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Human embryonic stem cells (hESCs) derived from blastocyst stage embryos present a primed state of pluripotency, whereas mouse ESCs (mESCs) display naïve pluripotency. Their unique characteristics make naïve hESCs more suitable for particular applications in biomedical research. This work aimed to derive hESCs from single blastomeres and determine their pluripotency state, which is currently unclear. We derived hESC lines from single blastomeres of 8-cell embryos and from whole blastocysts, and analysed several naïve pluripotency indicators, their transcriptomic profile and their trilineage differentiation potential. No significant differences were observed between blastomere-derived hESCs (bm-hESCs) and blastocyst-derived hESCs (bc-hESCs) for most naïve pluripotency indicators, including TFE3 localization, mitochondrial activity, and global DNA methylation and hydroxymethylation, nor for their trilineage differentiation potential. Nevertheless, bm-hESCs showed an increased single-cell clonogenicity and a higher expression of naïve pluripotency markers at early passages than bc-hESCs. Furthermore, RNA-seq revealed that bc-hESCs overexpressed a set of genes related to the post-implantational epiblast. Altogether, these results suggest that bm-hESCs, although displaying primed pluripotency, would be slightly closer to the naïve end of the pluripotency continuum than bc-hESCs., Competing Interests: Declaration of competing interest No competing interests declared., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Immunotherapy using primary T cells has revolutionized medical care in some pathologies in recent years, but limitations associated to challenging cell genome edition, insufficient cell number production, the use of only autologous cells, and the lack of product standardization have limited its clinical use. The alternative use of T cells generated in vitro from human pluripotent stem cells (hPSCs) offers great advantages by providing a self-renewing source of T cells that can be readily genetically modified and facilitate the use of standardized universal off-the-shelf allogeneic cell products and rapid clinical access. However, despite their potential, a better understanding of the feasibility and functionality of T cells differentiated from hPSCs is necessary before moving into clinical settings. In this study, we generated human-induced pluripotent stem cells from T cells (T-iPSCs), allowing for the preservation of already recombined TCR, with the same properties as human embryonic stem cells (hESCs). Based on these cells, we differentiated, with high efficiency, hematopoietic progenitor stem cells (HPSCs) capable of self-renewal and differentiation into any cell blood type, in addition to DN3a thymic progenitors from several T-iPSC lines. In order to better comprehend the differentiation, we analyzed the transcriptomic profiles of the different cell types and demonstrated that HPSCs differentiated from hiPSCs had very similar profiles to cord blood hematopoietic stem cells (HSCs). Furthermore, differentiated T-cell progenitors had a similar profile to thymocytes at the DN3a stage of thymic lymphopoiesis. Therefore, utilizing this approach, we were able to regenerate precursors of therapeutic human T cells in order to potentially treat a wide range of diseases.

Pancreatic β cell dysfunction is a central component of diabetes progression. During the last decades, the genetic basis of several monogenic forms of diabetes has been recognized. Genome-wide association studies (GWAS) have also facilitated the identification of common genetic variants associated with an increased risk of diabetes. These studies highlight the importance of impaired β cell function in all forms of diabetes. However, how most of these risk variants confer disease risk, remains unanswered. Understanding the specific contribution of genetic variants and the precise role of their molecular effectors is the next step toward developing treatments that target β cell dysfunction in the era of personalized medicine. Protocols that allow derivation of β cells from pluripotent stem cells, represent a powerful research tool that allows modeling of human development and versatile experimental designs that can be used to shed some light on diabetes pathophysiology. This article reviews different models to study the genetic basis of β cell dysfunction, focusing on the recent advances made possible by stem cell applications in the field of diabetes research.

Mitochondrial diseases disrupt cellular energy production and are among the most complex group of inherited genetic disorders. Affecting approximately 1 in 5000 live births, they are both clinically and genetically heterogeneous, and can be highly tissue specific, but most often affect cell types with high energy demands in the brain, heart, and kidneys. There are currently no clinically validated treatment options available, despite several agents showing therapeutic promise. However, modelling these disorders is challenging as many non-human models of mitochondrial disease do not completely recapitulate human phenotypes for known disease genes. Additionally, access to disease-relevant cell or tissue types from patients is often limited. To overcome these difficulties, many groups have turned to human pluripotent stem cells (hPSCs) to model mitochondrial disease for both nuclear-DNA (nDNA) and mitochondrial-DNA (mtDNA) contexts. Leveraging the capacity of hPSCs to differentiate into clinically relevant cell types, these models permit both detailed investigation of cellular pathomechanisms and validation of promising treatment options. Here we catalogue hPSC models of mitochondrial disease that have been generated to date, summarise approaches and key outcomes of phenotypic profiling using these models, and discuss key criteria to guide future investigations using hPSC models of mitochondrial disease.

Human pluripotent stem cells have the potential to change the way in which human diseases are cured. Clinical-grade human embryonic stem cells and human induced pluripotent stem cells have to be created according to current good manufacturing practices and regulations. Quality and safety must be of the highest importance when humans' lives are at stake. With the rising number of clinical trials, there is a need for a consensus on hPSCs characterization. Here, we summarize mandatory and 'for information only' characterization methods with release criteria for the establishment of clinical-grade hPSC lines.

In the future, stem cell-based technologies may be harnessed to replace conventional dialysis and transplantation in patients with diabetic nephropathy. Recently, there has been considerable effort to improve methods for the differentiation of human pluripotent stem cells (hPSCs) into kidney cells in culture. Here, we present a protocol for obtaining more advanced kidney structures than have currently been possible in vitro, including vascularized glomeruli and tubular elements. HPSCs are first differentiated in 2D culture to a kidney progenitor stage. These cells are then dissociated and injected subcutaneously into immunocompromised mice. Twelve weeks later, the cells have developed into mature kidney structures and are excised for further characterization. This method constitutes a significant improvement on protocols that involve either exclusively a 2D culture or placing the cells in 3D organoid culture at the air-liquid interface in vitro.

Human pluripotent stem cells (hPSCs) generate a variety of disease-relevant cells that can be used to improve the translation of preclinical research. Despite the potential of hPSCs, their use for genetic screening has been limited by technical challenges. We developed a scalable and renewable Cas9 and sgRNA-hPSC library in which loss-of-function mutations can be induced at will. Our inducible mutant hPSC library can be used for multiple genome-wide CRISPR screens in a variety of hPSC-induced cell types. As proof of concept, we performed three screens for regulators of properties fundamental to hPSCs: their ability to self-renew and/or survive (fitness), their inability to survive as single-cell clones, and their capacity to differentiate. We identified the majority of known genes and pathways involved in these processes, as well as a plethora of genes with unidentified roles. This resource will increase the understanding of human development and genetics. This approach will be a powerful tool to identify disease-modifying genes and pathways., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Recent advancements in the production of hepatocytes from human pluripotent stem cells (hPSC-Heps) afford tremendous possibilities for treatment of patients with liver disease. Validated current good manufacturing practice (cGMP) lines are an essential prerequisite for such applications but have only recently been established. Whether such cGMP lines are capable of hepatic differentiation is not known. To address this knowledge gap, we examined the proficiency of three recently derived cGMP lines (two hiPSC and one hESC) to differentiate into hepatocytes and their suitability for therapy. hPSC-Heps generated using a chemically defined four-step hepatic differentiation protocol uniformly demonstrated highly reproducible phenotypes and functionality. Seeding into a 3D poly(ethylene glycol)-diacrylate fabricated inverted colloid crystal scaffold converted these immature progenitors into more advanced hepatic tissue structures. Hepatic constructs could also be successfully encapsulated into the immune-privileged material alginate and remained viable as well as functional upon transplantation into immune competent mice. This is the first report we are aware of demonstrating cGMP-compliant hPSCs can generate cells with advanced hepatic function potentially suitable for future therapeutic applications. Stem Cells Translational Medicine 2019;8:124&14., (© 2018 The Authors. Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.)

Diabetes mellitus is a chronic disease that affects hundreds of millions of people worldwide. Type 1 diabetes (T1D) is characterized by the lack of pancreatic β-cells that had been destroyed as a result of an autoimmune response. Therefore, in patients with T1D, the replacement therapy with functional β-cells derived from extrinsic sources could be a preferable option as compared to insulin treatment. Unfortunately, successful transplantation of whole pancreata or pancreatic islets into patients with diabetes is available only to a fraction of them due to the scarcity of donors. The rapid development of cell reprogramming methods made it possible to generate large numbers of human β-like cells derived from human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs). This review describes the basis of in vitro differentiaton protocols of β-like cells that mimic changes of the main signaling pathways during the key stages of human and murine pancreas development, which are described first. During the last 15 years it was found that there are no important differences between hESCs and hiPSCs in their differentiation capacities into β-like cells and the expression profiles of the key transcription factors. The in vitro produced β-like cells are immature as demonstrated by functional tests in rodents and single-cell transcriptomic and proteomic analyses. After the transplantation of the β cell progenitors into immunocompromised diabetic mice, a few weeks have to pass before the increased insulin levels in response to glucose load appear. There is a continuous progress in the development of open-type encapsulation devices which allow the vascularization of the transplanted cells and protect them against host's immune cells. The results of the first clinical trial of human partially differentiated endocrine progenitors of β cells transplanted into patients with T1D will be published in the year 2019. It is hoped that further improvements in the techniques of large-scale generation of the β-like cells derived from human pluripotent stem cells will bring us closer to their clinical application as a form of cause-directed therapy for people with diabetes.

To elucidate the molecular basis of BMP4-induced differentiation of human pluripotent stem cells (PSCs) toward progeny with trophectoderm characteristics, we produced transcriptome, epigenome H3K4me3, H3K27me3, and CpG methylation maps of trophoblast progenitors, purified using the surface marker APA. We combined them with the temporally resolved transcriptome of the preprogenitor phase and of single APA+ cells. This revealed a circuit of bivalent TFAP2A, TFAP2C, GATA2, and GATA3 transcription factors, coined collectively the "trophectoderm four" (TEtra), which are also present in human trophectoderm in vivo. At the onset of differentiation, the TEtra factors occupy multiple sites in epigenetically inactive placental genes and in OCT4 Functional manipulation of GATA3 and TFAP2A indicated that they directly couple trophoblast-specific gene induction with suppression of pluripotency. In accordance, knocking down GATA3 in primate embryos resulted in a failure to form trophectoderm. The discovery of the TEtra circuit indicates how trophectoderm commitment is regulated in human embryogenesis., Competing Interests: The authors declare no conflict of interest., (Copyright © 2017 the Author(s). Published by PNAS.)

Organoid techniques provide unique platforms to model brain development and neurological disorders. Whereas several methods for recapitulating corticogenesis have been described, a system modeling human medial ganglionic eminence (MGE) development, a critical ventral brain domain producing cortical interneurons and related lineages, has been lacking until recently. Here, we describe the generation of MGE and cortex-specific organoids from human pluripotent stem cells that recapitulate the development of MGE and cortex domains, respectively. Population and single-cell RNA sequencing (RNA-seq) profiling combined with bulk assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) analyses revealed transcriptional and chromatin accessibility dynamics and lineage relationships during MGE and cortical organoid development. Furthermore, MGE and cortical organoids generated physiologically functional neurons and neuronal networks. Finally, fusing region-specific organoids followed by live imaging enabled analysis of human interneuron migration and integration. Together, our study provides a platform for generating domain-specific brain organoids and modeling human interneuron migration and offers deeper insight into molecular dynamics during human brain development., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Although human embryonic stem cells (hESCs) were first derived almost 20 years ago, it was only recently acknowledged that they share closer molecular and functional identity to postimplantation lineage-primed murine epiblast stem cells than to naïve preimplantation inner cell mass-derived mouse ESCs (mESCs). A myriad of transcriptional, epigenetic, biochemical, and metabolic attributes have now been described that distinguish naïve and primed pluripotent states in both rodents and humans. Conventional hESCs and human induced pluripotent stem cells (hiPSCs) appear to lack many of the defining hallmarks of naïve mESCs. These include important features of the naïve ground state murine epiblast, such as an open epigenetic architecture, reduced lineage-primed gene expression, and chimera and germline competence following injection into a recipient blastocyst-stage embryo. Several transgenic and chemical methods were recently reported that appear to revert conventional human PSCs to mESC-like ground states. However, it remains unclear if subtle deviations in global transcription, cell signaling dependencies, and extent of epigenetic/metabolic shifts in these various human naïve-reverted pluripotent states represent true functional differences or alternatively the existence of distinct human pluripotent states along a spectrum. In this study, we review the current understanding and developmental features of various human pluripotency-associated phenotypes and discuss potential biological mechanisms that may support stable maintenance of an authentic epiblast-like ground state of human pluripotency.

Stem cell-derived cardiomyocytes (CMs) hold great hopes for myocardium regeneration because of their ability to produce functional cardiac cells in large quantities. They also hold promise in dissecting the molecular principles involved in heart diseases and also in drug development, owing to their ability to model the diseases using patient-specific human pluripotent stem cell (hPSC)-derived CMs. The CM properties essential for the desired applications are frequently evaluated through morphologic and genotypic screenings. Even though these characterizations are necessary, they cannot in principle guarantee the CM functionality and their drug response. The CM functional characteristics can be quantified by phenotype assays, including electrophysiological, optical, and/or mechanical approaches implemented in the past decades, especially when used to investigate responses of the CMs to known stimuli (eg, adrenergic stimulation). Such methods can be used to indirectly determine the electrochemomechanics of the cardiac excitation-contraction coupling, which determines important functional properties of the hPSC-derived CMs, such as their differentiation efficacy, their maturation level, and their functionality. In this work, we aim to systematically review the techniques and methodologies implemented in the phenotype characterization of hPSC-derived CMs. Further, we introduce a novel approach combining atomic force microscopy, fluorescent microscopy, and external electrophysiology through microelectrode arrays. We demonstrate that this novel method can be used to gain unique information on the complex excitation-contraction coupling dynamics of the hPSC-derived CMs., (Copyright © 2016 John Wiley & Sons, Ltd.)

Recent evidence suggests that lncRNAs play an integral regulatory role in numerous functions, including determination of cellular identity. We determined global expression (RNA-seq) and genome-wide profiles (ChIP-seq) of histone post-translational modifications and p53 binding in human embryonic stem cells (hESCs) undergoing differentiation to define a high-confidence set of 40 lncRNAs, which are p53 transcriptional targets. We focused on lncRNAs highly expressed in pluripotent hESCs and repressed by p53 during differentiation to identify lncPRESS1 as a p53-regulated transcript that maintains hESC pluripotency in concert with core pluripotency factors. RNA-seq of hESCs depleted of lncPRESS1 revealed that lncPRESS1 controls a gene network that promotes pluripotency. Further, we found that lncPRESS1 physically interacts with SIRT6 and prevents SIRT6 chromatin localization, which maintains high levels of histone H3K56 and H3K9 acetylation at promoters of pluripotency genes. In summary, we describe a p53-regulated, pluripotency-specific lncRNA that safeguards the hESC state by disrupting SIRT6 activity., Competing Interests: The authors declare no conflict of interest., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The development of human erythroid cells has been mostly examined in models of adult hematopoiesis, while their early derivation during embryonic and fetal stages is largely unknown. We observed the development and maturation of erythroblasts derived from human pluripotent stem cells (hPSCs) by an efficient co-culture system. These hPSC-derived early erythroblasts initially showed definitive characteristics with a glycophorin A + (GPA + ) CD34 low CD36 - phenotype and were distinct from adult CD34 + cell-derived ones. After losing CD34 expression, early GPA + CD36 - erythroblasts matured into GPA + CD36 low/+ stage as the latter expressed higher levels of β-globin along with a gradual loss of mesodermal and endothelial properties, and terminally suppressed CD36. We establish a unique in vitro model to trace the early development of hPSC-derived erythroblasts by serial expression of CD34, GPA, and CD36. Our findings may provide insight into the understanding of human early erythropoiesis and, ultimately, therapeutic potential., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Telomeres are linear guanine-rich DNA structures at the ends of chromosomes. The length of telomeric DNA is actively regulated by a number of mechanisms in highly proliferative cells such as germ cells, cancer cells, and pluripotent stem cells. Telomeric DNA is synthesized by way of the ribonucleoprotein called telomerase containing a reverse transcriptase (TERT) subunit and RNA component (TERC). TERT is highly conserved across species and ubiquitously present in their respective pluripotent cells. Recent studies have uncovered intricate associations between telomeres and the self-renewal and differentiation properties of pluripotent stem cells. Interestingly, the past decade's work indicates that the TERT subunit also has the capacity to modulate mitochondrial function, to remodel chromatin structure, and to participate in key signaling pathways such as the Wnt/β-catenin pathway. Many of these non-canonical functions do not require TERT's catalytic activity, which hints at possible functions for the extensive number of alternatively spliced TERT isoforms that are highly expressed in pluripotent stem cells. In this review, some of the established and potential routes of pluripotency induction and maintenance are highlighted from the perspectives of telomere maintenance, known TERT isoform functions and their complex regulation.

Background: Human embryonic stem cells (hESCs) serve as a potential unlimited ex vivo source of cardiomyocytes for disease modeling, cardiotoxicity screening, drug discovery, and cell-based therapies. Despite the fundamental importance of Ca(2+)-induced Ca(2+) release in excitation-contraction coupling, the mechanistic basis of Ca(2+) handling of hESC-derived ventricular cardiomyocytes (VCMs) remains elusive., Objectives: To study Ca(2+) sparks as unitary events of Ca(2+) handling for mechanistic insights., Methods: To avoid ambiguities owing to the heterogeneous nature, we experimented with hESC-VCMs, purified on the basis of zeocin resistance and signature ventricular action potential after LV-MLC2v-tdTomato-T2A-Zeo transduction., Results: Ca(2+) sparks that were sensitive to inhibitors of sarco/endoplasmic reticulum Ca(2+)-ATPase (thapsigargin and cyclopiazonic acid) and ryanodine receptor (RyR; ryanodine, tetracaine) but not inositol trisphosphate receptors (xestospongin C and 2-aminoethyl diphenylborinate) could be recorded. In a permeabilization model, we further showed that RyRs could be sensitized by Ca(2+). Increasing external Ca(2+) dramatically escalated the basal Ca(2+) and spark frequency. Furthermore, RyR-mediated Ca(2+) release sensitized nearby RyRs, leading to compound Ca(2+) sparks. Depolarization or L-type Ca(2+) channel agonist (FPL 64176 and Bay K8644) pretreatment induced an extracellular Ca(2+)-dependent cytosolic Ca(2+) increase and reduced the sarcoplasmic reticulum content. By contrast, removal of external Na(+) or the addition of the Na(+)-Ca(2+) exchanger inhibitor (KB-R7943 and SN-6) had no effect, suggesting that the Na(+)-Ca(2+) exchanger is not involved in triggering sparks. Inhibition of mitochondrial Ca(2+) uptake by carbonyl cyanide m-chlorophenyl hydrazone promoted Ca(2+) waves., Conclusion: Taken collectively, our findings provide the first lines of direct evidence that hESC-VCMs have functional Ca(2+)-induced Ca(2+) release. However, the sarcoplasmic reticulum is leaky and without a mature terminating mechanism in early development., (© 2013 Heart Rhythm Society Published by Heart Rhythm Society All rights reserved.)

Differentiation of human embryonic stem (ES) and induced pluripotent stem (iPS) cells into hepatocyte-like cells provides a platform to study the molecular basis of human hepatocyte differentiation, to develop cell culture models of liver disease, and to potentially provide hepatocytes for treatment of end-stage liver disease. Additionally, hepatocyte-like cells generated from human pluripotent stem cells could serve as platforms for drug discovery, determination of pharmaceutical-induced hepatotoxicity, and evaluation of idiosyncratic drug-drug interactions. Here, we describe a step-wise protocol previously developed in our laboratory that facilitates the highly efficient and reproducible differentiation of human pluripotent stem cells into hepatocyte-like cells. Our protocol uses defined culture conditions and closely recapitulates key developmental events that are found to occur during hepatogenesis., (Copyright © 2013 John Wiley & Sons, Inc.)

Adult stem cells reside in hypoxic niches, and embryonic stem cells (ESCs) are derived from a low oxygen environment. However, it is not clear whether hypoxia is critical for stem cell fate since for example human ESCs (hESCs) are able to self-renew in atmospheric oxygen concentrations as well. We now show that hypoxia can govern cell fate decisions since hypoxia alone can revert hESC- or iPSC-derived differentiated cells back to a stem cell-like state, as evidenced by re-activation of an Oct4-promoter reporter. Hypoxia-induced "de-differentiated" cells also mimic hESCs in their morphology, long-term self-renewal capacity, genome-wide mRNA and miRNA profiles, Oct4 promoter methylation state, cell surface markers TRA1-60 and SSEA4 expression, and capacity to form teratomas. These data demonstrate that hypoxia can influence cell fate decisions and could elucidate hypoxic niche function., (© AlphaMed Press.)

Heart failure after a myocardial infarction continues to be a leading killer in the Western world. Currently, there are no therapies that effectively prevent or reverse the cardiac damage and negative left ventricular remodeling process that follows a myocardial infarction. Because the heart has limited regenerative capacity, there has been considerable effort to develop new therapies that could repair and regenerate the myocardium. Although cell transplantation alone was initially studied, more recently, tissue engineering strategies using biomaterial scaffolds have been explored. In this review, we cover the different approaches to engineering the myocardium, including cardiac patches, which are in vitro-engineered constructs of functional myocardium, and injectable scaffolds, which can either encourage endogenous repair and regeneration or act as vehicles to support the delivery of cells and other therapeutics., (Copyright © 2013 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

The combination of aminophylline and salbutamol is frequently used in clinical practice in the treatment of obstructive lung diseases. While the side effects (including arrhythmias) of the individual bronchodilator drugs were well described previously, the side effects of combined treatment are almost unknown. We aimed to study the arrhythmogenic potential of combined aminophylline and salbutamol treatment in vitro. For this purpose, we used the established atomic force microscopy (AFM) model coupled with cardiac organoids derived from human pluripotent stem cells (hPSC-CMs). We focused on the chronotropic, inotropic, and arrhythmogenic effects of salbutamol alone and aminophylline and salbutamol combined treatment. We used a method based on heart rate/beat rate variability (HRV/BRV) analysis to detect arrhythmic events in the hPSC-CM based AFM recordings. Salbutamol and aminophylline had a synergistic chronotropic and inotropic effect compared to the effects of monotherapy. Our main finding was that salbutamol reduced the arrhythmogenic effect of aminophylline, most likely mediated by endothelial nitric oxide synthase activated by beta-2 adrenergic receptors. These findings were replicated and confirmed using hPSC-CM derived from two cell lines (CCTL4 and CCTL12). Data suggest that salbutamol as an add-on therapy may not only deliver a bronchodilator effect but also increase the cardiovascular safety of aminophylline, as salbutamol reduces its arrhythmogenic potential. [ABSTRACT FROM AUTHOR]

Cranial placodes are transient ectodermal thickenings that contribute to a diverse array of organs in the vertebrate head. They develop from a common territory, the pre-placodal region that over time segregates along the antero-posterior axis into individual placodal domains: the adenohypophyseal, olfactory, lens, trigeminal, otic, and epibranchial placodes. These placodes terminally differentiate into the anterior pituitary, the lens, and contribute to sensory organs including the olfactory epithelium, and inner ear, as well as several cranial ganglia. To study cranial placodes and their derivatives and generate cells for therapeutic purposes, several groups have turned to in vitro derivation of placodal cells from human embryonic stem cells (hESCs) or induced pluripotent stem cells (hiPSCs). In this review, we summarize the signaling cues and mechanisms involved in cranial placode induction, specification, and differentiation in vivo , and discuss how this knowledge has informed protocols to derive cranial placodes in vitro. We also discuss the benefits and limitations of these protocols, and the potential of in vitro cranial placode modeling in regenerative medicine to treat cranial placode-related pathologies. [Display omitted] • Cranial placodes originate from a common territory, the pre-placodal region (PPR). • From the PPR emerge most sensory organs, the anterior pituitary and several cranial ganglia. • In vivo signaling cues has informed protocols to derive cranial placodes in vitro. • In vitro models of cranial placode development are powerful tools in regenerative medicine. [ABSTRACT FROM AUTHOR]

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) can be differentiated into cardiomyocytes (hESC-CMs and iPSC-CMs, respectively), which hold great promise for cardiac regenerative medicine and disease modeling efforts. However, the most widely employed differentiation protocols require undefined substrates that are derived from xenogeneic (animal) products, contaminating resultant hESC- and iPSC-CM cultures with xenogeneic proteins and limiting their clinical applicability. Additionally, typical hESC- and iPSC-CM protocols produce CMs that are significantly contaminated by non-CMs and that are immature, requiring lengthy maturation procedures. In this review, we will summarize recent studies that have investigated the ability of purified extracellular matrix (ECM) proteins to support hESC- and iPSC-CM differentiation, with a focus on commercially available ECM proteins and coatings to make such protocols widely available to researchers. The most promising of the substrates reviewed here include laminin-521 with laminin-221 together or Synthemax (a synthetic vitronectin-based peptide coating), which both resulted in highly pure CM cultures. Future efforts are needed to determine whether combinations of specific purified ECM proteins or derived peptides could further improve CM maturation and culture times, and significantly improve hESC- and iPSC-CM differentiation protocols. [ABSTRACT FROM AUTHOR]

Human embryonic stem cells (hESCs) are increasingly used in clinical trials as they can change the outcome of treatment for many human diseases. They are used as a starting material for further differentiation into specific cell types and to achieve the desirable result of the cell therapy; thus, the quality of hESCs has to be taken into account. Therefore, current good manufacturing practice (cGMP) has to be implemented in the transport of embryos, derivation of inner cell mass to xeno-free, feeder-free and defined hESC culture, and cell freezing. The in-depth characterization of hESC lines focused on safety, pluripotency, differentiation potential and genetic background has to complement this process. In this paper, we show the derivation of three clinical-grade hESC lines, MUCG01, MUCG02, and MUCG03, following these criteria. We developed and validated the system for the manufacture of xeno-free and feeder-free clinical-grade hESC lines that present high-quality starting material suitable for cell therapy according to cGMP. [ABSTRACT FROM AUTHOR]

Cardiac side effects of some pulmonary drugs are observed in clinical practice. Aminophylline, a methylxanthine bronchodilator with documented proarrhythmic action, may serve as an example. Data on the action of aminophylline on cardiac cell electrophysiology and contractility are not available. Hence, this study was focused on the analysis of changes in the beat rate and contraction force of human pluripotent stem cell–derived cardiomyocytes (hPSC-CMs) and HL-1 cardiomyocytes in the presence of increasing concentrations of aminophylline (10 µM–10 mM in hPSC-CM and 8–512 µM in HL-1 cardiomyocytes). Basic biomedical parameters, namely, the beat rate (BR) and contraction force, were assessed in hPSC-CMs using an atomic force microscope (AFM). The beat rate changes under aminophylline were also examined on the HL-1 cardiac muscle cell line via a multielectrode array (MEA). Additionally, calcium imaging was used to evaluate the effect of aminophylline on intracellular Ca2+ dynamics in HL-1 cardiomyocytes. The BR was significantly increased after the application of aminophylline both in hPSC-CMs (with 10 mM aminophylline) and in HL-1 cardiomyocytes (with 256 and 512 µM aminophylline) in comparison with controls. A significant increase in the contraction force was also observed in hPSC-CMs with 10 µM aminophylline (a similar trend was visible at higher concentrations as well). We demonstrated that all aminophylline concentrations significantly increased the frequency of rhythm irregularities (extreme interbeat intervals) both in hPSC-CMs and HL-1 cells. The occurrence of the calcium sparks in HL-1 cardiomyocytes was significantly increased with the presence of 512 µM aminophylline. We conclude that the observed aberrant cardiomyocyte response to aminophylline suggests an arrhythmogenic potential of the drug. The acquired data represent a missing link between the arrhythmic events related to the aminophylline/theophylline treatment in clinical practice and describe cellular mechanisms of methylxanthine arrhythmogenesis. An AFM combined with hPSC-CMs may serve as a robust platform for direct drug effect screening. [ABSTRACT FROM AUTHOR]

Serine and arginine-rich splicing factor 3 (SRSF3), the smallest member of the Ser/Arg-rich (SR) RNA-binding protein family, regulates multiple aspects of post-transcriptional gene expression program. Although SRSF3 is essential for early embryo development, reprogramming, and pluripotency maintenance, the RNA targets and specificity of RNA recognition of SRSF3 are not well understood in human pluripotent stem cells. In this study, we used inducible TRIBE (targets of RNA binding sites by editing) to identify RNA targets and binding motifs of SRSF3 in human embryonic stem cells (hESCs). We identified 3888 confident binding sites of SRSF3, corresponding to 1222 gene targets. Our results showed that nearly half of the binding sites were distributed in exons, reflecting the alternative splicing function of SRSF3. Motif analysis demonstrated that two of the SRSF3 recognition sequences were the same as the motifs identified in mouse embryonic stem cells, suggesting the recognition sequences of SRSF3 may be conserved in mammals. Overall, our analyses revealed the RNA targets of SRSF3 and uncovered its RNA recognition specificity, providing a valuable resource for understanding the function of SRSF3 in human embryonic stem cells. SRSF3 shows the characteristics of exon-specific binding preference. SRSF3 binds to pluripotency-related genes, indicating it important for hESC pluripotency maintenance. The motif of SRSF3 shows conservation between human and mouse. [ABSTRACT FROM AUTHOR]

In 2011, Goldring and colleagues published a review article describing the potential safety issues of novel stem cell-derived treatments. Immunogenicity and immunotoxicity of the administered cell product were considered risks in the light of clinical experience of transplantation. The relative immunogenicity of mesenchymal stem cells, embryonic stem cells (ESCs), and induced pluripotent stem cells (iPSCs) was being addressed through in vitro and in vivo models. But the question arose as to whether the implanted cells needed to be identical to the recipient in every respect, including epigenetically, to evade immune recognition? If so, this set a high bar which may preclude use of many cells derived from iPSCs which have vestiges of a fetal phenotype and epigenetic memory of their cell of origin. However, for autologous iPSCs, the immunogenicity reduces once the surface antigen expression profile becomes close to that of the parent somatic cells. Therefore, a cell product containing incompletely differentiated cells could be more immunogenic. The properties of the administered cells, the immune privilege of the administration site, and the host immune status influence graft success or failure. In addition, the various approaches available to characterize potential immunogenicity of a cell therapy will be discussed. [ABSTRACT FROM AUTHOR]

Many of the earliest stem cell studies were conducted on cells isolated from tumors rather than from embryos. Of particular interest was research on embryonic carcinoma cells (EC), a type of stem cell derived from teratocarcinoma. The EC research laid the foundation for the later discovery of and subsequent work on embryonic stem cells (ESC). Both ESC isolated from the mouse (mESC) and then later from humans (hESC) shared not only pluripotency with their EC cousins, but also robust tumorigenicity as each readily form teratoma. Surprisingly, decades after the discovery of mESC, the question of what drives ESC to form tumors remains largely an open one. This gap in the field is particularly serious as stem cell tumorigenicity represents the key obstacle to the safe use of stem cell-based regenerative medicine therapies. Although some adult stem cell therapies appear to be safe, they have only a very narrow range of uses in human disease. Our understanding of the tumorigenicity of human induced pluripotent stem cells (IPSC), perhaps the most promising modality for future patient-specific regenerative medicine therapies, is rudimentary. However, IPSC are predicted to possess tumorigenic potential equal to or greater than that of ESC. Here, the links between pluripotency and tumorigenicity are explored. New methods for more accurately testing the tumorigenic potential of IPSC and of other stem cells applicable to regenerative medicine are proposed. Finally, the most promising emerging approaches for overcoming the challenges of stem cell tumorigenicity are highlighted.

Cardiomyocytes (CMs) derived from human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs) are used to study cardiogenesis and mechanisms of heart disease, and are being used in methods for toxiological screening of drugs. The phenotype of stem-cell-derived CMs should ideally resemble native CMs. Here, we compare embryonic/fetal CMs with hESC-derived CMs according to function and morphology. CM clusters were obtained from human embryonic/fetal hearts from elective terminated pregnancies before gestational week 12, and separated into atrial and ventricular tissues. Specific markers for embryonic CMs and primary cilia were visualized using immunofluorescence microscopy analysis. Contracting human embryonic cardiomyocyte (hECM) clusters morphologically and phenotypically resemble CMs in the embryonic/fetal heart. In addition, the contracting hECM clusters expressed primary cilia similar to that of cells in the embryonic/fetal heart. The electrophysiological characteristics of atrial and ventricular CMs were established by recording action potentials (APs) using sharp electrodes. In contrast to ventricular APs, atrial APs displayed a marked early repolarization followed by a plateau phase. hESC-CMs displayed a continuum of AP shapes. In all embryonic/fetal clusters, both atrial and ventricular, AP duration was prolonged by exposure to the KV11.1 channel inhibitor dofetilide (50 nM); however, the prolongation was not significant, possibly due to the relatively small number of experiments. This study provides novel information on APs and functional characteristics of atrial and ventricular CMs in first trimester hearts, and demonstrates that Kv11.1 channels play a functional role already at these early stages. These results provide information needed to validate methods being developed on the basis of in vitro-derived CMs from either hESC or iPSC, and although there was a good correlation between the morphology of the two types of CMs, differences in electrophysiological characteristics exist. [ABSTRACT FROM AUTHOR]

Human pluripotent stem cells, namely human embryonic stem cells (hESC) and induced pluripotent stem cells (iPSC) have a theoretical potential to differentiate into any type of human cells, they can be maintained in vitro for extended periods of time and can easily be genetically manipulated and expanded to clinically relevant cell numbers. As such, they can potentially serve as off-the-shelf sources of normal or genetically modified cells for tissue regenerative and other medical applications, including immune therapies. This presentation will provide an overview of the current state of pluripotent stem cells-based therapies, with the particular focus on pluripotent stem cell-derived immune cells. Our group and others have established that T cells with increased affinity for cancer epitopes can be derived from genetically modified pluripotent stem cells. Such T cells phenotypically and functionally fully resemble normal T cells and kill haplotype matched target cells in a dose dependent manner in vitro and in vivo. Practical considerations suggest that the pluripotent derived stem cell-derived T cells can therapeutically be superior to genetically modified T cells taken from patients' blood, as they can be expanded to significantly greater numbers sufficient for treatment of a large number of patients and properly analyzed for genotoxic effects of vector integration through DNA sequencing approaches. These types of cell therapies hold promise for the treatment of a broad array of conditions, including cancer, HIV infection, and immune insufficiency disorders. [ABSTRACT FROM AUTHOR]

Background & objectives: Diabetes is a global disease burden. Various stem cell types are being explored to serve as an alternative source of islets. This study was conducted to evaluate the ability of in-house developed human embryonic stem (hES) cells-derived pancreatic progenitors to ameliorate diabetic symptoms in mice. Methods: Pancreatic progenitors were packed in macro-capsules and transplanted into six male Swiss mice and four mice were taken as controls. Thirty days post-transplantation, diabetes was induced by streptozotocin treatment. Mice were then followed up for >100 days and body weight and blood glucose levels were regularly monitored. Results: Control mice lost weight, maintained high glucose levels and did not survive beyond 40 days, whereas transplanted group maintained body weight and four of the six mice had lowered blood glucose levels. About five-fold increase was observed in human C-peptide levels in the recipients of progenitor transplants as compared to diabetic control. Interpretation & conclusions: The beneficial effect of transplanted cells was not long-lasting. Further studies are required to critically evaluate and compare the potential of endogenous pluripotent stem cells and hES cells-derived progenitors before moving from bench to the bedside. [ABSTRACT FROM AUTHOR]

Liver disease is an escalating global health issue. While liver transplantation is an effective mode of therapy, patient mortality has increased due to the shortage of donor organs. Therefore, developing renewable sources of human liver tissue is attractive. Pluripotent stem cell-derived liver tissue represents a potential alternative to cadaver derived hepatocytes and whole organ transplant. At present, two-dimensional differentiation procedures deliver tissue lacking certain functions and phenotypic instability. Efforts to overcome these limiting factors have led to the building of three-dimensional (3D) cellular aggregates. Although enabling for the field, their widespread application and adoption is limited due to the reliance on variable biological components. Our study focus on developing 3D liver tissue under defined conditions. We demonstrate that 3D derived tissue can be generated at scale and implanted underneath the skin of mice. Excitingly, implanted human tissue provides support to mice with metabolic liver disease. This includes immunocompetent recipients. In addition to their clinical application, in vitro generated 3D tissues have important roles to perform in developing safe and efficacious medicines to treat human diseases. We demonstrate that stem cell derived 3D liver tissue exhibits liver cell phenotype for over one year in culture, providing an attractive resource for long-term disease modelling and screening studies. In conclusion, stem cell derived liver tissue has great potential for in vitro and in vivo endeavours. Our most recent advances will be presented at the meeting. [ABSTRACT FROM AUTHOR]

Reprogramming of somatic cells to the phenotypic state termed 'induced pluripotency' is thought to occur through three consecutive stages: initiation, maturation, and stabilisation. The initiation phase is stochastic but nevertheless very important as it sets the gene expression pattern that permits completion of reprogramming; hence a better understanding of this phase and how this is regulated may provide the molecular cues for improving the reprogramming process. c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPKs) are stress activated MAPK kinases that play an essential role in several processes known to be important for successful completion of the initiation phase such as cellular proliferation, mesenchymal to epithelial transition (MET) and cell cycle regulation. In view of this, we postulated that manipulation of this pathway would have significant impacts on reprogramming of human fibroblasts to induced pluripotent stem cells. Accordingly, we found that key components of the JNK/SAPK signaling pathway increase expression as early as day 3 of the reprogramming process and continue to rise in reprogrammed cells throughout the initiation and maturation stages. Using both chemical inhibitors and RNA interference of MKK4, MKK7 and JNK1, we tested the role of JNK/SAPK signaling during the initiation stage of neonatal and adult fibroblast reprogramming. These resulted in complete abrogation of fully reprogrammed colonies and the emergence of partially reprogrammed colonies which disaggregated and were lost from culture during the maturation stage. Inhibition of JNK/SAPK signaling resulted in reduced cell proliferation, disruption of MET and loss of the pluripotent phenotype, which either singly or in combination prevented establishment of pluripotent colonies. Together these data provide new evidence for an indispensable role for JNK/SAPK signaling to overcome the well-established molecular barriers in human somatic cell induced reprogramming. S tem C ells 2016;34:1198-1212 [ABSTRACT FROM AUTHOR]

Aberrations in metabolism contribute to a large number of diseases, such as diabetes, obesity, cancer, and cardiovascular diseases, that have a substantial impact on the mortality rates and quality of life worldwide. However, the mechanisms leading to these changes in metabolic state – and whether they are conserved between diseases – is not well understood. Changes in metabolism similar to those seen in pathological conditions are observed during normal development in a number of different cell types. This provides hope that understanding the mechanism of these metabolic switches in normal development may provide useful insight in correcting them in pathological cases. Here, we focus on the metabolic remodeling observed both in early stage embryonic stem cells and during the maturation of cardiomyocytes. [ABSTRACT FROM AUTHOR]

Human pluripotent stem cells (hPSCs) hold great promise for applications in regenerative medicine and pharmaceutical development. Such applications require cell culture methods and reagents that are chemically defined, xeno-free, scalable, and low-cost. Herein, we describe non-mechanical passaging of hPSCs on spider silk films under chemically defined and xeno-free conditions. The cells were dissociated into single cells or small aggregates using Accutase or enzyme-free dissociation buffer and then passaged to spider silk films, where they expanded in monolayers until they covered the surface. Cells cultured over 10 passages on spider silk film remained karyotypically normal and pluripotent. In conclusion, a novel method for passaging dissociated hPSCs under conditions that are compatible with clinical applications is presented. The method is cost-efficient and may be useful for both research and clinical applications. [ABSTRACT FROM AUTHOR]

Standard treatment for severe inherited hematopoietic diseases consists of allogeneic stem cell transplantation. Alternatively, patients can be treated with gene therapy: gene-corrected autologous hematopoietic stem and progenitor cells (HSPC) are transplanted. By using retro- or lentiviral vectors, a copy of the functional gene is randomly inserted in the DNA of the HSPC and becomes constitutively expressed. Gene therapy is currently limited to monogenic diseases for which clinical trials are being actively conducted in highly specialized centers around the world. This approach, although successful, carries with it inherent safety and efficacy issues. Recently, two technologies became available that, when combined, may enable treatment of genetic defects by HSPC that have the non-functional allele replaced by a functional copy. One technology consists of the generation of induced pluripotent stem cells (iPSC) from patient blood samples or skin biopsies, the other concerns nuclease-mediated gene editing. Both technologies have been successfully combined in basic research and appear applicable in the clinic. This paper reviews recent literature, discusses what can be achieved in the clinic using present knowledge and points out further research directions. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are small non-coding RNAs that have emerged as critical regulators of human embryonic stem cell (hESC) pluripotency and differentiation. Despite the wealth of information about the role individual that miRNAs play in these two processes, there has yet to be a large-scale temporal analysis of the dynamics of miRNA expression as hESCs move from pluripotency into defined lineages. In this report, we used Next Generation Sequencing (NGS) to map temporal expression of miRNAs over ten 24-hour intervals as pluripotent cells were differentiated into pancreatic endoderm. Of the 2042 known human miRNAs, 694 had non-zero expression on all 11 days. Of these 694 miRNAs, 494 showed statistically significant changes in expression during differentiation. Clusters of miRNAs were identified, each displaying unique expression profiles distributed over multiple days. Selected miRNAs associated with pluripotency/differentiation (miR-302/367 and miR-371/372/373) and development/growth (miR-21, miR-25, miR-103, miR-9, and miR-92a) were found to have distinct expression profiles correlated with changes in media used to drive the differentiation process. Taken together, the clustering of miRNAs to identify expression dynamics that occur over longer periods of time (days vs. hours) provides unique insight into specific stages of differentiation. Major shifts in defined stages of hESC differentiation appear to be heavily dependent upon changes in external environmental factors, rather than intrinsic conditions in the cells. [ABSTRACT FROM AUTHOR]

Background Human genomic variations, including single nucleotide polymorphisms (SNPs) and copy number variations (CNVs), are associated with several phenotypic traits varying from mild features to hereditary diseases. Several genome-wide studies have reported genomic variants that correlate with gene expression levels in various tissue and cell types. Results We studied human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) measuring the SNPs and CNVs with Affymetrix SNP 6 microarrays and expression values with Affymetrix Exon microarrays. We computed the linear relationships between SNPs and expression levels of exons, transcripts and genes, and the associations between gene CNVs and gene expression levels. Further, for a few of the resulted genes, the expression value was associated with both CNVs and SNPs. Our results revealed altogether 217 genes and 584 SNPs whose genomic alterations affect the transcriptome in the same cells. We analyzed the enriched pathways and gene ontologies within these groups of genes, and found out that the terms related to alternative splicing and development were enriched. Conclusions Our results revealed that in the human pluripotent stem cells, the expression values of several genes, transcripts and exons were affected due to the genomic variation. [ABSTRACT FROM AUTHOR]

Abstract: The loss of beta cells in Type I diabetes ultimately leads to insulin dependence and major complications that are difficult to manage by insulin injections. Given the complications associated with long-term administration of insulin, cell-replacement therapy is now under consideration as an alternative treatment that may someday provide a cure for this disease. Over the past 10 years, islet transplantation trials have demonstrated that it is possible to replenish beta cell function in Type I diabetes patients and, at least temporarily, eliminate their dependency on insulin. While not yet optimal, the success of these trials has provided proof-of-principle that cell replacement therapy is a viable option for treating diabetes. Limited access to donor islets has launched a search for alternative source of beta cells for cell therapy purposes and focused the efforts of many investigators on the challenge of deriving such cells from human embryonic (hESCs) and induced pluripotent stem cells (hiPSCs). Over the past five years, significant advances have been made in understanding the signaling pathways that control lineage development from human pluripotent stem cells (hPSCs) and as a consequence, it is now possible to routinely generate insulin producing cells from both hESCs and hiPSCs. While these achievements are impressive, significant challenges do still exist, as the majority of insulin producing cells generated under these conditions are polyhormonal and non functional, likely reflecting the emergence of the polyhormonal population that is known to arise in the early embryo during the phase of pancreatic development known as the ‘first transition’. Functional beta cells, which arise during the second phase or transition of pancreatic development have been generated from hESCs, however they are detected only following transplantation of progenitor stage cells into immunocompromised mice. With this success, our challenge now is to define the pathways that control the development and maturation of this second transition population from hPSCs, and establish conditions for the generation of functional beta cells in vitro. [Copyright &y& Elsevier]

MicroRNAs (miRNAs) have been shown to be important in early development and maintenance of human embryonic stem cells (hESCs). The miRNA miR-302-367 is specifically expressed in hESCs, and its expression decays on differentiation. We previously identified the structure of the gene coding for the human miR-302-367 cluster and characterized its promoter. The promoter activity was functionally validated in hESCs, opening up new avenues to further investigate how these miRNA molecules fit in the complex molecular network conferring "stemness" properties to hESCs. The physiological roles of specific miRNA-mRNA interactions remain largely unknown. Here, we investigated putative miR-302-367 mRNA targets in hESCs, potentially relevant for ESC biology. We found that the Nodal inhibitors Lefty1 and Lefty2 are post-transcriptionally targeted by miR-302s in hESCs. Functional analyses indicate that miR-302s negatively modulate the level of lefties, and become upstream regulators of the TGFβ/Nodal pathway, functioning via Smad-2/3 signaling. Overexpression of the miR-302-367 cluster in hESCs causes a delay in early hESC differentiation, as measured by enhanced levels of ESC-specific transcription factors, coupled to a faster teratoma formation in mice transplanted with miR-302-367-expressing hESCs and a concomitant impairment of germ layer specification, displaying robust decreased levels of early mesodermal, endodermal, and ectodermal specific markers. These findings suggest that Lefty is negatively modulated by miR-302s in hESCs, which plays an important role in maintaining the balance between pluripotency and germ layer specification. [ABSTRACT FROM AUTHOR]

In order to assure the quality and safety of future advanced cell therapies it is vital to ensure that source materials including the donor cells have been assessed and demonstrated as suitable for use in the development and manufacture of such new medicines. Here we provide a brief overview of the key issues in the delivery of quality controlled and safety tested seed stocks of human pluripotent stem cell lines to support stem cell research and the development of advanced cell therapies. We also reflect on the importance of national and internationally coordinated cell banking systems in this process in order to promote more efficient development of cell therapies. [ABSTRACT FROM AUTHOR]