• Acute myocardial infarction
• Cardiac muscle cells
• Induced pluripotent stem cells
• Regenerative medicine
• Review

• Induced Pluripotent Stem Cells/cytology
• Myocardial Infarction/therapy
• Humans
• Cell Differentiation
• Animals
• Myocytes, Cardiac/cytology
• Stem Cell Transplantation/methods

• cell lineage
• heart stem cells
• stem-cell differentiation
• data processing

• Female
• Humans
• Animals
• Mice
• Placenta Growth Factor
• Endothelial Cells
• Myocardium
• Myocytes, Cardiac
• Cell Differentiation

• Vetenskapsrådet (Swedish Research Council)
• Hjärt-Lungfonden (Swedish Heart-Lung Foundation)
• Karolinska Institutet (Karolinska Institute)

• Cardiac repair
• Ischemic heart failure
• Myocardial infarction
• Neuro-immune response
• Therapeutic approaches

• Humans
• Myocardial Reperfusion Injury
• Myocardial Infarction/drug therapy
• Myocardium
• Heart Failure/drug therapy
• Immune System

• PG/18/49/33833 British Heart Foundation
• NIHR203377 Department of Health
• PG18/49/33833 British Heart Foundation
• MR/L012723/1 Medical Research Council
• PG/22/10929 British Heart Foundation
• PG22/10929 British Heart Foundation
• RM/21/290001 British Heart Foundation

• Myocardial infarction
• angiogenesis
• cell lineage
• cell plasticity
• myocardiocytes
• regeneration
• reprogramming
• somatic cell
• stem cell
• transcription factor
• transdifferentiation

• Transcription Factors/genetics
• Transcription Factors/metabolism
• T-Box Domain Proteins/genetics
• T-Box Domain Proteins/metabolism
• Myocytes, Cardiac/metabolism
• Cell Differentiation/genetics
• Myocardium

• arrhythmia
• cardiac disease
• molecular cardiology
• molecular therapy
• valve disease
• vascular disease

• cardiac fibrosis
• cardiomyocytes
• neonatal pig heart
• partial apex resection
• proliferative mesenchymal cells
• transient cardiac regeneration

• R15 HL159599 NHLBI NIH HHS
• R01HL157050; R01EB022018; T32HL134613 NIH HHS
• R15 HL140503 NHLBI NIH HHS
• R01 EB022018 NIBIB NIH HHS
• T32 HL134613 NHLBI NIH HHS

Heart regeneration is an unmet clinical need, hampered by limited renewal of adult cardiomyocytes and fibrotic scarring. Pluripotent stem cell-based strategies are emerging, but unravelling cellular dynamics of host–graft crosstalk remains elusive. Here, by combining lineage tracing and single-cell transcriptomics in injured non-human primate heart biomimics, we uncover the coordinated action modes of human progenitor-mediated muscle repair. Chemoattraction via CXCL12/CXCR4 directs cellular migration to injury sites. Activated fibroblast repulsion targets fibrosis by SLIT2/ROBO1 guidance in organizing cytoskeletal dynamics. Ultimately, differentiation and electromechanical integration lead to functional restoration of damaged heart muscle. In vivo transplantation into acutely and chronically injured porcine hearts illustrated CXCR4-dependent homing, de novo formation of heart muscle, scar-volume reduction and prevention of heart failure progression. Concurrent endothelial differentiation contributed to graft neovascularization. Our study demonstrates that inherent developmental programmes within cardiac progenitors are sequentially activated in disease, enabling the cells to sense and counteract acute and chronic injury.

In this study, the authors report that pluripotent stem cell-derived ventricular progenitors target loss of myocardium and fibrotic scarring to promote heart regeneration, thus offering new potential therapeutic strategies for heart injury.

• biofabrication
• biomaterial
• bioprinting
• cardiac tissue engineering
• cardiomyocyte maturation
• cell therapy
• heart disease
• regenerative medicine
• stem cell biology

Human pluripotent stem cells (hPSCs) constitute a valuable model to study the complexity of early human cardiac development and investigate the molecular mechanisms involved in heart diseases. The differentiation of hPSCs into cardiac lineages in vitro can be achieved by traditional two-dimensional (2D) monolayer approaches or by adopting innovative three-dimensional (3D) cardiac organoid protocols. Human cardiac organoids (hCOs) are complex multicellular aggregates that faithfully recapitulate the cardiac tissue’s transcriptional, functional, and morphological features. In recent years, significant advances in the field have dramatically improved the robustness and efficiency of hCOs derivation and have promoted the application of hCOs for drug screening and heart disease modeling. This review surveys the current differentiation protocols, focusing on the most advanced 3D methods for deriving hCOs from hPSCs. Furthermore, we describe the potential applications of hCOs in the pharmaceutical and tissue bioengineering fields, including their usage to investigate the consequences of Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV2) infection in the heart.

• King Abdullah University of Science and Technology

• Cardiac regeneration
• Coronary occlusion
• Heart failure
• Revascularization therapy
• VEGFA
• Zebrafish

• Animals
• Heart/physiology
• Myocardial Infarction/metabolism
• Myocardium/metabolism
• Myocytes, Cardiac/metabolism
• Zebrafish/metabolism
• Zebrafish Proteins/metabolism

• PJT-178037 CIHR

• cell division
• experimental models of disease

• Cardiology
• Heart failure

• Adult
• Aged
• Animals
• Animals, Newborn
• Benzothiazoles/pharmacology
• Cardiomyopathy, Dilated/metabolism
• Cytochrome P-450 Enzyme Inhibitors/pharmacology
• Cytochrome P450 Family 26/antagonists & inhibitors
• Female
• Gene Expression Regulation
• Guinea Pigs
• Heart Failure/metabolism
• Heart Ventricles/metabolism
• Humans
• Male
• Middle Aged
• Myocardium/metabolism
• Myocytes, Cardiac/drug effects
• Myocytes, Cardiac/metabolism
• Rats
• Tretinoin/metabolism
• Tretinoin/pharmacology
• Triazoles/pharmacology
• Ventricular Remodeling/drug effects
• Vitamin A/metabolism
• Young Adult

• R01 HD077260 NICHD NIH HHS
• R01 HL089847 NHLBI NIH HHS
• R01 HL105993 NHLBI NIH HHS
• R01 HL134821 NHLBI NIH HHS

Ventricular-like human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exhibit the electrophysiological characteristics of spontaneous beating. Previous studies demonstrated that dexmedetomidine (DMED), a highly selective and widely used α₂-adrenoceptor agonist for sedation, analgesia, and stress management, may induce antiarrhythmic effects, especially ventricular tachycardia. However, the underlying mechanisms of the DMED-mediated antiarrhythmic effects remain to be fully elucidated.

A conventional patch-clamp recording method was used to investigate the direct effects of DMED on spontaneous action potentials, pacemaker currents (I_f), potassium (K⁺) channel currents (I_K1 and I_Kr), sodium (Na⁺) channel currents (I_Na), and calcium (Ca²⁺) channel currents (I_Ca) in ventricular-like hiPSC-CMs.

DMED dose-dependently altered the frequency of ventricular-like spontaneous action potentials with a half-maximal inhibitory concentration (IC₅₀) of 27.9 µM (n=6) and significantly prolonged the action potential duration at 90% repolarization (APD₉₀). DMED also inhibited the amplitudes of the I_Na and I_Ca without affecting the activation and inactivation curves of these channels. DMED decreased the time constant of the Na⁺ and Ca²⁺ channel activation at potential –40 to –20 mv, and –20 mv. DMED increased the time constant of inactivation of the Na⁺ and Ca²⁺ channels. However, DMED did not affect the I_K1, I_Kr, I_f, and their current-voltage relationship. The ability of DMED to decrease the spontaneous action potential frequency and the Na⁺ and Ca²⁺ channel amplitudes, were not blocked by yohimbine, idazoxan, or phentolamine.

DMED could inhibit the frequency of spontaneous action potentials and decrease the I_Na and I_Ca of hiPSC-CMs via mechanisms that were independent of the α₂-adrenoceptor, the imidazoline receptor, and the α₁-adrenoceptor. These inhibitory effects on hiPSC-CMs may contribute to the antiarrhythmic effects of DMED.

• Dexmedetomidine (DMED)
• electrophysiology
• human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs)
• patch clamp recording

Direct cardiac reprogramming has emerged as a novel therapeutic approach to treat and regenerate injured hearts through the direct conversion of fibroblasts into cardiac cells. Most studies have focused on the reprogramming of fibroblasts into induced cardiomyocytes (iCMs). The first study in which this technology was described, showed that at least a combination of three transcription factors, GATA4, MEF2C and TBX5 (GMT cocktail), was required for the reprogramming into iCMs in vitro using mouse cells. However, this was later demonstrated to be insufficient for the reprogramming of human cells and additional factors were required. Thereafter, most studies have focused on implementing reprogramming efficiency and obtaining fully reprogrammed and functional iCMs, by the incorporation of other transcription factors, microRNAs or small molecules to the original GMT cocktail. In this respect, great advances have been made in recent years. However, there is still no consensus on which of these GMT-based varieties is best, and robust and highly reproducible protocols are still urgently required, especially in the case of human cells. On the other hand, apart from CMs, other cells such as endothelial and smooth muscle cells to form new blood vessels will be fundamental for the correct reconstruction of damaged cardiac tissue. With this aim, several studies have centered on the direct reprogramming of fibroblasts into induced cardiac progenitor cells (iCPCs) able to give rise to all myocardial cell lineages. Especially interesting are reports in which multipotent and highly expandable mouse iCPCs have been obtained, suggesting that clinically relevant amounts of these cells could be created. However, as of yet, this has not been achieved with human iCPCs, and exactly what stage of maturity is appropriate for a cell therapy product remains an open question. Nonetheless, the major concern in regenerative medicine is the poor retention, survival, and engraftment of transplanted cells in the cardiac tissue. To circumvent this issue, several cell pre-conditioning approaches are currently being explored. As an alternative to cell injection, in vivo reprogramming may face fewer barriers for its translation to the clinic. This approach has achieved better results in terms of efficiency and iCMs maturity in mouse models, indicating that the heart environment can favor this process. In this context, in recent years some studies have focused on the development of safer delivery systems such as Sendai virus, Adenovirus, chemical cocktails or nanoparticles. This article provides an in-depth review of the in vitro and in vivo cardiac reprograming technology used in mouse and human cells to obtain iCMs and iCPCs, and discusses what challenges still lie ahead and what hurdles are to be overcome before results from this field can be transferred to the clinical settings.

• cardiovascular diseases 4
• cardiovascular regeneration 6
• cardiovascular repair 5
• direct reprogramming 1
• iCMs (induced cardiomyocytes) 2
• iCPCs (induced cardiac progenitor cells) 3

Our understanding of the spatiotemporal regulation of cardiogenesis is hindered by the difficulties in modeling this complex organ currently by in vitro models. Here we develop a method to generate heart organoids from mouse embryonic stem cell-derived embryoid bodies. Consecutive morphological changes proceed in a self-organizing manner in the presence of the laminin-entactin (LN/ET) complex and fibroblast growth factor 4 (FGF4), and the resulting in vitro heart organoid possesses atrium- and ventricle-like parts containing cardiac muscle, conducting tissues, smooth muscle and endothelial cells that exhibited myocardial contraction and action potentials. The heart organoids exhibit ultrastructural, histochemical and gene expression characteristics of considerable similarity to those of developmental hearts in vivo. Our results demonstrate that this method not only provides a biomimetic model of the developing heart-like structure with simplified differentiation protocol, but also represents a promising research tool with a broad range of applications, including drug testing.

Our understanding of the development of the heart has been limited by a lack of in vitro cellular models. Here, the authors treat mouse embryonic stem cell-derived embryoid bodies with laminin-entactin (to mimic the developing microenvironment) and FGF4 to form heart organoids, with atrial and ventricular-like parts.

• Ambystoma velasci
• Heart
• Lung and gills
• Metamorphosis

• cardiac differentiation
• drug screening
• induced pluripotent stem cells
• microgroove
• structural color

• Cell Differentiation
• Humans
• Induced Pluripotent Stem Cells
• Myocytes, Cardiac

Intractable cardiovascular diseases are leading causes of mortality around the world. Adult mammalian hearts have poor regenerative capacity and are not capable of self-repair after injury. Recent studies of cell-free therapeutics such as those designed to stimulate endogenous cardiac regeneration have uncovered new feasible therapeutic avenues for cardiac repair. The Hippo pathway, a fundamental pathway with pivotal roles in cell proliferation, survival and differentiation, has tremendous potential for therapeutic manipulation in cardiac regeneration. In this review, we summarize the most recent studies that have revealed the function of the Hippo pathway in heart regeneration and homeostasis. In particular, we discuss the molecular mechanisms of how the Hippo pathway maintains cardiac homeostasis by directing cardiomyocyte chromatin remodeling and regulating the cell-cell communication between cardiomyocytes and non-cardiomyocytes in the heart.

• Hippo pathway
• cardiac regeneration
• chromatin reprogramming
• immune response
• proliferation
• tissue homeostasis

• Animals
• Cell Communication
• Cell Differentiation
• Cell Proliferation
• Cell-Free System
• Heart Injuries/metabolism
• Heart Injuries/therapy
• Hippo Signaling Pathway
• Homeostasis
• Humans
• Myocytes, Cardiac/physiology
• Protein Serine-Threonine Kinases/metabolism
• Regeneration
• Signal Transduction

• R01 HL142704 NHLBI NIH HHS
• R56 HL142704 NHLBI NIH HHS
• K01 DE026561 NIDCR NIH HHS
• R03 DE025873 NIDCR NIH HHS
• R01 DE029014 NIDCR NIH HHS

• cardiomyocytes
• cell differentiation
• fibroblasts
• genetic transcription
• mitochondria
• postnatal cardiac development

• Animals
• Basic Helix-Loop-Helix Transcription Factors/metabolism
• Cells, Cultured
• Gene Expression Regulation, Developmental
• Heart/embryology
• Heart/growth & development
• Humans
• Induced Pluripotent Stem Cells/cytology
• Mice
• Mitochondria, Heart/metabolism
• Myocytes, Cardiac/cytology
• Myocytes, Cardiac/metabolism
• Receptors, Estrogen/genetics
• Receptors, Estrogen/metabolism
• Signal Transduction
• ERRalpha Estrogen-Related Receptor

• P30 DK019525 NIDDK NIH HHS
• R01 HL058493 NHLBI NIH HHS
• T32 HL007843 NHLBI NIH HHS
• T32 HL007954 NHLBI NIH HHS

• Adipose-derived stem cells
• Ex vivo culture-expanded stem cells
• Mesenchymal stem cells
• Regenerative therapies
• Scaffold free-cellsheet technology
• Scaffold-based cellsheet technology
• Tissue derived stem cells
• Tissue engineering

• atrial cardiomyocytes
• human pluripotent stem cells
• nodal cardiomyocytes
• subtype-specific cardiomyocytes
• ventricular cardiomyocytes

Stem cell-based therapy has been considered as a promising option in the treatment of ischemic heart disease. Although stem cell administration resulted in the temporary improvement of myocardial contractility in the majority of studies, the formation of new cardiomyocytes within the injured myocardium has not been conclusively demonstrated. Consequently, the focus of research in the field has since shifted to stem cell-derived paracrine factors, including cytokines, growth factors, mRNA, and miRNA. Notably, both mRNA and miRNA can enter into the extracellular space either in soluble form or packed into membrane vesicles. Stem cell-derived paracrine factors have been shown to suppress inflammation and apoptosis, stimulate angiogenesis, and amplify the proliferation and differentiation of resident cardiac stem cells (CSCs). Such features have led to exosomes being considered as potential drug candidates affording myocardial regeneration. The search for chemical signals capable of stimulating cardiomyogenesis is ongoing despite continuous debates regarding the ability of mature cardiomyocytes to divide or dedifferentiate, transdifferentiation of other cells into cardiomyocytes, and the ability of CSCs to differentiate into cardiomyocytes. Future research is aimed at identifying novel cell candidates capable of differentiating into cardiomyocytes. The observation that CSCs can undergo intracellular development with the formation of “cell-in-cell structure” and subsequent release of transitory amplifying cells with the capacity to differentiate into cardiomyocytes may provide clues for stimulating regenerative cardiomyogenesis.

We developed cardiac-reprogrammed cell sheets via cardiac-mimetic cell culture system with biodegradable PLGA membrane. The prevascularized, multiple-layered cell sheets prevented heart failure after myocardial infarction.

• preclinical research
• regeneration
• rejuvenation
• repair

• Angiogenesis
• Cardiac progenitors
• Cardiac proliferation
• Cardiac regeneration
• Cell-based therapy
• Congenital heart disease
• Developmental cardiogenesis
• Gene therapy
• Growth factors
• Modified mRNA

• biomaterials
• cardiac progenitor cells
• cardiac tissue engineering
• direct reprogramming
• genetic engineering
• induced pluripotent stem cells
• transdifferentiation

• Animals
• Biocompatible Materials
• Cell Differentiation/genetics
• Cells, Cultured
• Cellular Reprogramming/genetics
• Cellular Reprogramming Techniques
• Genetic Engineering
• Humans
• Induced Pluripotent Stem Cells/cytology
• Induced Pluripotent Stem Cells/metabolism
• Multipotent Stem Cells/cytology
• Multipotent Stem Cells/metabolism
• Myoblasts, Cardiac/cytology
• Myoblasts, Cardiac/metabolism
• Myocytes, Cardiac/cytology
• Myocytes, Cardiac/metabolism
• Regeneration
• Stem Cell Transplantation
• Tissue Engineering

• cardiovascular disease
• coculture
• direct reprogramming
• electric stimulation
• membrane

• Cell differentiation
• Development
• SOXF
• Transcription factor
• Tumorigenesis

• differentiation
• disease model

• Animals
• Cell Differentiation/genetics
• Cell Line
• Disease Models, Animal
• Female
• Heart Defects, Congenital/metabolism
• Heart Defects, Congenital/prevention & control
• Male
• Mice
• Mice, Knockout
• Morpholinos/administration & dosage
• Morpholinos/pharmacology
• Mouse Embryonic Stem Cells/metabolism
• Recombinant Proteins/pharmacology
• Repressor Proteins/antagonists & inhibitors
• Repressor Proteins/genetics
• Repressor Proteins/metabolism
• Trans-Activators/antagonists & inhibitors
• Trans-Activators/genetics
• Trans-Activators/metabolism
• Transfection
• Wnt Proteins/pharmacology
• Wnt-5a Protein/pharmacology
• Zebrafish/embryology

• Wnt signaling
• cardiac development
• cardiac progenitor cell
• embryogenesis
• pluripotent stem cell
• single-cell RNA-seq

• Cell differentiation
• Nucleophilic substitution
• One-pot synthesis
• Triazine

It has been demonstrated that cardiac progenitor cells (CPCs) represent a more effective cell-based therapy for treatment of myocardial infarction. Unfortunately, their therapeutic application is limited by low yield of cell harvesting, declining quality and quantity during the ageing process, and the need for highly invasive heart biopsy. Therefore, there is an emerging interest in generating CPC-like stem cells from somatic cells via somatic reprogramming. This novel approach would provide an unlimited source of stem cells with cardiac differentiation potential. Here we would firstly discuss the different types of CPC and their importance in stem cell therapy for treatment of myocardial infarction; secondly, the necessity of generating induced CPC from somatic cells via somatic reprogramming; and finally the current progress of somatic reprogramming in cardiac cells, especially induced CPC generation.

• CPC
• cardiac progenitor cell
• induced CPC
• somatic reprogramming

• cardiomyocyte proliferation
• fructolysis
• hypoxia
• neonatal heart
• omics
• regeneration

Major cardiovascular events including myocardial infarction (MI) continue to dominate morbidity rates in the developed world. Although multiple device therapies and various pharmacological agents have been shown to improve patient care and reduce mortality rates, clinicians and researchers alike still lack a true panacea to regenerate damaged cardiac tissue. Over the previous two to three decades, cardiovascular stem cell therapies have held great promise. Several stem cell-based approaches have now been shown to improve ventricular function and are documented in preclinical animal models as well as phase I and phase II clinical trials. More recently, the cardiac progenitor cell has begun to gain momentum as an ideal candidate for stem cell therapy in heart disease. Here, we will highlight the most recent advances in cardiac stem/progenitor cell biology in regard to both the basics and applied settings.

• Cardiomyocytes
• Epigenetics
• Heart repair
• Smooth muscle cells
• Stem cells
• Vascular repair

• cardiac stem cells
• epigenomics
• single-cell epigenome
• single-cell sequencing
• single-cell transcriptome

• Cardiovascular development
• ESC
• Nodal cells
• Pacemaker
• Subtype differentiation
• System-based data analysis
• iPSC

Cardiomyocytes and endothelial cells in the heart are in close proximity and in constant dialogue. Endothelium regulates the size of the heart, supplies oxygen to the myocardium and secretes factors that support cardiomyocyte function. Robust and predictive cardiac disease models that faithfully recapitulate native human physiology in vitro would therefore ideally incorporate this cardiomyocyte-endothelium crosstalk. Here, we have generated and characterized human cardiac microtissues in vitro that integrate both cell types in complex 3D structures. We established conditions for simultaneous differentiation of cardiomyocytes and endothelial cells from human pluripotent stem cells following initial cardiac mesoderm induction. The endothelial cells expressed cardiac markers that were also present in primary cardiac microvasculature, suggesting cardiac endothelium identity. These cell populations were further enriched based on surface markers expression, then recombined allowing development of beating 3D structures termed cardiac microtissues. This in vitro model was robustly reproducible in both embryonic and induced pluripotent stem cells. It thus represents an advanced human stem cell-based platform for cardiovascular disease modelling and testing of relevant drugs.

Summary: Co-differentiation of endothelial cells and cardiomyocytes from human pluripotent stem cells provides a cardiac microtissue model with potential applications for disease modelling and drug discovery.

• Cardiac microtissue (MT)
• Human pluripotent stem cell-derived cardiomyocytes
• Human pluripotent stem cell-derived endothelial cells
• Mesoderm induction
• Three-dimensional culture model

• adoptive transfer
• cardiac repair
• cell therapy
• myocardium
• regeneration
• stem cells