Modeling mutation-specific arrhythmogenic phenotypes in isogenic human iPSC-derived cardiac tissues.

Disease modeling using human induced pluripotent stem cells (hiPSCs) from patients with genetic disease is a powerful approach for dissecting pathophysiology and drug discovery. Nevertheless, isogenic controls are required to precisely compare phenotypic outcomes from presumed causative mutations rather than differences in genetic backgrounds. Moreover, 2D cellular models often fail to exhibit authentic disease phenotypes resulting in poor validation in vitro.

Versatile extracellular vesicle-mediated information transfer: intercellular synchronization of differentiation and of cellular phenotypes, and future perspectives.

In recent years, extracellular vesicles (EVs) have attracted significant attention as carriers in intercellular communication. The vast array of information contained within EVs is critical for various cellular activities, such as proliferation and differentiation of multiple cell types. Moreover, EVs are being employed in disease diagnostics, implicated in disease etiology, and have shown promise in tissue repair.

Therapeutic potential of human induced pluripotent stem cell-derived cardiac tissue in an ischemic model with unloaded condition mimicking left ventricular assist device.

Objective: This study aimed to explore the therapeutic potential of human induced pluripotent stem cell (hiPSC)-derived cardiac tissues (HiCTs) in the emerging approach of bridge to recovery for severe heart failure with ventricular assist devices. We used a rat model of heterotopic heart transplantation (HTx) to mimic ventricular assist device support and heart unloading.

Methods: HiCTs were created by inserting gelatin hydrogel microspheres between cell sheets made from hiPSC-derived cardiovascular cells.

Extracellular vesicles and microRNAs in the regulation of cardiomyocyte differentiation and proliferation.

Cardiomyocyte differentiation and proliferation are essential processes for the regeneration of an injured heart. In recent years, there have been several reports highlighting the involvement of extracellular vesicles (EVs) in cardiomyocyte differentiation and proliferation. These EVs originate from mesenchymal stem cells, pluripotent stem cells, and heart constituting cells (cardiomyocytes, cardiac fibroblasts, cardiac progenitor cells, epicardium).

eSPRESSO: topological clustering of single-cell transcriptomics data to reveal informative genes for spatio-temporal architectures of cells.

Background: Bioinformatics capability to analyze spatio-temporal dynamics of gene expression is essential in understanding animal development. Animal cells are spatially organized as functional tissues where cellular gene expression data contain information that governs morphogenesis during the developmental process. Although several computational tissue reconstruction methods using transcriptomics data have been proposed, those methods have been ineffective in arranging cells in their correct positions in tissues or organs unless spatial information is explicitly provided.

Therapeutic potential of clinical-grade human induced pluripotent stem cell-derived cardiac tissues.

Objectives: To establish a protocol to prepare and transplant clinical-grade human induced pluripotent stem cell (hiPSC)-derived cardiac tissues (HiCTs) and to evaluate the therapeutic potential in an animal myocardial infarction (MI) model.

Methods: We simultaneously differentiated clinical-grade hiPSCs into cardiovascular cell lineages with or without the administration of canonical Wnt inhibitors, generated 5- layer cell sheets with insertion of gelatin hydrogel microspheres (GHMs) (HiCTs), and transplanted them onto an athymic rat MI model. Cardiac function was evaluated by echocardiography and cardiac magnetic resonance imaging and compared with that in animals with sham and transplantation of 5-layer cell sheets without GHMs.

StemPanTox: A fast and wide-target drug assessment system for tailor-made safety evaluations using personalized iPS cells.

An alternative model that reliably predicts human-specific toxicity is necessary because the translatability of effects on animal models for human disease is limited to context. Previously, we developed a method that accurately predicts developmental toxicity based on the gene networks of undifferentiated human embryonic stem (ES) cells. Here, we advanced this method to predict toxicities of 24 chemicals in six categories (neurotoxins, cardiotoxins, hepatotoxins, two types of nephrotoxins, and non-genotoxic carcinogens) and achieved high predictability (AUC = 0.

Extracellular vesicles synchronize cellular phenotypes of differentiating cells.

During embryonic development, cells differentiate in a coordinated manner, aligning their fate decisions and differentiation stages with those of surrounding cells. However, little is known about the mechanisms that regulate this synchrony. Here we show that cells in close proximity synchronize their differentiation stages and cellular phenotypes with each other via extracellular vesicle (EV)-mediated cellular communication.

AMPK activation reverts mouse epiblast stem cells to naive state.

Despite increasing knowledge on primed and naive pluripotency, the cell signaling that regulates the pluripotency type in stem cells remains not fully understood. Here we show that AMP kinase (AMPK) activators can induce the reversion of primed mouse epiblast stem cells (mEpiSCs) to the naive pluripotent state. The addition of AMPK activators alone or together with leukemia inhibitory factor to primed mEpiSCs induced the appearance of naive-like cells.

Specific induction and long-term maintenance of high purity ventricular cardiomyocytes from human induced pluripotent stem cells.

Currently, cardiomyocyte (CM) differentiation methods require a purification step after CM induction to ensure the high purity of the cell population. Here we show an improved human CM differentiation protocol with which high-purity ventricular-type CMs can be obtained and maintained without any CM purification process. We induced and collected a mesodermal cell population (platelet-derived growth factor receptor-α (PDGFRα)-positive cells) that can respond to CM differentiation cues, and then stimulated CM differentiation by means of Wnt inhibition.

The moral status of human embryo-like structures: potentiality matters?: The moral status of human synthetic embryos.

New techniques to generate and culture embryo-like structures from stem cells require a more fine-grained distinction of potential to define the moral status of these structures.

Accuracy of spiked cell counting methods for designing a pre-clinical tumorigenicity study model.

Background: Evaluations for the tumorigenicity of transplantation of stem cell products is mandatory for clinical application. It is of importance to establish a system to accurately quantify contaminated tumorigenic cells regardless of the format of stem cell product. In the present report, we aimed to examine the accuracy of the quantification of tumorigenic cell numbers with commonly used 2 methods, quantitative polymerase chain reaction (qPCR) and flow cytometry (FCM) using experimental models of stem cell products spiked with tumorigenic cells.

Protein kinase A accelerates the rate of early stage differentiation of pluripotent stem cells.

In normal development, the rate of cell differentiation is tightly controlled and critical for normal development and stem cell differentiation. However, the underlying mechanisms regulating the rate of the differentiation are unknown, and manipulation of the rate of the stem cell differentiation is currently difficult. Here we show that activation of protein kinase A (PKA) accelerates the rate of mouse embryonic stem cell (ESC) differentiation through an early loss of ESC pluripotency markers and early appearance of mesodermal and other germ layer cells.

AMPK activators contribute to maintain naïve pluripotency in mouse embryonic stem cells.

Pluripotent stem cells retain the property to self-renew and differentiate into all cell types under defined conditions. Among mouse embryonic stem cells (ESCs), which are pluripotent but heterogenous in gene expression and morphology, an ESC population cultured in small molecule inhibitors of two kinases, MAPK/ERK kinase (Mek) and Glycogen synthase kinase 3 (Gsk3), and leukemia inhibitory factor (Lif) (2i/L) is considered to be naïve pluripotent with uniform pluripotent machinery operation. Though the gene regulatory mechanism for the naïve pluripotency has been investigated in recent years, it is still not fully elucidated.

Human iPS cell-engineered three-dimensional cardiac tissues perfused by capillary networks between host and graft.

Stem cell-based cardiac regenerative therapy is expected to be a promising strategy for the treatment of severe heart diseases. Pluripotent stem cells enabled us to reconstruct regenerated myocardium in injured hearts as an engineered tissue aiming for cardiac regeneration. To establish a long-term survival of transplanted three-dimensional (3D) engineered heart tissues in vivo, it is indispensable to induce microcapillaries into the engineered tissues after transplantation.

Induced Pluripotent Stem Cells and Their Use in Human Models of Disease and Development.

The discovery of somatic cell nuclear transfer proved that somatic cells can carry the same genetic code as the zygote, and that activating parts of this code are sufficient to reprogram the cell to an early developmental state. The discovery of induced pluripotent stem cells (iPSCs) nearly half a century later provided a molecular mechanism for the reprogramming. The initial creation of iPSCs was accomplished by the ectopic expression of four specific genes (OCT4, KLF4, SOX2, and c-Myc; OSKM).

Sarcomere gene variants act as a genetic trigger underlying the development of left ventricular noncompaction.

Background: Left ventricular noncompaction (LVNC) is a primary cardiomyopathy with heterogeneous genetic origins. The aim of this study was to elucidate the role of sarcomere gene variants in the pathogenesis and prognosis of LVNC.

Methods And Results: We screened 82 Japanese patients (0-35 years old), with a diagnosis of LVNC, for mutations in seven genes encoding sarcomere proteins, by direct DNA sequencing.

Human iPS cell-derived cardiac tissue sheets for functional restoration of infarcted porcine hearts.

To realize human induced pluripotent stem cell (hiPSC)-based cardiac regenerative therapy, evidence of therapeutic advantages in human-sized diseased hearts are indispensable. In combination with an efficient and simultaneous differentiation of various cardiac lineages from hiPSCs and cell sheet technology, we aimed to generate clinical-sized large cardiac tissue sheets (L-CTSs) and to evaluate the therapeutic potential in porcine infarct heart. We simultaneously induced cardiomyocytes (CMs) and vascular cells [vascular endothelial cells (ECs) and vascular mural cells (MCs)] from hiPSCs.

Sameuramide A, a new cyclic depsipeptide isolated from an ascidian of the family Didemnidae.

Sameuramide A (1), a new cyclic depsipeptide encompassing one each of alanine, N-methyl alanine, N-methyl dehydroalanine, N,O-dimethyl threonine, phenyllactic acid, three β-hydroxy leucines, and two propionates, was isolated from a didemnid ascidian collected at the northern part of Japan. The planar structure was established based on the interpretation of MS and NMR data. The absolute configuration of the subunits was determined by the advanced Marfey's method and the chiral LC-MS analysis.

Type 3 iodothyronine deiodinase is expressed in human induced pluripotent stem cell derived cardiomyocytes.

Aims: Type 3 iodothyronine deiodinase (D3), which converts thyroxine (T) and 3,5,3'-triiodothyronine (T) to 3,3',5'-triiodothyronine (rT) and 3,3'-diiodothyronine (T), respectively, inactivates thyroid hormones. We investigated the expression and regulation of D3 in human cardiomyocytes which were differentiated from human induced pluripotent stem cells (hiPSCs).

Main Methods: We characterized D3 activity using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.

Identification of Cardiomyocyte-Fated Progenitors from Human-Induced Pluripotent Stem Cells Marked with CD82.

Here, we find that human-induced pluripotent stem cell (hiPSC)-derived cardiomyocyte (CM)-fated progenitors (CFPs) that express a tetraspanin family glycoprotein, CD82, almost exclusively differentiate into CMs both in vitro and in vivo. CD82 is transiently expressed in late-stage mesoderm cells during hiPSC differentiation. Purified CD82 cells gave rise to CMs under nonspecific in vitro culture conditions with serum, as well as in vivo after transplantation to the subrenal space or injured hearts in mice, indicating that CD82 successfully marks CFPs.

Modelling Torsade de Pointes arrhythmias in vitro in 3D human iPS cell-engineered heart tissue.

Torsade de Pointes (TdP) is a lethal arrhythmia that is often drug-induced, thus there is an urgent need for development of models to test or predict the drug sensitivity of human cardiac tissue. Here, we present an in vitro TdP model using 3D cardiac tissue sheets (CTSs) that contain a mixture of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and non-myocytes. We simultaneously monitor the extracellular field potential (EFP) and the contractile movement of the CTSs.