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Background The characteristic structure of motor neurons (MNs), particularly of the long axons, becomes damaged in the early stages of amyotrophic lateral sclerosis (ALS). However, the molecular pathophysiology of axonal degeneration remains to be fully elucidated. Method Two sets of isogenic human-induced pluripotent stem cell (hiPSCs)-derived MNs possessing the single amino acid difference (p.H517D) in the fused in sarcoma ( FUS ) were constructed. By combining MN reporter lentivirus, MN specific phenotype was analyzed. Moreover, RNA profiling of isolated axons were conducted by applying the microfluidic devices that enable axon bundles to be produced for omics analysis. The relationship between the target gene, which was identified as a pathological candidate in ALS with RNA-sequencing, and the MN phenotype was confirmed by intervention with si-RNA or overexpression to hiPSCs-derived MNs and even in vivo . The commonality was further confirmed with other ALS-causative mutant hiPSCs-derived MNs and human pathology. Findings We identified aberrant increasing of axon branchings in FUS -mutant hiPSCs-derived MN axons compared with isogenic controls as a novel phenotype. We identified increased level of Fos-B mRNA, the binding target of FUS, in FUS -mutant MNs. While Fos-B reduction using si-RNA or an inhibitor ameliorated the observed aberrant axon branching, Fos-B overexpression resulted in aberrant axon branching even in vivo . The commonality of those phenotypes was further confirmed with other ALS causative mutation than FUS . Interpretation Analyzing the axonal fraction of hiPSC-derived MNs using microfluidic devices revealed that Fos-B is a key regulator of FUS -mutant axon branching. Fund Japan Agency for Medical Research and development; Japanese Ministry of Education, Culture, Sports, Science and Technology Clinical Research, Innovation and Education Center, Tohoku University Hospital; Japan Intractable Diseases (Nanbyo) Research Foundation; the Kanae Foundation for the Promotion of Medical Science; and “Inochi-no-Iro” ALS research grant.

Amyotrophic lateral sclerosis (ALS) is a heterogeneous motor neuron disease for which no effective treatment is available, despite decades of research into SOD1-mutant familial ALS (FALS). The majority of ALS patients have no familial history, making the modeling of sporadic ALS (SALS) essential to the development of ALS therapeutics. However, as mutations underlying ALS pathogenesis have not yet been identified, it remains difficult to establish useful models of SALS. Using induced pluripotent stem cell (iPSC) technology to generate stem and differentiated cells retaining the patients’ full genetic information, we have established a large number of in vitro cellular models of SALS. These models showed phenotypic differences in their pattern of neuronal degeneration, types of abnormal protein aggregates, cell death mechanisms, and onset and progression of these phenotypes in vitro among cases. We therefore developed a system for case clustering capable of subdividing these heterogeneous SALS models by their in vitro characteristics. We further evaluated multiple-phenotype rescue of these subclassified SALS models using agents selected from non-SOD1 FALS models, and identified ropinirole as a potential therapeutic candidate. Integration of the datasets acquired in this study permitted the visualization of molecular pathologies shared across a wide range of SALS models. iPSC-derived motor neurons from over 30 heterogeneous sporadic ALS cases exhibit pathologies correlated with clinical disease progression, are more similar to FUS/TDP-43 familial ALS than SOD1-ALS and are corrected by repurposing of ropinirole.

Summary Human pluripotent stem cells (hPSCs) represent a potentially valuable cell source for applications in cell replacement therapy, drug development, and disease modeling. For all these uses, it is necessary to develop reproducible and robust protocols for differentiation into desired cell types. However, differentiation protocols remain unstable and inefficient, which makes minimizing the differentiation variance among hPSC lines and obtaining purified terminally differentiated cells extremely time consuming. Here, we report a simple treatment with three small molecules—SB431542, dorsomorphine, and CHIR99021—that enhanced hPSC differentiation into three germ layers with a chemically transitional embryoid-body-like state (CTraS). Induction of CTraS reduced the innate differentiation propensities of hPSCs (even unfavorably differentiated hPSCs) and shifted their differentiation into terminally differentiated cells, particularly neurons. In addition, CTraS induction accelerated in vitro pathological expression concurrently with neural maturation. Thus, CTraS can promote the latent potential of hPSCs for differentiation and potentially expand the utility and applicability of hPSCs., Graphical Abstract, Highlights • CTraS induction enhances hPSC differentiation into three germ layers without bias • CTraS induction is applicable to a wide range of hPSCs even without colony selection • Developing a robust neural induction protocol via CTraS for hPSC disease modeling • CTraS induction promotes in vitro pathological expression with maturation and aging, Simple treatment with three small molecules enhanced hPSC differentiation into three germ layers, namely CTraS. CTraS reduced the innate differentiation propensities of hPSCs and shifted them into terminal differentiations. CTraS induction accelerated in vitro pathological expression with maturation and aging. Thus, CTraS can bring out the latent potential of hPSCs.

Visual Abstract, Bipolar disorder (BP) and schizophrenia (SCZ) are major psychiatric disorders, but the molecular mechanisms underlying the complicated pathologies of these disorders remain unclear. It is difficult to establish adequate in vitro models for pathological analysis because of the heterogeneity of these disorders. In the present study, to recapitulate the pathologies of these disorders in vitro, we established in vitro models by differentiating mature neurons from human induced pluripotent stem cells (hiPSCs) derived from BP and SCZ patient with contributive copy number variations, as follows: two BP patients with PCDH15 deletion and one SCZ patient with RELN deletion. Glutamatergic neurons and GABAergic neurons were induced from hiPSCs under optimized conditions. Both types of induced neurons from both hiPSCs exhibited similar phenotypes of MAP2 (microtubule-associated protein 2)-positive dendrite shortening and decreasing synapse numbers. Additionally, we analyzed isogenic PCDH15- or RELN-deleted cells. The dendrite and synapse phenotypes of isogenic neurons were partially similar to those of patient-derived neurons. These results suggest that the observed phenotypes are general phenotypes of psychiatric disorders, and our in vitro models using hiPSC-based technology may be suitable for analysis of the pathologies of psychiatric disorders.

Induced pluripotent stem cells (iPSCs) are increasingly used in the study of disease mechanisms and the development of effective disease-modifying therapies for neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Recently, three candidate anti-ALS drugs – ropinirole (ROPI), retigabine, and bosutinib – have been identified in iPSC-based drug screens and are now being evaluated in clinical trials for safety and effectiveness. We review the preclinical data, clinical research design, and rationale for ROPI as an anti-ALS drug candidate compared with those of the other two drugs. We also discuss the use of iPSCs for understanding and monitoring treatment response as well as for new insights into the development of new drugs and therapeutic interventions for major neurodegenerative diseases.

Summary Modeling of neurological diseases using induced pluripotent stem cells (iPSCs) derived from the somatic cells of patients has provided a means of elucidating pathogenic mechanisms and performing drug screening. T cells are an ideal source of patient-specific iPSCs because they can be easily obtained from samples. Recent studies indicated that iPSCs retain an epigenetic memory relating to their cell of origin that restricts their differentiation potential. The classical method of differentiation via embryoid body formation was not suitable for T cell-derived iPSCs (TiPSCs). We developed a neurosphere-based robust differentiation protocol, which enabled TiPSCs to differentiate into functional neurons, despite differences in global gene expression between TiPSCs and adult human dermal fibroblast-derived iPSCs. Furthermore, neurons derived from TiPSCs generated from a juvenile patient with Parkinson's disease exhibited several Parkinson's disease phenotypes. Therefore, we conclude that TiPSCs are a useful tool for modeling neurological diseases., Highlights • TiPSCs are a suitable source for neural disease modeling • Developing a robust neurosphere-based induction protocol • An optimized differentiation protocol can overcome clonal variations • Modeling Parkinson's disease using TiPSC-derived neurons, In this article, Okano, Akamatsu, and colleagues show that an established neural induction protocol was able to induce neural cells from TiPSCs as well as fibroblast-derived iPSCs. We also observed that neurons derived from PARK2-TiPSCs can exhibit several Parkinson's disease-specific phenotypes observed in fibroblast-derived PARK2-iPSCs. Thus, T cells, which are easily accessible in patients, are suitable source for neural disease modeling.

Summary The CNS contains many diverse neuronal subtypes, and most neurological diseases target specific subtypes. However, the mechanism of neuronal subtype specificity of disease phenotypes remains elusive. Although in vitro disease models employing human pluripotent stem cells (PSCs) have great potential to clarify the association of neuronal subtypes with disease, it is currently difficult to compare various PSC-derived subtypes. This is due to the limited number of subtypes whose induction is established, and different cultivation protocols for each subtype. Here, we report a culture system to control the regional identity of PSC-derived neurons along the anteroposterior (A-P) and dorsoventral (D-V) axes. This system was successfully used to obtain various neuronal subtypes based on the same protocol. Furthermore, we reproduced subtype-specific phenotypes of amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD) by comparing the obtained subtypes. Therefore, our culture system provides new opportunities for modeling neurological diseases with PSCs., Graphical Abstract, Highlights • The regional identity of PSC-derived neurons can be controlled precisely • Phenotypes between different neuronal subtypes were compared successfully • Neuronal subtype-specific phenotypes of ALS and AD were reproduced in vitro • A novel tool is offered to study subtype specificity of disease phenotypes, Okano, Akamatsu, and colleagues established a culture system to control the regional identity of PSC-derived neurons. This system was used to obtain a variety of neuronal subtypes based on the same protocol. By comparing these subtypes, neurological disease phenotypes were reproduced in vitro in a subtype-specific manner. Therefore, this system is useful for the study of subtype specificity of disease phenotypes.

The characteristic structure of motor neurons (MNs), particularly of the long axons, becomes damaged in the early stages of amyotrophic lateral sclerosis (ALS). However, the molecular pathophysiology of axonal degeneration remains to be fully elucidated. In the present study, two sets of isogenic human-induced pluripotent stem cell (hiPSCs)-derived MNs were compared, and we found an abnormal increase in axon branching in the ALS-causative FUS-mutant lines. Moreover, we applied microfluidic devices that enable axon bundles to be produced for omics analysis and conducted RNA profiling of isolated axons. Thus, we identified increased level of Fos-B mRNA, the binding target of FUS, in FUS-mutant MNs. While Fos-B reduction using si-RNA or an inhibitor ameliorated the observed aberrant axon branching, Fos-B overexpression resulted in aberrant axon branching even in vivo. Analyzing the axonal fraction of hiPSC-derived MNs using microfluidic devices revealed that Fos-B is a key regulator of FUS-mutant axon branching. Funding Statement: This work was supported by Research and Study Project of Tokai University Educational System General Research Organization [to H.M]. Declaration of Interests: H.Ok. is a paid Scientific Advisor of SanBio Co.Ltd and K Pharma Inc. Y.O. is a scientific advisor for Kohjin Bio Co., Ltd. Other authors declare no competing financial interests. Ethics Approval Statement: All protocols were approved by the ethics committees of Tohoku University School of Medicine (No. 2010–306) and the Keio University School of Medicine (N0. 20080016).

The cerebral cortex is subdivided into distinct areas that have particular functions. The rostrocaudal (R-C) gradient of fibroblast growth factor 8 (FGF8) signaling defines this areal identity during neural development. In this study, we recapitulated cortical R-C patterning in human pluripotent stem cell (PSC) cultures. Modulation of FGF8 signaling appropriately regulated the R-C markers, and the patterns of global gene expression resembled those of the corresponding areas of human fetal brains. Furthermore, we demonstrated the utility of this culture system in modeling the area-specific forebrain phenotypes [presumptive upper motor neuron (UMN) phenotypes] of amyotrophic lateral sclerosis (ALS). We anticipate that our culture system will contribute to studies of human neurodevelopment and neurological disease modeling.

Summary Amyotrophic lateral sclerosis (ALS) is a late-onset motor neuron disorder. Although its neuropathology is well understood, the cellular and molecular mechanisms are yet to be elucidated due to limitations in the currently available human genetic data. In this study, we generated induced pluripotent stem cells (iPSC) from two familial ALS (FALS) patients with a missense mutation in the fused-in sarcoma (FUS) gene carrying the heterozygous FUS H517D mutation, and isogenic iPSCs with the homozygous FUS H517D mutation by genome editing technology. These cell-derived motor neurons mimicked several neurodegenerative phenotypes including mis-localization of FUS into cytosolic and stress granules under stress conditions, and cellular vulnerability. Moreover, exon array analysis using motor neuron precursor cells (MPCs) combined with CLIP-seq datasets revealed aberrant gene expression and/or splicing pattern in FALS MPCs. These results suggest that iPSC-derived motor neurons are a useful tool for analyzing the pathogenesis of human motor neuron disorders., Graphical Abstract, Highlights • Modeling familial ALS (FALS) using iPSC-derived motor neurons • Aberrant gene expression and/or splicing in FALS motor neuron precursor cells • Mis-localization of mutant FUS protein in FALS motor neurons • Increased apoptosis of FALS motor neurons, Okano, Yano, and colleagues established iPSCs from two familial ALS patients with the missense mutation in the FUS gene and differentiated them into motor neurons as a novel in vitro model for ALS. Moreover, this model enables the pursuit of correlations and new discovery of molecular pathophysiology in various cell biological phenomena by endogenous mutation in patient-derived motor neurons.

Patient-specific induced pluripotent stem cells (iPSCs) facilitate understanding of the etiology of diseases, discovery of new drugs and development of novel therapeutic interventions. A frequently used starting source of cells for generating iPSCs has been dermal fibroblasts (DFs) isolated from skin biopsies. However, there are also numerous repositories containing lymphoblastoid B-cell lines (LCLs) generated from a variety of patients. To date, this rich bioresource of LCLs has been underused for generating iPSCs, and its use would greatly expand the range of targeted diseases that could be studied by using patient-specific iPSCs. However, it remains unclear whether patient’s LCL-derived iPSCs (LiPSCs) can function as a disease model. Therefore, we generated Parkinson’s disease patient-specific LiPSCs and evaluated their utility as tools for modeling neurological diseases. We established iPSCs from two LCL clones, which were derived from a healthy donor and a patient carrying PARK2 mutations, by using existing non-integrating episomal protocols. Whole genome sequencing (WGS) and comparative genomic hybridization (CGH) analyses showed that the appearance of somatic variations in the genomes of the iPSCs did not vary substantially according to the original cell types (LCLs, T-cells and fibroblasts). Furthermore, LiPSCs could be differentiated into functional neurons by using the direct neurosphere conversion method (dNS method), and they showed several Parkinson’s disease phenotypes that were similar to those of DF-iPSCs. These data indicate that the global LCL repositories can be used as a resource for generating iPSCs and disease models. Thus, LCLs are the powerful tools for generating iPSCs and modeling neurological diseases. Electronic supplementary material The online version of this article (doi:10.1186/s13041-016-0267-6) contains supplementary material, which is available to authorized users.