Comparison of intracoronary and transendocardial delivery of allogeneic mesenchymal cells in a canine model of acute myocardial infarction

The Application of Mesenchymal Stem Cells in Different Cardiovascular Disorders: Ways of Administration, and the Effectors

The heart is an organ with a low ability to renew and repair itself. MSCs have cell surface markers such as CD45-, CD34-, CD31-, CD4+, CD11a+, CD11b+, CD15+, CD18+, CD25+, CD49d+, CD50+, CD105+, CD73+, CD90+, CD9+, CD10+, CD106+, CD109+, CD127+, CD120a+, CD120b+, CD124+, CD126+, CD140a+, CD140b+, adherent properties and the ability to differentiate into cells such as adipocytes, osteoblasts and chondrocytes. Autogenic, allogeneic, normal, pretreated and genetically modified MSCs and secretomes are used in preclinical and clinical studies. MSCs and their secretomes (the total released molecules) generally have cardioprotective effects. Studies on cardiovascular diseases using MSCs and their secretomes include myocardial infraction/ischemia, fibrosis, hypertrophy, dilated cardiomyopathy and atherosclerosis. Stem cells or their secretomes used for this purpose are administered to the heart via intracoronary (Antegrade intracoronary and retrograde coronary venous injection), intramyocardial (Transendocardial and epicardial injection) and intravenous routes. The protective effects of MSCs and their secretomes on the heart are generally attributed to their differentiation into cardiomyocytes and endothelial cells, their immunomodulatory properties, paracrine effects, increasing blood vessel density, cardiac remodeling, and ejection fraction and decreasing apoptosis, the size of the wound, end-diastolic volume, end-systolic volume, ventricular myo-mass, fibrosis, matrix metalloproteins, and oxidative stress. The present review aims to assist researchers and physicians in selecting the appropriate cell type, secretomes, and technique to increase the chance of success in designing therapeutic strategies against cardiovascular diseases.

The Use of Hematopoietic Stem Cells for Heart Failure: A Systematic Review

The purpose of this review is to summarize the current understanding of the therapeutic effect of stem cell-based therapies, including hematopoietic stem cells, for the treatment of ischemic heart damage. Following PRISMA guidelines, we conducted electronic searches in MEDLINE, and EMBASE. We screened 592 studies, and included RCTs, observational studies, and cohort studies that examined the effect of hematopoietic stem cell therapy in adult patients with heart failure. Studies that involved pediatric patients, mesenchymal stem cell therapy, and non-heart failure (HF) studies were excluded from our review. Out of the 592 studies, 7 studies met our inclusion criteria. Overall, administration of hematopoietic stem cells (via intracoronary or myocardial infarct) led to positive cardiac outcomes such as improvements in pathological left-ventricular remodeling, perfusion following acute myocardial infarction, and NYHA symptom class. Additionally, combined death, rehospitalization for heart failure, and infarction were significantly lower in patients treated with bone marrow-derived hematopoietic stem cells. Our review demonstrates that hematopoietic stem cell administration can lead to positive cardiac outcomes for HF patients. Future studies should aim to increase female representation and non-ischemic HF patients.

Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

Safety and biodistribution of XC001 (encoberminogene rezmadenovec) gene therapy in rats: a potential therapy for cardiovascular diseases

Adenovirus-mediated gene therapy holds promise for the treatment of cardiovascular diseases such as refractory angina. However, potential concerns around immunogenicity and vector dissemination from the target injected tissue require evaluation. This study was undertaken to evaluate the safety and biodistribution of XC001, a replication-deficient adenovirus serotype 5 vector expressing multiple isoforms of human vascular endothelial growth factor (VEGF), following direct administration into normal rat myocardium. Animals received the buffer formulation or increasing doses of XC001 (1 × 107, 2.5 × 108 or 2.5 × 109 viral particles). Based on in-life parameters (general health, body weights, clinical pathology, serum cardiac troponin I, plasma VEGF, and gross necropsy), there were no findings of clinical concern. On Day 8, intramyocardial administration of XC001 was associated with dose-related, left ventricular myocardial inflammation at injection sites, resolving by Day 30. XC001 DNA was not detected in blood at any time but was present at Day 8 around the site of injection and to a much lesser extent in the spleen, liver, and lungs, persisting at low levels in the heart and spleen until at least Day 91. These findings demonstrate that intramyocardial injection of XC001 is supported for use in human studies.

Mesenchymal STRO-1/STRO-3+ precursor cells for the treatment of chronic heart failure with reduced ejection fraction

The heart is susceptible to proinflammatory and profibrotic responses after myocardial injury, leading to further worsening of cardiac dysfunction. Important developments in the management of heart failure with reduced ejection fraction have reduced morbidity and mortality; however, these therapies focus on optimizing cardiac function through hemodynamic and neurohormonal pathways and not by repairing the underlying cardiac injury. The potential of cell-based therapy to reverse cardiac injury has received substantial attention. Herein are examined the phase II and III studies of bone marrow-derived mesenchymal STRO-1+ or STRO-1/STRO-3+ precursor cells in patients with ischemic and nonischemic heart failure with reduced ejection fraction, addressing the safety and efficacy of cell-based therapy throughout multiple clinical trials, the optimal dose and the steps toward revolutionizing the treatment of heart failure.

Direct cardiac reprogramming: A new technology for cardiac repair

Cardiovascular disease is one of the leading causes of morbidity and mortality worldwide, with myocardial infarctions being amongst the deadliest manifestations. Reduced blood flow to the heart can result in the death of cardiac tissue, leaving affected patients susceptible to further complications and recurrent disease. Further, contemporary management typically involves a pharmacopeia to manage the metabolic conditions contributing to atherosclerotic and hypertensive heart disease, rather than regeneration of the damaged myocardium. With modern healthcare extending lifespan, a larger demographic will be at risk for heart disease, driving the need for novel therapeutics that surpass those currently available in efficacy. Transdifferentiation and cellular reprogramming have been looked to as potential methods for the treatment of diseases throughout the body. Specifically targeting the fibrotic cells in cardiac scar tissue as a source to be reprogrammed into induced cardiomyocytes remains an appealing option. This review aims to highlight the history of and advances in cardiac reprogramming and describe its translational potential as a treatment for cardiovascular disease.

MicroRNAs as a Novel Player for Differentiation of Mesenchymal Stem Cells into Cardiomyocytes

Cardiovascular disease (CVD) is defined as a class of disorders affecting the heart and blood vessels. Cardiomyocytes and endothelial cells play important roles in cardiac regeneration and heart repair. However, the proliferating capacity of cardiomyocytes is limited. To overcome this issue, mesenchymal stem cells (MSCs) have emerged as an alternative strategy for CVD therapy. MSCs can proliferate and differentiate (or trans-differentiate) into cardiomyocytes. Several in vitro and in vivo differentiation protocols have been used to obtain MSCs-derived cardiomyocytes. It was recently investigated that microRNAs (miRNAs) by targeting several signaling pathways, including STAT3, Wnt/β-catenin, Notch, and TBX5, play a crucial role in regulating cardiomyocytes' differentiation of MSCs. In this review, we focused on the role of miRNAs in the differentiation of MSCs into cardiomyocytes.

Opportunities and challenges in stem cell therapy in cardiovascular diseases: Position standing in 2022

This study intends to evaluate the development, importance, pre-clinical and clinical study evaluation of stem cell therapy for the treatment of cardiovascular disease. Cardiovascular disease is one of the main causes of fatality in the whole world. Though there are great progressions in the pharmacological and other interventional treatment options, heart diseases remain a common disorder that causes long-term warnings. Recent accession promotes the symptoms and slows down the adverse effects regarding cardiac remodelling. But they cannot locate the problems of immutable loss of cardiac tissues. In this case, stem cell treatment holds a promising challenge. Stem cells are the cells that are capable of differentiating into many cells according to their needs. So, it is assumed that these cells can distinguish into many cells and if these cells can be individualized into cardiac cells then they can be used to replace the damaged tissues of the heart. There is some abridgment in this therapy, none the less stem cell therapy remains a hopeful destination in the treatment of heart disease.

Revascularization of chronic total occlusion coronary artery and cardiac regeneration

Coronary chronic total occlusion (CTO) contributes to the progression of heart failure in patients with ischemic cardiomyopathy. Randomized controlled trials demonstrated that percutaneous coronary intervention (PCI) for CTO significantly improves angina symptoms and quality of life but fails to reduce clinical events compared with optimal medical therapy. Even so, intervening physicians strongly support CTO-PCI. Cardiac regeneration therapy after CTO-PCI should be a promising approach to improving the prognosis of ischemic cardiomyopathy. However, the relationship between CTO revascularization and cardiac regeneration has rarely been studied, and experimental studies on cardiac regeneration usually employ rodent models with permanent ligation of the coronary artery rather than reopening of the occlusive artery. Limited early-stage clinical trials demonstrated that cell therapy for cardiac regeneration in ischemic cardiomyopathy reduces scar size, reverses cardiac remodeling, and promotes angiogenesis. This review focuses on the status quo of CTO-PCI in ischemic cardiomyopathy and the clinical prospect of cardiac regeneration in this setting.

Epicardial delivery of XC001 gene therapy for refractory angina coronary treatment (The EXACT Trial): Rationale, design, and clinical considerations

BACKGROUND

Patients with refractory angina (RA) have poor quality of life and new therapies are needed. XC001 is a novel adenoviral vector expressing multiple isoforms of vascular endothelial growth factor (VEGF) promoting an enhanced local angiogenic effect.

METHODS

The Epicardial Delivery of XC001 Gene Therapy for Refractory Angina Coronary Treatment (EXACT) trial is a 6-month (with 6-month extension) phase 1/2, first-in-human, multicenter, open-label, single-arm, dose-escalation study to evaluate the safety, tolerability, and preliminary efficacy of XC001 in patients with RA. The trial will enroll 33 patients in an initial (n = 12) ascending dose-escalation phase (1 × 10⁹, 1 × 10¹⁰, 4 × 10¹⁰, and 1 × 10¹¹ viral particles), followed by phase 2 (n = 21) assessing the highest tolerated dose. Patients must have stable Canadian Cardiovascular Society (CCS) class II-IV angina on maximally tolerated medical therapy without options for conventional revascularization, demonstrable ischemia on stress testing, and angina limiting exercise tolerance. XC001 will be delivered directly to ischemic myocardium via surgical transthoracic epicardial access. The primary outcome is safety via adverse event monitoring through 6 months. Efficacy assessments include difference from baseline to month 6 in time to 1 mm of ST segment depression, time to angina, and total exercise duration; myocardial blood flow at rest, and stress and coronary flow reserve by positron emission tomography; quality of life; CCS functional class; and angina frequency.

CONCLUSIONS

The EXACT trial will determine whether direct intramyocardial administration of XC001 in patients with RA is safe and evaluate its effect on exercise tolerance, myocardial perfusion, angina and physical activity, informing future clinical investigation.

CLINICAL TRIAL REGISTRATION

NCT04125732.

The Use of Mesenchymal Stem Cells and their Derived Extracellular Vesicles in Cardiovascular Disease Treatment

BACKGROUND

Cardiovascular disease (CVD), including disorders of cardiac muscle and vascular, is the major cause of death globally. Many unsuccessful attempts have been made to intervene in the disease's pathogenesis and treatment. Stem cell-based therapies, as a regeneration strategy, cast a new hope for CVD treatment. One of the most well-known stem cells is mesenchymal stem cells (MSCs), classified as one of the adult stem cells and can be obtained from different tissues. These cells have superior properties, such as proliferation and highly specialized differentiation. On the other hand, they have the potential to modulate the immune system and anti-inflammatory activity. One of their most important features is the secreting the extracellular vesicles (EVs) like exosomes (EXOs) as an intercellular communication system mediating the different physiological and pathophysiological affairs.

METHODS

In this review study, the importance of MSC and its secretory exosomes for the treatment of heart disease has been together and specifically addressed and the use of these promising natural and accessible agents is predicted to replace the current treatment modalities even faster than we imagine.

RESULTS

MSC derived EXOs by providing a pro-regenerative condition allowing innate stem cells to repair damaged tissues successfully. As a result, MSCs are considered as the appropriate cellular source in regenerative medicine. In the plethora of experiments, MSCs and MSC-EXOs have been used for the treatment and regeneration of heart diseases and myocardial lesions.

CONCLUSION

Administration of MSCs has been provided a replacement therapeutic option for heart regeneration, obtaining great attention among the basic researcher and the medical doctors.

Synergic effect of combined cyclosporin and melatonin protects the brain against acute ischemic reperfusion injury

BACKGROUND

This study tested whether combined cyclosporin-A (CsA) and melatonin (Mel) was superior to either one on protecting the brain against ischemia (occluded left-middle-cerebral-artery for 90-min)-reperfusion (for 14 days) injury.

METHODS AND RESULTS

Neuro-2a cells (N2a) were categorized into groups 1 (N2a), 2 (N2a-IR), 3 (N2a-IR-Mel), 4 (N2a-IR-CsA) and 5 (N2a-IR-CsA-Mel). in vitro results showed the protein expressions of cytosolic-cytochrome-C/mitochondrial-Bax/cleaved-capase-3/NOX-1/NOX-2 and flow-cytometric results of ROS (DCFDA/Mito-SOX) were highest in group 2, lowest in group 1, significantly lower in group 5 than in groups 3/4, but they showed no difference in groups 3/4 (all p < 0.001). Male-adult-SD rats (50) were equally categorized into groups 1 (sham-operated-control), 2 (IR), 3 (IR-CsA/20.0 mg/kg at 0.5/24/48 h intraperitoneally after IR), 4 (IR-Mel/50.0 mg/kg intraperitoneally at 30 min and 30 mg/kg at 6/24/48 h after IR) and 5 (IR-CsA-Mel). The brain-infarct-area (BIA) (at day-3 by TTC-stain) was lowest in group 1, highest in group 2, significantly lower in group 5 than groups 3/4, but it showed no difference between groups 3/4 whereas the brain-infarct-volume (at day 14 by MRI) was similar as BIA except for significantly lower in group 4 than in group 3 (all p < 0.0001). By day 14, microscopic finding showed the numbers of glial+/GFAP+/AQP + cells expressed an identical trend whereas the number of NeuN + cells exhibited an opposite pattern of BIA among the groups (all p < 0.0001). The protein expressions of oxidative-stress (NOX-1/NOX-2/p22phox/oxidized-protein), inflammatory (TNF-α/p-NF-κB/MMP-9), apoptotic (mitochondrial-Bax/caspase-3/PARP) and mitochondrial-damaged (Cyclophilin-D/DRP1/cytosolic-cytochrome-C) biomarkers displayed an identical pattern of BIA among the five groups (all p < 0.0001).

CONCLUSION

Combined CsA-Mel was superior to either CsA or Mel on protecting the brain against IR injury.

Cardiomyocyte Induction and Regeneration for Myocardial Infarction Treatment: Cell Sources and Administration Strategies

Occlusion of coronary artery and subsequent damage or death of myocardium can lead to myocardial infarction (MI) and even heart failure-one of the leading causes of deaths world wide. Notably, myocardium has extremely limited regeneration potential due to the loss or death of cardiomyocytes (i.e., the cells of which the myocardium is comprised) upon MI. A variety of stem cells and stem cell-derived cardiovascular cells, in situ cardiac fibroblasts and endogenous proliferative epicardium, have been exploited to provide renewable cellular sources to treat injured myocardium. Also, different strategies, including direct injection of cell suspensions, bioactive molecules, or cell-incorporated biomaterials, and implantation of artificial cardiac scaffolds (e.g., cell sheets and cardiac patches), have been developed to deliver renewable cells and/or bioactive molecules to the MI site for the myocardium regeneration. This article briefly surveys cell sources and delivery strategies, along with biomaterials and their processing techniques, developed for MI treatment. Key issues and challenges, as well as recommendations for future research, are also discussed.

Challenges of stem cell therapies in companion animal practice

Regenerative medicine using stem cells from various sources are emerging treatment modality in several refractory diseases in veterinary medicine. It is well-known that stem cells can differentiate into specific cell types, self-renew, and regenerate. In addition, the unique immunomodulatory effects of stem cells have made stem cell transplantation a promising option for treating a wide range of disease and injuries. Recently, the medical demands for companion animals have been rapidly increasing, and certain disease conditions require alternative treatment options. In this review, we focused on stem cell application research in companion animals including experimental models, case reports and clinical trials in dogs and cats. The clinical studies and therapeutic protocols were categorized, evaluated and summarized according to the organ systems involved. The results indicate that evidence for the effectiveness of cell-based treatment in specific diseases or organ systems is not yet conclusive. Nonetheless, stem cell therapy may be a realistic treatment option in the near future, therefore, considerable efforts are needed to find optimized cell sources, cell numbers and delivery methods in order to standardize treatment methods and evaluation processes.

Mesenchymal stem cell mediates cardiac repair through autocrine, paracrine and endocrine axes

In the past decade, despite key advances in therapeutic strategies following myocardial infarction, none can directly address the loss of cardiomyocytes following ischemic injury. Cardiac cell-based therapy is at the cornerstone of regenerative medicine that has shown potential for tissue repair. Mesenchymal stem cells (MSC) represent a strong candidate to heal the infarcted myocardium. While differentiation potential has been described as a possible avenue for MSC-based repair, their secreted mediators are responsible for the majority of the ascribed prohealing effects. MSC can either promote their own survival and proliferation through autocrine effect or secrete trophic factors that will act on adjacent cells through a paracrine effect. Prior studies have also documented beneficial effects even when MSCs were remotely delivered, much akin to an endocrine mechanism. This review aims to distinguish the paracrine activity of MSCs from an endocrine-like effect, where remotely transplanted cells can promote healing of the injured myocardium.

Clinical Safety Profile of Transendocardial Catheter Injection Systems: A Plea for Uniform Reporting

OBJECTIVES

The aim of this study was to characterize the clinical safety profile of transendocardial injection catheters (TIC) reported in the published literature.

BACKGROUND

Transendocardial delivery is a minimally invasive approach to deliver potential therapeutic agents directly into the myocardium. The rate of adverse events across TIC is uncertain.

METHODS

A systematic search was performed for trial publications using TIC. Procedure-associated adverse event data were abstracted, pooled and compared across catheters for active treatment and placebo injected patients. The transendocardial injection associated serious adverse events (TEI-SAE) was defined as the composite of death, myocardial infarction, stroke or transient ischemic attack within 30 days and cardiac perforation causing death or requiring evacuation, serious intraprocedural arrhythmias and serious coronary artery or peripheral vascular complications.

RESULTS

The search identified 4 TIC systems: a helical needle (HN), an electro-anatomically tracked straight needle (EAM-SN), a straight needle without tracking elements (SN), and a curved needle (CN). Of 1799 patients who underwent transendocardial injections, the combined TEI-SAE was 3.4% across all catheters, and 1.1%, 3.3%, 7.1%, and 8.3% for HN, EAM-SN, SN and CN, respectively. However, TIC procedure duration and post procedural cardiac biomarker levels were reported in only 24% and 36% of published trials, respectively.

CONCLUSIONS

Transendocardial injection is associated with varied TEI-SAE but the data are very limited. The HN catheter appeared to be associated with lower TEI-SAE, versus other catheters. Procedure duration and post procedure cardiac biomarker levels were under-reported. Clearly, standardized, procedure-related event reporting for trials involving transcatheter delivery would improve our understanding of complications across different systems.

Selective perfusion of coronary vasculature in preterm sheep: a methodological innovation undermined by unfavourable operation of the foramen ovale

Antenatal cardiac intervention affords new prospects for hypoplastic left heart syndrome. Its success, however, may come not only from absence of impediments to blood flow but also from a sufficiently developed cardiac wall. Here, we examined the feasibility to perfuse selectively the fetal coronary circulation for treatment with growth promoting agents. Pregnant sheep (94-114 days gestation, term 145 days) were used. An aortic stop-flow procedure was developed for intracoronary access in the nonexposed fetus and human mesenchymal stem cells and their exosomes served as test agents. We found that aortic stop-flow ensures preferential distribution of fluorescent microspheres to the heart. However, intracoronary administration of stem cells or exosomes was detrimental, with fetal demise occurring around surgery or at variable intervals afterwards. Coincidentally, stop-flow caused by itself a marked rise of intraluminal pressure within the occluded aorta along with histological signs of coronary obstruction. We conclude that it is feasible to perfuse selectively the coronary circulation of the preterm fetus, but treatments are not compatible with survival of the animals. The cause for failure is found in the absence of hemodynamic compensation to stop-flow via a left-to-right shunt. This unexpected event is attributed to a largely membranous foramen ovale, characteristic of sheep, that collapses under pressure.

Systemic and local delivery of mesenchymal stem cells for heart renovation: Challenges and innovations

In the beginning stage of heart disease, the blockage of blood flow frequently occurs due to the persistent damage and even death of myocardium. Cicatricial tissue developed after the death of myocardium can affect heart function, which ultimately leads to heart failure. In recent years, several studies carried out about the use of stem cells such as embryonic, pluripotent, cardiac and bone marrow-derived stem cells as well as myoblasts to repair injured myocardium. Current studies focus more on finding appropriate measures to enhance cell homing and survival in order to increase paracrine function. Until now, there is no universal delivery route for mesenchymal stem cells (MSCs) for different diseases. In this review, we summarize the advantages and challenges of the systemic and local pathways of MSC delivery. In addition, we also describe some advanced measures of cell delivery to improve the efficiency of transplantation. The combination of cells and therapeutic substances could be the most reliable method, which allows donor cells to deliver sufficient amounts of paracrine factors and provide long-lasting effects. The cardiac support devices or tissue engineering techniques have the potential to facilitate the controlled release of stem cells on local tissue for a sustained period. A novel promising epicardial drug delivery system is highlighted here, which not only provides MSCs with a favorable environment to promote retention but also increases the contact area and a number of cells recruited in the heart muscle.

Mesenchymal stem cell perspective: cell biology to clinical progress

The terms MSC and MSCs have become the preferred acronym to describe a cell and a cell population of multipotential stem/progenitor cells commonly referred to as mesenchymal stem cells, multipotential stromal cells, mesenchymal stromal cells, and mesenchymal progenitor cells. The MSCs can differentiate to important lineages under defined conditions in vitro and in limited situations after implantation in vivo. MSCs were isolated and described about 30 years ago and now there are over 55,000 publications on MSCs readily available. Here, we have focused on human MSCs whenever possible. The MSCs have broad anti-inflammatory and immune-modulatory properties. At present, these provide the greatest focus of human MSCs in clinical testing; however, the properties of cultured MSCs in vitro suggest they can have broader applications. The medical utility of MSCs continues to be investigated in over 950 clinical trials. There has been much progress in understanding MSCs over the years, and there is a strong foundation for future scientific research and clinical applications, but also some important questions remain to be answered. Developing further methods to understand and unlock MSC potential through intracellular and intercellular signaling, biomedical engineering, delivery methods and patient selection should all provide substantial advancements in the coming years and greater clinical opportunities. The expansive and growing field of MSC research is teaching us basic human cell biology as well as how to use this type of cell for cellular therapy in a variety of clinical settings, and while much promise is evident, careful new work is still needed.

On the Road to Regeneration: "Tools" and "Routes" Towards Efficient Cardiac Cell Therapy for Ischemic Cardiomyopathy

PURPOSE OF REVIEW

Cardiac regenerative medicine is a field bridging together biotechnology and surgical science. In this review, we present the explored surgical roads to cell delivery and the known effects of each delivery method on cell therapy efficiency. We also list the more recent clinical trials, exploring the safety and efficacy of delivery routes used for cardiac cell therapy approaches.

RECENT FINDINGS

There is no consensus in defining which way is the most suitable for the delivery of the different therapeutic cell types to the damaged heart tissue. In addition, it emerged that the "delivery issue" has not been systematically addressed in each clinical trial and for each and every cell type capable of cardiac repair. Cardiac damage occurring after an ischemic insult triggers a cascade of cellular events, eventually leading to heart failure through fibrosis and maladaptive remodelling. None of the pharmacological or medical interventions approved so far can rescue or reverse this phenomenon, and cardiovascular diseases are still the leading cause of death in the western world. Therefore, for nearly 20 years, regenerative medicine approaches have focused on cell therapy as a promising road to pursue, with numerous preclinical and clinical testing of cell-based therapies being studied and developed. Nonetheless, consistent clinical results are still missing to reach consensus on the most effective strategy for ischemic cardiomyopathy, based on patient selection, diagnosis and stage of the disease, therapeutic cell type, and delivery route.

Efficacy of mesenchymal stem cell therapy in systolic heart failure: a systematic review and meta-analysis

Background

Heart failure (HF) is the end stage of most heart disease. Mesenchymal stem cells (MSCs), with their specific biological effects, have been applied in several clinical trials to evaluate the efficacy in HF therapy. We performed this meta-analysis to review the clinical evidence of their therapeutic effect on HF.

Methods

Three databases were searched. The outcomes of interest were death, readmission, the 6-min walk test (6MWT), New York Heart Association (NYHA) class and left ventricular ejection fraction (LVEF). The relative risk (RR) and weighted mean difference (WMD) were calculated to evaluate the effects of MSCs on HF compared to placebo.

Results

A total of nine studies were included, involving 612 patients who underwent MSCs or placebo treatment. The overall rate of death showed a trend of reduction of 36% (RR [CI] = 0.64 [0.35, 1.16], p = 0.143) in the MSC treatment group. The incidence of readmission was reduced by 34% (RR [CI] = 0.66 [0.51, 0.85], p = 0.001). The patients in the MSC treatment group realised an average of 40.44 m (WMD [95% CI] = 40.44 m [19.07, 61.82], p < 0.0001) improvement in 6MWT. The NYHA class was reduced obviously in the MSC group (WMD [95% CI] = − 0.42 [− 0.64, − 0.20], p < 0.0001). The changes of LVEF from baseline were significantly more than 5.25% (WMD [95% CI] = 5.25 [3.58, 6.92], p < 0.0001) in the MSCs group, unlike in the placebo group.

Conclusions

Our results suggested that MSC treatment is an effective therapy for HF by improving the prognosis and exercise capacity. SCs derived from allosomes have superior therapeutic effects, and intracoronary injection is the optimum MSC delivery approach. Short-term cryopreservation is feasible in MSCs storage or transport.

Therapeutic potential of menstrual blood-derived endometrial stem cells in cardiac diseases

Despite significant developments in medical and surgical strategies, cardiac diseases remain the leading causes of morbidity and mortality worldwide. Numerous studies involving preclinical and clinical trials have confirmed that stem cell transplantation can help improve cardiac function and regenerate damaged cardiac tissue, and stem cells isolated from bone marrow, heart tissue, adipose tissue and umbilical cord are the primary candidates for transplantation. During the past decade, menstrual blood-derived endometrial stem cells (MenSCs) have gradually become a promising alternative for stem cell-based therapy due to their comprehensive advantages, which include their ability to be periodically and non-invasively collected, their abundant source material, their ability to be regularly donated, their superior proliferative capacity and their ability to be used for autologous transplantation. MenSCs have shown positive therapeutic potential for the treatment of various diseases. Therefore, aside from a brief introduction of the biological characteristics of MenSCs, this review focuses on the progress being made in evaluating the functional improvement of damaged cardiac tissue after MenSC transplantation through preclinical and clinical studies. Based on published reports, we conclude that the paracrine effect, transdifferentiation and immunomodulation by MenSC promote both regeneration of damaged myocardium and improvement of cardiac function.

Placental Stem Cells from Domestic Animals: Translational Potential and Clinical Relevance

The field of regenerative medicine is moving toward clinical practice in veterinary science. In this context, placenta-derived stem cells isolated from domestic animals have covered a dual role, acting both as therapies for patients and as a valuable cell source for translational models. The biological properties of placenta-derived cells, comparable among mammals, make them attractive candidates for therapeutic approaches. In particular, stemness features, low immunogenicity, immunomodulatory activity, multilineage plasticity, and their successful capacity for long-term engraftment in different host tissues after autotransplantation, allo-transplantation, or xenotransplantation have been demonstrated. Their beneficial regenerative effects in domestic animals have been proven using preclinical studies as well as clinical trials starting to define the mechanisms involved. This is, in particular, for amniotic-derived cells that have been thoroughly studied to date. The regenerative role arises from a mutual tissue-specific cell differentiation and from the paracrine secretion of bioactive molecules that ultimately drive crucial repair processes in host tissues (e.g., anti-inflammatory, antifibrotic, angiogenic, and neurogenic factors). The knowledge acquired so far on the mechanisms of placenta-derived stem cells in animal models represent the proof of concept of their successful use in some therapeutic treatments such as for musculoskeletal disorders. In the next future, legislation in veterinary regenerative medicine will be a key element in order to certify those placenta-derived cell-based protocols that have already demonstrated their safety and efficacy using rigorous approaches and to improve the degree of standardization of cell-based treatments among veterinary clinicians.

Mesenchymal stem cell basic research and applications in dog medicine

The stem cells, owing to their special characteristics like self-renewal, multiplication, homing, immunomodulation, anti-inflammatory, and dedifferentiation are considered to carry an "all-in-one-solution" for diverse clinical problems. However, the limited understanding of cellular physiology currently limits their definitive therapeutic use. Among various stem cell types, currently mesenchymal stem cells are extensively studied for dog clinical applications owing to their readily available sources, easy harvesting, and ability to differentiate both into mesodermal, as well as extramesodermal tissues. The isolated, culture expanded, and characterized cells have been applied both at preclinical as well as clinical settings in dogs with variable but mostly positive results. The results, though positive, are currently inconclusive and demands further intensive research on the properties and their dependence on the applications. Further, numerous clinical conditions of dog resemble to that of human counterparts and thus, if proved rewarding in the former may act as basis of therapy for the latter. The current review throws some light on dog mesenchymal stem cell properties and their potential therapeutic applications.

Cancer metastasis versus stem cell homing: Role of platelets

One of the major obstacles in achieving a successful stem cell therapy is insufficient homing of transplanted cells. To overcome this obstacle, understanding the underlying mechanisms of stem cell homing is of obvious importance. Central to this review is the concept that cancer metastasis can be viewed as a role model to build up a comprehensive concept of stem cell homing. In this novel perspective, the prosurvival choices of the cancerous cells in the bloodstream, their arrest, extravasation, and proliferation at the secondary site can be exploited in favor of targeted stem cell homing. To date, tumor cells have been found to employ a wide variety of strategies to promote metastasis. One of these strategies is through their ability to activate platelets and subsequently activated platelets serve cancer cell survival and metastasis. Accordingly, in the first part of this review the roles of platelets in cancer metastasis as well as stem cell homing are discussed. Next, we provide some lessons learned from cancer metastasis in favor of developing strategies for improvement of stem cell homing with emphasis on the role of platelets. Based on direct or indirect evidence from metastasis, strategies such as manipulation of stem cells to enhance interaction with platelets, preconditioning-pretreatment of stem cells with platelets in vitro, and coinjection of both stem cells and platelets are proposed to improve stem cell homing.

Current Status of Canine Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Veterinary Medicine

Stem cell therapy has prompted the expansion of veterinary medicine both experimentally and clinically, with the potential to contribute to contemporary treatment strategies for various diseases and conditions for which limited or no therapeutic options are presently available. Although the application of various types of stem cells, such as bone marrow-derived mesenchymal stem cells (BM-MSCs), adipose tissue-derived mesenchymal stem cells (AT-MSCs), and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), has promising potential to improve the health of different species, it is crucial that the benefits and drawbacks are completely evaluated before use. Umbilical cord blood (UCB) is a rich source of stem cells; nonetheless, isolation of mesenchymal stem cells (MSCs) from UCB presents technical challenges. Although MSCs have been isolated from UCB of diverse species such as human, equine, sheep, goat, and canine, there are inherent limitations of using UCB from these species for the expansion of MSCs. In this review, we investigated canine UCB (cUCB) and compared it with UCB from other species by reviewing recent articles published from February 2003 to June 2017 to gain an understanding of the limitations of cUCB in the acquisition of MSCs and to determine other suitable sources for the isolation of MSCs from canine. Our review indicates that cUCB is not an ideal source of MSCs because of insufficient volume and ethical issues. However, canine reproductive organs discarded during neutering may help broaden our understanding of effective isolation of MSCs. We recommend exploring canine reproductive and adipose tissue rather than UCB to fulfill the current need in veterinary medicine for the well-designed and ethically approved source of MSCs.

The CardiAMP Heart Failure trial: A randomized controlled pivotal trial of high-dose autologous bone marrow mononuclear cells using the CardiAMP cell therapy system in patients with post-myocardial infarction heart failure: Trial rationale and study design

BACKGROUND

Heart failure following myocardial infarction is a common, disabling, and deadly condition. Direct injection of autologous bone marrow mononuclear cells into the myocardium may result in improved functional recovery, relieve symptoms, and improve other cardiovascular outcomes.

METHODS

CardiAMP-HF is a randomized, double-blind, sham-controlled, pivotal trial designed to investigate the safety and efficacy of autologous bone marrow mononuclear cells treatment for patients with medically refractory and symptomatic ischemic cardiomyopathy. The primary end point is change in 6-minute walk distance adjusted for major adverse cardiovascular events at 12 months following treatment. Particularly novel aspects of this trial include a cell potency assay to screen subjects who have bone marrow cell characteristics that suggest a favorable response to treatment, a point-of-care treatment method, a high target dose of 200 million cells, and an efficient transcatheter intramyocardial delivery method that is associated with high cell retention.

CONCLUSIONS

This novel approach may lead to a new treatment for those with ischemic heart disease suffering from medically refractory heart failure.

Percutaneous Contrast Echocardiography-guided Intramyocardial Injection and Cell Delivery in a Large Preclinical Model

Cell and gene therapy are exciting and promising strategies for the purpose of cardiac regeneration in the setting of heart failure with reduced ejection fraction (HFrEF). Before they can be considered for use, and implemented in humans, extensive preclinical studies are required in large animal models to evaluate the safety, efficacy, and fate of the injectate (e.g., stem cells) once delivered into the myocardium. Small rodent models offer advantages (e.g., cost effectiveness, amenability for genetic manipulation); however, given inherent limitations of these models, the findings in these rarely translate into the clinic. Conversely, large animal models such as rabbits, have advantages (e.g., similar cardiac electrophysiology compared to humans and other large animals), whilst retaining a good cost-effective balance. Here, we demonstrate how to perform a percutaneous contrast echocardiography-guided intramyocardial injection (IMI) technique, which is minimally invasive, safe, well tolerated, and very effective in the targeted delivery of injectates, including cells, into several locations within the myocardium of a rabbit model. For the implementation of this technique, we also have taken advantage of a widely available clinical echocardiography system. After putting in practice the protocol described here, a researcher with basic ultrasound knowledge will become competent in the performance of this versatile and minimally invasive technique for routine use in experiments, aimed at hypothesis testing of the capabilities of cardiac regenerative therapeutics in the rabbit model. Once competency is achieved, the whole procedure can be performed within 25 min after anaesthetizing the rabbit.

Concise Review: Mesenchymal Stem Cells in Cardiovascular Regeneration: Emerging Research Directions and Clinical Applications

Experimental and early clinical data suggest that, due to several unique properties, mesenchymal stem cells (MSCs) may be more effective than other cell types for diseases that are difficult to treat or untreatable. Owing to their ease of isolation and culture as well as their secretory and immunomodulatory abilities, MSCs are the most promising option in the field of cell-based therapies. Although MSCs from various sources share several common characteristics, they also exhibit several important differences. These variations may reflect, in part, specific regional properties of the niches from which the cells originate. Moreover, morphological and functional features of MSCs are susceptible to variations across isolation protocols and cell culture conditions. These observations suggest that careful preparation of manufacturing protocols will be necessary for the most efficient use of MSCs in future clinical trials. A typical human myocardial infarct involves the loss of approximately 1 billion cardiomyocytes and 2-3 billion other (mostly endothelial) myocardial cells, leading (despite maximized medical therapy) to a significant negative impact on the length and quality of life. Despite more than a decade of intensive research, search for the "best" (safe and maximally effective) cell type to drive myocardial regeneration continues. In this review, we summarize information about the most important features of MSCs and recent discoveries in the field of MSCs research, and describe current data from preclinical and early clinical studies on the use of MSCs in cardiovascular regeneration. Stem Cells Translational Medicine 2017;6:1859-1867.

Dose Comparison Study of Allogeneic Mesenchymal Stem Cells in Patients With Ischemic Cardiomyopathy (The TRIDENT Study)

RATIONALE

Cell dose and concentration play crucial roles in phenotypic responses to cell-based therapy for heart failure.

OBJECTIVE

To compare the safety and efficacy of 2 doses of allogeneic bone marrow-derived human mesenchymal stem cells identically delivered in patients with ischemic cardiomyopathy.

METHODS AND RESULTS

Thirty patients with ischemic cardiomyopathy received in a blinded manner either 20 million (n=15) or 100 million (n=15) allogeneic human mesenchymal stem cells via transendocardial injection (0.5 cc per injection × 10 injections per patient). Patients were followed for 12 months for safety and efficacy end points. There were no treatment-emergent serious adverse events at 30 days or treatment-related serious adverse events at 12 months. The Major Adverse Cardiac Event rate was 20.0% (95% confidence interval [CI], 6.9% to 50.0%) in 20 million and 13.3% (95% CI, 3.5% to 43.6%) in 100 million (P=0.58). Worsening heart failure rehospitalization was 20.0% (95% CI, 6.9% to 50.0%) in 20 million and 7.1% (95% CI, 1.0% to 40.9%) in 100 million (P=0.27). Whereas scar size reduced to a similar degree in both groups: 20 million by -6.4 g (interquartile range, -13.5 to -3.4 g; P=0.001) and 100 million by -6.1 g (interquartile range, -8.1 to -4.6 g; P=0.0002), the ejection fraction improved only with 100 million by 3.7 U (interquartile range, 1.1 to 6.1; P=0.04). New York Heart Association class improved at 12 months in 35.7% (95% CI, 12.7% to 64.9%) in 20 million and 42.9% (95% CI, 17.7% to 71.1%) in 100 million. Importantly, proBNP (pro-brain natriuretic peptide) increased at 12 months in 20 million by 0.32 log pg/mL (95% CI, 0.02 to 0.62; P=0.039), but not in 100 million (-0.07 log pg/mL; 95% CI, -0.36 to 0.23; P=0.65; between group P=0.07).

CONCLUSIONS

Although both cell doses reduced scar size, only the 100 million dose increased ejection fraction. This study highlights the crucial role of cell dose in the responses to cell therapy. Determining optimal dose and delivery is essential to advance the field, decipher mechanism(s) of action and enhance planning of pivotal Phase III trials.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02013674.

Is Cardioprotection Dead?

For >4 decades, the holy grail in the treatment of acute myocardial infarction has been the mitigation of lethal injury. Despite promising initial results and decades of investigation by the cardiology research community, the only treatment with proven efficacy is early reperfusion of the occluded coronary artery. The remarkable record of failure has led us and others to wonder if cardioprotection is dead. The path to translation, like the ascent to Everest, is certainly littered with corpses. We do, however, highlight a therapeutic principle that provides a glimmer of hope: cellular postconditioning. Administration of cardiosphere-derived cells after reperfusion limits infarct size measured acutely, while providing long-term structural and functional benefits. The recognition that cell therapy may be cardioprotective, and not just regenerative, merits further exploration before we abandon the pursuit entirely.

Cellular mechanisms underlying cardiac engraftment of stem cells

INTRODUCTION

Over the past decade, it has become clear that long-term engraftment of any ex vivo expanded cell product transplanted into injured myocardium is modest and all therapeutic regeneration is mediated by stimulation of endogenous repair rather than differentiation of transplanted cells into working myocardium. Given that increasing the retention of transplanted cells boosts myocardial function, focus on the fundamental mechanisms limiting retention and survival of transplanted cells may enable strategies to help to restore normal cardiac function. Areas covered: This review outlines the challenges confronting cardiac engraftment of ex vivo expanded cells and explores means of enhancing cell-mediated repair of injured myocardium. Expert opinion: Stem cell therapy has already come a long way in terms of regenerating damaged hearts though the poor retention of transplanted cells limits the full potential of truly cardiotrophic cell products. Multifaceted strategies directed towards fundamental mechanisms limiting the long-term survival of transplanted cells will be needed to enhance transplanted cell retention and cell-mediated repair of damaged myocardium for cardiac cell therapy to reach its full potential.

Suppression of Canine Dendritic Cell Activation/Maturation and Inflammatory Cytokine Release by Mesenchymal Stem Cells Occurs Through Multiple Distinct Biochemical Pathways

Mesenchymal stem cells (MSC) represent a readily accessible source of cells with potent immune modulatory activity. MSC can suppress ongoing inflammatory responses by suppressing T cell function, while fewer studies have examined the impact of MSC on dendritic cell (DC) function. The dog spontaneous disease model represents an important animal model with which to evaluate the safety and effectiveness of cellular therapy with MSC. This study evaluated the effects of canine MSC on the activation and maturation of canine monocyte-derived DC, as well as mechanisms underlying these effects. Adipose-derived canine MSC were cocultured with canine DC, and the MSC effects on DC maturation and activation were assessed by flow cytometry, cytokine ELISA, and confocal microscopy. We found that canine MSC significantly suppressed lipopolysaccharide (LPS)-stimulated upregulation of DC activation markers such as major histocompatibility class II (MHCII), CD86, and CD40. Furthermore, pretreatment of MSC with interferon gamma (IFNγ) augmented this suppressive activity. IFNγ-activated MSC also significantly reduced LPS-elicited DC secretion of tumor necrosis factor alpha without reducing secretion of interleukin-10. The suppressive effect of IFNγ-treated MSC on LPS-induced DC activation was mediated by soluble factors secreted by both MSC and DC. Pathways of DC functional suppression included programmed death ligand-1 expression and secretion of nitrous oxide, prostaglandin E2, and adenosine by activated MSC. Coculture of DC with IFNγ-treated MSC maintained DC in an immature state and prolonged DC antigen uptake during LPS maturation stimulus. Taken together, canine MSC are capable of potently suppressing DC function in a potentially inflammatory microenvironment through several separate immunological pathways and confirm the potential for immune therapy with MSC in canine immune-mediated disease models.

Cellular Therapy for Heart Failure

The pathogenesis of cardiomyopathy and heart failure (HF) is underpinned by complex changes at subcellular, cellular and extracellular levels in the ventricular myocardium. For all of the gains that conventional treatments for HF have brought to mortality and morbidity, they do not adequately address the loss of cardiomyocyte numbers in the remodeling ventricle. Originally conceived to address this problem, cellular transplantation for HF has already gone through several stages of evolution over the past two decades. Various cell types and delivery routes have been implemented to positive effect in preclinical models of ischemic and nonischemic cardiomyopathy, with pleiotropic benefits observed in terms of myocardial remodeling, systolic and diastolic performance, perfusion, fibrosis, inflammation, metabolism and electrophysiology. To a large extent, these salubrious effects are now attributed to the indirect, paracrine capacity of transplanted stem cells to facilitate endogenous cardiac repair processes. Promising results have also followed in early phase human studies, although these have been relatively modest and somewhat inconsistent. This review details the preclinical and clinical evidence currently available regarding the use of pluripotent stem cells and adult-derived progenitor cells for cardiomyopathy and HF. It outlines the important lessons that have been learned to this point in time, and balances the promise of this exciting field against the key challenges and questions that still need to be addressed at all levels of research, to ensure that cell therapy realizes its full potential by adding to the armamentarium of HF management.

Externally Applied Static Magnetic Field Enhances Cardiac Retention and Functional Benefit of Magnetically Iron-Labeled Adipose-Derived Stem Cells in Infarcted Hearts

: Although adipose-derived stem cells (ASCs) hold the promise of effective therapy for myocardial infarction, low cardiac retention of implanted ASCs has hindered their therapeutic efficiency. We investigated whether an externally applied static magnetic field (SMF) enhances cardiac localization of "magnetic" cells and promotes heart function recovery when ASCs are preloaded with superparamagnetic iron oxide (SPIO) nanoparticles. The influence of SMF (0.1 Tesla) on the biological activities of SPIO-labeled ASCs (_SPIOASCs) was investigated first. Fifty-six female rats with myocardial infarction underwent intramyocardial injection of cell culture medium (CCM) or male _SPIOASCs with or without the subcutaneous implantable magnet (CCM-magnet or _SPIOASC-magnet). Four weeks later, endothelial differentiation, angiogenic cytokine secretion, angiogenesis, cardiomyocyte apoptosis, cell retention, and cardiac performance were examined. The 0.1-Tsela SMF did not adversely affect the viability, proliferation, angiogenic cytokine secretion, and DNA integrity of _SPIOASCs. The implanted _SPIOASCs could differentiate into endothelial cell, incorporate into newly formed vessels, and secrete multiple angiogenic cytokines. Four weeks after cell transplantation, the number of cardiac _SPIOASCs was significantly increased, vascular density was markedly enlarged, fewer apoptotic cardiomyocytes were present, and heart contractile function was substantially improved in the _SPIOASC-magnet treated rats in comparison with the _SPIOASC-treated rats. The _SPIOASCs could differentiate into endothelial cells, incorporate into vessels, promote angiogenesis, and inhibit ischemic cardiomyocyte apoptosis. An externally applied SMF offered a secure environment for biological properties of _SPIOASCs, increased the cardiac retention of implanted magnetic _SPIOASCs, and further enhanced heart function recovery after myocardial infarction.

SIGNIFICANCE

This pilot proof-of-concept study suggests that a 0.1-Tesla static magnetic field does not adversely affect the viability, proliferation, angiogenic cytokine secretion, or DNA integrity of the superparamagnetic iron oxide-labeled adipose-derived stem cells (_SPIOASCs). Implantation of adipose-derived stem cells promotes myocardial neovascularization and inhibits ischemic cardiomyocyte apoptosis through endothelial differentiation, incorporation into vessels, and paracrine factor secretion. An externally applied static magnetic field enhanced myocardial retention of intramyocardially injected "magnetic" _SPIOASCs and promoted cardiac function recovery after myocardial infarction. With further preclinical optimization, this approach may improve the outcome of current stem cell therapy for ischemic myocardial infarction.

Rebuilding the Damaged Heart: Mesenchymal Stem Cells, Cell-Based Therapy, and Engineered Heart Tissue

Mesenchymal stem cells (MSCs) are broadly distributed cells that retain postnatal capacity for self-renewal and multilineage differentiation. MSCs evade immune detection, secrete an array of anti-inflammatory and anti-fibrotic mediators, and very importantly activate resident precursors. These properties form the basis for the strategy of clinical application of cell-based therapeutics for inflammatory and fibrotic conditions. In cardiovascular medicine, administration of autologous or allogeneic MSCs in patients with ischemic and nonischemic cardiomyopathy holds significant promise. Numerous preclinical studies of ischemic and nonischemic cardiomyopathy employing MSC-based therapy have demonstrated that the properties of reducing fibrosis, stimulating angiogenesis, and cardiomyogenesis have led to improvements in the structure and function of remodeled ventricles. Further attempts have been made to augment MSCs' effects through genetic modification and cell preconditioning. Progression of MSC therapy to early clinical trials has supported their role in improving cardiac structure and function, functional capacity, and patient quality of life. Emerging data have supported larger clinical trials that have been either completed or are currently underway. Mechanistically, MSC therapy is thought to benefit the heart by stimulating innate anti-fibrotic and regenerative responses. The mechanisms of action involve paracrine signaling, cell-cell interactions, and fusion with resident cells. Trans-differentiation of MSCs to bona fide cardiomyocytes and coronary vessels is also thought to occur, although at a nonphysiological level. Recently, MSC-based tissue engineering for cardiovascular disease has been examined with quite encouraging results. This review discusses MSCs from their basic biological characteristics to their role as a promising therapeutic strategy for clinical cardiovascular disease.

Human Umbilical Cord-Derived Mesenchymal Stromal Cells Improve Left Ventricular Function, Perfusion, and Remodeling in a Porcine Model of Chronic Myocardial Ischemia

: Stem cell therapy has emerged as a new strategy for treatment of ischemic heart disease. Although umbilical cord-derived mesenchymal stromal cells (UC-MSCs) have been used preferentially in the acute ischemia model, data for the chronic ischemia model are lacking. In this study, we investigated the effect of UC-MSCs originated from Wharton's jelly in the treatment of chronic myocardial ischemia in a porcine model induced by ameroid constrictor. Four weeks after ameroid constrictor placement, the surviving animals were divided randomly into two groups to undergo saline injection (n = 6) or UC-MSC transplantation (n = 6) through the left main coronary artery. Two additional intravenous administrations of UC-MSCs were performed in the following 2 weeks to enhance therapeutic effect. Cardiac function and perfusion were examined just before and at 4 weeks after intracoronary transplantation. The results showed that pigs with UC-MSC transplantation exhibited significantly greater left ventricular ejection fraction compared with control animals (61.3% ± 1.3% vs. 50.3% ± 2.0%, p < .05). The systolic thickening fraction in the infarcted left ventricular wall was also improved (41.2% ± 3.3% vs. 46.2% ± 2.3%, p < .01). Additionally, the administration of UC-MSCs promoted collateral development and myocardial perfusion. The indices of fibrosis and apoptosis were also significantly reduced. Immunofluorescence staining showed clusters of CM-DiI-labeled cells in the border zone, some of which expressed von Willebrand factor. These results suggest that UC-MSC treatment improves left ventricular function, perfusion, and remodeling in a porcine model with chronic myocardial ischemia.

SIGNIFICANCE

Ischemic heart disease is the leading cause of death worldwide. Many patients with chronic myocardial ischemia are not suitable for surgery and have no effective drug treatment; they are called "no-option" patients. This study finds that umbilical cord-derived mesenchymal stromal cells transplanted by intracoronary delivery combined with two intravenous administrations was safe and could significantly improve left ventricular function, perfusion, and remodeling in a large-animal model of chronic myocardial ischemia, which provides a new choice for the no-option patients. In addition, this study used clinical-grade mesenchymal stem cells with delivery and assessment methods commonly used clinically to facilitate further clinical transformation.

Modeling Doxorubicin-Induced Cardiotoxicity in Human Pluripotent Stem Cell Derived-Cardiomyocytes

Doxorubicin is a highly efficacious anti-cancer drug but causes cardiotoxicity in many patients. The mechanisms of doxorubicin-induced cardiotoxicity (DIC) remain incompletely understood. We investigated the characteristics and molecular mechanisms of DIC in human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). We found that doxorubicin causes dose-dependent increases in apoptotic and necrotic cell death, reactive oxygen species production, mitochondrial dysfunction and increased intracellular calcium concentration. We characterized genome-wide changes in gene expression caused by doxorubicin using RNA-seq, as well as electrophysiological abnormalities caused by doxorubicin with multi-electrode array technology. Finally, we show that CRISPR-Cas9-mediated disruption of TOP2B, a gene implicated in DIC in mouse studies, significantly reduces the sensitivity of hPSC-CMs to doxorubicin-induced double stranded DNA breaks and cell death. These data establish a human cellular model of DIC that recapitulates many of the cardinal features of this adverse drug reaction and could enable screening for protective agents against DIC as well as assessment of genetic variants involved in doxorubicin response.

Widespread Myocardial Delivery of Heart-Derived Stem Cells by Nonocclusive Triple-Vessel Intracoronary Infusion in Porcine Ischemic Cardiomyopathy: Superior Attenuation of Adverse Remodeling Documented by Magnetic Resonance Imaging and Histology

Single-vessel, intracoronary infusion of stem cells under stop-flow conditions has proven safe but achieves only limited myocardial coverage. Continuous flow intracoronary delivery to one or more coronary vessels may achieve broader coverage for treating cardiomyopathy, but has not been investigated. Using nonocclusive coronary guiding catheters, we infused allogeneic cardiosphere-derived cells (CDCs) either in a single vessel or sequentially in all three coronary arteries in porcine ischemic cardiomyopathy and used magnetic resonance imaging (MRI) to assess structural and physiological outcomes. Vehicle-infused animals served as controls. Single-vessel stop-flow and continuous-flow intracoronary infusion revealed equivalent effects on scar size and function. Sequential infusion into each of the three major coronary vessels under stop-flow or continuous-flow conditions revealed equal efficacy, but less elevation of necrotic biomarkers with continuous-flow delivery. In addition, multi-vessel delivery resulted in enhanced global and regional tissue function compared to a triple-vessel placebo-treated group. The functional benefits after global cell infusion were accompanied histologically by minimal inflammatory cellular infiltration, attenuated regional fibrosis and enhanced vessel density in the heart. Sequential multi-vessel non-occlusive delivery of CDCs is safe and provides enhanced preservation of left ventricular function and structure. The current findings provide preclinical validation of the delivery method currently undergoing clinical testing in the Dilated cardiomYopathy iNtervention With Allogeneic MyocardIally-regenerative Cells (DYNAMIC) trial of CDCs in heart failure patients.

Intracoronary Transplantation of Mesenchymal Stem Cells with Overexpressed Integrin-Linked Kinase Improves Cardiac Function in Porcine Myocardial Infarction

The effect of mesenchymal stem cell (MSCs)-based therapy on treating acute myocardial infarction (MI) is limited due to poor engraftment and limited regenerative potential. Here we engineered MSCs with integrin-linked kinase (ILK), a pleiotropic protein critically regulating cell survival, proliferation, differentiation, and angiogenesis. We firstly combined ferumoxytol with poly-L-lysine (PLL), and found this combination promisingly enabled MRI visualization of MSCs in vitro and in vivo with good safety. We provided visually direct evidence that intracoronary ILK-MSCs had substantially enhanced homing capacity to infarct myocardium in porcine following cardiac catheterization induced MI. Intracoronary transplantation of allogeneic ILK-MSCs, but not vector-MSCs, significantly enhanced global left ventricular ejection fraction (LVEF) by 7.8% compared with baseline, by 10.3% compared with vehicles, and inhibited myocardial remodeling compared with vehicles at 15-day follow-up. Compared with vector-MSCs, ILK-MSCs significantly improved regional LV contractile function, reduced scar size, fibrosis, cell apoptosis, and increased regional myocardial perfusion and cell proliferation. This preclinical study indicates that ILK-engineered MSCs might promote the clinical translation of MSC-based therapy in post-MI patients, and provides evidence that ferumoxytol labeling of cells combined with PLL is feasible in in vivo cell tracking.

Concise Review: Review and Perspective of Cell Dosage and Routes of Administration From Preclinical and Clinical Studies of Stem Cell Therapy for Heart Disease

An important stage in the development of any new therapeutic agent is establishment of the optimal dosage and route of administration. Inconsistent findings have been reported regarding the relationship between the cell dose and clinical benefit. The present study summarizes the data regarding the optimal cell dosage and route of administration from studies of stem cell therapy for heart disease and offers a perspective on future directions.

An important stage in the development of any new therapeutic agent is establishment of the optimal dosage and route of administration. This can be particularly challenging when the treatment is a biologic agent that might exert its therapeutic effects via complex or poorly understood mechanisms. Multiple preclinical and clinical studies have shown paradoxical results, with inconsistent findings regarding the relationship between the cell dose and clinical benefit. Such phenomena can, at least in part, be attributed to variations in cell dosing or concentration and the route of administration (ROA). Although clinical trials of cell-based therapy for cardiovascular disease began more than a decade ago, specification of the optimal dosage and ROA has not been established. The present review summarizes what has been learned regarding the optimal cell dosage and ROA from preclinical and clinical studies of stem cell therapy for heart disease and offers a perspective on future directions.

Significance

Preclinical and clinical studies on cell-based therapy for cardiovascular disease have shown inconsistent results, in part because of variations in study-specific dosages and/or routes of administration (ROA). Future preclinical studies and smaller clinical trials implementing cell-dose and ROA comparisons are warranted before proceeding to pivotal trials.

Xenotransplantation of Human Cardiomyocyte Progenitor Cells Does Not Improve Cardiac Function in a Porcine Model of Chronic Ischemic Heart Failure. Results from a Randomized, Blinded, Placebo Controlled Trial

BACKGROUND

Recently cardiomyocyte progenitor cells (CMPCs) were successfully isolated from fetal and adult human hearts. Direct intramyocardial injection of human CMPCs (hCMPCs) in experimental mouse models of acute myocardial infarction significantly improved cardiac function compared to controls.

AIM

Here, our aim was to investigate whether xenotransplantation via intracoronary infusion of fetal hCMPCs in a pig model of chronic myocardial infarction is safe and efficacious, in view of translation purposes.

METHODS & RESULTS

We performed a randomized, blinded, placebo controlled trial. Four weeks after ischemia/reperfusion injury by 90 minutes of percutaneous left anterior descending artery occlusion, pigs (n = 16, 68.5 ± 5.4 kg) received intracoronary infusion of 10 million fetal hCMPCs or placebo. All animals were immunosuppressed by cyclosporin (CsA). Four weeks after infusion, endpoint analysis by MRI displayed no difference in left ventricular ejection fraction, left ventricular end diastolic and left ventricular end systolic volumes between both groups. Serial pressure volume (PV-)loop and echocardiography showed no differences in functional parameters between groups at any timepoint. Infarct size at follow-up, measured by late gadolinium enhancement MRI showed no difference between groups. Intracoronary pressure and flow measurements showed no signs of coronary obstruction 30 minutes after cell infusion. No premature death occurred in cell treated animals.

CONCLUSION

Xenotransplantation via intracoronary infusion of hCMPCs is feasible and safe, but not associated with improved left ventricular performance and infarct size compared to placebo in a porcine model of chronic myocardial infarction.