Safety confirmation of induced pluripotent stem cell-derived cardiomyocyte patch transplantation for ischemic cardiomyopathy: first three case reports

Spaceflight alters protein levels and gene expression associated with stress response and metabolic characteristics in human cardiac spheroids

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) possess tremendous advantage for cardiac regeneration. However, cell survival is challenging upon cell transplantation. Since microgravity can profoundly affect cellular properties, we investigated the effect of spaceflight on hiPSC-CMs. Cardiac spheroids derived from hiPSCs were transported to the International Space Station (ISS) via the SpaceX Crew-8 mission and cultured under space microgravity for 8 days. Beating cardiac spheroids were observed on the ISS and upon successful experimentation by the astronauts in space, the live cultures were returned to Earth. These cells had normal displacement (an indicator of contraction) and Ca2+ transient parameters in 3D live cell imaging. Proteomic analysis revealed that spaceflight upregulated many proteins involved in metabolism (n = 90), cellular component of mitochondrion (n = 62) and regulation of proliferation (n = 10). Specific metabolic pathways enriched by spaceflight included glutathione metabolism, biosynthesis of amino acids, and pyruvate metabolism. In addition, the top upregulated proteins in spaceflight samples included those involved in cellular stress response, cell survival, and metabolism. Transcriptomic profiles indicated that spaceflight upregulated genes associated with cardiomyocyte development, and cellular components of cardiac structure and mitochondrion. Furthermore, spaceflight upregulated genes in metabolic pathways associated with cell survival such as glycerophospholipid metabolism and glycerolipid metabolism. These findings indicate that short-term exposure of 3D hiPSC-CMs to the space environment led to significant changes in protein levels and gene expression involved in cell survival and metabolism.

Human pluripotent stem cell-based cardiac repair: Lessons learned and challenges ahead

The transplantation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) and hPSC-derived cardiac progenitors (hPSC-CPs) represents a promising strategy for regenerating hearts damaged by myocardial infarction (MI). After nearly two decades of experience testing these cell populations in various small- and large-animal MI models, multiple clinical trials have recently been initiated. In this review, we consider the principal lessons learned from preclinical experience with hPSC-CMs and -CPs, focusing on three conclusions that have been supported by the majority of reported transplantation studies. First, hPSC-CMs and -CPs stably engraft in injured hearts and partially remuscularize the infarct scar, but more progress is needed to improve graft cell retention and survival. Second, the transplantation of hPSC-CMs and -CPs has been found to improve contractile function in infarcted hearts, but the mechanistic basis for these effects remains incompletely elucidated. Third, the graft tissue formed by these cells can integrate and activate synchronously with host myocardium, but this capacity for electromechanical integration has been associated with an elevated risk of graft-related arrhythmias. Here, we summarize the preclinical evidence supporting these three observations, identify the relevant gaps and barriers to translation, and summarize ongoing efforts to improve the safety and efficacy of hPSC-CM- and -CP-based regenerative therapies.

Trials and tribulations of cell therapy for heart failure: an update on ongoing trials

Heart failure (HF) remains a leading cause of mortality, responsible for 13% of all deaths worldwide. The prognosis for patients with HF is poor, with only a 50% survival rate within 5 years. A major challenge of ischaemia-driven HF is the loss of cardiomyocytes, compounded by the minimal regenerative capacity of the adult heart. To date, replacement of irreversibly damaged heart muscle can only be achieved by complete heart transplantation. In the past 20 years, cell therapy has emerged and evolved as a promising avenue for cardiac repair and regeneration. During this time, cell therapy for HF has encountered substantial barriers in both preclinical studies and clinical trials but the field continues to progress and evolve from lessons learned from such research. In this Review, we provide an overview of ongoing trials of cell-based and cell product-based therapies for the treatment of HF. Findings from these trials will facilitate the clinical translation of cardiac regenerative and reparative therapies not only by evaluating the safety and efficacy of specific cell-based therapeutics but also by establishing the feasibility of novel or underexplored treatment protocols such as repeated intravenous dosing, personalized patient selection based on pharmacogenomics, systemic versus intramural cell delivery, and epicardial engraftment of engineered tissue products.

Progress and challenges in developing allogeneic cell therapies

The new era of cell therapeutics has started with autologous products to avoid immune rejection. However, therapeutics derived from allogeneic cells could be scaled and made available for a much larger patient population if immune rejection could reliably be overcome. In this review, we outline gene engineering concepts aimed at generating immune-evasive cells. First, we summarize the current state of allogeneic immune cell therapies, and second, we compile the still limited data for allogeneic cell replacement therapies. We emphasize the advances in this fast-developing field and provide an optimistic outlook for future allogeneic cell therapies.

Engineered heart tissue patches: A milestone in cardiac regenerative medicine

Researchers have demonstrated that a stem cell-derived heart muscle patch can safely remuscularize failing hearts.1 Published in Nature, the study shows successful long-term cardiac integration of a patch in a primate model and a human patient with no adverse effects. This breakthrough marks a major step toward regenerative therapies for advanced heart failure.

Engineered heart muscle allografts for heart repair in primates and humans

Cardiomyocytes can be implanted to remuscularize the failing heart1-7. Challenges include sufficient cardiomyocyte retention for a sustainable therapeutic impact without intolerable side effects, such as arrhythmia and tumour growth. We investigated the hypothesis that epicardial engineered heart muscle (EHM) allografts from induced pluripotent stem cell-derived cardiomyocytes and stromal cells structurally and functionally remuscularize the chronically failing heart without limiting side effects in rhesus macaques. After confirmation of in vitro and in vivo (nude rat model) equivalence of the newly developed rhesus macaque EHM model with a previously established Good Manufacturing Practice-compatible human EHM formulation8, long-term retention (up to 6 months) and dose-dependent enhancement of the target heart wall by EHM grafts constructed from 40 to 200 million cardiomyocytes/stromal cells were demonstrated in macaques with and without myocardial infarction-induced heart failure. In the heart failure model, evidence for EHM allograft-enhanced target heart wall contractility and ejection fraction, which are measures for local and global heart support, was obtained. Histopathological and gadolinium-based perfusion magnetic resonance imaging analyses confirmed cell retention and functional vascularization. Arrhythmia and tumour growth were not observed. The obtained feasibility, safety and efficacy data provided the pivotal underpinnings for the approval of a first-in-human clinical trial on tissue-engineered heart repair. Our clinical data confirmed remuscularization by EHM implantation in a patient with advanced heart failure.

Pluripotent stem-cell-derived therapies in clinical trial: A 2025 update

Since the first derivation of human pluripotent stem cells (hPSCs) 27 years ago, technologies to control their differentiation and manufacturing have advanced immensely, enabling increasing numbers of clinical trials with hPSC-derived products. Here, we revew the landscape of interventional hPSC trials worldwide, highlighting available data on clinical safety and efficacy. As of December 2024, we identify 116 clinical trials with regulatory approval, testing 83 hPSC products. The majority of trials are targeting eye, central nervous system, and cancer. To date, more than 1,200 patients have been dosed with hPSC products, accumulating to >1011 clinically administered cells, so far showing no generalizable safety concerns.

The Low Tumorigenic Risk and Subtypes of Cardiomyocytes Derived from Human-induced Pluripotent Stem Cells

BACKGROUND

Clinical application of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is a promising approach for the treatment of heart diseases. However, the tumorigenicity of hiPSC-CMs remains a concern for their clinical applications and the composition of the hiPSC-CM subtypes need to be clearly identified.

METHODS

In the present study, hiPSC-CMs were induced from hiPSCs via modulation of Wnt signaling followed by glucose deprivation purification. The structure, function, subpopulation composition, and tumorigenic risk of hiPSC-CMs were evaluated by single-cell RNA sequencing (scRNAseq), whole exome sequencing (WES), and integrated molecular biology, cell biology, electrophysiology, and/or animal experiments.

RESULTS

The high purity of hiPSC-CMs, determined by flow cytometry analysis, was generated. ScRNAseq analysis of differentiation day (D) 25 hiPSC-CMs did not identify the transcripts representative of undifferentiated hiPSCs. WES analysis showed a few newly acquired confidently identified mutations and no mutations in tumor susceptibility genes. Further, no tumor formation was observed after transplanting hiPSC-CMs into NOD-SCID mice for 3 months. Moreover, D25 hiPSC-CMs were composed of subtypes of ventricular-like cells (23.19%) and atrial-like cells (66.45%) in different cell cycle stages or mature levels, based on the scRNAseq analysis. Furthermore, a subpopulation of more mature ventricular cells (3.21%) was identified, which displayed significantly up-regulated signaling pathways related to myocardial contraction and action potentials. Additionally, a subpopulation of cardiomyocytes in an early differentiation stage (3.44%) experiencing nutrient stress-induced injury and heading toward apoptosis was observed.

CONCLUSIONS

This study confirmed the biological safety of hiPSC-CMs and described the composition and expression profile of cardiac subtypes in hiPSC-CMs which provide standards for quality control and theoretical supports for the translational applications of hiPSC-CMs.

Integrating Prime Editing and Cellular Reprogramming as Novel Strategies for Genetic Cardiac Disease Modeling and Treatment

PURPOSE OF REVIEW

This review aims to evaluate the potential of CRISPR-based gene editing tools, particularly prime editors (PE), in treating genetic cardiac diseases. It seeks to answer how these tools can overcome current therapeutic limitations and explore the synergy between PE and induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) for personalized medicine.

RECENT FINDINGS

Recent advancements in CRISPR technology, including CRISPR-Cas9, base editors, and PE, have demonstrated precise genome correction capabilities. Notably, PE has shown exceptional precision in correcting genetic mutations. Combining PE with iPSC-CMs has emerged as a robust platform for disease modeling and developing innovative treatments for genetic cardiac diseases. The review finds that PE, when combined with iPSC-CMs, holds significant promise for treating genetic cardiac diseases by addressing their root causes. This approach could revolutionize personalized medicine, offering more effective and precise treatments. Future research should focus on refining these technologies and their clinical applications.

Label-Free Raman Spectroscopy for Assessing Purity and Maturation of hiPSC-Derived Cardiac Tissue

I.

BACKGROUND

Human induced pluripotent stem cell (hiPSC) derived cardiomyocytes (CMs) have been utilized in drug toxicity evaluation, drug discovery, and treating heart failure patients, showing substantial effects. Ensuring the quality, purity, and maturation of hiPSC-CMs during large-scale production is crucial. There is a growing demand for a novel method to characterize cell molecular profiles without labels and without causing damage. II.

METHODS

In this study, we employed label-free Raman microscopy to evaluate hiPSC-derived CMs. The study involved the characterization of cell molecular profiles without labels and without causing damage. The correlation between Raman spectroscopy of specific components, such as cytochrome c and myoglobin, and CM purity and maturation following hiPSC differentiation was investigated. Additionally, the validation of this correlation was performed by assessing mixtures of commercially available CMs (iCell cardiomyocytes2) and fibroblasts at various ratios as well as hiPSC-derived CMs with different efficiencies. Furthermore, CMs were matured using rapid pacing of traveling waves, and the Raman profiles of matured CMs were compared to those of immature ones. III.

RESULTS

Raman spectroscopy indicated that the cytochrome c and myoglobin showed correlation with the purity and maturation of CMs following differentiation of hiPSCs. This correlation was validated through experiments involving different CM-fibroblast mixtures and hiPSC-derived CMs with varying efficiencies. Moreover, matured CMs exhibited markedly different Raman profiles compared to immature ones, indicating the potential of Raman imaging as a tool for assessing CM maturation. IV.

CONCLUSIONS

We discovered that Raman spectroscopy of certain components, such as cytochrome c and myoglobin, correlates with the CM purity and maturation following hiPSC differentiation. The findings of this study highlight the potential of label-free Raman microscopy as a nondestructive, high-content, and time-efficient method for quality control of hiPSC-derived CMs. This approach could significantly contribute to ensuring the quality and maturity of hiPSC-CMs for various applications in drug discovery and regenerative medicine.

Bridging the Gap: Advances and Challenges in Heart Regeneration from In Vitro to In Vivo Applications

Cardiovascular diseases, particularly ischemic heart disease, area leading cause of morbidity and mortality worldwide. Myocardial infarction (MI) results in extensive cardiomyocyte loss, inflammation, extracellular matrix (ECM) degradation, fibrosis, and ultimately, adverse ventricular remodeling associated with impaired heart function. While heart transplantation is the only definitive treatment for end-stage heart failure, donor organ scarcity necessitates the development of alternative therapies. In such cases, methods to promote endogenous tissue regeneration by stimulating growth factor secretion and vascular formation alone are insufficient. Techniques for the creation and transplantation of viable tissues are therefore highly sought after. Approaches to cardiac regeneration range from stem cell injections to epicardial patches and interposition grafts. While numerous preclinical trials have demonstrated the positive effects of tissue transplantation on vasculogenesis and functional recovery, long-term graft survival in large animal models is rare. Adequate vascularization is essential for the survival of transplanted tissues, yet pre-formed microvasculature often fails to achieve sufficient engraftment. Recent studies report success in enhancing cell survival rates in vitro via tissue perfusion. However, the transition of these techniques to in vivo models remains challenging, especially in large animals. This review aims to highlight the evolution of cardiac patch and stem cell therapies for the treatment of cardiovascular disease, identify discrepancies between in vitro and in vivo studies, and discuss critical factors for establishing effective myocardial tissue regeneration in vivo.

Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) for modeling cardiac arrhythmias: strengths, challenges and potential solutions

Ion channels and cytoskeletal proteins in the cardiac dyad play a critical role in maintaining excitation-contraction (E-C) coupling and provide cardiac homeostasis. Functional changes in these dyad proteins, whether induced by genetic, epigenetic, metabolic, therapeutic, or environmental factors, can disrupt normal cardiac electrophysiology, leading to abnormal E-C coupling and arrhythmias. Animal models and heterologous cell cultures provide platforms to elucidate the pathogenesis of arrhythmias for basic cardiac research; however, these traditional systems do not truly reflect human cardiac electro-pathophysiology. Notably, patients with the same genetic variants of inherited channelopathies (ICC) often exhibit incomplete penetrance and variable expressivity which underscores the need to establish patient-specific disease models to comprehend the mechanistic pathways of arrhythmias and determine personalized therapies. Patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) inherit the genetic background of the patient and reflect the electrophysiological characteristics of the native cardiomyocytes. Thus, iPSC-CMs provide an innovative and translational pivotal platform in cardiac disease modeling and therapeutic screening. In this review, we will examine how patient-specific iPSC-CMs historically evolved to model arrhythmia syndromes in a dish, and their utility in understanding the role of specific ion channels and their functional characteristics in causing arrhythmias. We will also examine how CRISPR/Cas9 have enabled the establishment of patient-independent and variant-induced iPSC-CMs-based arrhythmia models. Next, we will examine the limitations of using human iPSC-CMs with respect to in vitro arrhythmia modeling that stems from variations in iPSCs or toxicity due to gene editing on iPSC or iPSC-CMs and explore how such hurdles are being addressed. Importantly, we will also discuss how novel 3D iPSC-CM models can better capture in vitro characteristics and how all-optical platforms provide non-invasive and high- throughput electrophysiological data that is useful for stratification of emerging arrhythmogenic variants and drug discovery. Finally, we will examine strategies to improve iPSC-CM maturity, including powerful gene editing and optogenetic tools that can introduce/modify specific ion channels in iPSC-CMs and tailor cellular and functional characteristics. We anticipate that an elegant synergy of iPSCs, novel gene editing, 3D- culture models, and all-optical platforms will offer a high-throughput template to faithfully recapitulate in vitro arrhythmogenic events necessary for personalized arrhythmia monitoring and drug screening process.

Induced pluripotent stem cell therapies in heart failure treatment: a meta-analysis and systematic review

Background: Heart failure (HF) causes over 266,400 deaths annually. Despite treatment advancements, HF mortality remains high. Induced pluripotent stem cells (iPSCs) offer promising new options. This review assesses iPSC-based treatments for HF.Method: the review included studies from PubMed, ScienceDirect and Web of Science.Results: Analysis of 25 studies with 553 animals showed a baseline ejection fraction (EF) of 39.2 ± 8.9%. iPSC treatment significantly improved EF (MD = 8.6, p < 0.001) and fractional shortening (MD = 6.38, p < 0.001), and reduced ventricular remodeling without increasing arrhythmia risk.Conclusion: iPSC-based therapy improves heart function and reduces ventricular volumes in HF animal models, aligning with promising early clinical trial outcomes.

Fabrication of heart tubes from iPSC derived cardiomyocytes and human fibrinogen by rotating mold technology

Due to its structural and functional complexity the heart imposes immense physical, physiological and electromechanical challenges on the engineering of a biological replacement. Therefore, to come closer to clinical translation, the development of a simpler biological assist device is requested. Here, we demonstrate the fabrication of tubular cardiac constructs with substantial dimensions of 6 cm in length and 11 mm in diameter by combining human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and human foreskin fibroblast (hFFs) in human fibrin employing a rotating mold technology. By centrifugal forces employed in the process a cell-dense layer was generated enabling a timely functional coupling of iPSC-CMs demonstrated by a transgenic calcium sensor, rhythmic tissue contractions, and responsiveness to electrical pacing. Adjusting the degree of remodeling as a function of hFF-content and inhibition of fibrinolysis resulted in stable tissue integrity for up to 5 weeks. The rotating mold device developed in frame of this work enabled the production of tubes with clinically relevant dimensions of up to 10 cm in length and 22 mm in diameter which-in combination with advanced bioreactor technology for controlled production of functional iPSC-derivatives-paves the way towards the clinical translation of a biological cardiac assist device.

Regenerative medicine in cardiovascular disease

Owing to the rapid increase in the number of people with severe heart failure, regenerative medicine is anticipated to play a role in overcoming the limitations inherent in existing surgical interventions. There are essentially two types of cardiac regenerative therapies for a failing heart. Cellular regenerative therapies using various stem cells improve the functional recovery of the heart mainly by cytokine paracrine effects. The implantation of induced pluripotent stem cell-derived cardiomyocytes can contribute not only to the inhibition of adverse heart remodeling by paracrine effects but also to the supply of newly born functional myocytes with the recipient myocardium as "mechanically working cells." Cell transplantation, including autologous myoblast transplantation, reduces heart failure exacerbations and benefits patients without the need for other treatment options. Although cellular therapy is currently the mainstream approach, it requires an in-house cell-processing center with an aseptic environment. In addition, these stem cells are usually introduced via several invasive delivery methods, including intracoronary administration, and cellular sheet implantation. Simplifying the culture methods for these cells is a crucial problem that needs to be resolved. Drug-induced regenerative therapy is another option that enhances self-endogenous regenerative systems in the human body and does not require invasive methods or cell cultures. Therefore, drug-induced regenerative therapies may overcome the disadvantages of these cellular therapies. The purpose of this report is to summarize cell transplantation therapy in the cardiovascular system and regenerative therapy for heart failure using an autologous endogenous regenerative system.

Current Status of Cardiac Regenerative Therapy Using Induced Pluripotent Stem Cells

Heart failure (HF) is a life-threatening disorder and is treated by drug therapies and surgical interventions such as heart transplantation and left ventricular assist device (LVAD). However, these treatments can lack effectiveness in the long term and are associated with issues such as donor shortage in heart transplantation, and infection, stroke, or gastrointestinal bleeding in LVADs. Therefore, alternative therapeutic strategies are still needed. In this respect, stem cell therapy has been introduced for the treatment of HF and numerous preclinical and clinical studies are employing a range of stem cell varieties. These stem cells, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have been shown to improve cardiac function and attenuate left ventricular remodeling. IPSCs, which have a capacity for unlimited proliferation and differentiation into cardiomyocytes, are a promising cell source for myocardial regeneration therapy. In this review, we discuss the following topics: (1) what are iPSCs; (2) the limitations and solutions for the translation of iPSC-CMs practically; and (3) the current therapeutic clinical trials.

The role of cardiac microenvironment in cardiovascular diseases: implications for therapy

Due to aging populations and changes in lifestyle, cardiovascular diseases including cardiomyopathy, hypertension, and atherosclerosis, are the leading causes of death worldwide. The heart is a complicated organ composed of multicellular types, including cardiomyocytes, fibroblasts, endothelial cells, vascular smooth muscle cells, and immune cells. Cellular specialization and complex interplay between different cell types are crucial for the cardiac tissue homeostasis and coordinated function of the heart. Mounting studies have demonstrated that dysfunctional cells and disordered cardiac microenvironment are closely associated with the pathogenesis of various cardiovascular diseases. In this paper, we discuss the composition and the homeostasis of cardiac tissues, and focus on the role of cardiac environment and underlying molecular mechanisms in various cardiovascular diseases. Besides, we elucidate the novel treatment for cardiovascular diseases, including stem cell therapy and targeted therapy. Clarification of these issues may provide novel insights into the prevention and potential targets for cardiovascular diseases.

Progress in preclinical research on induced pluripotent stem cell therapy for acute myocardial infarction

Induced pluripotent stem cells (iPSCs) are obtained by introducing exogenous genes or adding chemicals to the culture medium to induce somatic cell differentiation. Similarly to embryonic stem cells, iPSCs have the ability to differentiate into all three embryonic cell lines. iPSCs can differentiate into cardiac muscle cells through two-dimensional differentiation methods such as monolayer cell culture and co-culture, or through embryoid body and scaffold-based three-dimensional differentiation methods. In addition, the process of iPSCs differentiation into cardiac muscle cells also requires activation or inhibition of specific signaling pathways,such as Wnt, BMP, Notch signaling pathways to mimic the development of the heart in vivo. In recent years, suspension culturing in bioreactors has been shown to produce large number of iPSCs derived cardiac muscle cells (iPSC-CMs). Before transplantation, it is necessary to purify iPSC-CMs through metabolic regulation or cell sorting to eliminate undifferentiated iPSCs, which may lead to teratoma formation. The transplantation methods for iPSC-CMs are mainly injection of cell suspension and transplantation of cell patches into the infarcted myocardium. Animal studies have shown that transplantation of iPSC-CMs into the infarcted myocardium can improve cardiac function. This article reviews the progress in preclinical studies on iPSC-CMs therapy for acute myocardial infarction and discusses the limitations and challenges of its clinical application to provide references for further clinical research and application.

Stem Cell Therapy against Ischemic Heart Disease

Ischemic heart disease, which is one of the top killers worldwide, encompasses a series of heart problems stemming from a compromised coronary blood supply to the myocardium. The severity of the disease ranges from an unstable manifestation of ischemic symptoms, such as unstable angina, to myocardial death, that is, the immediate life-threatening condition of myocardial infarction. Even though patients may survive myocardial infarction, the resulting ischemia-reperfusion injury triggers a cascade of inflammatory reactions and oxidative stress that poses a significant threat to myocardial function following successful revascularization. Moreover, despite evidence suggesting the presence of cardiac stem cells, the fact that cardiomyocytes are terminally differentiated and cannot significantly regenerate after injury accounts for the subsequent progression to ischemic cardiomyopathy and ischemic heart failure, despite the current advancements in cardiac medicine. In the last two decades, researchers have realized the possibility of utilizing stem cell plasticity for therapeutic purposes. Indeed, stem cells of different origin, such as bone-marrow- and adipose-derived mesenchymal stem cells, circulation-derived progenitor cells, and induced pluripotent stem cells, have all been shown to play therapeutic roles in ischemic heart disease. In addition, the discovery of stem-cell-associated paracrine effects has triggered intense investigations into the actions of exosomes. Notwithstanding the seemingly promising outcomes from both experimental and clinical studies regarding the therapeutic use of stem cells against ischemic heart disease, positive results from fraud or false data interpretation need to be taken into consideration. The current review is aimed at overviewing the therapeutic application of stem cells in different categories of ischemic heart disease, including relevant experimental and clinical outcomes, as well as the proposed mechanisms underpinning such observations.