Intramyocardial transplantation of mesenchymal stromal cells for chronic myocardial ischemia and impaired left ventricular function: Results of the MESAMI 1 pilot trial

Cellular and molecular mechanisms driving cardiac tissue fibrosis: On the precipice of personalized and precision medicine

Cardiac fibrosis is a significant contributor to heart failure, a condition that continues to affect a growing number of patients worldwide. Various cardiovascular comorbidities can exacerbate cardiac fibrosis. While fibroblasts are believed to be the primary cell type underlying fibrosis, recent and emerging data suggest that other cell types can also potentiate or expedite fibrotic processes. Over the past few decades, clinicians have developed therapeutics that can blunt the development and progression of cardiac fibrosis. While these strategies have yielded positive results, overall clinical outcomes for patients suffering from heart failure continue to be dire. Herein, we overview the molecular and cellular mechanisms underlying cardiac tissue fibrosis. To do so, we establish the known mechanisms that drive fibrosis in the heart, outline the diagnostic tools available, and summarize the treatment options used in contemporary clinical practice. Finally, we underscore the critical role the immune microenvironment plays in the pathogenesis of cardiac fibrosis.

Unlocking the Potential of Extracellular Vesicles as the Next Generation Therapy: Challenges and Opportunities

BACKGROUND

Mesenchymal stem cells (MSCs) have undergone extensive investigation for their potential therapeutic applications, primarily attributed to their paracrine activity. Recently, researchers have been exploring the therapeutic potential of extracellular vesicles (EVs) released by MSCs.

METHODS

MEDLINE/PubMed and Google scholar databases were used for the selection of literature. The keywords used were mesenchymal stem cells, extracellular vesicles, clinical application of EVs and challenges EVs production.

RESULTS

These EVs have demonstrated robust capabilities in transporting intracellular cargo, playing a critical role in facilitating cell-to-cell communication by carrying functional molecules, including proteins, RNA species, DNAs, and lipids. Utilizing EVs as an alternative to stem cells offers several benefits, such as improved safety, reduced immunogenicity, and the ability to traverse biological barriers. Consequently, EVs have emerged as an increasingly attractive option for clinical use.

CONCLUSION

From this perspective, this review delves into the advantages and challenges associated with employing MSC-EVs in clinical settings, with a specific focus on their potential in treating conditions like lung diseases, cancer, and autoimmune disorders.

Stem Cell Therapy for Myocardial Infarction and Heart Failure: A Comprehensive Systematic Review and Critical Analysis

In exploring therapeutic options for ischemic heart disease (IHD) and heart failure, cell-based cardiac repair has gained prominence. This systematic review delves into the current state of knowledge surrounding cell-based therapies for cardiac repair. Employing a comprehensive search across relevant databases, the study identifies 35 included studies with diverse cell types and methodologies. Encouragingly, these findings reveal the promise of cell-based therapies in cardiac repair, demonstrating significant enhancements in left ventricular ejection fraction (LVEF) across the studies. Mechanisms of action involve growth factors that stimulate angiogenesis, differentiation, and the survival of transplanted cells. Despite these positive outcomes, challenges persist, including low engraftment rates, limitations in cell differentiation, and variations in clinical reproducibility. The optimal dosage and frequency of cell administration remain subjects of debate, with potential benefits from repeated dosing. Additionally, the choice between autologous and allogeneic stem cell transplantation poses a critical decision. This systematic review underscores the potential of cell-based therapies for cardiac repair, bearing implications for innovative treatments in heart diseases. However, further research is imperative to optimize cell type selection, delivery techniques, and long-term efficacy, fostering a more comprehensive understanding of cell-based cardiac repair.

Recent advances in mesenchymal stem cell therapy for myocardial infarction

Myocardial infarction refers to the ischemic necrosis of myocardium, characterized by a sharp reduction or interruption of blood flow in the coronary arteries due to the coronary artery occlusion, resulting in severe and prolonged ischemia in the corresponding myocardium and ultimately leading to ischemic necrosis of the myocardium. Given its high risk, it is considered as one of the most serious health threats today. In current clinical practice, multiple approaches have been explored to diminish myocardial oxygen consumption and alleviate symptoms, but notable success remains elusive. Accumulated clinical evidence has showed that the implantation of mesenchymal stem cell for treating myocardial infarction is both effective and safe. Nevertheless, there persists controversy and variability regarding the standardizing MSC transplantation protocols, optimizing dosage, and determining the most effective routes of administration. Addressing these remaining issues will pave the way of integration of MSCs as a feasible mainstream cardiac treatment.

Freeze-Dried Mesenchymal Stem Cells: From Bench to Bedside. Review

This review describes the freeze-dried mesenchymal stem cells (MSCs) and their ability to restore damaged tissues and organs. An analysis of the literature shows that after the lyophilization MSCs retain >80% of paracrine factors and that the mechanism of their action on the restoration of damaged tissues and organs is similar to the mechanism of action of paracrine factors in fresh and cryopreserved mesenchymal stem cells. Based on the own materials, the use of paracrine factors of freeze-dried MSCs in vivo and in vitro for the treatment of various diseases of organs and tissues has shown to be effective. The study also discusses about the advantages and disadvantages of freeze-dried MSCs versus cryopreserved MSCs. However, for the effective use of freeze-dried MSCs in clinical practice, a more detailed study of the mechanism of interaction of paracrine factors of freeze-dried MSCs with target cells and tissues is required. It is also necessary to identify possible other specific paracrine factors of freeze-dried MSCs. In addition, develop new therapeutic strategies for the use of freeze-dried MSCs in regenerative medicine and tissue bioengineering.

Exoskeleton Partial-Coated Stem Cells for Infarcted Myocardium Restoring

The integration of abiotic materials with live cells has emerged as an exciting strategy for the control of cellular functions. Exoskeletons consisting ofmetal-organic frameworks are generated to produce partial-coated bone marrow stem cells (BMSCs) to overcome low cell survival leading to disappointing effects for cell-based cardiac therapy. Partially coated exoskeletons can promote the survival of suspended BMSCs by integrating the support of exoskeletons and unimpaired cellular properties. In addition, partial exoskeletons exhibit protective effects against detrimental environmental conditions, including reactive oxygen species, pH changes, and osmotic pressure. The partial-coated cells exhibit increased intercellular adhesion forces to aggregate and adhere, promoting cell survival and preventing cell escape during cell therapy. The exoskeletons interact with cell surface receptors integrin α5β1, leading to augmented biological functions with profitable gene expression alteration, such as Vegfa, Cxcl12, and Adm. The partial-coated BMSCs display enhanced cell retention in infarcted myocardium through non-invasive intravenous injections. The repair of myocardial infarction has been achieved with improved cardiac function, myocardial angiogenesis, proliferation, and inhibition of cell apoptosis. This discovery advances the elucidation of potential molecular and cellular mechanisms for cell-exoskeleton interactions and benefits the rational design and manufacture of next-generation nanobiohybrids.

Stem cells derived exosomes and biomaterials to modulate autophagy and mend broken hearts

Autophagy maintains cellular homeostasis and plays a crucial role in managing pathological conditions including ischemic myocardial injury leading to heart failure (HF). Despite treatments, no intervention can replace lost cardiomyocytes. Stem cell therapy offers potential for post-myocardial infarction repair but struggles with poor cell retention due to immune rejection. In the search for effective therapies, stem cell-derived extracellular vesicles (EVs), especially exosomes, have emerged as promising tools. These tiny bioactive molecule carriers play vital roles in intercellular communication and tissue engineering. They offer numerous therapeutic benefits including modulating immune responses, promoting tissue repair, and boosting angiogenesis. Additionally, biomaterials provide a conducive 3D microenvironment for cell, exosome, and biomolecule delivery, and enhance heart muscle strength, making it a comprehensive cardiac repair strategy. In this regard, the current review delves into the intricate application of extracellular vesicles (EVs) and biomaterials for managing autophagy in the heart muscle during cardiac injury. Central to our investigation is the exploration of how these elements interact within the context of cardiac repair and regeneration. Additionally, this review also casts light on the formidable challenges that plague this field, such as the issues of safety, efficacy, controlled delivery, and acceptance of these therapeutic strategies for effective clinical translation. Addressing these challenges is crucial for unlocking the full therapeutic potential of EV and biomaterial-based therapies and ensuring their successful translation from bench to bedside.

Pathogenic Role of Adipose Tissue-Derived Mesenchymal Stem Cells in Obesity and Obesity-Related Inflammatory Diseases

Adipose tissue-derived mesenchymal stem cells (ASCs) are adult stem cells, endowed with self-renewal, multipotent capacities, and immunomodulatory properties, as mesenchymal stem cells (MSCs) from other origins. However, in a pathological context, ASCs like MSCs can exhibit pro-inflammatory properties and attract inflammatory immune cells at their neighborhood. Subsequently, this creates an inflammatory microenvironment leading to ASCs' or MSCs' dysfunctions. One such example is given by obesity where adipogenesis is impaired and insulin resistance is initiated. These opposite properties have led to the classification of MSCs into two categories defined as pro-inflammatory ASC1 or anti-inflammatory ASC2, in which plasticity depends on the micro-environmental stimuli. The aim of this review is to (i) highlight the pathogenic role of ASCs during obesity and obesity-related inflammatory diseases, such as rheumatoid arthritis, multiple sclerosis, psoriasis, inflammatory bowel disease, and cancer; and (ii) describe some of the mechanisms leading to ASCs dysfunctions. Thus, the role of soluble factors, adhesion molecules; TLRs, Th17, and Th22 cells; γδ T cells; and immune checkpoint overexpression will be addressed.

Cell-Based and Selected Cell-Free Therapies for Myocardial Infarction: How Do They Compare to the Current Treatment Options?

Because of cardiomyocyte death or dysfunction frequently caused by myocardial infarction (MI), heart failure is a leading cause of morbidity and mortality in modern society. Paradoxically, only limited and non-curative therapies for heart failure or MI are currently available. As a result, over the past two decades research has focused on developing cell-based approaches promoting the regeneration of infarcted tissue. Cell-based therapies for myocardial regeneration include powerful candidates, such as multipotent stem cells (mesenchymal stem cells (MSCs), bone-marrow-derived stem cells, endothelial progenitor cells, and hematopoietic stem cells) and induced pluripotent stem cells (iPSCs). These possess unique properties, such as potency to differentiate into desired cell types, proliferation capacity, and patient specificity. Preclinical and clinical studies have demonstrated modest improvement in the myocardial regeneration and reduced infarcted areas upon transplantation of pluripotent or multipotent stem cells. Another cell population that need to be considered as a potential source for cardiac regeneration are telocytes found in different organs, including the heart. Their therapeutic effect has been studied in various heart pathologies, such as MI, arrhythmias, or atrial amyloidosis. The most recent cell-free therapeutic tool relies on the cardioprotective effect of complex cargo carried by small membrane-bound vesicles—exosomes—released from stem cells via exocytosis. The MSC/iPSC-derived exosomes could be considered a novel exosome-based therapy for cardiovascular diseases thanks to their unique content. There are also other cell-free approaches, e.g., gene therapy, or acellular cardiac patches. Therefore, our review provides the most recent insights into the novel strategies for myocardial repair based on the regenerative potential of different cell types and cell-free approaches.

Pre-Conditioning Methods and Novel Approaches with Mesenchymal Stem Cells Therapy in Cardiovascular Disease

Transplantation of mesenchymal stem cells (MSCs) in the setting of cardiovascular disease, such as heart failure, cardiomyopathy and ischemic heart disease, has been associated with good clinical outcomes in several trials. A reduction in left ventricular remodeling, myocardial fibrosis and scar size, an improvement in endothelial dysfunction and prolonged cardiomyocytes survival were reported. The regenerative capacity, in addition to the pro-angiogenic, anti-apoptotic and anti-inflammatory effects represent the main target properties of these cells. Herein, we review the different preconditioning methods of MSCs (hypoxia, chemical and pharmacological agents) and the novel approaches (genetically modified MSCs, MSC-derived exosomes and engineered cardiac patches) suggested to optimize the efficacy of MSC therapy.

Mesenchymal Stem Cell (MSCs) Therapy for Ischemic Heart Disease: A Promising Frontier

Although tremendous progress has been made in conventional treatment for ischemic heart disease, it still remains a major cause of death and disability. Cell-based therapeutics holds an exciting frontier of research for complete cardiac recuperation. The capacity of diverse stem and progenitor cells to stimulate cardiac renewal has been analysed, with promising results in both pre-clinical and clinical trials. Mesenchymal stem cells have been ascertained to have regenerative ability via a variety of mechanisms, including differentiation from the mesoderm lineage, immunomodulatory properties, and paracrine effects. Also, their availability, maintenance, and ability to replenish endogenous stem cell niches have rendered them suitable for front-line research. This review schemes to outline the use of mesenchymal stem cell therapeutics for ischemic heart disease, their characteristics, the potent mechanisms of mesenchymal stem cell-based heart regeneration, and highlight preclinical data. Additionally, we discuss the results of the clinical trials to date as well as ongoing clinical trials on ischemic heart disease.

Emerging Trends in Mesenchymal Stem Cells Applications for Cardiac Regenerative Therapy: Current Status and Advances

Irreversible myocardium infarction is one of the leading causes of cardiovascular disease (CVD) related death and its quantum is expected to grow in coming years. Pharmacological intervention has been at the forefront to ameliorate injury-related morbidity and mortality. However, its outcomes are highly skewed. As an alternative, stem cell-based tissue engineering/regenerative medicine has been explored quite extensively to regenerate the damaged myocardium. The therapeutic modality that has been most widely studied both preclinically and clinically is based on adult multipotent mesenchymal stem cells (MSC) delivered to the injured heart. However, there is debate over the mechanistic therapeutic role of MSC in generating functional beating cardiomyocytes. This review intends to emphasize the role and use of MSC in cardiac regenerative therapy (CRT). We have elucidated in detail, the various aspects related to the history and progress of MSC use in cardiac tissue engineering and its multiple strategies to drive cardiomyogenesis. We have further discussed with a focus on the various therapeutic mechanism uncovered in recent times that has a significant role in ameliorating heart-related problems. We reviewed recent and advanced technologies using MSC to develop/create tissue construct for use in cardiac regenerative therapy. Finally, we have provided the latest update on the usage of MSC in clinical trials and discussed the outcome of such studies in realizing the full potential of MSC use in clinical management of cardiac injury as a cellular therapy module.

Allogeneic vs. autologous mesenchymal stem/stromal cells in their medication practice

Mesenchymal stem/stromal cell (MSC)-based therapeutics is already available for treatment of a range of diseases or medical conditions. Autologous or allogeneic MSCs obtained from self or donors have their own advantages and disadvantages in their medical practice. Therapeutic benefits of using autologous vs. allogeneic MSCs are inconclusive. Transplanted MSCs within the body interact with their physical microenvironment or niche, physiologically or pathologically, and such cells in a newly established tissue microenvironment may be impacted by the pathological harmful environmental factors to alter their unique biological behaviors. Meanwhile, a temporary microenvironment/niche may be also altered by the resident or niche-surrounding MSCs. Therefore, the functional plasticity and heterogeneity of MSCs caused by different donors and subpopulations of MSCs may result in potential uncertainty in their safe and efficacious medical practice. Acknowledging a connection between MSCs' biology and their existing microenvironment, donor-controlled clinical practice for the long-term therapeutic benefit is suggested to further consider minimizing MSCs potential harm for MSC-based individual therapies. In this review, we summarize the advantages and disadvantages of autologous vs. allogeneic MSCs in their therapeutic applications. Among other issues, we highlight the importance of better understanding of the various microenvironments that may affect the properties of niche-surrounding MSCs and discuss the clinical applications of MSCs within different contexts for treatment of different diseases including cardiomyopathy, lupus and lupus nephritis, diabetes and diabetic complications, bone and cartilage repair, cancer and tissue fibrosis.

Adipose-Derived Stem Cells in the Treatment of Perianal Fistulas in Crohn's Disease: Rationale, Clinical Results and Perspectives

Between 20 to 25% of Crohn’s disease (CD) patients suffer from perianal fistulas, a marker of disease severity. Seton drainage combined with anti-TNFα can result in closure of the fistula in 70 to 75% of patients. For the remaining 25% of patients there is room for in situ injection of autologous or allogenic mesenchymal stem cells such as adipose-derived stem/stromal cells (ADSCs). ADSCs exert their effects on tissues and effector cells through paracrine phenomena, including the secretome and extracellular vesicles. They display anti-inflammatory, anti-apoptotic, pro-angiogenic, proliferative, and immunomodulatory properties, and a homing within the damaged tissue. They also have immuno-evasive properties allowing a clinical allogeneic approach. Numerous clinical trials have been conducted that demonstrate a complete cure rate of anoperineal fistulas in CD ranging from 46 to 90% of cases after in situ injection of autologous or allogenic ADSCs. A pivotal phase III-controlled trial using allogenic ADSCs (Alofisel^®) demonstrated that prolonged clinical and radiological remission can be obtained in nearly 60% of cases with a good safety profile. Future studies should be conducted for a better knowledge of the local effect of ADSCs as well as for a standardization in terms of the number of injections and associated procedures.

Extracellular Vesicles Derived From Human Umbilical Cord Mesenchymal Stem Cells Protect Against DOX-Induced Heart Failure Through the miR-100-5p/NOX4 Pathway

The end result of a variety of cardiovascular diseases is heart failure. Heart failure patients’ morbidity and mortality rates are increasing year after year. Extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (HucMSC-EVs) have recently been discovered to be an alternative treatment for heart failure, according to recent research. In this study, we aimed to explore the underlying mechanisms in which HucMSC-EVs inhibited doxorubicin (DOX)-induced heart failure in AC16 cells. An miR-100-5p inhibitor and an miR-100-5p mimic were used to transfect HucMSCs using Lipofectamine 2000. HucMSC-EVs were isolated and purified using the ultracentrifugation method. AC16 cells were treated with DOX combined with HucMSC-EVs or an EV miR-100-5-p inhibitor or EV miR-100-5-p mimic. ROS levels were measured by a flow cytometer. The levels of LDH, SOD, and MDA were measured by biochemical methods. Apoptotic cells were assessed by a flow cytometer. Cleaved-caspase-3 and NOX4 protein expression were determined by Western blot. The experiment results showed that HucMSC-EVs inhibited DOX-induced increased levels of ROS, LDH, and MDA, and decreased levels of SOD which were reversed by an EV miR-100-5-p inhibitor, while EV miR-100-5-p mimic had a similar effect to HucMSC-EVs. At the same time, HucMSC-EV-inhibited DOX induced the increases of apoptotic cells as well as NOX4 and cleaved-caspase-3 protein expression, which were reversed by an EV miR-100-5-p inhibitor. Furthermore, the NOX4 expression was negatively regulated by miR-100-5p. Overexpression of NOX4 abolished the effects in which HucMSC-EVs inhibited DOX-induced ROS, oxidative stress, and apoptosis increases. In conclusion, these results indicate that HucMSC-EVs inhibit DOX-induced heart failure through the miR-100-5p/NOX4 pathway.

Regenerative Medicine for the Treatment of Ischemic Heart Disease; Status and Future Perspectives

Cardiovascular disease is now the leading cause of adult death in the world. According to new estimates from the World Health Organization, myocardial infarction (MI) is responsible for four out of every five deaths due to cardiovascular disease. Conventional treatments of MI are taking aspirin and nitroglycerin as intermediate treatments and injecting antithrombotic agents within the first 3 h after MI. Coronary artery bypass grafting and percutaneous coronary intervention are the most common long term treatments. Since none of these interventions will fully regenerate the infarcted myocardium, there is value in pursuing more innovative therapeutic approaches. Regenerative medicine is an innovative interdisciplinary method for rebuilding, replacing, or repairing the missed part of different organs in the body, as similar as possible to the primary structure. In recent years, regenerative medicine has been widely utilized as a treatment for ischemic heart disease (one of the most fatal factors around the world) to repair the lost part of the heart by using stem cells. Here, the development of mesenchymal stem cells causes a breakthrough in the treatment of different cardiovascular diseases. They are easily obtainable from different sources, and expanded and enriched easily, with no need for immunosuppressing agents before transplantation, and fewer possibilities of genetic abnormality accompany them through multiple passages. The production of new cardiomyocytes can result from the transplantation of different types of stem cells. Accordingly, due to its remarkable benefits, stem cell therapy has received attention in recent years as it provides a drug-free and surgical treatment for patients and encourages a more safe and feasible cardiac repair. Although different clinical trials have reported on the promising benefits of stem cell therapy, there is still uncertainty about its mechanism of action. It is important to conduct different preclinical and clinical studies to explore the exact mechanism of action of the cells. After reviewing the pathophysiology of MI, this study addresses the role of tissue regeneration using various materials, including different types of stem cells. It proves some appropriate data about the importance of ethical problems, which leads to future perspectives on this scientific method.

Preclinical Evaluation of the Safety and Immunological Action of Allogeneic ADSC-Collagen Scaffolds in the Treatment of Chronic Ischemic Cardiomyopathy

The use of allogeneic adipose-derived mesenchymal stromal cells (alloADSCs) represents an attractive approach for treating myocardial infarction (MI). Furthermore, adding a natural support improves alloADSCs engraftment and survival in heart tissues, leading to a greater therapeutic effect. We aimed to examine the safety and immunological reaction induced by epicardial implantation of a clinical-grade collagen scaffold (CS) seeded with alloADSCs for its future application in humans. Thus, cellularized scaffolds were myocardially or subcutaneously implanted in immunosuppressed rodent models. The toxicological parameters were not significantly altered, and tumor formation was not found over the short or long term. Furthermore, biodistribution analyses in the infarcted immunocompetent rats displayed cell engraftment in the myocardium but no migration to other organs. The immunogenicity of alloADSC-CS was also evaluated in a preclinical porcine model of chronic MI; no significant humoral or cellular alloreactive responses were found. Moreover, CS cellularized with human ADSCs cocultured with human allogeneic immune cells produced no alloreactive response. Interestingly, alloADSC-CS significantly inhibited lymphocyte responses, confirming its immunomodulatory action. Thus, alloADSC-CS is likely safe and does not elicit any alloreactive immunological response in the host. Moreover, it exerts an immunomodulatory action, which supports its translation to a clinical setting.

Mesenchymal Stem Cells Therapies on Fibrotic Heart Diseases

Stem cell therapy is a promising alternative approach to heart diseases. The most prevalent source of multipotent stem cells, usually called somatic or adult stem cells (mesenchymal stromal/stem cells, MSCs) used in clinical trials is bone marrow (BM-MSCs), adipose tissue (AT-MSCs), umbilical cord (UC-MSCs) and placenta. Therapeutic use of MSCs in cardiovascular diseases is based on the benefits in reducing cardiac fibrosis and inflammation that compose the cardiac remodeling responsible for the maintenance of normal function, something which may end up causing progressive and irreversible dysfunction. Many factors lead to cardiac fibrosis and failure, and an effective therapy is lacking to reverse or attenuate this condition. Different approaches have been shown to be promising in surpassing the poor survival of transplanted cells in cardiac tissue to provide cardioprotection and prevent cardiac remodeling. This review includes the description of pre-clinical and clinical investigation of the therapeutic potential of MSCs in improving ventricular dysfunction consequent to diverse cardiac diseases.

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.

Surfing the clinical trials of mesenchymal stem cell therapy in ischemic cardiomyopathy

While existing remedies failed to fully address the consequences of heart failure, stem cell therapy has been introduced as a promising approach. The present review is a comprehensive appraisal of the impacts of using mesenchymal stem cells (MSCs) in clinical trials mainly conducted on ischemic cardiomyopathy. The benefits of MSC therapy for dysfunctional myocardium are likely attributed to numerous secreted paracrine factors and immunomodulatory effects. The positive outcomes associated with MSC therapy are scar size reduction, reverse remodeling, and angiogenesis. Also, a decreasing in the level of chronic inflammatory markers of heart failure progression like TNF-α is observed. The intense inflammatory reaction in the injured myocardial micro-environment predicts a poor response of scar tissue to MSC therapy. Subsequently, the interval delay between myocardial injury and MSC therapy is not yet determined. The optimal requested dose of cells ranges between 100 to 150 million cells. Allogenic MSCs have different advantages compared to autogenic cells and intra-myocardial injection is the preferred delivery route. The safety and efficacy of MSCs-based therapy have been confirmed in numerous studies, however several undefined parameters like route of administration, optimal timing, source of stem cells, and necessary dose are limiting the routine use of MSCs therapeutic approach in clinical practice. Lastly, pre-conditioning of MSCs and using of exosomes mediated MSCs or genetically modified MSCs may improve the overall therapeutic effect. Future prospective studies establishing a constant procedure for MSCs transplantation are required in order to apply MSC therapy in our daily clinical practice and subsequently improving the overall prognosis of ischemic heart failure patients.

Combining stem cells in myocardial infarction: The road to superior repair?

Myocardial infarction irreversibly destroys millions of cardiomyocytes in the ventricle, making it the leading cause of heart failure worldwide. Over the past two decades, many progenitor and stem cell types were proposed as the ideal candidate to regenerate the heart after injury. The potential of stem cell therapy has been investigated thoroughly in animal and human studies, aiming at cardiac repair by true tissue replacement, by immune modulation, or by the secretion of paracrine factors that stimulate endogenous repair processes. Despite some successful results in animal models, the outcome from clinical trials remains overall disappointing, largely due to the limited stem cell survival and retention after transplantation. Extensive interest was developed regarding the combinational use of stem cells and various priming strategies to improve the efficacy of regenerative cell therapy. In this review, we provide a critical discussion of the different stem cell types investigated in preclinical and clinical studies in the field of cardiac repair. Moreover, we give an update on the potential of stem cell combinations as well as preconditioning and explore the future promises of these novel regenerative strategies.

Cell Therapy in Patients with Heart Failure: A Comprehensive Review and Emerging Concepts

This review summarizes the results of clinical trials of cell therapy in patients with heart failure (HF). In contrast to acute myocardial infarction (where results have been consistently negative for more than a decade), in the setting of HF the results of Phase I–II trials are encouraging, both in ischaemic and non-ischaemic cardiomyopathy. Several well-designed Phase II studies have met their primary endpoint and demonstrated an efficacy signal, which is remarkable considering that only one dose of cells was used. That an efficacy signal was seen 6–12 months after a single treatment provides a rationale for larger, rigorous trials. Importantly, no safety concerns have emerged. Amongst the various cell types tested, mesenchymal stromal cells derived from bone marrow (BM), umbilical cord, or adipose tissue show the greatest promise. In contrast, embryonic stem cells are not likely to become a clinical therapy. Unfractionated BM cells and cardiosphere-derived cells have been abandoned. The cell products used for HF will most likely be allogeneic. New approaches, such as repeated cell treatment and intravenous delivery, may revolutionize the field. As is the case for most new therapies, the development of cell therapies for HF has been slow, plagued by multifarious problems, and punctuated by many setbacks; at present, the utility of cell therapy in HF remains to be determined. What the field needs is rigorous, well-designed Phase III trials. The most important things to move forward are to keep an open mind, avoid preconceived notions, and let ourselves be guided by the evidence.

Cardiac Cell Therapy: Insights into the Mechanisms of Tissue Repair

Stem cell-based cardiac therapies have been extensively studied in recent years. However, the efficacy of cell delivery, engraftment, and differentiation post-transplant remain continuous challenges and represent opportunities to further refine our current strategies. Despite limited long-term cardiac retention, stem cell treatment leads to sustained cardiac benefit following myocardial infarction (MI). This review summarizes the current knowledge on stem cell based cardiac immunomodulation by highlighting the cellular and molecular mechanisms of different immune responses to mesenchymal stem cells (MSCs) and their secretory factors. This review also addresses the clinical evidence in the field.

Neovascularization: The Main Mechanism of MSCs in Ischemic Heart Disease Therapy

Mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been shown to effectively limit the infarct area in numerous clinical and preclinical studies. However, the primary mechanism associated with this activity in MSC transplantation therapy remains unclear. Blood supply is fundamental for the survival of myocardial tissue, and the formation of an efficient vascular network is a prerequisite for blood flow. The paracrine function of MSCs, which is throughout the neovascularization process, including MSC mobilization, migration, homing, adhesion and retention, regulates angiogenesis and vasculogenesis through existing endothelial cells (ECs) and endothelial progenitor cells (EPCs). Additionally, MSCs have the ability to differentiate into multiple cell lineages and can be mobilized and migrate to ischemic tissue to differentiate into ECs, pericytes and smooth muscle cells in some degree, which are necessary components of blood vessels. These characteristics of MSCs support the view that these cells improve ischemic myocardium through angiogenesis and vasculogenesis. In this review, the results of recent clinical and preclinical studies are discussed to illustrate the processes and mechanisms of neovascularization in ischemic heart disease.

Stem Cell Therapy for Acute Myocardial Infarctions: A Systematic Review

Each year 790,000 people in the United States suffer from a myocardial infarction. This results in the permanent loss of cardiomyocytes and an irreversible loss of cardiac function. Current therapies lower mortality rates, but do not address the core pathology, which opens a pathway to step-wise heart failure. Utilizing stem cells to regenerate the dead tissue is a potential method to reverse these devastating effects. Several clinical trials have already demonstrated the safety of stem cell therapy. In this review, we highlight clinical trials, which have utilized various stem cell lineages, and discuss areas for future research.

Challenges and Limitations of Strategies to Promote Therapeutic Potential of Human Mesenchymal Stem Cells for Cell-Based Cardiac Repair

Mesenchymal stem cells (MSCs) represent a population of adult stem cells residing in many tissues, mainly bone marrow, adipose tissue, and umbilical cord. Due to the safety and availability of standard procedures and protocols for isolation, culturing, and characterization of these cells, MSCs have emerged as one of the most promising sources for cell-based cardiac regenerative therapy. Once transplanted into a damaged heart, MSCs release paracrine factors that nurture the injured area, prevent further adverse cardiac remodeling, and mediate tissue repair along with vasculature. Numerous preclinical studies applying MSCs have provided significant benefits following myocardial infarction. Despite promising results from preclinical studies using animal models, MSCs are not up to the mark for human clinical trials. As a result, various approaches have been considered to promote the therapeutic potency of MSCs, such as genetic engineering, physical treatments, growth factor, and pharmacological agents. Each strategy has targeted one or multi-potentials of MSCs. In this review, we will describe diverse approaches that have been developed to promote the therapeutic potential of MSCs for cardiac regenerative therapy. Particularly, we will discuss major characteristics of individual strategy to enhance therapeutic efficacy of MSCs including scientific principles, advantages, limitations, and improving factors. This article also will briefly introduce recent novel approaches that MSCs enhanced therapeutic potentials of other cells for cardiac repair.

Therapeutic effects of mesenchymal stem cells on cutaneous leishmaniasis lesions caused by Leishmania major

OBJECTIVES

Leishmania major (L. major) is a cutaneous leishmaniasis causative agent. Current chemotherapeutic methods are not totally effective in treatment of this disease. The immunomodulation and tissue repairing capability of mesenchymal stem cells (MSCs), ease of isolation, detection and in vitro culture, have encouraged biologists to use MSCs for cell therapy in different infections such as cutaneous leishmaniasis.

METHODS

BALB/c mice (6-8 weeks old) were infected with L. major then divided into four groups and treated with MSCs, Glucantime, Glucantime + MSCs, or PBS. Regression of lesions, potency of macrophages for phagocytosis, proliferation of immune cells against Leishmania soluble antigen, reduction of spleen parasite burden and healing of the lesions were evaluated on days 10, 20 and 30 of treatment.

RESULTS

The results indicated that the mice intralesionally injected with MSCs showed significant regression in the lesions produced by L. major by day 30. Proliferation of splenocytes stimulated with SLA (soluble leishmania antigen) in vitro in MSC-treated mice on day 20 was significantly higher than in the other groups. The potency of phagocytosis in macrophages of mice treated with MSCs was significantly higher by day 30 and healing of the lesions in this group of mice showed more progress on histopathological examinations. Spleen parasite burden showed significant reduction in the mice treated with Glucantime + MSCs by day 30.

CONCLUSIONS

The results showed that including MSCs in treatment of cutaneous leishmaniasis caused by L. major is a promising approach.

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.

Mesenchymal stromal cells; a new horizon in regenerative medicine

In recent decades, mesenchymal stromal cells (MSCs) biomedical utilizing has attracted worldwide growing attention. After the first report of the human MSCs obtaining from the bone marrow (BM) tissue, these cells were isolated from wide types of the other tissues, ranging from adipose tissue to dental pulp. Their specific characteristics, comprising self-renewality, multipotency, and availability accompanied by their immunomodulatory properties and little ethical concern denote their importance in the context of regenerative medicine. Considering preclinical studies, MSCs can modify immune reactions during tissue repair and restoration, providing suitable milieu for tissue recovery; on the other hand, they can be differentiated into comprehensive types of the body cells, such as osteoblast, chondrocyte, hepatocyte, cardiomyocyte, fibroblast, and neural cells. Though a large number of studies have investigated MSCs capacities in regenerative medicine in varied animal models, the oncogenic capability of unregulated MSCs differentiation must be more assessed to enable their application in the clinic. In the current review, we provide a brief overview of MSCs sources, isolation, and expansion as well as immunomodulatory activities. More important, we try to collect and discuss recent preclinical and clinical research and evaluate current challenges in the context of the MSC-based cell therapy for regenerative medicine.

Down-Regulated Exosomal MicroRNA-221 - 3p Derived From Senescent Mesenchymal Stem Cells Impairs Heart Repair

The composition and biological activity of donor cells is largely determined by the exosomes they secrete. In this study, we isolated exosomes from young (Young-Exo) and aged (Age-Exo) mesenchymal stem cells (MSCs) and compared their regeneration activity. Young Exo MSCs were more efficient than Aged-Exo at promoting the formation of endothelial tube, reducing fibrosis, and inhibiting apoptosis of cardiomyocytes in vitro; and improving cardiac structure and function in vivo in the hearts of rats following myocardial infarction (MI). MicroRNA sequencing and polymerase chain reaction (PCR) analysis revealed that miR-221-3p was significantly down-regulated in Aged-Exo. The aged MSCs were rejuvenated and their reparative cardiac ability restored when miR-221-3p was overexpressed in Aged-Exo. The protective effect was lost when miR-221-3p expression was knocked down in Young-Exo. These effects of miR-221-3p were achieved through enhancing Akt kinase activity by inhibiting phosphatase and tensin homolog (PTEN). In conclusion, exosomal miR-221-3p secreted from Aged MSCs attenuated the function of angiogenesis and promoted survival of cardiomyocytes. Up-regulation of miR-221-3p in aged MSCs improved their ability of angiogenesis, migration and proliferation, and suppressed apoptosis via the PTEN/Akt pathway.

The use of large animals to facilitate the process of MSC going from laboratory to patient-'bench to bedside'

Large animal models have been widely used to facilitate the translation of mesenchymal stem cells (MSC) from the laboratory to patient. MSC, with their multi-potent capacity, have been proposed to have therapeutic benefits in a number of pathological conditions. Laboratory studies allow the investigation of cellular and molecular interactions, while small animal models allow initial 'proof of concept' experiments. Large animals (dogs, pigs, sheep, goats and horses) are more similar physiologically and structurally to man. These models have allowed clinically relevant assessments of safety, efficacy and dosing of different MSC sources prior to clinical trials. In this review, we recapitulate the use of large animal models to facilitate the use of MSC to treat myocardial infarction-an example of one large animal model being considered the 'gold standard' for research and osteoarthritis-an example of the complexities of using different large animal models in a multifactorial disease. These examples show how large animals can provide a research platform that can be used to evaluate the value of cell-based therapies and facilitate the process of 'bench to bedside'.

Insulin-Producing Cell Transplantation Platform for Veterinary Practice

Diabetes mellitus (DM) remains a global concern in both human and veterinary medicine. Type I DM requires prolonged and consistent exogenous insulin administration to address hyperglycemia, which can increase the risk of diabetes complications such as retinopathy, nephropathy, neuropathy, and heart disorders. Cell-based therapies have been successful in human medicine using the Edmonton protocol. These therapies help maintain the production of endogenous insulin and stabilize blood glucose levels and may possibly be adapted to veterinary clinical practice. The limited number of cadaveric pancreas donors and the long-term use of immunosuppressive agents are the main obstacles for this protocol. Over the past decade, the development of potential therapies for DM has mainly focused on the generation of effective insulin-producing cells (IPCs) from various sources of stem cells that can be transplanted into the body. Another successful application of stem cells in type I DM therapies is transplanting generated IPCs. Encapsulation can be an alternative strategy to protect IPCs from rejection by the body due to their immunoisolation properties. This review summarizes current concepts of IPCs and encapsulation technology for veterinary clinical application and proposes a potential stem-cell-based platform for veterinary diabetic regenerative therapy.

Insight into adipokines to optimize therapeutic effects of stem cell for tissue regeneration

Stem cell therapy is considered as a promising regenerative medicine for repairing and treating damaged tissues and/or preventing various diseases. But there are still some obstacles such as low cell migration, poor stem cell engraftment and decreased cell survival that need to be overcome before transplantation. Therefore, a large body of studies has focused on improving the efficiency of stem cell therapy. For instance, preconditioning of stem cells has emerged as an effective strategy to reinforce therapeutic efficacy. Adipokines are signaling molecules, secreted by adipose tissue, which regulate a variety of biological processes in adipose tissue and other organs including the brain, liver, and muscle. In this review article, we shed light on the biological effects of some adipokines including apelin, oncostatin M, omentin-1 and vaspin on stem cell therapy and the most recent preclinical advances in our understanding of how these functions ameliorate stem cell therapy outcome.

Long-Term Results of Intracardiac Mesenchymal Stem Cell Transplantation in Patients With Cardiomyopathy

BACKGROUND

Mesenchymal stem cells (MSCs), which have the potential to differentiate into cardiomyocytes or vascular endothelial cells, have been used clinically as therapy for cardiomyopathy. In this study, we aimed to evaluate the long-term follow-up results.Methods and Results:We studied 8 patients with symptomatic heart failure (HF) on guideline-directed therapy (ischemic cardiomyopathy, n=3; nonischemic cardiomyopathy, n=5) who underwent intracardiac MSC transplantation using a catheter-based injection method between May 2004 and April 2006. Major adverse events and hospitalizations were investigated up to 10 years afterward. Compared with baseline, there were no significant differences in B-type natriuretic peptide (BNP) (from 211 to 173 pg/mL), left ventricular ejection fraction (LVEF) (from 24% to 26%), and peak oxygen uptake (from 16.5 to 19.2 mL/min/kg) at 2 months. During the follow-up period, no patients experienced serious adverse events such as arrhythmias. Three patients died of pneumonia in the 1st year, liver cancer in the 6th year, and HF in the 7th year. Of the remaining 5 patients, 3 patients were hospitalized for exacerbated HF, 1 of whom required heart transplantation in the 2nd year; 2 patients survived for 10 years without worsening HF.

CONCLUSIONS

The results of this exploratory study of intracardiac MSCs administration suggest further research regarding the feasibility and efficacy is warranted.

Isolation, Characterization, and Differentiation of Cardiac Stem Cells from the Adult Mouse Heart

Myocardial infarction (MI) is a leading cause of morbidity and mortality around the world. A major goal of regenerative medicine is to replenish the dead myocardium after MI. Although several strategies have been used to regenerate myocardium, stem cell therapy remains a major approach to replenish the dead myocardium of an MI heart. Accumulating evidence suggests the presence of resident cardiac stem cells (CSCs) in the adult heart and their endocrine and/or paracrine effects on cardiac regeneration. However, CSC isolation and their characterization and differentiation toward myocardial cells, especially cardiomyocytes, remains a technical challenge. In the present study, we provided a simple method for the isolation, characterization, and differentiation of CSCs from the adult mouse heart. Here, we describe a density gradient method for the isolation of CSCs, where the heart is digested by a 0.2% collagenase II solution. To characterize the isolated CSCs, we evaluated the expression of CSCs/cardiac markers Sca-1, NKX2-5, and GATA4, and pluripotency/stemness markers OCT4, SOX2, and Nanog. We also determined the proliferation potential of isolated CSCs by culturing them in a Petri dish and assessing the expression of the proliferation marker Ki-67. For evaluating the differentiation potential of CSCs, we selected seven- to ten-days cultured CSCs. We transferred them to a new plate with a cardiomyocyte differentiation medium. They are incubated in a cell culture incubator for 12 days, while the differentiation medium is changed every three days. The differentiated CSCs express cardiomyocyte-specific markers: actinin and troponin I. Thus, CSCs isolated with this protocol have stemness and cardiac markers, and they have a potential for proliferation and differentiation toward cardiomyocyte lineage.

Cell-Based Therapies for Cardiac Regeneration: A Comprehensive Review of Past and Ongoing Strategies

Despite considerable improvements in the treatment of cardiovascular diseases, heart failure (HF) still represents one of the leading causes of death worldwide. Poor prognosis is mostly due to the limited regenerative capacity of the adult human heart, which ultimately leads to left ventricular dysfunction. As a consequence, heart transplantation is virtually the only alternative for many patients. Therefore, novel regenerative approaches are extremely needed, and several attempts have been performed to improve HF patients’ clinical conditions by promoting the replacement of the lost cardiomyocytes and by activating cardiac repair. In particular, cell-based therapies have been shown to possess a great potential for cardiac regeneration. Different cell types have been extensively tested in clinical trials, demonstrating consistent safety results. However, heterogeneous efficacy data have been reported, probably because precise end-points still need to be clearly defined. Moreover, the principal mechanism responsible for these beneficial effects seems to be the paracrine release of antiapoptotic and immunomodulatory molecules from the injected cells. This review covers past and state-of-the-art strategies in cell-based heart regeneration, highlighting the advantages, challenges, and limitations of each approach.

Safety and Efficacy of Adult Stem Cell Therapy for Acute Myocardial Infarction and Ischemic Heart Failure (SafeCell Heart): A Systematic Review and Meta-Analysis

Preclinical and clinical evidence suggests that mesenchymal stem cells (MSCs) may be beneficial in treating both acute myocardial infarction (AMI) and ischemic heart failure (IHF). However, the safety profile and efficacy of MSC therapy is not well‐known. We conducted a systematic review of clinical trials that evaluated the safety or efficacy of MSCs for AMI or IHF. Embase, PubMed/Medline, and Cochrane Central Register of Controlled Trials were searched from inception to September 27, 2017. Studies that examined the use of MSCs administered to adults with AMI or IHF were eligible. The Cochrane risk of bias tool was used to assess bias of included studies. The primary outcome was safety assessed by adverse events and the secondary outcome was efficacy which was assessed by mortality and left ventricular ejection fraction (LVEF). A total of 668 citations were reviewed and 23 studies met eligibility criteria. Of these, 11 studies evaluated AMI and 12 studies evaluated IHF. There was no association between MSCs and acute adverse events. There was a significant improvement in overall LVEF in patients who received MSCs (SMD 0.73, 95% CI 0.24–1.21). No significant difference in mortality was noted (Peto OR 0.68, 95% CI 0.38–1.22). Results from our systematic review suggest that MSC therapy for ischemic heart disease appears to be safe. There is a need for a well‐designed adequately powered randomized control trial (with rigorous adverse event reporting and evaluations of cardiac function) to further establish a clear risk‐benefit profile of MSCs. Stem Cells Translational Medicine2018;7:857–866

Stem Cell Therapies in Cardiovascular Disease

Despite considerable advances in medicine, cardiovascular disease is still rising, with ischemic heart disease being the leading cause of death and disability worldwide. Thus extensive efforts are continuing to establish effective therapeutic modalities that would improve both quality of life and survival in this patient population. Novel therapies are being investigated not only to protect the myocardium against ischemia-reperfusion injury but also to regenerate the heart. Stem cell therapy, such as potential use of human mesenchymal stem cells and induced pluripotent stem cells and their exosomes, will make it possible not only to address molecular mechanisms of cardiac conditioning, but also to develop new therapies for ischemic heart disease. Despite the studies and progress made over the last 15 years on the use of stem cell therapy for cardiovascular disease, the efforts are still in their infancy. Even though the expectations have been high, the findings indicate that most of the clinical trials generally have been small and the results inconclusive. Because of many negative findings, there is certain pessimism that cardiac cell therapy is likely to yield any meaningful results over the next decade or so. Similar to other new technologies, early failures are not unusual and they may be followed by impressive success. Nevertheless, there has been considerable attention to safety by the clinical investigators because the adverse events of stem cell therapy have been impressively rare. In summary, although regenerative biology might not help the cardiovascular patient in the near term, it is destined to do so over the next several decades.

Concise Review: Optimized Strategies for Stem Cell-Based Therapy in Myocardial Repair: Clinical Translatability and Potential Limitation

Ischemic heart diseases (IHDs) remain major public health problems with high rates of morbidity and mortality worldwide. Despite significant advances, current therapeutic approaches are unable to rescue the extensive and irreversible loss of cardiomyocytes caused by severe ischemia. Over the past 16 years, stem cell-based therapy has been recognized as an innovative strategy for cardiac repair/regeneration and functional recovery after IHDs. Although substantial preclinical animal studies using a variety of stem/progenitor cells have shown promising results, there is a tremendous degree of skepticism in the clinical community as many stem cell trials do not confer any beneficial effects. How to accelerate stem cell-based therapy toward successful clinical application attracts considerate attention. However, many important issues need to be fully addressed. In this Review, we have described and compared the effects of different types of stem cells with their dose, delivery routes, and timing that have been routinely tested in recent preclinical and clinical findings. We have also discussed the potential mechanisms of action of stem cells, and explored the role and underlying regulatory components of stem cell-derived secretomes/exosomes in myocardial repair. Furthermore, we have critically reviewed the different strategies for optimizing both donor stem cells and the target cardiac microenvironments to enhance the engraftment and efficacy of stem cells, highlighting their clinical translatability and potential limitation. Stem Cells 2018;36:482-500.

Recent Progress in Stem Cell Modification for Cardiac Regeneration

During the past decades, stem cell-based therapy has acquired a promising role in regenerative medicine. The application of novel cell therapeutics for the treatment of cardiovascular diseases could potentially achieve the ambitious aim of effective cardiac regeneration. Despite the highly positive results from preclinical studies, data from phase I/II clinical trials are inconsistent and the improvement of cardiac remodeling and heart performance was found to be quite limited. The major issues which cardiac stem cell therapy is facing include inefficient cell delivery to the site of injury, accompanied by low cell retention and weak effectiveness of remaining stem cells in tissue regeneration. According to preclinical and clinical studies, various stem cells (adult stem cells, embryonic stem cells, and induced pluripotent stem cells) represent the most promising cell types so far. Beside the selection of the appropriate cell type, researchers have developed several strategies to produce “second-generation” stem cell products with improved regenerative capacity. Genetic and nongenetic modifications, chemical and physical preconditioning, and the application of biomaterials were found to significantly enhance the regenerative capacity of transplanted stem cells. In this review, we will give an overview of the recent developments in stem cell engineering with the goal to facilitate stem cell delivery and to promote their cardiac regenerative activity.

Adult Stem Cells in Vascular Remodeling

Understanding the contribution of vascular cells to blood vessel remodeling is critical for the development of new therapeutic approaches to cure cardiovascular diseases (CVDs) and regenerate blood vessels. Recent findings suggest that neointimal formation and atherosclerotic lesions involve not only inflammatory cells, endothelial cells, and smooth muscle cells, but also several types of stem cells or progenitors in arterial walls and the circulation. Some of these stem cells also participate in the remodeling of vascular grafts, microvessel regeneration, and formation of fibrotic tissue around biomaterial implants. Here we review the recent findings on how adult stem cells participate in CVD development and regeneration as well as the current state of clinical trials in the field, which may lead to new approaches for cardiovascular therapies and tissue engineering.

Role of Extracellular Matrix in Cardiac Cellular Therapies

The extracellular matrix (ECM) is an essential regulator of homeostasis at the cellular, tissue, and organ level. It is now very well known that ECM dynamic remodeling is indispensable not only for normal growth and development but also recovery from tissue injuries. Indeed, abnormal remodeling of the ECM plays a major role in many pathophysiological processes and contributes to many different pathologies including cardiovascular disorders. Recently, cellular therapies have emerged as a potential therapeutic strategy for restoration of lost cardiomyocytes or their rejuvenation after cardiac damage and injuries. Harnessing the biological properties of ECM could be a viable strategy to enhance the therapeutic effects of cellular therapies by improving the engraftment, integration, survival, and functional adaptation of newly transplanted cells in many different platforms. Conversely, transplanted cells could restore the functionality and original composition of damaged ECM by secreting and depositing new ECM or stimulating normal ECM production by cardiac tissue native cells. Although the ultimate role of cell therapy in treatment of cardiac disorders is still a matter of great debate, the potential utility of ECM in improving the therapeutic effect of transplanted cells and vice versa the potential role of cell therapy as a means to restore the structure and functionality of damaged ECM should be carefully considered in implementation of future clinical cardiovascular cell therapy trials.

Sevoflurane preconditioning promotes activation of resident CSCs by transplanted BMSCs via miR-210 in a rat model for myocardial infarction

Objective

To assess the effect of sevoflurane preconditioning (SFpre) on bone marrow mesenchymal stem cells (BMSCs) for the treatment of acute myocardial infarction.

Results

24 hours after the transplantation, decreased apoptosis of implanted BMSCs and up-regulation of cytokines expression were found within the ischemic area in ^SFpreBMSCs group compared with BMSCs group (P < 0.05). 4 weeks later, ^SFpreBMSCs group showed more viable implanted BMSCs, CSC-derived cardiomyocytes, and higher vessel and myocardial density within the infarcted region and improved cardiac function, compared with control and BMSCs groups (P < 0.05). Compared with untreated BMSCs, promoted migration, inhibited apoptosis, increased cytokine secretion, and enhanced activation to CSCs were detected in ^SFpreBMSCs exposed to profound hypoxia and serum deprivation, via up-regulating miR-210 expression (P < 0.05).

Conclusions

Sevoflurane preconditioning can protect BMSCs against hypoxia by activating miR-210 expression and promote their paracrine functions and effects on resident CSCs.

Methods

After the preconditioning, rat BMSCs (^SFpreBMSCs group) were transplanted into rat AMI models, while BMSCs group received unconditioned BMSCs. Apoptosis and paracrine functions of the transplanted BMSCs, angiogenesis, resident cardiac stem cells (CSCs) derived myocardial regeneration, cardiac function and remodeling were assessed at various time points. In vitro experiments were performed to determine the expression of miR-210 in BMSCs exposed to sevoflurane and the effect of sevoflurane on BMSCs’ migration, apoptosis and secretion of cytokines under hypoxic condition, as well as cytokine-induced CSCs activation.

Systemic recovery and therapeutic effects of transplanted allogenic and xenogenic mesenchymal stromal cells in a rat blunt chest trauma model

BACKGROUND

Effective therapy of Acute Lung Injury (ALI) is still a major scientific and clinical problem. To define novel therapeutic strategies for sequelae of blunt chest trauma (TxT) like ALI/Acute Respiratory Distress Syndrome, we have investigated the immunomodulatory and regenerative effects of a single dose of ex vivo expanded human or rat mesenchymal stromal cells (hMSCs/rMSCs) with or without priming, immediately after the induction of TxT in Wistar rats.

METHODS

We analyzed the histological score of lung injury, the cell count of the broncho alveolar lavage fluid (BAL), the change in local and systemic cytokine level and the recovery of the administered cells 24 h and 5 days post trauma.

RESULTS

The treatment with hMSCs reduced the injury score 24 h after trauma by at least 50% compared with TxT rats without MSCs. In general, TxT rats treated with hMSCs exhibited a lower level of pro-inflammatory cytokines (interleukin [IL]-1B, IL-6) and chemokines (C-X-C motif chemokine ligand 1 [CXCL1], C-C motif chemokine ligand 2 [CCL2]), but a higher tumor necrosis factor alpha induced protein 6 (TNFAIP6) level in the BAL compared with TxT rats after 24 h. Five days after trauma, cytokine levels and the distribution of inflammatory cells were similar to sham rats. In contrast, the treatment with rMSCs did not reveal such therapeutic effects on the injury score and cytokine levels, except for TNFAIP6 level.

CONCLUSION

TxT represents a suitable model to study effects of MSCs as an acute treatment strategy after trauma. However, the source of MSCs has to be carefully considered in the design of future studies.

Umbilical cord mesenchyme stem cell local intramuscular injection for treatment of uterine niche: Protocol for a prospective, randomized, double-blinded, placebo-controlled clinical trial

BACKGROUND

Uterine niche is defined as a triangular anechoic structure at the site of the scar or a gap in the myometrium at the site of a previous caesarean section. The main clinical manifestations are postmenstrual spotting and intrauterine infection, which may seriously affect the daily life of nonpregnant women. Trials have shown an excellent safety and efficacy for the potential of mesenchymal stem cells (MSCs) as a therapeutic option for scar reconstruction. Therefore, this study is designed to investigate the safety and efficacy of using MSCs in the treatment for the uterine niche.

METHODS/DESIGN

This phase II clinical trial is a single-center, prospective, randomized, double-blind, placebo-controlled with 2 arms. One hundred twenty primiparous participants will be randomly (1:1 ratio) assigned to receive direct intramuscular injection of MSCs (a dose of 1*10 cells in 1 mL of 0.9% saline) (MSCs group) or an identical-appearing 1 mL of 0.9% saline (placebo-controlled group) near the uterine incision. The primary outcome of this trial is to evaluate the proportion of participants at 6 months who is found uterine niche in the uterus by transvaginal utrasonography. Adverse events will be documented in a case report form. The study will be conducted at the Department of Obstetric of Southern Medical University Affiliated Maternal & Child Health Hospital of Foshan.

DISCUSSION

This trial is the first investigation of the potential for therapeutic use of MSCs for the management of uterine niche after cesarean delivery.

CONCLUSION

This protocol will help to determine the efficacy and safety of MSCs treatment in uterine niche and bridge the gap with regards to the current preclinical and clinical evidence.

TRIAL REGISTRATION NUMBER

NCT02968459 (Clinical Trials.gov: http://clinicaltrials.gov/).

Cardiac Stem Cells for Myocardial Regeneration: They Are Not Alone

Heart failure is the number one killer worldwide with ~50% of patients dying within 5 years of prognosis. The discovery of stem cells, which are capable of repairing the damaged portion of the heart, has created a field of cardiac regenerative medicine, which explores various types of stem cells, either autologous or endogenous, in the hope of finding the “holy grail” stem cell candidate to slow down and reverse the disease progression. However, there are many challenges that need to be overcome in the search of such a cell candidate. The ideal cells have to survive the harsh infarcted environment, retain their phenotype upon administration, and engraft and be activated to initiate repair and regeneration in vivo. Early bench and bedside experiments mostly focused on bone marrow-derived cells; however, heart regeneration requires multiple coordinations and interactions between various cell types and the extracellular matrix to form new cardiomyocytes and vasculature. There is an observed trend that when more than one cell is coadministered and cotransplanted into infarcted animal models the degree of regeneration is enhanced, when compared to single-cell administration. This review focuses on stem cell candidates, which have also been tested in human trials, and summarizes findings that explore the interactions between various stem cells in heart regenerative therapy.

Biomaterial-Free Three-Dimensional Bioprinting of Cardiac Tissue using Human Induced Pluripotent Stem Cell Derived Cardiomyocytes

We have developed a novel method to deliver stem cells using 3D bioprinted cardiac patches, free of biomaterials. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), fibroblasts (FB) and endothelial cells (EC) were aggregated to create mixed cell spheroids. Cardiac patches were created from spheroids (CM:FB:EC = 70:15:15, 70:0:30, 45:40:15) using a 3D bioprinter. Cardiac patches were analyzed with light and video microscopy, immunohistochemistry, immunofluorescence, cell viability assays and optical electrical mapping. Cardiac tissue patches of all cell ratios beat spontaneously after 3D bioprinting. Patches exhibited ventricular-like action potential waveforms and uniform electrical conduction throughout the patch. Conduction velocities were higher and action potential durations were significantly longer in patches containing a lower percentage of FBs. Immunohistochemistry revealed staining for CM, FB and EC markers, with rudimentary CD31+ blood vessel formation. Immunofluorescence revealed the presence of Cx43, the main cardiac gap junction protein, localized to cell-cell borders. In vivo implantation suggests vascularization of 3D bioprinted cardiac patches with engraftment into native rat myocardium. This constitutes a significant step towards a new generation of stem cell-based treatment for heart failure.

Intramyocardial fate and effect of iron nanoparticles co-injected with MACS® purified stem cell products

BACKGROUND

Magnetic activated cell sorting (MACS^®) is routinely used to isolate stem cell subpopulations intended for the treatment of cardiovascular diseases. In strong contrast, studies examining the amount, effect and intramyocardial distribution of iron nanoparticles used for magnetic cell labelling are missing, although iron excess can cause functional disorders in the heart.

METHODS AND RESULTS

CD133⁺ haematopoietic and CD271⁺ mesenchymal stem cells were purified from bone marrow using automatically and manually MACS^® based systems. Flow cytometric measurements demonstrated a rapid loss of MACS^® MicroBeads from cells under culture conditions, while storage under hypothermic conditions decelerated their detachment. Moreover, an average loading of ∼11 fg iron/cell caused by magnetic labelling was determined in magnetic particle spectroscopy. Importantly, hemodynamic measurements as well as histological examinations using a myocardial ischemia/reperfusion mouse model showed no influence of MACS^® MicroBeads on cardiac regeneration, while the transplantation of stem cells caused a significant improvement. Furthermore, immunostainings demonstrated the clearance of co-injected iron nanoparticles from stem cells and the surrounding heart tissue within 48 h post transplantation.

CONCLUSIONS

Our results indicate that iron amounts typically co-injected with MACS^® purified stem cells do not harm cardiac functions and are cleared from heart tissue within a few hours. Therefore, we conclude that MACS^® MicroBeads exhibit a good compatibility in the cardiac environment.