Role of small molecules as drug candidates for reprogramming somatic cells into induced pluripotent stem cells: A comprehensive review

With the use of specific genetic factors and recent developments in cellular reprogramming, it is now possible to generate lineage-committed cells or induced pluripotent stem cells (iPSCs) from readily available and common somatic cell types. However, there are still significant doubts regarding the safety and effectiveness of the current genetic methods for reprogramming cells, as well as the conventional culture methods for maintaining stem cells. Small molecules that target specific epigenetic processes, signaling pathways, and other cellular processes can be used as a complementary approach to manipulate cell fate to achieve a desired objective. It has been discovered that a growing number of small molecules can support lineage differentiation, maintain stem cell self-renewal potential, and facilitate reprogramming by either increasing the efficiency of reprogramming or acting as a genetic reprogramming factor substitute. However, ongoing challenges include improving reprogramming efficiency, ensuring the safety of small molecules, and addressing issues with incomplete epigenetic resetting. Small molecule iPSCs have significant clinical applications in regenerative medicine and personalized therapies. This review emphasizes the versatility and potential safety benefits of small molecules in overcoming challenges associated with the iPSCs reprogramming process.

Human Stem Cells for Cardiac Disease Modeling and Preclinical and Clinical Applications—Are We on the Road to Success?

Cardiovascular diseases (CVDs) are pointed out by the World Health Organization (WHO) as the leading cause of death, contributing to a significant and growing global health and economic burden. Despite advancements in clinical approaches, there is a critical need for innovative cardiovascular treatments to improve patient outcomes. Therapies based on adult stem cells (ASCs) and embryonic stem cells (ESCs) have emerged as promising strategies to regenerate damaged cardiac tissue and restore cardiac function. Moreover, the generation of human induced pluripotent stem cells (iPSCs) from somatic cells has opened new avenues for disease modeling, drug discovery, and regenerative medicine applications, with fewer ethical concerns than those associated with ESCs. Herein, we provide a state-of-the-art review on the application of human pluripotent stem cells in CVD research and clinics. We describe the types and sources of stem cells that have been tested in preclinical and clinical trials for the treatment of CVDs as well as the applications of pluripotent stem-cell-derived in vitro systems to mimic disease phenotypes. How human stem-cell-based in vitro systems can overcome the limitations of current toxicological studies is also discussed. Finally, the current state of clinical trials involving stem-cell-based approaches to treat CVDs are presented, and the strengths and weaknesses are critically discussed to assess whether researchers and clinicians are getting closer to success.

Human Stem Cells for Cardiac Disease Modeling and Preclinical and Clinical Applications-Are We on the Road to Success?

Cardiovascular diseases (CVDs) are pointed out by the World Health Organization (WHO) as the leading cause of death, contributing to a significant and growing global health and economic burden. Despite advancements in clinical approaches, there is a critical need for innovative cardiovascular treatments to improve patient outcomes. Therapies based on adult stem cells (ASCs) and embryonic stem cells (ESCs) have emerged as promising strategies to regenerate damaged cardiac tissue and restore cardiac function. Moreover, the generation of human induced pluripotent stem cells (iPSCs) from somatic cells has opened new avenues for disease modeling, drug discovery, and regenerative medicine applications, with fewer ethical concerns than those associated with ESCs. Herein, we provide a state-of-the-art review on the application of human pluripotent stem cells in CVD research and clinics. We describe the types and sources of stem cells that have been tested in preclinical and clinical trials for the treatment of CVDs as well as the applications of pluripotent stem-cell-derived in vitro systems to mimic disease phenotypes. How human stem-cell-based in vitro systems can overcome the limitations of current toxicological studies is also discussed. Finally, the current state of clinical trials involving stem-cell-based approaches to treat CVDs are presented, and the strengths and weaknesses are critically discussed to assess whether researchers and clinicians are getting closer to success.

A Descriptive Whole-Genome Transcriptomics Study in a Stem Cell-Based Tool Predicts Multiple Tissue-Specific Beneficial Potential and Molecular Targets of Carnosic Acid

Carnosic acid (CA) is a phenolic diterpene widely distributed in herbal plants, rosemary and sage. Although its medicinal properties, such as antioxidant, antimicrobial, and neuroprotective effects, have been well-documented, its relevant biochemical processes and molecular targets have not been fully explored yet. In the present study, we conducted an untargeted whole-genome transcriptomics analysis to investigate CA-induced early biological and molecular events in human amniotic epithelial stem cells (hAESCs) with the aim of exploring its multiple tissue-specific functionalities and potential molecular targets. We found that seven days of CA treatment in hAESCs could induce mesoderm-lineage-specific differentiation. Tissue enrichment analysis revealed that CA significantly enriched lateral plate mesoderm-originated cardiovascular and adipose tissues. Further tissue-specific PPI analysis and kinase and transcription factor enrichment analyses identified potential upstream regulators and molecular targets of CA in a tissue-specific manner. Gene ontology enrichment analyses revealed the metabolic, antioxidant, and antifibrotic activities of CA. Altogether, our comprehensive whole-genome transcriptomics analyses offer a thorough understanding of the possible underlying molecular mechanism of CA.

Adventures and Advances in Time Travel With Induced Pluripotent Stem Cells and Automated Patch Clamp

In the Hollywood blockbuster “The Curious Case of Benjamin Button” a fantastical fable unfolds of a man’s life that travels through time reversing the aging process; as the tale progresses, the frail old man becomes a vigorous, vivacious young man, then man becomes boy and boy becomes baby. The reality of cellular time travel, however, is far more wondrous: we now have the ability to both reverse and then forward time on mature cells. Four proteins were found to rewind the molecular clock of adult cells back to their embryonic, “blank canvas” pluripotent stem cell state, allowing these pluripotent stem cells to then be differentiated to fast forward their molecular clocks to the desired adult specialist cell types. These four proteins – the “Yamanaka factors” – form critical elements of this cellular time travel, which deservedly won Shinya Yamanaka the Nobel Prize for his lab’s work discovering them. Human induced pluripotent stem cells (hiPSCs) hold much promise in our understanding of physiology and medicine. They encapsulate the signaling pathways of the desired cell types, such as cardiomyocytes or neurons, and thus act as model cells for defining the critical ion channel activity in healthy and disease states. Since hiPSCs can be derived from any patient, highly specific, personalized (or stratified) physiology, and/or pathophysiology can be defined, leading to exciting developments in personalized medicines and interventions. As such, hiPSC married with high throughput automated patch clamp (APC) ion channel recording platforms provide a foundation for significant physiological, medical and drug discovery advances. This review aims to summarize the current state of affairs of hiPSC and APC: the background and recent advances made; and the pros, cons and challenges of these technologies. Whilst the authors have yet to finalize a fully functional time traveling machine, they will endeavor to provide plausible future projections on where hiPSC and APC are likely to carry us. One future projection the authors are confident in making is the increasing necessity and adoption of these technologies in the discovery of the next blockbuster, this time a life-enhancing ion channel drug, not a fantastical movie.

Regulating Early Biological Events in Human Amniotic Epithelial Stem Cells Using Natural Bioactive Compounds: Extendable Multidirectional Research Avenues

Stem cells isolated from perinatal tissue sources possess tremendous potential for biomedical and clinical applications. On the other hand, emerging data have demonstrated that bioactive natural compounds regulate numerous cellular and biochemical functions in stem cells and promote cell migration, proliferation, and attachment, resulting in maintaining stem cell proliferation or inducing controlled differentiation. In our previous studies, we have reported for the first time that various natural compounds could induce targeted differentiation of hAESCs in a lineage-specific manner by modulating early biological and molecular events and enhance the therapeutic potential of hAESCs through modulating molecular signaling. In this perspective, we will discuss the advantages of using naturally occurring active compounds in hAESCs and their potential implications for biological research and clinical applications.

Label-Free Imaging to Track Reprogramming of Human Somatic Cells

The process of reprogramming patient samples to human-induced pluripotent stem cells (iPSCs) is stochastic, asynchronous, and inefficient, leading to a heterogeneous population of cells. In this study, we track the reprogramming status of patient-derived erythroid progenitor cells (EPCs) at the single-cell level during reprogramming with label-free live-cell imaging of cellular metabolism and nuclear morphometry to identify high-quality iPSCs. EPCs isolated from human peripheral blood of three donors were used for our proof-of-principle study. We found distinct patterns of autofluorescence lifetime for the reduced form of nicotinamide adenine dinucleotide (phosphate) and flavin adenine dinucleotide during reprogramming. Random forest models classified iPSCs with ∼95% accuracy, which enabled the successful isolation of iPSC lines from reprogramming cultures. Reprogramming trajectories resolved at the single-cell level indicated significant reprogramming heterogeneity along different branches of cell states. This combination of micropatterning, autofluorescence imaging, and machine learning provides a unique, real-time, and nondestructive method to assess the quality of iPSCs in a biomanufacturing process, which could have downstream impacts in regenerative medicine, cell/gene therapy, and disease modeling.

A large scale mass spectrometry-based histone screening for assessing epigenetic developmental toxicity

Toxicoepigenetics is an emerging field that studies the toxicological impact of compounds on protein expression through heritable, non-genetic mechanisms, such as histone post-translational modifications (hPTMs). Due to substantial progress in the large-scale study of hPTMs, integration into the field of toxicology is promising and offers the opportunity to gain novel insights into toxicological phenomena. Moreover, there is a growing demand for high-throughput human-based in vitro assays for toxicity testing, especially for developmental toxicity. Consequently, we developed a mass spectrometry-based proof-of-concept to assess a histone code screening assay capable of simultaneously detecting multiple hPTM-changes in human embryonic stem cells. We first validated the untargeted workflow with valproic acid (VPA), a histone deacetylase inhibitor. These results demonstrate the capability of mapping the hPTM-dynamics, with a general increase in acetylations as an internal control. To illustrate the scalability, a dose–response study was performed on a proof-of-concept library of ten compounds (1) with a known effect on the hPTMs (BIX-01294, 3-Deazaneplanocin A, Trichostatin A, and VPA), (2) classified as highly embryotoxic by the European Centre for the Validation of Alternative Methods (ECVAM) (Methotrexate, and All-trans retinoic acid), (3) classified as non-embryotoxic by ECVAM (Penicillin G), and (4) compounds of abuse with a presumed developmental toxicity (ethanol, caffeine, and nicotine).

DNA Microarray-Based Global Gene Expression Profiling in Human Amniotic Epithelial Cells Predicts the Potential of Microalgae-Derived Squalene for the Nervous System and Metabolic Health

In recent years, perinatal stem cells, such as human amniotic epithelial cells (hAECs), have attracted increasing interest as a novel tool of stem cell-based high-throughput drug screening. In the present study, we investigated the bioactivities of squalene (SQ) derived from ethanol extract (99.5%) of a microalgae Aurantiochytrium Sp. (EEA-SQ) in hAECs using whole-genome DNA microarray analysis. Tissue enrichment analysis showed that the brain was the most significantly enriched tissue by the differentially expressed genes (DEGs) between EEA-SQ-treated and control hAECs. Further gene set enrichment analysis and tissue-specific functional analysis revealed biological functions related to nervous system development, neurogenesis, and neurotransmitter modulation. Several adipose tissue-specific genes and functions were also enriched. Gene-disease association analysis showed nervous system-, metabolic-, and immune-related diseases were enriched. Altogether, our study suggests the potential health benefits of microalgae-derived SQ and we would further encourage investigation in EEA-SQ and its derivatives as potential therapeutics for nervous system- and metabolism-related diseases.

The mutational impact of culturing human pluripotent and adult stem cells

Genetic changes acquired during in vitro culture pose a risk for the successful application of stem cells in regenerative medicine. To assess the genetic risks induced by culturing, we determined all mutations in individual human stem cells by whole genome sequencing. Individual pluripotent, intestinal, and liver stem cells accumulate 3.5 ± 0.5, 7.2 ± 1.1 and 8.3 ± 3.6 base substitutions per population doubling, respectively. The annual in vitro mutation accumulation rate of adult stem cells is nearly 40-fold higher than the in vivo mutation accumulation rate. Mutational signature analysis reveals that in vitro induced mutations are caused by oxidative stress. Reducing oxygen tension in culture lowers the mutational load. We use the mutation rates, spectra, and genomic distribution to model the accumulation of oncogenic mutations during typical in vitro expansion, manipulation or screening experiments using human stem cells. Our study provides empirically defined parameters to assess the mutational risk of stem cell based therapies.

Genetic changes acquired during in vitro culture pose a challenge to application of stem cells. Here the authors use whole genome sequencing to show that cultured human adult and pluripotent stem cells have a high mutational load caused by oxidative stress and reduced oxygen tension in culture lowers mutation rates.

Human-induced pluripotent stems cells as a model to dissect the selective neurotoxicity of methylmercury

Methylmercury (MeHg) is a potent neurotoxicant affecting both the developing and mature central nervous system (CNS) with apparent indiscriminate disruption of multiple homeostatic pathways. However, genetic and environmental modifiers contribute significant variability to neurotoxicity associated with human exposures. MeHg displays developmental stage and neural lineage selective neurotoxicity. To identify mechanistic-based neuroprotective strategies to mitigate human MeHg exposure risk, it will be critical to improve our understanding of the basis of MeHg neurotoxicity and of this selective neurotoxicity. Here, we propose that human-based pluripotent stem cell cellular approaches may enable mechanistic insight into genetic pathways that modify sensitivity of specific neural lineages to MeHg-induced neurotoxicity. Such studies are crucial for the development of novel disease modifying strategies impinging on MeHg exposure vulnerability.

Neuroprotective efficacy of thymoquinone against amyloid beta-induced neurotoxicity in human induced pluripotent stem cell-derived cholinergic neurons

The natural antioxidant Thymoquinone (TQ) is the most abundant ingredient in the curative plant Nigella sativa seed's oil. An extensive number of studies have revealed that TQ is the most active and most responsible component for the plant's pharmacological properties. It has been documented in several studies that TQ has a wide range of protective activities and many neuropharmacological attributes. Amyloid beta (Aβ) is the major role player peptide in the progression of Alzheimer's disease (AD). Our current study has been implemented to explore the protective possibilities of TQ on Aβ_1–42 -induced neurotoxicity. To test TQ's effect we used cultured human induced pluripotent stem cell (hiPSC)-derived cholinergic neurons. The obtained results showed that Aβ_1–42 caused cell death and apoptosis, which was efficiently attenuated by the co-treatment of TQ. Moreover, TQ restored the decrease in the intracellular antioxidant enzyme glutathione levels and inhibited the generation of reactive oxygen species induced by Aβ_1–42. Furthermore, using the fluorescent dye FM1–43 we demonstrated that TQ was able to reduce synaptic toxicity caused by Aβ_1–42. Thus, the findings of our study suggest that TQ holds a neuroprotective potential and could be a promising therapeutic agent to reduce the risk of developing AD and other disorders of the central nervous system.

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TQ protected hiPSC-derived cholinergic neurons against Aβ_1–42 induced apoptosis.

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TQ restored reduced Glutathione level in hiPSC-derived cholinergic neurons.

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TQ protected hiPSC-derived cholinergic neurons against ROS generation induced by Aβ_1–42.

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TQ attenuated Aβ_1–42 – induced synaptic toxicity.

Bacterial Cellulose Promotes Long-Term Stemness of mESC

Stem cells possess unique properties, such as the ability to self-renew and the potential to differentiate into an organism's various cell types. These make them highly valuable in regenerative medicine and tissue engineering. Their properties are precisely regulated in vivo through complex mechanisms that include multiple cues arising from the cell interaction with the surrounding extracellular matrix, neighboring cells, and soluble factors. Although much research effort has focused on developing systems and materials that mimic this complex microenvironment, the controlled regulation of differentiation and maintenance of stemness in vitro remains elusive. In this work, we demonstrate, for the first time, that the nanofibrous bacterial cellulose (BC) membrane derived from Komagataeibacter xylinus can inhibit the differentiation of mouse embryonic stem cells (mESC) under long-term conditions (17 days), improving their mouse embryonic fibroblast (MEF)-free cultivation in comparison to the MEF-supported conventional culture. The maintained cells' pluripotency was confirmed by the mESCs' ability to differentiate into the three germ layers (endo-, meso-, and ectoderm) after having been cultured on the BC membrane for 6 days. In addition, the culturing of mESCs on flexible, free-standing BC membranes enables the quick and facile manipulation and transfer of stem cells between culture dishes, both of which significantly facilitate the use of stem cells in routine culture and various applications. To investigate the influence of the structural and topographical properties of the cellulose on stem cell differentiation, we used the cellulose membranes differing in membrane thickness, porosity, and surface roughness. This work identifies bacterial cellulose as a novel convenient and flexible membrane material enabling long-term maintenance of mESCs' stemness and significantly facilitating the handling and culturing of stem cells.

Droplet Microarray Based on Patterned Superhydrophobic Surfaces Prevents Stem Cell Differentiation and Enables High-Throughput Stem Cell Screening

Over the past decades, stem cells have attracted growing interest in fundamental biological and biomedical research as well as in regenerative medicine, due to their unique ability to self-renew and differentiate into various cell types. Long-term maintenance of the self-renewal ability and inhibition of spontaneous differentiation, however, still remain challenging and are not fully understood. Uncontrolled spontaneous differentiation of stem cells makes high-throughput screening of stem cells also difficult. This further hinders investigation of the underlying mechanisms of stem cell differentiation and the factors that might affect it. In this work, a dual functionality of nanoporous superhydrophobic-hydrophilic micropatterns is demonstrated in their ability to inhibit differentiation of mouse embryonic stem cells (mESCs) and at the same time enable formation of arrays of microdroplets (droplet microarray) via the effect of discontinuous dewetting. Such combination makes high-throughput screening of undifferentiated mouse embryonic stem cells possible. The droplet microarray is used to investigate the development, differentiation, and maintenance of stemness of mESC, revealing the dependence of stem cell behavior on droplet volume in nano- and microliter scale. The inhibition of spontaneous differentiation of mESCs cultured on the droplet microarray for up to 72 h is observed. In addition, up to fourfold increased cell growth rate of mESCs cultured on our platform has been observed. The difference in the behavior of mESCs is attributed to the porosity and roughness of the polymer surface. This work demonstrates that the droplet microarray possesses the potential for the screening of mESCs under conditions of prolonged inhibition of stem cells' spontaneous differentiation. Such a platform can be useful for applications in the field of stem cell research, pharmacological testing of drug efficacy and toxicity, biomedical research as well as in the field of regenerative medicine and tissue engineering.

Cell-based therapeutic strategies for replacement and preservation in retinal degenerative diseases

Cell-based therapeutics offer diverse options for treating retinal degenerative diseases, such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). AMD is characterized by both genetic and environmental risks factors, whereas RP is mainly a monogenic disorder. Though treatments exist for some patients with neovascular AMD, a majority of retinal degenerative patients have no effective therapeutics, thus indicating a need for universal therapies to target diverse patient populations. Two main cell-based mechanistic approaches are being tested in clinical trials. Replacement therapies utilize cell-derived retinal pigment epithelial (RPE) cells to supplant lost or defective host RPE cells. These cells are similar in morphology and function to native RPE cells and can potentially supplant the responsibilities of RPE in vivo. Preservation therapies utilize supportive cells to aid in visual function and photoreceptor preservation partially by neurotrophic mechanisms. The goal of preservation strategies is to halt or slow the progression of disease and maintain remaining visual function. A number of clinical trials are testing the safety of replacement and preservation cell therapies in patients; however, measures of efficacy will need to be further evaluated. In addition, a number of prevailing concerns with regards to the immune-related response, longevity, and functionality of the grafted cells will need to be addressed in future trials. This review will summarize the current status of cell-based preclinical and clinical studies with a focus on replacement and preservation strategies and the obstacles that remain regarding these types of treatments.

Three-Dimensional Human Cardiac Tissue Engineered by Centrifugation of Stacked Cell Sheets and Cross-Sectional Observation of Its Synchronous Beatings by Optical Coherence Tomography

Three-dimensional (3D) tissues are engineered by stacking cell sheets, and these tissues have been applied in clinical regenerative therapies. The optimal fabrication technique of 3D human tissues and the real-time observation system for these tissues are important in tissue engineering, regenerative medicine, cardiac physiology, and the safety testing of candidate chemicals. In this study, for aiming the clinical application, 3D human cardiac tissues were rapidly fabricated by human induced pluripotent stem (iPS) cell-derived cardiac cell sheets with centrifugation, and the structures and beatings in the cardiac tissues were observed cross-sectionally and noninvasively by two optical coherence tomography (OCT) systems. The fabrication time was reduced to approximately one-quarter by centrifugation. The cross-sectional observation showed that multilayered cardiac cell sheets adhered tightly just after centrifugation. Additionally, the cross-sectional transmissions of beatings within multilayered human cardiac tissues were clearly detected by OCT. The observation showed the synchronous beatings of the thicker 3D human cardiac tissues, which were fabricated rapidly by cell sheet technology and centrifugation. The rapid tissue-fabrication technique and OCT technology will show a powerful potential in cardiac tissue engineering, regenerative medicine, and drug discovery research.

Increasing The Genetic Admixture of Available Lines of Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) may significantly improve drug development pipeline, serving as an in vitro system for the identification of novel leads, and for testing drug toxicity. Furthermore, these cells may be used to address the issue of differential drug response, a phenomenon greatly influenced by genetic factors. This application depends on the availability of hPSC lines from populations with diverse ancestries. So far, it has been reported that most lines of hPSCs derived worldwide are of European or East Asian ancestries. We have established 23 lines of hPSCs from Brazilian individuals, and we report the analysis of their genomic ancestry. We show that embryo-derived PSCs are mostly of European descent, while induced PSCs derived from participants of a national-wide Brazilian cohort study present high levels of admixed European, African and Native American genomic ancestry. Additionally, we use high density SNP data and estimate local ancestries, particularly those of CYP genes loci. Such information will be of key importance when interpreting variation among cell lines with respect to cellular phenotypes of interest. The availability of genetically admixed lines of hPSCs will be of relevance when setting up future in vitro studies of drug response.

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.

Substrate stiffness orchestrates epithelial cellular heterogeneity with controlled proliferative pattern via E-cadherin/β-catenin mechanotransduction

Epithelial cellular heterogeneity has been observed in pathological tissues with abnormal matrix stiffness and cells cultured on rigid substrates. However, it remains unclear how matrix stiffness influences cellular heterogeneity formation in multi-cellular population. Here, we demonstrated that cellular heterogeneity regulated by substrate stiffness is evident starting from the initial single-cell stage (indicated by cellular Young's modulus and morphology) until the resulting multi-cellular stage (indicated by cellular functions) through distinguished proliferative patterns. Epithelial cells on soft substrate proliferated in a neighbor-dependent manner with stronger E-cadherin expression and more homogeneous E-cadherin/β-catenin localization compared to those on coverslips, which resulted in reduced heterogeneity in downstream cellular functions of the multi-cellular population. In particular, decreased heterogeneity in human embryonic stem cells upon expansion and endodermal induction was achieved on soft substrate. Overall, our work provides new insights on mechanotransduction during epithelial proliferation which regulates the formation of cellular heterogeneity and potentially provides a highly efficient approach to regulate stem cell fate by fine-tuning substrate stiffness.

STATEMENT OF SIGNIFICANCE

This study demonstrates that cellular heterogeneity regulated by substrate stiffness is evident starting from the initial single-cell stage until the resulting multi-cellular stage through distinguished proliferative patterns. During this process, E-cadherin/β-catenin mechanotransduction is found to play important role in substrate stiffness-regulated epithelial cellular heterogeneity formation. In particular, decreased heterogeneity in human embryonic stem cells upon expansion and endodermal induction is achieved on soft substrate. Hence, we believe that this work not only provides new insights on mechanotransduction of E-cadherin/β-catenin which regulates the formation of cellular heterogeneity during proliferation, but also potentially provides a highly efficient approach to regulate stem cell fate by fine-tuning substrate stiffness.

Transcriptome Profiling of Patient-Specific Human iPSC-Cardiomyocytes Predicts Individual Drug Safety and Efficacy Responses In Vitro

Understanding individual susceptibility to drug-induced cardiotoxicity is key to improving patient safety and preventing drug attrition. Human induced pluripotent stem cells (hiPSCs) enable the study of pharmacological and toxicological responses in patient-specific cardiomyocytes (CMs) and may serve as preclinical platforms for precision medicine. Transcriptome profiling in hiPSC-CMs from seven individuals lacking known cardiovascular disease-associated mutations and in three isogenic human heart tissue and hiPSC-CM pairs showed greater inter-patient variation than intra-patient variation, verifying that reprogramming and differentiation preserve patient-specific gene expression, particularly in metabolic and stress-response genes. Transcriptome-based toxicology analysis predicted and risk-stratified patient-specific susceptibility to cardiotoxicity, and functional assays in hiPSC-CMs using tacrolimus and rosiglitazone, drugs targeting pathways predicted to produce cardiotoxicity, validated inter-patient differential responses. CRISPR/Cas9-mediated pathway correction prevented drug-induced cardiotoxicity. Our data suggest that hiPSC-CMs can be used in vitro to predict and validate patient-specific drug safety and efficacy, potentially enabling future clinical approaches to precision medicine.

Full biological characterization of human pluripotent stem cells will open the door to translational research

Since the discovery of human embryonic stem cells (hESC) and human-induced pluripotent stem cells (hiPSC), great hopes were held for their therapeutic application including disease modeling, drug discovery screenings, toxicological screenings and regenerative therapy. hESC and hiPSC have the advantage of indefinite self-renewal, thereby generating an inexhaustible pool of cells with, e.g., specific genotype for developing putative treatments; they can differentiate into derivatives of all three germ layers enabling autologous transplantation, and via donor-selection they can express various genotypes of interest for better disease modeling. Furthermore, drug screenings and toxicological screenings in hESC and hiPSC are more pertinent to identify drugs or chemical compounds that are harmful for human, than a mouse model could predict. Despite continuing research in the wide field of therapeutic applications, further understanding of the underlying basic mechanisms of stem cell function is necessary. Here, we summarize current knowledge concerning pluripotency, self-renewal, apoptosis, motility, epithelial-to-mesenchymal transition and differentiation of pluripotent stem cells.

iPS Cells-The Triumphs and Tribulations

The year 2006 will be remembered monumentally in science, particularly in the stem cell biology field, for the first instance of generation of induced pluripotent stem cells (iPSCs) from mouse embryonic/adult fibroblasts being reported by Takahashi and Yamanaka. A year later, human iPSCs (hiPSCs) were generated from adult human skin fibroblasts by using quartet of genes, Oct4, Sox2, Klf4, and c-Myc. This revolutionary technology won Yamanaka Nobel Prize in Physiology and Medicine in 2012. Like human embryonic stem cells (hESCs), iPSCs are pluripotent and have the capability for self-renewal. Moreover, complications of immune rejection for therapeutic applications would be greatly eliminated by generating iPSCs from individual patients. This has enabled their use for drug screening/discovery and disease modelling in vitro; and for immunotherapy and regenerative cellular therapies in vivo, paving paths for new therapeutics. Although this breakthrough technology has a huge potential, generation of these unusual cells is still slow, ineffectual, fraught with pitfalls, and unsafe for human use. In this review, I describe how iPSCs are being triumphantly used to lay foundation for a fully functional discipline of regenerative dentistry and medicine, alongside discussing the challenges of translating therapies into clinics. I also discuss their future implications in regenerative dentistry field.

Dissecting microRNA-mediated regulation of stemness, reprogramming, and pluripotency

Increasing evidence indicates that microRNAs (miRNAs), endogenous short non-coding RNAs 19–24 nucleotides in length, play key regulatory roles in various biological events at the post-transcriptional level. Embryonic stem cells (ESCs) represent a valuable tool for disease modeling, drug discovery, developmental studies, and potential cell-based therapies in regenerative medicine due to their unlimited self-renewal and pluripotency. Therefore, remarkable progress has been made in recent decades toward understanding the expression and functions of specific miRNAs in the establishment and maintenance of pluripotency. Here, we summarize the recent knowledge regarding the regulatory roles of miRNAs in self-renewal of pluripotent ESCs and during cellular reprogramming, as well as the potential role of miRNAs in two distinct pluripotent states (naïve and primed).

Toxicity testing and drug screening using iPSC-derived hepatocytes, cardiomyocytes, and neural cells

Unexpected toxicity in areas such as cardiotoxicity, hepatotoxicity, and neurotoxicity is a serious complication of clinical therapy and one of the key causes for failure of promising drug candidates in development. Animal studies have been widely used for toxicology research to provide preclinical security evaluation of various therapeutic agents under development. Species differences in drug penetration of the blood-brain barrier, drug metabolism, and related toxicity contribute to failure of drug trials from animal models to human. The existing system for drug discovery has relied on immortalized cell lines, animal models of human disease, and clinical trials in humans. Moreover, drug candidates that are passed as being safe in the preclinical stage often show toxic effects during the clinical stage. Only around 16% drugs are approved for human use. Research on induced pluripotent stem cells (iPSCs) promises to enhance drug discovery and development by providing simple, reproducible, and economically effective tools for drug toxicity screening under development and, on the other hand, for studying the disease mechanism and pathways. In this review, we provide an overview of basic information about iPSCs, and discuss efforts aimed at the use of iPSC-derived hepatocytes, cardiomyocytes, and neural cells in drug discovery and toxicity testing.

Cryopreservation of Human Pluripotent Stem Cell-Derived Cardiomyocytes: Strategies, Challenges, and Future Directions

In recent years, human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have emerged as a vital cell source for in vitro modeling of genetic cardiovascular disorders, drug screening, and in vivo cardiac regeneration research. Looking forward, the ability to efficiently cryopreserve hPSC-CMs without compromising their normal biochemical and physiologic functions will dramatically facilitate their various biomedical applications. Although working protocols for freezing, storing, and thawing hPSC-CMs have been established, the question remains as to whether they are optimal. In this chapter, we discuss our current understanding of cryopreservation appertaining to hPSC-CMs, and proffer key questions regarding the mechanical, contractile, and regenerative properties of cryopreserved hPSC-CMs.

Electrophysiological analysis of mammalian cells expressing hERG using automated 384-well-patch-clamp

BACKGROUND

An in vitro electrophysiological assay system, which can assess compound effects and thus show cardiotoxicity including arrhythmia risks of test drugs, is an essential method in the field of drug development and toxicology.

METHODS

In this study, high-throughput electrophysiological recordings of human embryonic kidney (HEK 293) cells and Chinese hamster ovary (CHO) cells stably expressing human ether-a-go-go related gene (hERG) were performed utilizing an automated 384-well-patch-clamp system, which records up to 384 cells simultaneously. hERG channel inhibition, which is closely related to a drug-induced QT prolongation and is increasing the risk of sudden cardiac death, was investigated in the high-throughput screening patch-clamp system.

RESULTS

In the automated patch-clamp measurements performed here, Kv currents were investigated with high efficiency. Various hERG channel blockers showed concentration-dependent inhibition, the 50 % inhibitory concentrations (IC50) of those blockers were in good agreement with previous reports.

CONCLUSIONS

The high-throughput patch-clamp system has a high potential in the field of pharmacology, toxicology, and cardiac physiology, and will contribute to the acceleration of pharmaceutical drug development and drug safety testing.

The modeling of Alzheimer's disease by the overexpression of mutant Presenilin 1 in human embryonic stem cells

Cellular disease models are useful tools for Alzheimer's disease (AD) research. Pluripotent stem cells, including human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), are promising materials for creating cellular models of such diseases. In the present study, we established cellular models of AD in hESCs that overexpressed the mutant Presenilin 1 (PS1) gene with the use of a site-specific gene integration system. The overexpression of PS1 did not affect the undifferentiated status or the neural differentiation ability of the hESCs. We found increases in the ratios of amyloid-β 42 (Aβ42)/Aβ40 and Aβ43/Aβ40. Furthermore, synaptic dysfunction was observed in a cellular model of AD that overexpressed mutant PS1. These results suggest that the AD phenotypes, in particular, the electrophysiological abnormality of the synapses in our AD models might be useful for AD research and drug discovery.

Neural Differentiation of Human Pluripotent Stem Cells for Nontherapeutic Applications: Toxicology, Pharmacology, and In Vitro Disease Modeling

Human pluripotent stem cells (hPSCs) derived from either blastocyst stage embryos (hESCs) or reprogrammed somatic cells (iPSCs) can provide an abundant source of human neuronal lineages that were previously sourced from human cadavers, abortuses, and discarded surgical waste. In addition to the well-known potential therapeutic application of these cells in regenerative medicine, these are also various promising nontherapeutic applications in toxicological and pharmacological screening of neuroactive compounds, as well as for in vitro modeling of neurodegenerative and neurodevelopmental disorders. Compared to alternative research models based on laboratory animals and immortalized cancer-derived human neural cell lines, neuronal cells differentiated from hPSCs possess the advantages of species specificity together with genetic and physiological normality, which could more closely recapitulate in vivo conditions within the human central nervous system. This review critically examines the various potential nontherapeutic applications of hPSC-derived neuronal lineages and gives a brief overview of differentiation protocols utilized to generate these cells from hESCs and iPSCs.

A platform for rapid generation of single and multiplexed reporters in human iPSC lines

Induced pluripotent stem cells (iPSC) are important tools for drug discovery assays and toxicology screens. In this manuscript, we design high efficiency TALEN and ZFN to target two safe harbor sites on chromosome 13 and 19 in a widely available and well-characterized integration-free iPSC line. We show that these sites can be targeted in multiple iPSC lines to generate reporter systems while retaining pluripotent characteristics. We extend this concept to making lineage reporters using a C-terminal targeting strategy to endogenous genes that express in a lineage-specific fashion. Furthermore, we demonstrate that we can develop a master cell line strategy and then use a Cre-recombinase induced cassette exchange strategy to rapidly exchange reporter cassettes to develop new reporter lines in the same isogenic background at high efficiency. Equally important we show that this recombination strategy allows targeting at progenitor cell stages, further increasing the utility of the platform system. The results in concert provide a novel platform for rapidly developing custom single or dual reporter systems for screening assays.

Probit analysis of comparative assays on toxicities of lead chloride and lead acetate to in vitro cultured human umbilical cord blood lymphocytes

This work describes that cytotoxicity of lead chloride and lead acetate to in vitro cultured lymphocytes from human umbilical cord blood, using four monitoring methods namely, trypan blue staining, acridine orange/ethidium bromide staining, 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyl tetrazolium bromide (MTT) and neutral red uptake assays; lead genotoxicity to lymphocytes was monitored by comet assay. The MIC value in each method was invariably 300 mg/L for PbCl₂. Lethal concentration₂₅ (LC₂₅) values were almost in an agreeable range: 691.83 to 831.76 mg/L; LC₅₀ values in each method were almost in the range: 1174.9 to 1348.9 mg/L; LC₁₀₀ values were in the range: 3000 to 3300 mg/L, for lead chloride. Similarly, The MIC value in each method were invariably 150 mg/L; LC₂₅ values were almost in the range: 295.12 to 371.53 mg/L; LC₅₀ values were in the range: 501.18 to 588.84 mg/L; LC₁₀₀ value was 1500 mg/L in all assays, for lead acetate. The comet assay also indicated that the LC₁₀₀ values were 3300 mg/L lead chloride and 1500 mg/L lead acetate. Thus, both cytotoxicity and genotoxicity were recorded at 3300 mg/L lead chloride and 1500 mg/L lead acetate with lymphocytes.

Induced pluripotent stem cells: applications in regenerative medicine, disease modeling, and drug discovery

Recent progresses in the field of Induced Pluripotent Stem Cells (iPSCs) have opened up many gateways for the research in therapeutics. iPSCs are the cells which are reprogrammed from somatic cells using different transcription factors. iPSCs possess unique properties of self renewal and differentiation to many types of cell lineage. Hence could replace the use of embryonic stem cells (ESC), and may overcome the various ethical issues regarding the use of embryos in research and clinics. Overwhelming responses prompted worldwide by a large number of researchers about the use of iPSCs evoked a large number of peple to establish more authentic methods for iPSC generation. This would require understanding the underlying mechanism in a detailed manner. There have been a large number of reports showing potential role of different molecules as putative regulators of iPSC generating methods. The molecular mechanisms that play role in reprogramming to generate iPSCs from different types of somatic cell sources involves a plethora of molecules including miRNAs, DNA modifying agents (viz. DNA methyl transferases), NANOG, etc. While promising a number of important roles in various clinical/research studies, iPSCs could also be of great use in studying molecular mechanism of many diseases. There are various diseases that have been modeled by uing iPSCs for better understanding of their etiology which maybe further utilized for developing putative treatments for these diseases. In addition, iPSCs are used for the production of patient-specific cells which can be transplanted to the site of injury or the site of tissue degeneration due to various disease conditions. The use of iPSCs may eliminate the chances of immune rejection as patient specific cells may be used for transplantation in various engraftment processes. Moreover, iPSC technology has been employed in various diseases for disease modeling and gene therapy. The technique offers benefits over other similar techniques such as animal models. Many toxic compounds (different chemical compounds, pharmaceutical drugs, other hazardous chemicals, or environmental conditions) which are encountered by humans and newly designed drugs may be evaluated for toxicity and effects by using iPSCs. Thus, the applications of iPSCs in regenerative medicine, disease modeling, and drug discovery are enormous and should be explored in a more comprehensive manner.

Concise review: modeling central nervous system diseases using induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) offer an opportunity to delve into the mechanisms underlying development while also affording the potential to take advantage of a number of naturally occurring mutations that contribute to either disease susceptibility or resistance. Just as with any new field, several models of screening are being explored, and innovators are working on the most efficient methods to overcome the inherent limitations of primary cell screens using iPSCs. In the present review, we provide a background regarding why iPSCs represent a paradigm shift for central nervous system (CNS) disease modeling. We describe the efforts in the field to develop more biologically relevant CNS disease models, which should provide screening assays useful for the pharmaceutical industry. We also provide some examples of successful uses for iPSC-based screens and suggest that additional development could revolutionize the field of drug discovery. The development and implementation of these advanced iPSC-based screens will create a more efficient disease-specific process underpinned by the biological mechanism in a patient- and disease-specific manner rather than by trial-and-error. Moreover, with careful and strategic planning, shared resources can be developed that will enable exponential advances in the field. This will undoubtedly lead to more sensitive and accurate screens for early diagnosis and allow the identification of patient-specific therapies, thus, paving the way to personalized medicine.

Biotechnological challenges of bioartificial kidney engineering

With the world-wide increase of patients with renal failure, the development of functional renal replacement therapies have gained significant interest and novel technologies are rapidly evolving. Currently used renal replacement therapies insufficiently remove accumulating waste products, resulting in the uremic syndrome. A more preferred treatment option is kidney transplantation, but the shortage of donor organs and the increasing number of patients waiting for a transplant warrant the development of novel technologies. The bioartificial kidney (BAK) is such promising biotechnological approach to replace essential renal functions together with the active secretion of waste products. The development of the BAK requires a multidisciplinary approach and evolves at the intersection of regenerative medicine and renal replacement therapy. Here we provide a concise review embracing a compact historical overview of bioartificial kidney development and highlighting the current state-of-the-art, including implementation of living-membranes and the relevance of extracellular matrices. We focus further on the choice of relevant renal epithelial cell lines versus the use of stem cells and co-cultures that need to be implemented in a suitable device. Moreover, the future of the BAK in regenerative nephrology is discussed.

Inducing pluripotency for disease modeling, drug development and craniofacial applications

INTRODUCTION

The induced pluripotent stem cells (iPSCs) have characteristics similar to embryonic stem cells, including the capability of self-renewal and large-scale expansion and the ability to differentiate into all types of cells including germ cells, which defines pluripotency. Using iPSC avoids problems of immunological rejection and ethical controversy. The possible future uses of iPSC are diverse and go beyond the differentiation into somatic cells for regeneration of damaged tissues.

AREAS COVERED

A unique feature of iPSC is the potential to generate patient disease-specific tissues. Thus, cells from patients can be differentiated into relevant cells of interest for drug screening, characterization of drug effects and cytotoxic assays. This review presents key aspects related to iPSC, such as their generation, potential for disease modeling, treatment, drug development and future contributions to the craniofacial complex.

EXPERT OPINION

It is undisputable that the evolution in iPSC knowledge will improve the approaches for drug screening and development, help to understand and treat disease origins and mechanisms and provide new strategies to clinical treatment. However, it is necessary to fine-tune protocols to establish iPSCs that are cost-effective and safe for clinical use.

Three dimensional cellular microarray platform for human neural stem cell differentiation and toxicology

We developed a three-dimensional (3D) cellular microarray platform for the high-throughput (HT) analysis of human neural stem cell (hNSC) growth and differentiation. The growth of an immortalized hNSC line, ReNcell VM, was evaluated on a miniaturized cell culture chip consisting of 60nl spots of cells encapsulated in alginate, and compared to standard 2D well plate culture conditions. Using a live/dead cell viability assay, we demonstrated that the hNSCs are able to expand on-chip, albeit with lower proliferation rates and viabilities than in conventional 2D culture platforms. Using an in-cell, on-chip immunofluorescence assay, which provides quantitative information on cellular levels of proteins involved in neural fate, we demonstrated that ReNcell VM can preserve its multipotent state during on-chip expansion. Moreover, differentiation of the hNSCs into glial progeny was achieved both off- and on-chip six days after growth factor removal, accompanied by a decrease in the neural progenitor markers. The versatility of the platform was further demonstrated by complementing the cell culture chip with a chamber system that allowed us to screen for differential toxicity of small molecules to hNSCs. Using this approach, we showed differential toxicity when evaluating three neurotoxic compounds and one antiproliferative compound, and the null effect of a non-toxic compound at relevant concentrations. Thus, our 3D high-throughput microarray platform may help predict, in vitro, which compounds pose an increased threat to neural development and should therefore be prioritized for further screening and evaluation.

Exploiting pluripotent stem cell technology for drug discovery, screening, safety, and toxicology assessments

In order for the pharmaceutical industry to maintain a constant flow of novel drugs and therapeutics into the clinic, compounds must be thoroughly validated for safety and efficacy in multiple biological and biochemical systems. Pluripotent stem cells, because of their ability to develop into any cell type in the body and recapitulate human disease, may be an important cellular system to add to the drug development repertoire. This review will discuss some of the benefits of using pluripotent stem cells for drug discovery and safety studies as well as some of the recent applications of stem cells in drug screening studies. We will also address some of the hurdles that need to be overcome in order to make stem cell-based approaches an efficient and effective tool in the quest to produce clinically successful drug compounds.

Cytokinesis-block micronucleus assay adapted for analyzing genomic instability of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are multipotent cells used in cell therapy research. One of the problems involving hMSCs is the possibility of genetic instability during in vitro expansion required to obtain a suitable number of cells for clinical applications. The cytokinesis-block micronucleus (CBMN) assay measures genetic instability by analyzing the presence of micronucleus (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs) in binucleated cells. The present study describes modifications in the CBMN assay methodology to analyze genetic instability in hMSCs isolated from the umbilical vein and in vitro expanded. The best protocol to achieve binucleated hMSCs with preserved cytoplasm was as follows: cytochalasin B concentration (4.0 μg/mL), use of hypotonic treatment (3 min), and the fixative solution (9 methanol:1 acetic acid). These adaptations were reproduced in three hMSC primary cell cultures and also in XP4PA and A549 cell lines. The frequency of hMSCs treated with mitomycin-C presenting MN was lower than that with other nuclear alterations, indicating that the hMSCs contain mechanisms to avoid a high level of chromosomal breaks. However, a high frequency of cells with NPBs was detected and spontaneous anaphase bridges under normal hMSC in vitro culture were observed. Considering that anaphase bridges are characteristic alterations in tumor cells, the CBMN assay is indicated as an important tool associated with other genetic analyses in order to ensure the safe clinical use of hMSCs in cell therapy.

Stem cells: are we ready for therapy?

Cell therapy as a replacement for diseased or destroyed endogenous cells is a major component of regenerative medicine. Various types of stem cells are or will be used in clinical settings as autologous or allogeneic products. In this chapter, the progress that has been made to translate basic stem cell research into pharmaceutical manufacturing processes will be reviewed. Even if in public perception, embryonic stem (ES) cells and more recently induced pluripotent stem (iPS) cells dominate the field of regenerative medicine and will be discussed in great detail, it is the adult stem cells that are used for decades as therapeutics. Hence, these cells will be compared to ES and iPS cells. Finally, special emphasis will be placed on the scientific, technical, and economic challenges of developing stem cell-based in vitro model systems and cell therapies that can be commercialized.

Reconsidering pluripotency tests: do we still need teratoma assays?

The induction of teratoma in mice by the transplantation of stem cells into extra-uterine sites has been used as a read-out for cellular pluripotency since the initial description of this phenomenon in 1954. Since then, the teratoma assay has remained the assay of choice to demonstrate pluripotency, gaining prominence during the recent hype surrounding human stem cell research. However, the scientific significance of the teratoma assay has been debated due to the fact that transplanted cells are exposed to a non-physiological environment. Since many mice are used for a result that is heavily questioned, it is time to reconsider the teratoma assay from an ethical point of view. Candidate alternatives to the teratoma assay comprise the directed differentiation of pluripotent stem cells into organotypic cells, differentiation of cells in embryoid bodies, the analysis of pluripotency-associated biomarkers with high correlation to the teratoma forming potential of stem cells, predictive epigenetic footprints, or a combination of these technologies. Each of these assays is capable of addressing one or more aspects of pluripotency, however it is essential that these assays are validated to provide an accepted robust, reproducible alternative. In particular, the rapidly expanding number of human induced pluripotent stem cell lines, requires the development of simple, affordable standardized in vitro and in silico assays to reduce the number of animal experiments performed.

iPSCs and small molecules: a reciprocal effort towards better approaches for drug discovery

The revolutionary induced pluripotent stem cell (iPSC) technology provides a new path for cell replacement therapies and drug screening. Patient-specific iPSCs and subsequent differentiated cells manifesting disease phenotypes will finally position human disease pathology at the core of drug discovery. Cells used to test the toxic effects of drugs can also be generated from normal iPSCs and provide a much more accurate and cost-effective system than many animal models. Here, we highlight the recent progress in iPSC-based cell therapy, disease modeling and drug evaluations. In addition, we discuss the use of small molecule drugs to improve the generation of iPSCs and understand the reprogramming mechanism. It is foreseeable that the interplay between iPSC technology and small molecule compounds will push forward the applications of iPSC-based therapy and screening systems in the real world and eventually revolutionize the methods used to treat diseases.

Microenvironment-evoked cell lineage conversion: Shifting the focus from internal reprogramming to external forcing

Seeking possible ways to create replacement cells for the faded ones with deficits in functionality or quantity inspires comprehensive needs for cell lineage conversion. To fulfill this promise, reprogramming and microenvironment direction have been used to manipulate abundant cell fates. We briefly describe the evolution and fundamental insights of these two major strategies applied for lineage specification, comment generally on their current limitations, and analyze the orchestral interplay between them. We also present several future directions and discuss the potential clinical uses. Based on the relatively slight safety and technical issues, we conclude that microenvironment-evoked cell lineage conversion, instead of reprogramming, will be the shifting focus in regenerative medicine.

Prevention of β-amyloid induced toxicity in human iPS cell-derived neurons by inhibition of Cyclin-dependent kinases and associated cell cycle events

Alzheimer's disease (AD) is a neurodegenerative disorder that causes progressive memory and cognitive decline due to the selective neuronal loss in the cortex and hippocampus of the brains. Generation of human induced pluoripotent stem (hiPS) cells holds great promise for disease modeling and drug discovery in AD. In this study, we used neurons with forebrain marker expression from two unrelated hiPS cell lines. As both populations of neurons were vulnerable to β-amyloid 1-42 (Aβ1-42) aggregates, a hallmark of AD pathology, we used them to investigate cellular mediators of Aβ1-42 toxicity. We observed in neurons differentiated from both hiPS cell lines that Aβ induced toxicity correlated with cell cycle re-entry and was inhibited by pharmacological inhibitors or shRNAs against Cyclin-dependent kinase 2 (Cdk2). As one of the hiPS cell lines has been developed commercially to supply large quantities of differentiated neurons (iCell® Neurons), we screened a chemical library containing several hundred compounds and discovered several small molecules as effective blockers against Aβ1-42 toxicity, including a Cdk2 inhibitor. To our knowledge, this is the first demonstration of an Aβ toxicity screen using hiPS cell-derived neurons. This study provided an excellent example of how hiPS cells can be used for disease modeling and high-throughput compound screening for neurodegenerative diseases.