of cell-based delivery, and type of cell-based regeneration that could further inform acquired cardiac disease applications. Here, we review the current knowledge on the field of stem cell therapy and tissue engineering in children with CHD, and discuss the gaps and future perspectives on cell-based strategies to treat patients with CHD.

Stem cell therapies in patients with single ventricle physiology

Single ventricle physiology, especially hypoplastic left heart syndrome, is one of the most high-risk lesions in children with congenital heart disease, and the ensuing heart failure remains as a major problem related to adverse outcomes in these patients. The field of stem cell therapy for heart failure has shown striking advances during the past 10 years, and many clinical trials using stem cell technologies have been conducted in adults, which suggest that stem cell therapy is associated with long-term improvement in cardiac function. Cardiac progenitor cells have recently been discovered, and their strong regenerative ability has been demonstrated in several studies. Although no large clinical trials have been performed in the field of congenital heart disease, recent investigations indicate that stem cell therapy may hold great potential to treat children with cardiac defects.

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!

Cardiac regeneration in children

Very young mammals have an impressive cardiac regeneration capacity. In contrast, cardiac regeneration is very limited in adult humans. The hearts of young children have a higher regenerative capacity compared with adults, as, for example, seen after surgical correction of an anomalous left coronary artery arising from the pulmonary artery or in children with univentricular hearts, who present enormous morphological changes after volume unloading. In addition, the enormous regenerative potential of growing children's hearts is reflected in the spontaneous courses of children with severely deteriorated cardiac function (e.g., patients with dilated cardiomyopathy). The extent of this regenerative capacity and its time dependency remain to be elucidated in the future and should be exploited to improve the treatment of children with severe heart insufficiency.

CD133(+) Cells for the Treatment of Degenerative Diseases: Update and Perspectives

Stem cells are used in cell therapy for degenerative disorders. The main advantage of stem cells is that they can replenish their numbers for long periods through cell division and produce a progeny that can differentiate into multiple cell lineages with specific functions. CD133 is a member of a novel family of cell surface glycoproteins. The expression of human CD133 (AC133 antigen) was originally described in the hematopoietic CD34(+) stem cells, but now it becomes more and more evident that CD133 is a marker of stem and progenitor cell populations originating from various tissues and organs. The main objective of this chapter is to describe the potential sources of CD133(+) stem cells that harbor the ability to engraft, proliferate, and differentiate into functional cells. The characterization of such CD133(+) stem cells unlocks new opportunities in the treatment of degenerative diseases such as Duchenne muscular dystrophy.

CD133(+) cells isolated from various sources and their role in future clinical perspectives

BACKGROUND

CD133 is a member of a novel family of cell surface glycoproteins. Initially, the expression of CD133 antigen was seen only in the hematopoietic derived CD34(+) stem cells. At present, CD133 expression is demonstrated in undifferentiated epithelium, different types of tumors and myogenic cells. CD133(+) neurosphere cells isolated from brain are able to differentiate into both neurons and glial cells. These data suggested that CD133 could be a specific marker for various stem and progenitor cell populations.

OBJECTIVES

The main goal would be to describe the role for CD133 as a marker of stem cells able to engraft and differentiate, to form functional non-hematopoietic adult lineages and contribute to disease amelioration via tissue regeneration.

RESULTS/CONCLUSION

In conclusion, since the rise of CD133 antigen as a suitable stem cell marker, the possible use of CD133(+) stem cells in therapeutic applications has opened a new promising field in the treatment of degenerating diseases. The human circulating cells expressing the CD133 antigen behave as a stem cell population capable of commitment to hematopoietic, endothelial and myogenic lineages. CD133 cell therapy may represent a promising treatment for many diseases.