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Liddle syndrome (LS) is an autosomal dominant genetic disorder characterized by early onset hypertension, hypokalemia, and low plasma aldosterone or renin concentration. It is caused by mutations in subunits of the epithelial sodium channel (ENaC). The clinical phenotypes of LS are variable and nonspecific, making it prone to both misdiagnosis and missed diagnosis. Genetic analysis is necessary to confirm the diagnosis of LS. Herein, we report the case of a 42-year-old male with LS and a 30-year history of hypertension. He was being treated for possible primary aldosteronism (PA) over the preceding 7 years; however, his hypertension was poorly controlled despite intensive combination therapy. His 13-year-old son served as a proband for a diagnosis of LS, as he had hypertension, hypokalemia, and a significant family history of hypertension. Genetic testing revealed a heterozygous pathological variant in the SCNN1B gene. This led to a diagnosis of LS, as the father was found to harbor the same mutation. Both were treated with ENaC inhibitors and a salt-restricted diet, which improved their symptoms markedly. The son’s genetic diagnosis facilitated the subsequent proper diagnosis and treatment of his father. LS causes early onset hypertension; hence, its early diagnosis and treatment can prevent complications. Hereditary hypertension should be considered in cases of early onset hypertension with a significant family history. Patients diagnosed with PA using outdated criteria may have concomitant LS and require careful evaluation of biochemical and endocrine tests according to the current criteria.

Background: Despite the obesity paradox, visceral adiposity is associated with poor clinical outcomes in patients with heart failure with preserved ejection fraction (HFpEF). However, it remains unclear whether a relationship between visceral fat and clinical outcomes exists in Asian patients with HFpEF, in whom obesity is rare. Methods: Visceral and subcutaneous adipose tissue (VAT and SAT) volume and area were measured using computed tomography (CT) in 196 HFpEF patients. The primary endpoint was a composite of all-cause mortality or HF hospitalization. Results: Participants had a normal body mass index (BMI) (22.5 ± 4.4 kg/m2), and obesity (BMI > 30 kg/m2) was rare (4.6 %). The primary outcome was observed in 64 patients during a median follow-up of 11.6 months. Lower VAT and SAT volumes were associated with underweight and malnutrition. Composite outcomes increased as body weight, BMI, and height-indexed SAT volume and area decreased. Lower height-indexed VAT volume and area were also associated with the outcomes. The height-indexed SAT area provided independent and incremental prognostic value over age, BMI, blood pressure, and creatinine and albumin levels. Conclusions: In lean East Asian patients with HFpEF, a lower VAT volume was associated with poorer clinical outcomes. CT-based assessments of adiposity may provide incremental prognostic value over simple anthropometric indices in lean HFpEF patients.

Pseudohypoparathyroidism 1A (PHP1A) and pseudopseudohypoparathyroidism (PPHP) are caused by loss-of-function variants of GNAS, which encodes Gsα. We present two unrelated Japanese families with PHP1A and PPHP harboring unreported pathogenic variants of GNAS (c.1141delG, p.Asp381Thrfs*23 and c.1117delC, p.Arg373Alafs*31). These variants introduce abnormal amino acids in the β6 strand/α5 helix of Gsα, which interact with G protein coupling receptor (GPCR). We conclude that these variants alter the association of Gsα with GPCR and cause PHP1A or PPHP.

Abstract Objectives To evaluate the effect of abolishing instructions to fast prior to contrast-enhanced CT on acute adverse reactions (AARs). Methods In our institution, we instructed patients to fast one meal before contrast-enhanced CT examinations. However, we abolished these instructions at the end of March 2019, and solid food intake was not restricted before contrast-enhanced CT after this date. The differences in the incidence of AARs before (December 2015–November 2018, n = 43,927) and after (April 2019–March 2020, n = 14,676) abolishing instructions to fast were compared. We allowed 4 months (December 2018–March 2019) for this policy change to fully permeate the CT referrals. The medical records of patients who vomited were retrospectively reviewed by one of the authors for notations of aspiration or aspiration pneumonia attributable to vomiting. Results The overall incidence of AARs before (1.60%, n = 705) and after abolition (1.40%, n = 205) did not change significantly. As the chemotoxic reactions, the incidence of nausea decreased significantly (0.31 to 0.18%, p = 0.006). The incidence of vomiting did not change (0.12 to 0.16%), and there were no cases of aspiration pneumonia attributable to vomiting during the study period. The incidence of severe hypersensitivity/allergy-like reactions did not change (0.06 to 0.05%). Conclusions Abolishing instructions to fast decreased the incidence of nausea, but did not affect the incidence of vomiting. No cases of aspiration pneumonia attributable to vomiting were found. Our study confirmed that fasting is not required prior to contrast-enhanced CT.

Background: Visceral fat produces inflammatory cytokines and may play a major role in heart failure with preserved ejection fraction (HFpEF). However, little data exist regarding how qualitative and quantitative abnormalities of visceral fat would contribute to left ventricular diastolic dysfunction (LVDD). Methods: We studied 77 participants who underwent open abdominal surgery for intra-abdominal tumors (LVDD, n = 44; controls without LVDD, n = 33). Visceral fat samples were obtained during the surgery, and mRNA levels of inflammatory cytokines were measured. Visceral and subcutaneous fat areas were measured using abdominal computed tomography. Results: Patients with significant LVDD had greater LV remodeling and worse LVDD than controls. While body weight, body mass index, and subcutaneous fat area were similar in patients with LVDD and controls, the visceral fat area was larger in patients with LVDD than in controls. The visceral fat area was correlated with BNP levels, LV mass index, mitral e′ velocity, and E/e′ ratio. There were no significant differences in the mRNA expressions of visceral adipose tissue cytokines (IL-2, -6, -8, and -1β, TNFα, CRP, TGFβ, IFNγ, leptin, and adiponectin) between the groups. Conclusions: Our data may suggest the pathophysiological contribution of visceral adiposity to LVDD.

Abstract Background Blood pressure variability has been found to be a predictor of a stroke, heart failure, and ischemic heart disease that is independent of blood pressure control. This study used the variability independent of the mean (VIM) to evaluate the visit‐to‐visit blood pressure variability in patients previously undergoing catheter ablation (CA) of paroxysmal atrial fibrillation (PAF), and its relationship with AF recurrence was examined. Method and Results The subjects were 274 consecutive PAF patients who underwent CA at our hospital. Finally, 237 subjects were included in the analysis. The mean follow‐up period was 29.6 months, during which 37 subjects had recurrences, and 200 did not. During the outpatient blood pressure examinations, the VIM of the systolic blood pressure (VIM SBP) was significantly higher in the recurrence group, suggesting that blood pressure variability is associated with recurrence. The Cox proportional hazards ratio of the VIM SBP was significantly higher in the recurrence (4.839) than no‐recurrence group, even after an adjustment, suggesting that the extent of the variability was a risk factor of recurrence post‐CA. In addition, the Cox proportional hazard ratio for recurrence was significantly lower in the patients taking dihydropyridine calcium channel blockers, suggesting that the risk of recurrence may differ depending on the type of antihypertensive drug. Conclusions Blood pressure variability may be a risk for AF recurrence after CA.

Dendritic spines are unique postsynaptic structures that emerge from the dendrites of neurons. They undergo activity-dependent morphological changes known as structural plasticity. The changes involve actin cytoskeletal remodeling, which is regulated by actin-binding proteins. CaMKII is a crucial molecule in synaptic plasticity. Notably, CaMKIIβ subtype is known to bind to filamentous-actin and is closely involved in structural plasticity. We have shown that CaMKIIβ binds to drebrin, and is localized in spines as both drebrin-dependent and drebrin-independent pools. However, the nanoscale relationship between drebrin and CaMKIIβ within dendritic spines has not been clarified. In this study, we used stochastic optical reconstruction microscopy (STORM) to examine the detailed localization of these proteins. STORM imaging showed that CaMKIIβ co-localized with drebrin in the core region of spines, and localized in the submembrane region of spines without drebrin. Interestingly, the dissociation of CaMKIIβ and drebrin in the core region was induced by NMDA receptor activation. In drebrin knockdown neurons, CaMKIIβ was decreased in the core region but not in the submembrane region. Together it indicates that the clustering of CaMKIIβ in the spine core region is dependent on drebrin. These findings suggest that drebrin-dependent CaMKIIβ is in a standby state before its activation.

Ischemic stroke is a major cerebrovascular disease with high morbidity and mortality rates; however, effective treatments for ischemic stroke-related neurological dysfunction have yet to be developed. In this study, we generated neural progenitor cells from human leukocyte antigen major loci gene-homozygous-induced pluripotent stem cells (hiPSC-NPCs) and evaluated their therapeutic effects against ischemic stroke. hiPSC-NPCs were intracerebrally transplanted into rat ischemic brains produced by transient middle cerebral artery occlusion at either the subacute or acute stage, and their in vivo survival, differentiation, and efficacy for functional improvement in neurological dysfunction were evaluated. hiPSC-NPCs were histologically identified in host brain tissues and showed neuronal differentiation into vGLUT-positive glutamatergic neurons, extended neurites into both the ipsilateral infarct and contralateral healthy hemispheres, and synaptic structures formed 12 weeks after both acute and subacute stage transplantation. They also improved neurological function when transplanted at the subacute stage with γ-secretase inhibitor pretreatment. However, their effects were modest and not significant and showed a possible risk of cells remaining in their undifferentiated and immature status in acute-stage transplantation. These results suggest that hiPSC-NPCs show cell replacement effects in ischemic stroke-damaged neural tissues, but their efficacy is insufficient for neurological functional improvement after acute or subacute transplantation. Further optimization of cell preparation methods and the timing of transplantation is required to balance the efficacy and safety of hiPSC-NPC transplantation.

Abstract Background This study aimed to evaluate the predictors of recurrence of atrial tachyarrhythmias by structural and functional mapping: voltage, dominant frequency (DF), and rotor mapping after a pulmonary vein isolation (PVI) in nonparoxysmal atrial fibrillation (AF) patients. Methods A total of 66 nonparoxysmal AF patients were prospectively investigated. After the PVI, an online real‐time phase mapping system was used to detect the location of rotors with critical nonpassively activated ratios (%NPs) of ≧50% in each left atrial (LA) segment, and high‐DFs of ≧7 Hz were simultaneously mapped. After restoring sinus rhythm, low‐voltage areas (LVAs 3.3% after one procedure over 11.6 ± 0.8 months of follow‐up (77.1% vs. 33.3%, p

Abstract There have been no report of objective clinical characteristics or prognostic factors that predict fatal outcome of acute respiratory distress syndrome (ARDS) since the Berlin definition was published. The aim of this study is to identify clinically available predictors that distinguish between two phenotypes of fatal ARDS due to pneumonia. In total, 104 cases of Japanese patients with pneumonia-induced ARDS were extracted from our prospectively collected database. Fatal cases were divided into early (

Abstract The generation of mature synaptic structures using neurons differentiated from human-induced pluripotent stem cells (hiPSC-neurons) is expected to be applied to physiological studies of synapses in human cells and to pathological studies of diseases that cause abnormal synaptic function. Although it has been reported that synapses themselves change from an immature to a mature state as neurons mature, there are few reports that clearly show when and how human stem cell-derived neurons change to mature synaptic structures. This study was designed to elucidate the synapse formation process of hiPSC-neurons. We propagated hiPSC-derived neural progenitor cells (hiPSC-NPCs) that expressed localized markers of the ventral hindbrain as neurospheres by dual SMAD inhibition and then differentiated them into hiPSC-neurons in vitro. After 49 days of in vitro differentiation, hiPSC-neurons significantly expressed pre- and postsynaptic markers at both the transcript and protein levels. However, the expression of postsynaptic markers was lower than in normal human or normal rat brain tissues, and immunostaining analysis showed that it was relatively modest and was lower than that of presynaptic markers and that its localization in synaptic structures was insufficient. Neurophysiological analysis using a microelectrode array also revealed that no synaptic activity was generated on hiPSC-neurons at 49 days of differentiation. Analysis of subtype markers by immunostaining revealed that most hiPSC-neurons expressed vesicular glutamate transporter 2 (VGLUT2). The presence or absence of NGF, which is required for the survival of cholinergic neurons, had no effect on their cell fractionation. These results suggest that during the synaptogenesis of hiPSC-neurons, the formation of presynaptic structures is not the only requirement for the formation of postsynaptic structures and that the mRNA expression of postsynaptic markers does not correlate with the formation of their mature structures. Technically, we also confirmed a certain level of robustness and reproducibility of our neuronal differentiation method in a multicenter setting, which will be helpful for future research. Synapse formation with mature postsynaptic structures will remain an interesting issue for stem cell-derived neurons, and the present method can be used to obtain early and stable quality neuronal cultures from hiPSC-NPCs.

Abstract The primary cilium is a plasma membrane‐protruding sensory organelle that efficiently conveys signaling cascades in a highly ordered microenvironment. Its signaling is mediated, in part, by a limited set of GPCRs preferentially enriched in the cilium membrane. This includes melanin‐concentrating hormone (MCH) receptor 1 (MCHR1), which plays a role in feeding and mood. In addition to its receptor composition, the length of the cilium is a characteristic parameter that is implicated in its function. We previously found that MCH can dynamically shorten cilia length via the Gi/o and Akt pathways in both MCHR1‐expressing hTERT‐RPE1 cells (hRPE1 cells) and rat hippocampal neurons. However, the detailed mechanisms by which MCH regulates cilia length through ciliary MCHR1 remains unclear. In this study, we aimed to determine the transcriptome changes in MCHR1‐expressing hRPE1 cells in response to MCH to identify the target molecules involved in cilia length regulation via MCHR1 activation. RNA sequencing analysis of ciliated cells subjected to MCH treatment showed upregulation of 424 genes and downregulation of 112 genes compared with static control cells. Validation by quantitative real‐time PCR, knocking down, and CRISPR/Cas9‐mediated knockout technology identified a molecule, PDZ and LIM domain‐containing protein 5 (PDLIM5). Thus, it was considered as the most significant key factor for MCHR1‐mediated shortening of cilia length. Additional analyses revealed that the actin‐binding protein alpha‐actinin 1/4 is a crucial downstream target of the PDLIM5 signaling pathway that exerts an effect on MCHR1‐induced cilia shortening. In the endogenous MCHR1‐expressing hippocampus, transcriptional upregulation of PDLIM5 and actinin 1/4, following the application of MCH, was detected when the MCHR1‐positive cilia were shortened. Together, our transcriptome study based on ciliary MCHR1 function uncovered a novel and important regulatory step underlying cilia length control. These results will potentially serve as a basis for understanding the mechanism underlying the development of obesity and mood disorders.

Abstract GAP-43 is a vertebrate neuron-specific protein and that is strongly related to axon growth and regeneration; thus, this protein has been utilized as a classical molecular marker of these events and growth cones. Although GAP-43 was biochemically characterized more than a quarter century ago, how this protein is related to these events is still not clear. Recently, we identified many phosphorylation sites in the growth cone membrane proteins of rodent brains. Two phosphorylation sites of GAP-43, S96 and T172, were found within the top 10 hit sites among all proteins. S96 has already been characterized (Kawasaki et al., 2018), and here, phosphorylation of T172 was characterized. In vitro (cultured neurons) and in vivo, an antibody specific to phosphorylated T172 (pT172 antibody) specifically recognized cultured growth cones and growing axons in developing mouse neurons, respectively. Immunoblotting showed that pT172 antigens were more rapidly downregulated throughout development than those of pS96 antibody. From the primary structure, this phosphorylation site was predicted to be conserved in a wide range of animals including primates. In the developing marmoset brainstem and in differentiated neurons derived from human induced pluripotent stem cells, immunoreactivity with pT172 antibody revealed patterns similar to those in mice. pT172 antibody also labeled regenerating axons following sciatic nerve injury. Taken together, the T172 residue is widely conserved in a wide range of mammals including primates, and pT172 is a new candidate molecular marker for growing axons.

Background: The term “addiction” encompasses both substance dependence and behavioral addiction and is associated with major societal problems. Measures to combat addiction are currently insufficient in Japan, and further research on addiction is necessary. Methods: Science Council of Japan (SCJ) has three subcommittees – the Addiction Subcommittee, Brain and Mind Subcommittee, and Neuroscience Subcommittee among others. Those three subcommittees are dealing directly or indirectly with addiction problems in Japan. Thus, all authors of this review, members of those subcommittees, collectively recommended what research activities are required in Japan for continuing effort in overcoming addiction problems in Japan. Results: We proposed the following measures. Proposal 1: Understand diversity in addiction and promote related research and education; Proposal 2: Promote personalized measures for patients with addiction disorders; Proposal 3: Foster addiction research personnel; Proposal 4: Develop new guidelines for the rehabilitation of patients with drug dependence; Proposal 5: Establish an institute specializing in addiction research and comprehensively handling information collection, research, countermeasures, treatment, and public relation related to addiction. Conclusion: The opinions of the review are based on the recommendations that were published in 2020 in Japanese by the Addiction Subcommittee, Brain and Mind Subcommittee, and Neuroscience Subcommittee of the SCJ. The authors here are sharing colleagues of Taiwanese Society of Psychiatry with these proposed research activities required to overcome addiction problems in Japan.

Apparent permeability coefficients (Papp) across a human intestinal epithelial Caco-2 cell monolayer were measured for a range of industrial/drug chemicals. A predictive equation for determining in vitro Papp values of fifty-six substances was set up using multivariate regression analysis based on in silico-estimated physicochemical properties (molecular weights and water distribution coefficients for apical and basal pH environments) (r = 0.77, p

Abstract Background The use of baseline tumor burden (TB) as a prognostic factor for non‐small cell lung cancer (NSCLC) patients treated with immune checkpoint inhibitors (ICIs) and associations between TB and other prognostic biomarkers remain unclear. In this study, we investigated the association between TB and survival in NSCLC patients treated with ICIs in comparison with other biomarkers. Methods We retrospectively evaluated 83 NSCLC patients with ICIs administered between February 2016 and December 2018. TB was measured as the sum of the unidimensional diameters of up to five target lesions. Results The median observation period was 14.2 months. A total of 42 patients died during the follow‐up. Univariate Cox regression analysis showed that baseline TB was associated with OS. Cox regression analysis adjusted for Eastern Cooperative Oncology Group performance status (ECOG PS) alone or with addition of programmed cell death ligand 1 expression and treatment line showed that TB was a prognostic factor for OS. Using time‐dependent receiver operating characteristic curve analysis, the optimal TB cutoff for predicting OS was 12 cm, and patients were divided into a high TB group (n = 21) and a low TB group (n = 62). The low TB group achieved significantly longer OS than the high TB group (median OS: 18.5 months, [95% CI = 11.7‐not reached] vs. 2.3 months [95% CI = 1.3–2.9], P

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a valuable tool to characterize the pharmacology and toxic effects of drugs on heart cells. In particular, hiPSC-CMs can be used to identify drugs that generate arrhythmias. However, it is unclear whether the expression of genes related to generation of CM action potentials differs between hiPSC-CM cell lines and the mature human heart. To address this, we obtained accurate gene expression profiles of commercially available hiPSC-CM cell lines with quantitative real time RT-PCR analysis. Expression analysis of ten cardiac proteins important for generation of action potentials and three cardiac proteins important for muscle contractility was performed using GAPDH for normalization. Comparison revealed large variations in expression levels among hiPSC-CM cell lines and between hiPSC-CMs and normal human heart. In general, gene expression in hiPSC-CM cell lines was more similar to an immature, stem-like cell than a mature cardiomyocyte from human heart samples. These results provide quantitative information about differences in gene expression between hiPSC-CM cell lines, essential for interpreting pharmacology experiments. Our approach can be used as an experimental guideline for future research on gene expression in hiPSC-CMs. Keywords: iPS cells, Quantitative real time-PCR, Reference gene, Cardiac ion channels, Action potential

Objective: The prognosis of adrenoleukodystrophy (ALD)with neurological involvement is generally dismal; however, allogeneic stem cell transplantation (SCT) is recognized as effective to stabilize or improve the clinical symptoms of ALD. Herein, we report the clinical outcomes of patients with ALD who consecutively underwent allogeneic stem cell transplantation with reduced intensity conditioning at our institution. Patients: Sixteen patients with ALD, who were symptomatic (n = 14) or presymptomatic (n = 2), received SCT from 2010 to 2016. The stem cell source was cord blood (n = 14), or bone marrow from a human leukocyte antigen identical sibling (n = 2). The conditioning regimen prior to transplantation was reduced intensity and consisted of fludarabine (125 mg/m2), melphalan (140 mg/m2) and low dose total body irradiation (TBI) of 4Gy (n = 15) or 3Gy (n = 1). Results: Primary engraftment was obtained in 11 patients, and 4 of the 5 patients who lost the primary graft received a second cord blood transplantation and were engrafted. Five years overall and event-free survival were 90.9% and 61.1% respectively, with a median of 45 months (range 16–91). Loes score stabilized or improved by 18 months after transplantation except for patients with internal capsule involvement. Conclusion: Allogeneic SCT with reduced intensity conditioning for patients with ALD was safely performed without major transplant-related complications even in symptomatic patients and neurological symptoms were stabilized after SCT in patients without internal capsule involvement. Keywords: Adrenoleukodystrophy, Allogeneic stem cell transplantation, Loes score, Very long chain fatty acid

Summary: To assess the utility of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) as an in vitro proarrhythmia model, we evaluated the concentration dependence and sources of variability of electrophysiologic responses to 28 drugs linked to low, intermediate, and high torsades de pointes (TdP) risk categories using two commercial cell lines and standardized protocols in a blinded multisite study using multielectrode array or voltage-sensing optical approaches. Logistical and ordinal linear regression models were constructed using drug responses as predictors and TdP risk categories as outcomes. Three of seven predictors (drug-induced arrhythmia-like events and prolongation of repolarization at either maximum tested or maximal clinical exposures) categorized drugs with reasonable accuracy (area under the curve values of receiver operator curves ∼0.8). hiPSC-CM line, test site, and platform had minimal influence on drug categorization. These results demonstrate the utility of hiPSC-CMs to detect drug-induced proarrhythmic effects as part of the evolving Comprehensive In Vitro Proarrhythmia Assay paradigm. : Blinova et al. tested human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) for improving torsades de pointes arrhythmia risk prediction of drugs in the Comprehensive In Vitro Proarrhythmia Assay (CiPA) initiative. This validation study confirms their utility based on electrophysiologic responses to 28 blinded drugs, with minimal influence from cell lines, test sites, and electrophysiological platforms. Keywords: comprehensive in vitro proarrhythmia assay, CiPA, human-induced pluripotent stem cell-derived cardiomycotes, hiPSC-CM, drug-induced ventricular arrhythmia Torsade de Pointes, microelectrode array, voltage-sensitive dyes

We examined electrophysiological indices of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) sheets in order to quantitatively estimate Na+, K+ and Ca2+ channel blocking actions of bepridil and amiodarone using microelectrode array system in comparison with that of E-4031. We analyzed the field potential duration, effective refractory period, current threshold and conduction property using a programmed electrical stimulation protocol to obtain the post repolarization refractoriness and coefficient a of the relationship between the pacing cycle length and field potential duration. Electropharmacological profile of each drug was successfully characterized; namely, 1) the changes in the current threshold and conduction property provided basic information of Na+ channel blocking kinetics, 2) the relationship between pacing cycle length and field potential duration reflected drug-induced inhibition of human ether-à-go-go-related gene (hERG) K+ channel, 3) the post repolarization refractoriness indicated the relative contribution of these drugs to Na+ and K+ channel blockade, and 4) L-type Ca2+ channel blocking action was more obvious in the field potential waveform of the hiPSC-CMs sheets than that expected in the electrocardiogram in humans. Thus, this information may help to better utilize the hiPSC-CMs sheets for grasping the properties and net effects of drug-induced Na+, Ca2+ and K+ channel blockade. Keywords: Human induced pluripotent stem cell-derived cardiomyocytes, Post repolarization refractoriness, Multichannel blocker, Antiarrhythmic property

Insertional mutagenesis is an important risk with all genetically modified cell therapies, including chimeric antigen receptor (CAR)-T cell therapy used for hematological malignancies. Here we describe a new tagmentation-assisted PCR (tag-PCR) system that can determine the integration sites of transgenes without using restriction enzyme digestion (which can potentially bias the detection) and allows library preparation in fewer steps than with other methods. Using this system, we compared the integration sites of CD19-specific CAR genes in final T cell products generated by retrovirus-based and lentivirus-based gene transfer and by the piggyBac transposon system. The piggyBac system demonstrated lower preference than the retroviral system for integration near transcriptional start sites and CpG islands and higher preference than the lentiviral system for integration into genomic safe harbors. Integration into or near proto-oncogenes was similar in all three systems. Tag-PCR mapping is a useful technique for assessing the risk of insertional mutagenesis. Keywords: CD19 CAR-T cell, piggyBac transposon, Integration site mapping, Tag-PCR

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are expected to become a useful tool for proarrhythmia risk prediction in the non-clinical drug development phase. Several features including electrophysiological properties, ion channel expression profile and drug responses were investigated using commercially available hiPSC-CMs, such as iCell-CMs and Cor.4U-CMs. Although drug-induced arrhythmia has been extensively examined by microelectrode array (MEA) assays in iCell-CMs, it has not been fully understood an availability of Cor.4U-CMs for proarrhythmia risk. Here, we evaluated the predictivity of proarrhythmia risk using Cor.4U-CMs. MEA assay revealed linear regression between inter-spike interval and field potential duration (FPD). The hERG inhibitor E−4031 induced reverse-use dependent FPD prolongation. We next evaluated the proarrhythmia risk prediction by a two-dimensional map, which we have previously proposed. We determined the relative torsade de pointes risk score, based on the extent of FPD with Fridericia's correction (FPDcF) change and early afterdepolarization occurrence, and calculated the margins normalized to free effective therapeutic plasma concentrations. The drugs were classified into three risk groups using the two-dimensional map. This risk-categorization system showed high concordance with the torsadogenic information obtained by a public database CredibleMeds. Taken together, these results indicate that Cor.4U-CMs can be used for drug-induced proarrhythmia risk prediction. Keywords: Early afterdepolarization, hiPSC-CMs, Microelectrode array, Proarrhythmia, Safety assessment

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been used in many studies to assess proarrhythmic risks of chemical compounds. In those studies, field potential durations (FPD) of hiPSC-CMs have been corrected by clinically used Fridericia's and/or Bazett's formulae, however, the rationale for the use of these formulae has not been well established. In the present study, we developed a correction formula for experiments using hiPSC-CMs. First, we analyzed the effect of beating rate on FPD in the hiPSC-CMs sheets with electrical stimuli and a HCN channel inhibitor zatebradine. Next, we examined the relationship between the electrophysiological properties and the expression levels of ion channel genes in the cell sheets. Zatebradine slowed the beating rate and allowed to analyze FPD changes at various pacing cycle lengths. Rate-dependent change in the repolarization period was smaller in the cell sheets than that reported on the human hearts, which can be partly explained by lower gene expression level of hKCNJ2 and hKCNE1. Thus, non-linear equation for correcting FPD in the cell sheet; FPDc = FPD/RR0.22 with RR given in second was obtained, which may make it feasible to assess net repolarization delay by various chemical compounds with a chronotropic action.

Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes hold great potentials to predict pro-arrhythmic risks in preclinical cardiac safety screening, although the hiPSC cardiomyocytes exhibit rather immature functional and structural characteristics, including spontaneous activity. Our physiological characterization and mathematical simulation showed that low expression of the inward-rectifier potassium (IK1) channel is a determinant of spontaneous activity. To understand impact of the low IK1 expression on the pharmacological properties, we tested if transduction of hiPSC-derived cardiomyocytes with KCNJ2, which encodes the IK1 channel, alters pharmacological response to cardiac repolarization processes. The transduction of KCNJ2 resulted in quiescent hiPSC-derived cardiomyocytes, which need pacing to elicit action potentials. Significant prolongation of paced action potential duration in KCNJ2-transduced hiPSC-derived cardiomyocytes was stably measured at 0.1 μM E-4031, although the same concentration of E-4031 ablated firing of non-treated hiPSC-derived cardiomyocytes. These results in single cells were confirmed by mathematical simulations. Using the hiPSC-derived cardiac sheets with KCNJ2-transduction, we also investigated effects of a range of drugs on field potential duration recorded at 1 Hz. The KCNJ2 overexpression in hiPSC-derived cardiomyocytes may contribute to evaluate a part of QT-prolonging drugs at toxicological concentrations with high accuracy.

Currently, cardiomyocyte (CM) differentiation methods require a purification step after CM induction to ensure the high purity of the cell population. Here we show an improved human CM differentiation protocol with which high-purity ventricular-type CMs can be obtained and maintained without any CM purification process. We induced and collected a mesodermal cell population (platelet-derived growth factor receptor-α (PDGFRα)-positive cells) that can respond to CM differentiation cues, and then stimulated CM differentiation by means of Wnt inhibition. This method reproducibly generated CMs with purities above 95% in several human pluripotent stem cell lines. Furthermore, these CM populations were maintained in culture at such high purity without any further CM purification step for over 200 days. The majority of these CMs (>95%) exhibited a ventricular-like phenotype with a tendency to structural and electrophysiological maturation, including T-tubule-like structure formation and the ability to respond to QT prolongation drugs. This is a simple and valuable method to stably generate CM populations suitable for cardiac toxicology testing, disease modeling and regenerative medicine.

Induced pluripotent stem (iPS) cells are promising tools to investigate disease mechanism and develop new drugs. Intraneuronal transport, which is fundamental for neuronal survival and function, is vulnerable to various pharmacological and chemical agents and is disrupted in some neurodegenerative disorders. We applied a quantification method for axonal transport by counting CM-DiI–labeled particles traveling along the neurite, which allowed us to monitor and quantitate, for the first time, intraneuronal transport in human neurons differentiated from iPS cells (iCell neurons). We evaluated the acute effects of several anti-neoplastic agents that have been previously shown to affect intraneuronal transport. Vincristine, paclitaxel and oxaliplatin decreased the number of moving particle along neurites. Cisplatin, however, produced no effect on intraneuronal transport, which is in contrast to our previous report indicating that it inhibits transport in chick dorsal root ganglion neurons. Our system may be a useful method for assessing intraneuronal transport and neurotoxicity in human iPS neurons.