The use of induced pluripotent stem cells in drug development. Clin Pharmacol Ther. 2011;89:655-661. [PMID: 21430656 DOI: 10.1038/clpt.2011.38]

Generation of Alzheimer's Disease Model Derived from Induced Pluripotent Stem Cells with APP Gene Mutation

Alzheimer's disease (AD), the most common cause of dementia, is characterized by disruptions in memory, cognition, and personality, significantly impacting morbidity and mortality rates among older adults. However, the exact pathophysiological mechanism of AD remains unknown, and effective treatment options for AD are still lacking. Human induced pluripotent stem cells (iPSC) are emerging as promising platforms for disease research, offering the ability to model the genetic mutations associated with various conditions. Patient-derived iPSCs are useful for modeling neurodegenerative and neurodevelopmental disorders. In this study, we generated AD iPSCs from peripheral blood mononuclear cells obtained from a 65-year-old patient with AD carrying the E682K mutation in the gene encoding the amyloid precursor protein. Cerebral organoids derived from AD iPSCs recapitulated the AD phenotype, exhibiting significantly increased levels of tau protein. Our analysis revealed that an iPSC disease model of AD is a valuable assessment tool for pathophysiological research and drug screening.

Induced pluripotent stem cells (iPSCs): molecular mechanisms of induction and applications

The induced pluripotent stem cell (iPSC) technology has transformed in vitro research and holds great promise to advance regenerative medicine. iPSCs have the capacity for an almost unlimited expansion, are amenable to genetic engineering, and can be differentiated into most somatic cell types. iPSCs have been widely applied to model human development and diseases, perform drug screening, and develop cell therapies. In this review, we outline key developments in the iPSC field and highlight the immense versatility of the iPSC technology for in vitro modeling and therapeutic applications. We begin by discussing the pivotal discoveries that revealed the potential of a somatic cell nucleus for reprogramming and led to successful generation of iPSCs. We consider the molecular mechanisms and dynamics of somatic cell reprogramming as well as the numerous methods available to induce pluripotency. Subsequently, we discuss various iPSC-based cellular models, from mono-cultures of a single cell type to complex three-dimensional organoids, and how these models can be applied to elucidate the mechanisms of human development and diseases. We use examples of neurological disorders, coronavirus disease 2019 (COVID-19), and cancer to highlight the diversity of disease-specific phenotypes that can be modeled using iPSC-derived cells. We also consider how iPSC-derived cellular models can be used in high-throughput drug screening and drug toxicity studies. Finally, we discuss the process of developing autologous and allogeneic iPSC-based cell therapies and their potential to alleviate human diseases.

A robust reprogramming strategy for generating hepatocyte-like cells usable in pharmaco-toxicological studies

BACKGROUND

High-throughput pharmaco-toxicological testing frequently relies on the use of established liver-derived cell lines, such as HepG2 cells. However, these cells often display limited hepatic phenotype and features of neoplastic transformation that may bias the interpretation of the results. Alternate models based on primary cultures or differentiated pluripotent stem cells are costly to handle and difficult to implement in high-throughput screening platforms. Thus, cells without malignant traits, optimal differentiation pattern, producible in large and homogeneous amounts and with patient-specific phenotypes would be desirable.

METHODS

We have designed and implemented a novel and robust approach to obtain hepatocytes from individuals by direct reprogramming, which is based on a combination of a single doxycycline-inducible polycistronic vector system expressing HNF4A, HNF1A and FOXA3, introduced in human fibroblasts previously transduced with human telomerase reverse transcriptase (hTERT). These cells can be maintained in fibroblast culture media, under standard cell culture conditions.

RESULTS

Clonal hTERT-transduced human fibroblast cell lines can be expanded at least to 110 population doublings without signs of transformation or senescence. They can be easily differentiated at any cell passage number to hepatocyte-like cells with the simple addition of doxycycline to culture media. Acquisition of a hepatocyte phenotype is achieved in just 10 days and requires a simple and non-expensive cell culture media and standard 2D culture conditions. Hepatocytes reprogrammed from low and high passage hTERT-transduced fibroblasts display very similar transcriptomic profiles, biotransformation activities and show analogous pattern behavior in toxicometabolomic studies. Results indicate that this cell model outperforms HepG2 in toxicological screening. The procedure also allows generation of hepatocyte-like cells from patients with given pathological phenotypes. In fact, we succeeded in generating hepatocyte-like cells from a patient with alpha-1 antitrypsin deficiency, which recapitulated accumulation of intracellular alpha-1 antitrypsin polymers and deregulation of unfolded protein response and inflammatory networks.

CONCLUSION

Our strategy allows the generation of an unlimited source of clonal, homogeneous, non-transformed induced hepatocyte-like cells, capable of performing typical hepatic functions and suitable for pharmaco-toxicological high-throughput testing. Moreover, as far as hepatocyte-like cells derived from fibroblasts isolated from patients suffering hepatic dysfunctions, retain the disease traits, as demonstrated for alpha-1-antitrypsin deficiency, this strategy can be applied to the study of other cases of anomalous hepatocyte functionality.

Polyphenols as potential enhancers of stem cell therapy against neurodegeneration

The potential of polyphenols for treating chronic-degenerative diseases (particularly neurodegenerative diseases) is attractive. However, the selection of the best polyphenol for each treatment, the mechanisms by which they act, and their efficacy are frequently discussed. In this review, the basics and the advances in the field, as well as suggestions for using natural and synthetic polyphenols alone or in a combinatorial strategy with stem cell assays, are compiled and discussed. Thus, stem cells exhibit several responses when polyphenols are added to their environment, which could provide us with knowledge for advancing the elucidation of the origin of neurodegeneration. But also, polyphenols are being included in the innovative strategies of novel therapies for treating neurodegenerative diseases as well as metabolic diseases related to neurodegeneration. In this regard, flavonoid compounds are suggested as the best natural polyphenols due to their several mechanisms for acting in ameliorative effects; but increasing reports are involving other polyphenols. Even if some facts limiting bioactivity prevent them from conventional use, some natural polyphenols and derivatives hold the promise for being improved compounds, judged by their induced effects. The current results suggest polyphenols as enhancers of stem cell therapy against the targeted diseases.

Quality criteria for in vitro human pluripotent stem cell-derived models of tissue-based cells

The advent of the technology to isolate or generate human pluripotent stem cells provided the potential to develop a wide range of human models that could enhance understanding of mechanisms underlying human development and disease. These systems are now beginning to mature and provide the basis for the development of in vitro assays suitable to understand the biological processes involved in the multi-organ systems of the human body, and will improve strategies for diagnosis, prevention, therapies and precision medicine. Induced pluripotent stem cell lines are prone to phenotypic and genotypic changes and donor/clone dependent variability, which means that it is important to identify the most appropriate characterization markers and quality control measures when sourcing new cell lines and assessing differentiated cell and tissue culture preparations for experimental work. This paper considers those core quality control measures for human pluripotent stem cell lines and evaluates the state of play in the development of key functional markers for their differentiated cell derivatives to promote assurance of reproducibility of scientific data derived from pluripotent stem cell-based systems.

Induced pluripotent stem cell-based organ-on-a-chip as personalized drug screening tools: A focus on neurodegenerative disorders

The Organ-on-a-Chip (OoC) technology shows great potential to revolutionize the drugs development pipeline by mimicking the physiological environment and functions of human organs. The translational value of OoC is further enhanced when combined with patient-specific induced pluripotent stem cells (iPSCs) to develop more realistic disease models, paving the way for the development of a new generation of patient-on-a-chip devices. iPSCs differentiation capacity leads to invaluable improvements in personalized medicine. Moreover, the connection of single-OoC into multi-OoC or body-on-a-chip allows to investigate drug pharmacodynamic and pharmacokinetics through the study of multi-organs cross-talks. The need of a breakthrough thanks to this technology is particularly relevant within the field of neurodegenerative diseases, where the number of patients is increasing and the successful rate in drug discovery is worryingly low. In this review we discuss current iPSC-based OoC as drug screening models and their implication in development of new therapies for neurodegenerative disorders.

The Promoting Equity in Stem Cell Genomics Survey

Aim: This study aimed to determine knowledge and attitudes toward induced pluripotent stem cell technology and biobanking. Methods: A survey instrument was developed to determine individuals' knowledge of and attitudes toward these technologies. Results: Results from 276 ethnically diverse participants who took the online survey demonstrated significant associations (p ≤ 0. 05) in knowledge by ethnicity and race regarding properties of stem cells, different types of stem cells and previous sample donation behavior. Significantly more Whites 39% (n = 53) compared with Blacks or African-Americans 19.2% (n = 14) had previous knowledge of induced pluripotent stem cells (χ² = 8.544; p = 0.003) Conclusion: Overall, White race was associated with greater knowledge about stem cells and biobanks and greater willingness to donate samples for future research.

Comparison of 2,3,5,4'-tetrahydroxystilbene-2-O-b-D-glucoside-induced proliferation and differentiation of dental pulp stem cells in 2D and 3D culture systems-gene analysis

Background/purpose

Culture environments play a critical role in stem cell expansion. This study aimed to evaluate the effects of 2,3,5,4′-tetrahydroxystilbene-2-O-b-D-glucoside (THSG) on the proliferation and differentiation of human dental pulp stem cells (DPSCs) in 2-dimensional (2D) and 3-dimensional (3D) culture systems.

Materials and methods

Human DPSCs were seeded in T25 flasks for 2D cultivation. For the 3D culture system, DPSCs were mixed with microcarriers and cultured in spinner flasks. Cells in both culture systems were treated with THSG, and cell proliferation was determined using a cell counter and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. In THSG-treated DPSCs, the genes associated with proliferation, adipogenesis, neurogenesis, osteogenesis, pluripotency, oncogenesis, and apoptosis were analyzed using real-time polymerase chain reactions.

Results

The spinner flask time-dependently improved cell numbers, cell viability, and expansion rates in THSG-treated DPSCs. In both the T25 and spinner flasks, the messenger RNA (mRNA) levels of proliferation, osteogenesis, and pluripotent-related genes had a significant maximum expression with 10 μM THSG treatment. However, 0.1 μM of THSG may be the most suitable condition for triggering neurogenesis and adipogenesis gene expression when DPSCs were cultured in spinner flasks. Furthermore, the number of oncogenes and apoptotic genes decreased considerably in the presence of THSG in both the T25 and spinner flasks.

Conclusion

The spinner flask bioreactor combined with THSG may upregulate proliferation and lineage-specific differentiation in DPSCs. Thus, the combination can be used to mass-produce and cultivate human DPSCs for regenerative dentistry.

Cardiovascular Regeneration via Stem Cells and Direct Reprogramming: A Review

Despite recent advancements in treatment strategies, cardiovascular disease such as heart failure remains a significant source of global mortality. Stem cell technology and cellular reprogramming are rapidly growing fields that will continue to prove useful in cardiac regenerative therapeutics. This review provides information on the role of human pluripotent stem cells (hPSCs) in cardiac regeneration and discusses the practical applications of hPSC-derived cardiomyocytes (CMCs). Moreover, we discuss the practical applications of hPSC-derived CMCs while outlining the relevance of directly-reprogrammed CMCs in regenerative medicine. This review critically summarizes the most recent advances in the field will help to guide future research in this developing area.

Cardiovascular disease (CVD) is the leading causes of morbidity and death globally. In particular, a heart failure remains a major problem that contributes to global mortality. Considerable advancements have been made in conventional pharmacological therapies and coronary intervention surgery for cardiac disorder treatment. However, more than 15% of patients continuously progress to end-stage heart failure and eventually require heart transplantation. Over the past year, numerous numbers of protocols to generate cardiomyocytes (CMCs) from human pluripotent stem cells (hPSCs) have been developed and applied in clinical settings. Number of studies have described the therapeutic effects of hPSCs in animal models and revealed the underlying repair mechanisms of cardiac regeneration. In addition, biomedical engineering technologies have improved the therapeutic potential of hPSC-derived CMCs in vivo. Recently substantial progress has been made in driving the direct differentiation of somatic cells into mature CMCs, wherein an intermediate cellular reprogramming stage can be bypassed. This review provides information on the role of hPSCs in cardiac regeneration and discusses the practical applications of hPSC-derived CMCs; furthermore, it outlines the relevance of directly reprogrammed CMCs in regenerative medicine.

Challenges for the Applications of Human Pluripotent Stem Cell-Derived Liver Organoids

The current organoid culture systems allow pluripotent and adult stem cells to self-organize to form three-dimensional (3D) structures that provide a faithful recapitulation of the architecture and function of in vivo organs. In particular, human pluripotent stem cell-derived liver organoids (PSC-LOs) can be used in regenerative medicine and preclinical applications, such as disease modeling and drug discovery. New bioengineering tools, such as microfluidics, biomaterial scaffolds, and 3D bioprinting, are combined with organoid technologies to increase the efficiency of hepatic differentiation and enhance the functional maturity of human PSC-LOs by precise control of cellular microenvironment. Long-term stabilization of hepatocellular functions of in vitro liver organoids requires the combination of hepatic endodermal, endothelial, and mesenchymal cells. To improve the biological function and scalability of human PSC-LOs, bioengineering methods have been used to identify diverse and zonal hepatocyte populations in liver organoids for capturing heterogeneous pathologies. Therefore, constructing engineered liver organoids generated from human PSCs will be an extremely versatile tool in in vitro disease models and regenerative medicine in future. In this review, we aim to discuss the recent advances in bioengineering technologies in liver organoid culture systems that provide a timely and necessary study to model disease pathology and support drug discovery in vitro and to generate cell therapy products for transplantation.

Analysis of the response of human iPSC-derived cardiomyocyte tissue to ICaL block. A combined in vitro and in silico approach

The high incidence of cardiac arrythmias underlines the need for the assessment of pharmacological therapies. In this field of drug efficacy, as in the field of drug safety highlighted by the Comprehensive in Vitro Proarrhythmia Assay initiative, new pillars for research have become crucial: firstly, the integration of in-silico experiments, and secondly the evaluation of fully integrated biological systems, such as human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). In this study, we therefore aimed to combine in-vitro experiments and in-silico simulations to evaluate the antiarrhythmic effect of L-type calcium current (I_CaL) block in hiPSC-CMs. For this, hiPSC-CM preparations were cultured and an equivalent virtual tissue was modeled. Re-entry patterns of electrical activation were induced and several biomarkers were obtained before and after I_CaL block. The virtual hiPSC-CM simulations were also reproduced using a tissue composed of adult ventricular cardiomyocytes (hAdultV-CMs). The analysis of phases, currents and safety factor for propagation showed an increased size of the re-entry core when I_CaL was blocked as a result of depressed cellular excitability. The bigger wavefront curvature yielded reductions of 12.2%, 6.9%, and 4.2% in the frequency of the re-entry for hiPSC-CM cultures, virtual hiPSC-CM, and hAdultV-CM tissues, respectively. Furthermore, I_CaL block led to a 47.8% shortening of the vulnerable window for re-entry in the virtual hiPSC-CM tissue and to re-entry vanishment in hAdultV-CM tissue. The consistent behavior between in-vitro and in-silico hiPSC-CMs and between in-silico hiPSC-CMs and hAdultV-CMs evidences that virtual hiPSC-CM tissues are suitable for assessing cardiac efficacy, as done in the present study through the analysis of I_CaL block.

Cell type-specific changes in transcriptomic profiles of endothelial cells, iPSC-derived neurons and astrocytes cultured on microfluidic chips

In vitro neuronal models are essential for studying neurological physiology, disease mechanisms and potential treatments. Most in vitro models lack controlled vasculature, despite its necessity in brain physiology and disease. Organ-on-chip models offer microfluidic culture systems with dedicated micro-compartments for neurons and vascular cells. Such multi-cell type organs-on-chips can emulate neurovascular unit (NVU) physiology, however there is a lack of systematic data on how individual cell types are affected by culturing on microfluidic systems versus conventional culture plates. This information can provide perspective on initial findings of studies using organs-on-chip models, and further optimizes these models in terms of cellular maturity and neurovascular physiology. Here, we analysed the transcriptomic profiles of co-cultures of human induced pluripotent stem cell (hiPSC)-derived neurons and rat astrocytes, as well as one-day monocultures of human endothelial cells, cultured on microfluidic chips. For each cell type, large gene expression changes were observed when cultured on microfluidic chips compared to conventional culture plates. Endothelial cells showed decreased cell division, neurons and astrocytes exhibited increased cell adhesion, and neurons showed increased maturity when cultured on a microfluidic chip. Our results demonstrate that culturing NVU cell types on microfluidic chips changes their gene expression profiles, presumably due to distinct surface-to-volume ratios and substrate materials. These findings inform further NVU organ-on-chip model optimization and support their future application in disease studies and drug testing.

Derivation of Thyroid Follicular Cells From Pluripotent Stem Cells: Insights From Development and Implications for Regenerative Medicine

Stem cell-based therapies to reconstitute in vivo organ function hold great promise for future clinical applications to a variety of diseases. Hypothyroidism resulting from congenital lack of functional thyrocytes, surgical tissue removal, or gland ablation, represents a particularly attractive endocrine disease target that may be conceivably cured by transplantation of long-lived functional thyroid progenitors or mature follicular epithelial cells, provided a source of autologous cells can be generated and a variety of technical and biological challenges can be surmounted. Here we review the emerging literature indicating that thyroid follicular epithelial cells can now be engineered in vitro from the pluripotent stem cells (PSCs) of mice, normal humans, or patients with congenital hypothyroidism. We review the in vivo embryonic development of the thyroid gland and explain how emerging discoveries in developmental biology have been utilized as a roadmap for driving PSCs, which resemble cells of the early embryo, into mature functional thyroid follicles in vitro. Finally, we discuss the bioengineering, biological, and clinical hurdles that now need to be addressed if the goals of life-long cure of hypothyroidism through cell- and/or gene-based therapies are to be attained.

Characterization hiPSC-derived neural progenitor cells and neurons to investigate the role of NOS1AP isoforms in human neuron dendritogenesis

Abnormal dendritic arbor development has been implicated in a number of neurodevelopmental disorders, such as autism and Rett syndrome, and the neuropsychiatric disorder schizophrenia. Postmortem brain samples from subjects with schizophrenia show elevated levels of NOS1AP in the dorsolateral prefrontal cortex, a region of the brain associated with cognitive function. We previously reported that the long isoform of NOS1AP (NOS1AP-L), but not the short isoform (NOS1AP-S), negatively regulates dendrite branching in rat hippocampal neurons. To investigate the role that NOS1AP isoforms play in human dendritic arbor development, we adapted methods to generate human neural progenitor cells and neurons using induced pluripotent stem cell (iPSC) technology. We found that increased protein levels of either NOS1AP-L or NOS1AP-S decrease dendrite branching in human neurons at the developmental time point when primary and secondary branching actively occurs. Next, we tested whether pharmacological agents can decrease the expression of NOS1AP isoforms. Treatment of human iPSC-derived neurons with d-serine, but not clozapine, haloperidol, fluphenazine, or GLYX-13, results in a reduction in endogenous NOS1AP-L, but not NOS1AP-S, protein expression; however, d-serine treatment does not reverse decreases in dendrite number mediated by overexpression of NOS1AP isoforms. In summary, we demonstrate how an in vitro model of human neuronal development can help in understanding the etiology of schizophrenia and can also be used as a platform to screen drugs for patients.

Nanofountain Probe Electroporation Enables Versatile Single-Cell Intracellular Delivery and Investigation of Postpulse Electropore Dynamics

Introducing exogenous molecules into cells with high efficiency and dosage control is a crucial step in basic research as well as clinical applications. Here, the capability of the nanofountain probe electroporation (NFP-E) system to deliver proteins and plasmids in a variety of continuous and primary cell types with appropriate dosage control is reported. It is shown that the NFP-E can achieve fine control over the relative expression of two cotransfected plasmids. Finally, the dynamics of electropore closure after the pulsing ends with the NFP-E is investigated. Localized electroporation has recently been utilized to demonstrate the converse process of delivery (sampling), in which a small volume of the cytosol is retrieved during electroporation without causing cell lysis. Single-cell temporal sampling confers the benefit of monitoring the same cell over time and can provide valuable insights into the mechanisms underlying processes such as stem cell differentiation and disease progression. NFP-E parameters that maximize the membrane resealing time, which is essential for increasing the sampled volume and in meeting the challenge of monitoring low copy number biomarkers, are identified. Its application in CRISPR/Cas9 gene editing, stem cell reprogramming, and single-cell sampling studies is envisioned.

A Comparative Approach of Cellular Reprogramming in the Rodentia Order

Cellular reprogramming mainly involves induction of reactivation of genes responsible for nuclear plasticity, a process that can be performed in vitro through production of cloned embryos by somatic cell nuclear transfer or by induction of cells into the pluripotent state through exogenous transcription factor expression. While these techniques are already well known and utilized in mice and rats, their application in other rodent species would be greatly beneficial, especially for conservation purposes. Within the diverse Rodentia order, wild species stand out as they play an important role in balancing the ecosystem by facilitating seed diversion, soil aeration, and consequently, reforestation. Many of these species are currently approaching extinction, and application of techniques, such as nuclear reprogramming, aimed at species conservation and multiplication and to produce stem cells is of interest. Thus, in this review, we aimed to present the evolution and success of nuclear reprogramming, mainly highlighting its potential application for the conservation of wild rodents.

Human pluripotent stem cell-derived models and drug screening in CNS precision medicine

Development of effective therapeutics for neurological disorders has historically been challenging partly because of lack of accurate model systems in which to investigate disease etiology and test new therapeutics at the preclinical stage. Human stem cells, particularly patient-derived induced pluripotent stem cells (iPSCs) upon differentiation, have the ability to recapitulate aspects of disease pathophysiology and are increasingly recognized as robust scalable systems for drug discovery. We review advances in deriving cellular models of human central nervous system (CNS) disorders using iPSCs along with strategies for investigating disease-relevant phenotypes, translatable biomarkers, and therapeutic targets. Given their potential to identify novel therapeutic targets and leads, we focus on phenotype-based, small-molecule screens employing human stem cell-derived models. Integrated efforts to assemble patient iPSC-derived cell models with deeply annotated clinicopathological data, along with molecular and drug-response signatures, may aid in the stratification of patients, diagnostics, and clinical trial success, shifting translational science and precision medicine approaches. A number of remaining challenges, including the optimization of cost-effective, large-scale culture of iPSC-derived cell types, incorporation of aging into neuronal models, as well as robustness and automation of phenotypic assays to support quantitative drug efficacy, toxicity, and metabolism testing workflows, are covered. Continued advancement of the field is expected to help fully humanize the process of CNS drug discovery.

Negative Symptoms of Schizophrenia and Dopaminergic Transmission: Translational Models and Perspectives Opened by iPSC Techniques

Negative symptoms (NS) represent a heterogeneous dimension of schizophrenia (SCZ), associated with a poor functional outcome. A dysregulated dopamine (DA) system, including a reduced D1 receptor activation in the prefrontal cortex, DA hypoactivity in the caudate and alterations in D3 receptor activity, seems to contribute to the pathogenesis of NS. However, failure to take into account the NS heterogeneity has slowed down progress in research on their neurobiological correlates and discoveries of new effective treatments. A better neurobiological characterization of NS is needed, and this requires objective quantification of their features that can be applied in translational models, such as animal models and human inducible pluripotent stem cells (iPSC). In this review we summarize the evidence for dopaminergic alterations relevant to NS in translational animal models focusing on dysfunctional motivation, a core aspect of NS. Among others, experiments on mutant rodents with an overexpression of DA D2 or D3 receptors and the dopamine deficient mice are discussed. In the second part we summarize the findings from recent studies using iPSC to model the pathogenesis of SCZ. By retaining the genetic background of risk genetic variants, iPSC offer the possibility to study the effect of de novo mutations or inherited polymorphisms from subgroups of patients and their response to drugs, adding an important tool for personalized psychiatry. Given the key role of DA in NS, we focus on findings of iPSC-derived DA neurons. Since implementation of iPSC-derived neurons to study the neurobiology of SCZ is a relatively recent acquisition, the available data are limited. We highlight some methodological aspects of relevance in the interpretation of in vitro testing results, including limitations and strengths, offering a critical viewpoint for the implementation of future pharmacological studies aimed to the discovery and characterization of novel treatments for NS.

Elimination of Teratogenic Human Induced Pluripotent Stem Cells by Bee Venom via Calcium-Calpain Pathway

Induced pluripotent stem cells (iPSCs) are regarded as a promising option for cell-based regenerative medicine. To obtain safe and efficient iPSC-based cell products, it is necessary to selectively eliminate the residual iPSCs prior to in vivo implantation due to the risk of teratoma formation. Bee venom (BV) has long been used in traditional Chinese medicine to treat inflammatory diseases and relieve pain, and has been shown to exhibit anti-cancer, anti-mutagenic, anti-nociceptive, and radioprotective activities. However, the potential benefits of BV in iPSC therapy, particularly its anti-teratoma activity, have not been examined. In this study, we found that BV selectively induced cell death in iPSCs, but not in iPSC-derived differentiated cells (iPSCs-Diff). BV rapidly disrupted cell membrane integrity and focal adhesions, followed by induction of apoptosis and necroptosis in iPSCs. We also found that BV remarkably enhanced intracellular calcium levels, calpain activation, and reactive oxygen speciesgeneration in iPSCs. BV treatment before in ovo grafting efficiently prevented iPSC-derived teratoma formation. In contrast, no DNA damage was observed in iPSCs-Diff following BV treatment, further demonstrating the safety of BV for use with iPSCs-Diff. Taken together, these findings show that BV has potent anti-teratoma activity by eliminating residual iPSCs, and can be used for the development of effective and safe iPSC-based cell therapies.

Prunellae Spica Extract Suppresses Teratoma Formation of Pluripotent Stem Cells through p53-Mediated Apoptosis

Induced pluripotent stem cells (iPSCs) have similar properties to embryonic stem cells in terms of indefinite self-renewal and differentiation capacity. After in vitro differentiation of iPSCs, undifferentiated iPSCs (USCs) may exist in cell therapy material and can form teratomas after in vivo transplantation. Selective elimination of residual USCs is, therefore, very important. Prunellae Spica (PS) is a traditional medicinal plant that has been shown to exert anti-cancer, antioxidant, and anti-inflammatory activities; however, its effects on iPSCs have not been previously characterized. In this study, we find that ethanol extract of PS (EPS) effectively induces apoptotic cell death of USCs through G2/M cell cycle arrest, generation of intracellular reactive oxygen species, alteration of mitochondrial membrane potentials, and caspase activation of USCs. In addition, EPS increases p53 accumulation and expression of its downstream targets. In p53 knockout (KO) iPSCs, the EPS did not induce apoptosis, indicating that EPS-mediated apoptosis of USCs was p53-dependent. In addition, EPS was not genotoxic towards iPSCs-derived differentiated cells. EPS treatment before injection efficiently prevented in ovo teratoma formation of p53 wild-type (WT) iPSCs but not p53KO iPSCs. Collectively, these results indicate that EPS has potent anti-teratoma activity and no genotoxicity to differentiated cells. It can, therefore, be used in the development of safe and efficient iPSC-based cell therapies.

The application of human pluripotent stem cells to model the neuronal and glial components of neurodevelopmental disorders

Cellular models of neurodevelopmental disorders provide a valuable experimental system to uncover disease mechanisms and novel therapeutic strategies. The ability of induced pluripotent stem cells (iPSCs) to generate diverse brain cell types offers great potential to model several neurodevelopmental disorders. Further patient-derived iPSCs have the unique genetic and molecular signature of the affected individuals, which allows researchers to address limitations of transgenic behavioural models, as well as generate hypothesis-driven models to study disorder-relevant phenotypes at a cellular level. In this article, we review the extant literature that has used iPSC-based modelling to understand the neuronal and glial contributions to neurodevelopmental disorders including autism spectrum disorder (ASD), Rett syndrome, bipolar disorder (BP), and schizophrenia. For instance, several molecular candidates have been shown to influence cellular phenotypes in three-dimensional iPSC-based models of ASD patients. Delays in differentiation of astrocytes and morphological changes of neurons are associated with Rett syndrome. In the case of bipolar disorders and schizophrenia, patient-derived models helped to identify cellular phenotypes associated with neuronal deficits (e.g., excitability) and mutation-specific abnormalities in oligodendrocytes (e.g., CSPG4). Further we provide a critical review of the current limitations of this field and provide methodological suggestions to enhance future modelling efforts of neurodevelopmental disorders. Future developments in experimental design and methodology of disease modelling represent an exciting new avenue relevant to neurodevelopmental disorders.

Benzothiazole amphiphiles promote RasGRF1-associated dendritic spine formation in human stem cell-derived neurons

Synaptic dysfunction has been implicated as an early cause of cognitive decline in neurodegenerative diseases (NDDs) such as Alzheimer’s disease (AD). Methods to slow down or reverse the loss of functional synapses, therefore, represent a promising avenue to explore for treating NDDs. We have previously reported the development of a class of benzothiazole amphiphiles (BAMs) that exhibited the capability to improve memory and learning both in wild‐type mice and in an AD rodent model, putatively through promoting RasGRF1‐associated formation of dendritic spines in hippocampal neurons. While these results represent a good first step in exploring a new approach to treating NDDs, the capability of these compounds to increase spine density has not been previously examined in a human neuronal model. Here, we found that neurons derived from differentiated human induced pluripotent stem cells exhibited both an increase in RasGRF1 expression and a phenotypic increase in the density of postsynaptic density protein 95‐positive puncta (which we use to provide an estimate of dendritic spine density) in BAM‐treated vs. control neurons. These results demonstrate that the previously observed spinogenic effects of BAMs in rodent neurons can be recapitulated in a human neuronal model, which further supports the potential utility of BAM agents for treating human diseases associated with spine deficits such as AD or other NDDs.

Direct conversion of human fibroblast to hepatocytes using a single inducible polycistronic vector

BACKGROUND

Human fibroblasts can be reprogrammed into induced hepatocyte-like cells through the expression of a set of transcription factors. Although the generation of induced hepatocyte-like cells by HNF4A, HNF1A, and FOXA3 expression has proven to be a robust experimental strategy, using multiple lentivirus results in a highly variable heterogeneous population.

METHODS

We designed and implemented a novel approach based on the delivery of reprogramming factors and green fluorescent protein in a single doxycycline-inducible lentiviral vector using 2A self-cleaving peptides.

RESULTS

Fibroblasts infected with the lentiviral vector can be amplified in basic fibroblast culture media in the absence of doxycycline without induction of hepatic genes. Upon switching to hepatic maturation media containing doxycycline, cells stop proliferating, activate hepatic gene transcription, and perform metabolic functions characteristic of hepatocytes.

CONCLUSION

Our strategy can generate an unlimited source of homogeneously induced hepatocyte-like cells from different genetic background donors, capable of performing typical hepatic functions suitable for drug research and other in vitro applications.

Advances in the Differentiation of Retinal Ganglion Cells from Human Pluripotent Stem Cells

Human pluripotent stem cell (hPSC) technology has revolutionized the field of biology through the unprecedented ability to study the differentiation of human cells in vitro. In the past decade, hPSCs have been applied to study development, model disease, develop drugs, and devise cell replacement therapies for numerous biological systems. Of particular interest is the application of this technology to study and treat optic neuropathies such as glaucoma. Retinal ganglion cells (RGCs) are the primary cell type affected in these diseases, and once lost, they are unable to regenerate in adulthood. This necessitates the development of strategies to study the mechanisms of degeneration as well as develop translational therapeutic approaches to treat early- and late-stage disease progression. Numerous protocols have been established to derive RGCs from hPSCs, with the ability to generate large populations of human RGCs for translational applications. In this review, the key applications of hPSCs within the retinal field are described, including the use of these cells as developmental models, disease models, drug development, and finally, cell replacement therapies. In greater detail, the current report focuses on the differentiation of hPSC-derived RGCs and the many unique characteristics associated with these cells in vitro including their genetic identifiers, their electrophysiological activity, and their morphological maturation. Also described is the current progress in the use of patient-specific hPSCs to study optic neuropathies affecting RGCs, with emphasis on the use of these RGCs for studying disease mechanisms and pathogenesis, drug screening, and cell replacement therapies in future studies.

Phenotype-Based High-Throughput Classification of Long QT Syndrome Subtypes Using Human Induced Pluripotent Stem Cells

For long QT syndrome (LQTS), recent progress in genome-sequencing technologies enabled the identification of rare genomic variants with diagnostic, prognostic, and therapeutic implications. However, pathogenic stratification of the identified variants remains challenging, especially in variants of uncertain significance. This study aimed to propose a phenotypic cell-based diagnostic assay for identifying LQTS to recognize pathogenic variants in a high-throughput manner suitable for screening. We investigated the response of LQT2-induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) following I_Kr blockade using a multi-electrode array, finding that the response to I_Kr blockade was significantly smaller than in Control-iPSC-CMs. Furthermore, we found that LQT1-iPSC-CMs and LQT3-iPSC-CMs could be distinguished from Control-iPSC-CMs by I_Ks blockade and I_Na blockade, respectively. This strategy might be helpful in compensating for the shortcomings of genetic testing of LQTS patients.

Insights into the biology of fibrodysplasia ossificans progressiva using patient-derived induced pluripotent stem cells

The demand for development of new drugs remains on the upward trend because of the large number of patients suffering from intractable diseases for which effective treatment has not been established yet. Recently, several researchers have attempted to apply induced pluripotent stem cell (iPSC) technology as a powerful tool for studying the mechanisms underlying the onset of various diseases and for new drug screening. This technology has made an enormous breakthrough, since it permits us to recapitulate the disease phenotype in vitro, outside of the patient's body. Here, we discuss the latest findings that uncovered a mechanism underlying the pathology of a rare genetic musculoskeletal disease, fibrodysplasia ossificans progressiva (FOP), by modeling the phenotypes with FOP patient-derived iPSCs, and that discovered promising candidate drugs for FOP treatment. We also discussed future directions of FOP research.

Potential therapeutic roles of stem cells in ischemia-reperfusion injury

Ischemia-reperfusion injury (I/RI), produced by an initial interruption of organ blood flow and its subsequent restoration, contributes significantly to the pathophysiologies of stroke, myocardial infarction, renal I/RI, intestinal I/RI and liver I/RI, which are major causes of disability (including transplant failure) and even mortality. While the restoration of blood flow is required to restore oxygen and nutrient requirements, reperfusion often triggers local and systemic inflammatory responses and subsequently elevate the ischemic insult where the duration of ischemia determines the magnitude of I/RI damage. I/RI increases vascular leakage, changes transcriptional and cell death programs, drives leukocyte entrapment and inflammation and oxidative stress in tissues. Therapeutic approaches which reduce complications associated with I/RI are desperately needed to address the clinical and economic burden created by I/RI. Stem cells (SC) represent ubiquitous and uncommitted cell populations with the ability to self-renew and differentiate into one or more developmental 'fates'. Like immune cells, stem cells can home to and penetrate I/R-injured tissues, where they can differentiate into target tissues and induce trophic paracrine signaling which suppress injury and maintain tissue functions perturbed by ischemia-reperfusion. This review article summarizes the present use and possible protective mechanisms underlying stem cell protection in diverse forms of ischemia-reperfusion.

Astrocytes Regulate the Development and Maturation of Retinal Ganglion Cells Derived from Human Pluripotent Stem Cells

Retinal ganglion cells (RGCs) form the connection between the eye and the brain, with this connectivity disrupted in numerous blinding disorders. Previous studies have demonstrated the ability to derive RGCs from human pluripotent stem cells (hPSCs); however, these cells exhibited some characteristics that indicated a limited state of maturation. Among the many factors known to influence RGC development in the retina, astrocytes are known to play a significant role in their functional maturation. Thus, efforts of the current study examined the functional maturation of hPSC-derived RGCs, including the ability of astrocytes to modulate this developmental timeline. Morphological and functional properties of RGCs were found to increase over time, with astrocytes significantly accelerating the functional maturation of hPSC-derived RGCs. The results of this study clearly demonstrate the functional and morphological maturation of RGCs in vitro, including the effects of astrocytes on the maturation of hPSC-derived RGCs.

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Improved maturation of hPSC-derived RGCs in a temporally appropriate manner

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Co-cultures of RGCs and astrocytes recapitulate cellular interactions in the retina

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Astrocytes enhance functional and morphological maturation of hPSC-derived RGCs

Modeling Parkinson's Disease and Atypical Parkinsonian Syndromes Using Induced Pluripotent Stem Cells

Parkinson’s disease (PD) and atypical parkinsonian syndromes are age-dependent multifactorial neurodegenerative diseases, which are clinically characterized by bradykinesia, tremor, muscle rigidity and postural instability. Although these diseases share several common clinical phenotypes, their pathophysiological aspects vary among the disease categories. Extensive animal-based approaches, as well as postmortem studies, have provided important insights into the disease mechanisms and potential therapeutic targets. However, the exact pathological mechanisms triggering such diseases still remain elusive. Furthermore, the effects of drugs observed in animal models are not always reproduced in human clinical trials. By using induced pluripotent stem cell (iPSC) technology, it has become possible to establish patient-specific iPSCs from their somatic cells and to effectively differentiate these iPSCs into different types of neurons, reproducing some key aspects of the disease phenotypes in vitro. In this review, we summarize recent findings from iPSC-based modeling of PD and several atypical parkinsonian syndromes including multiple system atrophy, frontotemporal dementia and parkinsonism linked to chromosome 17 and Perry syndrome. Furthermore, we discuss future challenges and prospects for modeling and understanding PD and atypical parkinsonian syndromes.

Microphysiological 3D model of amyotrophic lateral sclerosis (ALS) from human iPS-derived muscle cells and optogenetic motor neurons

Amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease involving loss of motor neurons (MNs) and muscle atrophy, still has no effective treatment, despite much research effort. To provide a platform for testing drug candidates and investigating the pathogenesis of ALS, we developed an ALS-on-a-chip technology (i.e., an ALS motor unit) using three-dimensional skeletal muscle bundles along with induced pluripotent stem cell (iPSC)-derived and light-sensitive channelrhodopsin-2-induced MN spheroids from a patient with sporadic ALS. Each tissue was cultured in a different compartment of a microfluidic device. Axon outgrowth formed neuromuscular junctions on the muscle fiber bundles. Light was used to activate muscle contraction, which was measured on the basis of pillar deflections. Compared to a non-ALS motor unit, the ALS motor unit generated fewer muscle contractions, there was MN degradation, and apoptosis increased in the muscle. Furthermore, the muscle contractions were recovered by single treatments and cotreatment with rapamycin (a mechanistic target of rapamycin inhibitor) and bosutinib (an Src/c-Abl inhibitor). This recovery was associated with up-regulation of autophagy and degradation of TAR DNA binding protein-43 in the MNs. Moreover, administering the drugs via an endothelial cell barrier decreased the expression of P-glycoprotein (an efflux pump that transports bosutinib) in the endothelial cells, indicating that rapamycin and bosutinib cotreatment has considerable potential for ALS treatment. This ALS-on-a-chip and optogenetics technology could help to elucidate the pathogenesis of ALS and to screen for drug candidates.

The march of pluripotent stem cells in cardiovascular regenerative medicine

Cardiovascular disease (CVD) continues to be the leading cause of global morbidity and mortality. Heart failure remains a major contributor to this mortality. Despite major therapeutic advances over the past decades, a better understanding of molecular and cellular mechanisms of CVD as well as improved therapeutic strategies for the management or treatment of heart failure are increasingly needed. Loss of myocardium is a major driver of heart failure. An attractive approach that appears to provide promising results in reducing cardiac degeneration is stem cell therapy (SCT). In this review, we describe different types of stem cells, including embryonic and adult stem cells, and we provide a detailed discussion of the properties of induced pluripotent stem cells (iPSCs). We also present and critically discuss the key methods used for converting somatic cells to pluripotent cells and iPSCs to cardiomyocytes (CMs), along with their advantages and limitations. Integrating and non-integrating reprogramming methods as well as characterization of iPSCs and iPSC-derived CMs are discussed. Furthermore, we critically present various methods of differentiating iPSCs to CMs. The value of iPSC-CMs in regenerative medicine as well as myocardial disease modeling and cardiac regeneration are emphasized.

Pluripotent Stem Cell Platforms for Drug Discovery

Use of human pluripotent stem cells (hPSCs) and their differentiated derivatives have led to recent proof-of-principle drug discoveries, defining a pathway to the implementation of hPSC-based drug discovery (hPDD). Current hPDD strategies, however, have inevitable conceptual biases and technological limitations, including the dimensionality of cell-culture methods, cell maturity and functionality, experimental variability, and data reproducibility. In this review, we dissect representative hPDD systems via analysis of hPSC-based 2D-monolayers, 3D culture, and organoids. We discuss mechanisms of drug discovery and drug repurposing, and roles of membrane drug transporters in tissue maturation and hPDD using the example of drugs that target various mutations of CFTR, the cystic fibrosis transmembrane conductance regulator gene, in patients with cystic fibrosis.

Alpha6-Containing Nicotinic Acetylcholine Receptors Mediate Nicotine-Induced Structural Plasticity in Mouse and Human iPSC-Derived Dopaminergic Neurons

Midbrain dopamine (DA) neurons are considered a critical substrate for the reinforcing and sensitizing effects of nicotine and tobacco dependence. While the role of the α4 and β2 subunit containing nicotinic acetylcholine receptors (α4β2^∗nAChRs) in mediating nicotine effects on DA release and DA neuron activity has been widely explored, less information is available on their role in the morphological adaptation of the DA system to nicotine, eventually leading to dysfunctional behaviors observed in nicotine dependence. In particular, no information is available on the role of α6^∗nAChRs in nicotine-induced structural plasticity in rodents and no direct evidence exists regarding the occurrence of structural plasticity in human DA neurons exposed to nicotine. To approach this problem, we used two parallel in vitro systems, mouse primary DA neuron cultures from E12.5 embryos and human DA neurons differentiated from induced pluripotent stem cells (iPSCs) of healthy donors, identified using TH⁺ immunoreactivity. In both systems, nicotine 1–10 μM produced a dose-dependent increase of maximal dendrite length, number of primary dendrites, and soma size when measured after 3 days in culture. These effects were blocked by pretreatments with the α6^∗nAChR antagonists α-conotoxin MII and α-conotoxin PIA, as well as by the α4β2nAChR antagonist dihydro-β-erythroidine (DHβE) in both mouse and human DA neurons. Nicotine was also ineffective when the primary DA neurons were obtained from null mutant mice for either the α6 subunit or both the α4 and α6 subunits of nAChR. When pregnant mice were exposed to nicotine from gestational day 15, structural plasticity was also observed in the midbrain DA neurons of postnatal day 1 offspring only in wild-type mice and not in both null mutant mice. This study confirmed the critical role of α4α6^∗nAChRs in mediating nicotine-induced structural plasticity in both mouse and human DA neurons, supporting the translational relevance of neurons differentiated from human iPSCs for pharmacological studies.

Vascularized microfluidic organ-chips for drug screening, disease models and tissue engineering

Vascularization of micro-tissues in vitro has enabled formation of tissues larger than those limited by diffusion with appropriate nutrient/gas exchange as well as waste elimination. Furthermore, angiocrine signaling from the vasculature may be essential in mimicking organ-level functions in these micro-tissues. In drug screening applications, the presence of an appropriate blood-organ barrier in the form of a vasculature and its supporting cells (pericytes, appropriate stromal cells) may be essential to reproducing organ-scale drug delivery pharmacokinetics. Cutting-edge techniques including 3D bioprinting and in vitro angiogenesis and vasculogenesis could be applied to vascularize a range of tissues and organoids. Herein, we describe the latest developments in vascularization and prevascularization of micro-tissues and provide an outlook on potential future strategies.

Engineered 3D vascular and neuronal networks in a microfluidic platform

Neurovascular coupling plays a key role in the pathogenesis of neurodegenerative disorders including motor neuron disease (MND). In vitro models provide an opportunity to understand the pathogenesis of MND, and offer the potential for drug screening. Here, we describe a new 3D microvascular and neuronal network model in a microfluidic platform to investigate interactions between these two systems. Both 3D networks were established by co-culturing human embryonic stem (ES)-derived MN spheroids and endothelial cells (ECs) in microfluidic devices. Co-culture with ECs improves neurite elongation and neuronal connectivity as measured by Ca2+ oscillation. This improvement was regulated not only by paracrine signals such as brain-derived neurotrophic factor secreted by ECs but also through direct cell-cell interactions via the delta-notch pathway, promoting neuron differentiation and neuroprotection. Bi-directional signaling was observed in that the neural networks also affected vascular network formation under perfusion culture. This in vitro model could enable investigations of neuro-vascular coupling, essential to understanding the pathogenesis of neurodegenerative diseases including MNDs such as amyotrophic lateral sclerosis.

A New Cell Separation Method Based on Antibody-Immobilized Nanoneedle Arrays for the Detection of Intracellular Markers

Focusing on intracellular targets, we propose a new cell separation technique based on a nanoneedle array (NNA) device, which allows simultaneous insertion of multiple needles into multiple cells. The device is designed to target and lift ("fish") individual cells from a mixed population of cells on a substrate using an antibody-functionalized NNA. The mechanics underlying this approach were validated by force analysis using an atomic force microscope. Accurate high-throughput separation was achieved using one-to-one contacts between the nanoneedles and the cells by preparing a single-cell array in which the positions of the cells were aligned with 10,000 nanoneedles in the NNA. Cell-type-specific separation was realized by controlling the adhesion force so that the cells could be detached in cell-type-independent manner. Separation of nestin-expressing neural stem cells (NSCs) derived from human induced pluripotent stem cells (hiPSCs) was demonstrated using the proposed technology, and successful differentiation to neuronal cells was confirmed.

Three-Dimensional Hyaluronic Acid Hydrogel-Based Models for In Vitro Human iPSC-Derived NPC Culture and Differentiation

Human induced pluripotent stem cell-derived neural progenitor cells (hiPSC-NPCs) are considered as a promising cell source for transplantation and have been used for organoid fabrication to recapitulate central nervous system (CNS) diseases in vitro. The establishment of three-dimensional (3D) in vitro model with hiPSC-NPCs and control of their differentiation is significantly critical for understanding biological processes and CNS disease and regeneration. Here we implemented 3D methacrylated hyaluronic acid (Me-HA) hydrogels with encapsulation of hiPSC-NPCs as in vitro culture models and further investigated the role of the hydrogel rigidity on the cell behavior of hiPSC-NPCs. We first encapsulated single dispersive hiPSC-NPCs within both soft and stiff Me-HA hydrogel and found that hiPSC-NPCs gradually self-assembled and aggregated to form 3D spheroids. Then, the hiPSC-NPCs were laden into Me-HA hydrogels in the form of spheroids to evaluate their spontaneous differentiation in response to hydrogel rigidity. The soft Me-HA hydrogel-encapsulated hiPSC-NPCs displayed robust neurite outgrowth and showed high levels of spontaneous neural differentiation. We further encapsulated Down Syndrome (DS) patient-specific hiPSC-derived NPCs (DS-NPCs) spheroids within our hydrogels. DS-NPCs remained excellent cell viability in both soft and stiff Me-HA hydrogels. Similarly, soft hydrogels promoted neural differentiation of DS-NPCs by significantly upregulating neural maturation markers. This study demonstrates that soft matrix promotes neural differentiation of hiPSC-NPCs and HA-based hydrogels with hiPSC-NPCs or DS-NPCs are effective 3D models for CNS disease study.

Pluripotent stem cells and their utility in treating photoreceptor degenerations

Age-related macular degeneration and inherited retinal degenerations represent the leading causes of blindness in industrialized countries. Despite different initiating causes, they share a common final pathophysiology, the loss of the light sensitive photoreceptors. Replacement by transplantation may offer a potential treatment strategy for both patient populations. The last decade has seen remarkable progress in our ability to generate retinal cell types, including photoreceptors, from a variety of murine and human pluripotent stem cell sources. Driven in large part by the requirement for renewable cell sources, stem cells have emerged not only as a promising source of replacement photoreceptors but also to provide in vitro systems with which to study retinal development and disease processes and to test therapeutic agents.

Induced pluripotent stem cell technology: a decade of progress

Since the advent of induced pluripotent stem cell (iPSC) technology a decade ago, enormous progress has been made in stem cell biology and regenerative medicine. Human iPSCs have been widely used for disease modelling, drug discovery and cell therapy development. Novel pathological mechanisms have been elucidated, new drugs originating from iPSC screens are in the pipeline and the first clinical trial using human iPSC-derived products has been initiated. In particular, the combination of human iPSC technology with recent developments in gene editing and 3D organoids makes iPSC-based platforms even more powerful in each area of their application, including precision medicine. In this Review, we discuss the progress in applications of iPSC technology that are particularly relevant to drug discovery and regenerative medicine, and consider the remaining challenges and the emerging opportunities in the field.

Modeling susceptibility to drug-induced long QT with a panel of subject-specific induced pluripotent stem cells

A large number of drugs can induce prolongation of cardiac repolarization and life-threatening cardiac arrhythmias. The prediction of this side effect is however challenging as it usually develops in some genetically predisposed individuals with normal cardiac repolarization at baseline. Here, we describe a platform based on a genetically diverse panel of induced pluripotent stem cells (iPSCs) that reproduces susceptibility to develop a cardiotoxic drug response. We generated iPSC-derived cardiomyocytes from patients presenting in vivo with extremely low or high changes in cardiac repolarization in response to a pharmacological challenge with sotalol. In vitro, the responses to sotalol were highly variable but strongly correlated to the inter-individual differences observed in vivo. Transcriptomic profiling identified dysregulation of genes (DLG2, KCNE4, PTRF, HTR2C, CAMKV) involved in downstream regulation of cardiac repolarization machinery as underlying high sensitivity to sotalol. Our findings offer novel insights for the development of iPSC-based screening assays for testing individual drug reactions.

Human iPSC-derived cardiomyocytes and tissue engineering strategies for disease modeling and drug screening

Improved methodologies for modeling cardiac disease phenotypes and accurately screening the efficacy and toxicity of potential therapeutic compounds are actively being sought to advance drug development and improve disease modeling capabilities. To that end, much recent effort has been devoted to the development of novel engineered biomimetic cardiac tissue platforms that accurately recapitulate the structure and function of the human myocardium. Within the field of cardiac engineering, induced pluripotent stem cells (iPSCs) are an exciting tool that offer the potential to advance the current state of the art, as they are derived from somatic cells, enabling the development of personalized medical strategies and patient specific disease models. Here we review different aspects of iPSC-based cardiac engineering technologies. We highlight methods for producing iPSC-derived cardiomyocytes (iPSC-CMs) and discuss their application to compound efficacy/toxicity screening and in vitro modeling of prevalent cardiac diseases. Special attention is paid to the application of micro- and nano-engineering techniques for the development of novel iPSC-CM based platforms and their potential to advance current preclinical screening modalities.

Potential of Induced Pluripotent Stem Cells (iPSCs) for Treating Age-Related Macular Degeneration (AMD)

The field of stem cell biology has rapidly evolved in the last few decades. In the area of regenerative medicine, clinical applications using stem cells hold the potential to be a powerful tool in the treatment of a wide variety of diseases, in particular, disorders of the eye. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are promising technologies that can potentially provide an unlimited source of cells for cell replacement therapy in the treatment of retinal degenerative disorders such as age-related macular degeneration (AMD), Stargardt disease, and other disorders. ESCs and iPSCs have been used to generate retinal pigment epithelium (RPE) cells and their functional behavior has been tested in vitro and in vivo in animal models. Additionally, iPSC-derived RPE cells provide an autologous source of cells for therapeutic use, as well as allow for novel approaches in disease modeling and drug development platforms. Clinical trials are currently testing the safety and efficacy of these cells in patients with AMD. In this review, the current status of iPSC disease modeling of AMD is discussed, as well as the challenges and potential of this technology as a viable option for cell replacement therapy in retinal degeneration.

Genomic-based diagnosis of arrhythmia disease in a personalized medicine era

INTRODUCTION

Although thousands of potentially disease-causing mutations have been identified in a handful of genes, the genetic heterogeneity has led to diagnostic confusions, stemming directly from the limitations in our arsenal of genetic tools.

AREAS COVERED

We discuss the genetic basis of cardiac ion channelopathies, the gaps in our knowledge and how Next-generation sequencing technology (NGS) and can be used to bridge them, and how induced pluripotent stem cell (iPSC) derived-cardiomyocytes can be used for drug discovery.

EXPERT COMMENTARY

Univariate, arrhythmogenic arrhythmias can explain some congenital arrhythmias, however, it is far from a comprehensive understanding of the complexity of many arrhythmias. Mutational screening is a critical step in personalized medicine and is critical to the management of patients with arrhythmias. The success of personalized medicine requires a more efficient way to identify a high number of genetic variants potentially implicated in cardiac arrhythmogenic diseases than traditional sequencing methods (eg, Sanger sequencing). Next-generation sequencing technology provides us with unprecedented opportunities to achieve high-throughput, rapid, and cost-effective detection of congenital arrhythmias in patients. Moreover, in personalized medicine era, IPSC derived-cardiomyocytes can be used as 'cardiac arrhythmia in a dish' model for drug discovery, and help us improve management of arrhythmias in patients by developing patient-specific drug therapies with target specificity.

BMS-708163 and Nilotinib restore synaptic dysfunction in human embryonic stem cell-derived Alzheimer's disease models

Alzheimer’s disease (AD) is the most common form of dementia. Cellular AD models derived from human pluripotent stem cells are promising tools in AD research. We recently developed human embryonic stem cell-derived AD models which overexpress mutant Presenilin1 genes, and which exhibit AD phenotypes, including synaptic dysfunction. In this study, we found that our AD models showed reduced levels of RAB3A and SV2B proteins in the pre-synapses, which is a possible cause of electrophysiological abnormalities. Through the screening of chemical compounds using our AD models, we have identified Aβ peptide inhibitors which decrease the concentration of Aβ in culture supernatant. Among these, BMS-708163 and Nilotinib were found to improve the expression levels of RAB3A and SV2B proteins and to recover the electrophysiological function in our AD models. These results suggest that the AD models we developed are promising materials for the discovery of AD drugs that target the expression of pre-synaptic proteins and synaptic function.

Plasma-activated medium selectively eliminates undifferentiated human induced pluripotent stem cells

Human pluripotent stem cells, including human induced pluripotent stem cells (hiPSCs), are promising materials for regenerative medicine and cell transplantation therapy. However, tumorigenic potential of residual undifferentiated stem cells hampers their use in these therapies. Therefore, it is important to develop methods that selectively eliminate undifferentiated stem cells from a population of differentiated cells before their transplantation. In the present study, we investigated whether plasma-activated medium (PAM) selectively eliminated undifferentiated hiPSCs by inducing external oxidative stress. PAM was prepared by irradiating cell culture medium with non-thermal atmospheric pressure plasma. We observed that PAM selectively and efficiently killed undifferentiated hiPSCs cocultured with normal human dermal fibroblasts (NHDFs), which were used as differentiated cells. We also observed that undifferentiated hiPSCs were more sensitive to PAM than hiPSC-derived differentiated cells. Gene expression analysis suggested that lower expression of oxidative stress-related genes, including those encoding enzymes involved in hydrogen peroxide (H₂O₂) degradation, in undifferentiated hiPSCs was one of the mechanisms underlying PAM-induced selective cell death. PAM killed undifferentiated hiPSCs more efficiently than a medium containing the same concentration of H₂O₂ as that in PAM, suggesting that H₂O₂ and various reactive oxygen/nitrogen species in PAM selectively eliminated undifferentiated hiPSCs. Thus, our results indicate that PAM has a great potential to eliminate tumorigenic hiPSCs from a population of differentiated cells and that it may be a very useful tool in regenerative medicine and cell transplantation therapy.