Applying Deep Learning with Convolutional Neural Networks to Laryngoscopic Imaging for Automated Segmentation and Classification of Vocal Cord Leukoplakia.

Objectives: Vocal cord leukoplakia is clinically described as a white plaque or patch on the vocal cords observed during macroscopic examination, which does not take into account histological features or prognosis. A clinical challenge in managing vocal cord leukoplakia is to assess the potential malignant transformation of the lesion. This study aims to investigate the potential of deep learning (DL) for the simultaneous segmentation and classification of vocal cord leukoplakia using narrow band imaging (NBI) and white light imaging (WLI). The primary objective is to assess the model's accuracy in detecting and classifying lesions, comparing its performance in WLI and NBI. Methods: We applied DL to segment and classify NBI and WLI of vocal cord leukoplakia, and used pathological diagnosis as the gold standard. Results: The DL model autonomously detected lesions with an average intersection-over-union (IoU) >70%. In classification tasks, the model differentiated between lesions in the surgical group with a sensitivity of 93% and a specificity of 94% for WLI, and a sensitivity of 99% and a specificity of 97% for NBI. In addition, the model achieved a mean average precision of 81% in WLI and 92% in NBI, with an IoU threshold >0.5. Conclusions: The model proposed by us is helpful in assisting in accurate diagnosis of vocal cord leukoplakia from NBI and WLI.

The attenuation of gut microbiota-derived short-chain fatty acids elevates lipid transportation through suppression of the intestinal HDAC3-H3K27ac-PPAR-γ axis in gestational diabetes mellitus.

Gut flora is considered to modulate lipid transport from the intestine into the bloodstream, and thus may potentially participate in the development of GDM. Although previous studies have shown that the intestinal microbiota influences lipid transport and metabolism in GDM, the precise mechanisms remain elusive. To address this, we used a high-fat diet (HFD)-induced GDM mouse model and conducted 16s rRNA sequencing and fecal metabolomics to assess gut microbial community shifts and associated metabolite changes. Western blot, ELISA, and chromatin immunoprecipitation (ChIP) were utilized to elucidate how gut microbiota affect intestinal lipid transport and the insulin sensitivity of hepatic, adipose, and skeletal muscle tissues. We found that HFD impaired the oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) in pregnant mice. 16s rRNA sequencing demonstrated profound compositional changes, especially in the relative abundances of Firmicutes and Bacteroidetes. Metabolomics analysis presented a decline in the concentration of short-chain fatty acids (SCFAs) in the GDM group. Western blot analyses showed an upregulation of HDAC3 and a concurrent reduction in H3K27 acetylation in the intestine. ChIP-qPCR showed that PPAR-γ was inhibited, which in turn activated lipid-transporter CD36. ELISA and insulin signaling pathway detection in insulin-target organs showed high concentrations of circulating fatty acids and triglycerides and insulin resistance in insulin-target organs. Our results suggest that gut microbiota is closely associated with the development of GDM, partly because decreased gut flora-associated SCFAs activate CD36 by suppressing the HDAC3-H3K27ac-PPAR-γ axis to transport excessive fatty acids and triglycerides into blood circulation, thereby dysregulating the insulin sensitivity of insulin target organs.

Glutamate decarboxylase 1 gene polymorphisms are associated with respiratory symptoms in panic disorder.

BACKGROUND: Genetic factors play an important role in the pathogenesis of panic disorder (PD). However, the effect of genetic variants on PD remains controversial. AIM: To evaluate the associations between glutamate decarboxylase 1 (GAD1) gene polymorphisms and PD risk and assess the effect of GAD1 gene polymorphisms on the severity of clinical symptoms in PD. METHODS: We recruited 230 PD patients and 224 healthy controls in this study. All participants were assessed for anxiety and panic symptom severity using the Hamilton Anxiety Rating Scale (HAM-A) and Panic Disorder Severity Scale (PDSS). GAD1 gene polymorphisms (rs1978340 and rs3749034) were genotyped and assessed for allele frequencies. RESULTS: There were no significant differences between cases and controls in the genotype distributions or allele frequencies of GAD1 (rs1978340 and rs3749034). In addition, the effect of GAD1 (rs1978340 and rs3749034) on PD severity was not significant. However, regarding respiratory symptoms, patients with the GAD1 rs1978340 A/A genotype had significantly higher scores than those with the A/G or G/G genotype. CONCLUSION: Here, we showed that the A/A genotype of GAD1 rs1978340 was associated with increased severity of respiratory symptoms in patients with PD.

[Genetic Analysis of Thalassemia in 22 940 Pregnant Women in Xiangxi Tujia and Miao Autonomous Prefecture].

OBJECTIVE: To investigate the incidence and types of thalassemia in Xiangxi Tujia and Miao Autonomous Prefecture. METHODS: Automatic capillary electrophoresis was used to screen the thalassemia phenotypes of 22 940 blood samples of pregnant women and puerperants collected in our hospital and some other medical institutions in the prefecture during 2017-2019, among which there were 3 356 cases of Tujia ethnicity, 2 821 cases of Miao ethnicity, and 2 233 cases of Han ethnicity included, whose ethnicity were indicated. The samples with positive result would undergo further genetic testing. RESULTS: There were 2 314 cases of suspicious thalassemia were screened from 22 940 cases by the electrophoresis, thus the positive rate was 10.1% (hematological phenotypes from some other institutions were not included). Specifically, there were 1 706 cases with HBA2 less than 2.5%, 255 cases with HBA2 ranged from 2.5% to 3.5%, which displayed abnormal hematology (MCV or/and MCH) or other abnormal bands, and 353 cases with HBA2>3.5%. There were 436 suspected positive patients in 2 314 suspicious samples received further thalassemia gene testing in our hospital, among them 48 cases were diagnosed with α-thalassemia, 85 cases with ß-thalassemia, and 2 cases as compound type. The positive diagnosis rate of α-thalassemia gene test was 11.0%, ß-thalassemia was 19.4%, and positive pregnant women was 31.0%. CONCLUSION: The positive rate of thalassemia screening in Xiangxi Autonomous Prefecture is roughly the same as that in other regions of Hunan. The positive predictive value of ß-thalassemia screening is as high as 86%. Compared with the missed screening data, it is recommended to use hematology (MCV, MCH) method combined with capillary hemoglobin electrophoresis for thalassemia screening.

Treatment of atrial fibrillation with doxapram: TASK-1 potassium channel inhibition as a novel pharmacological strategy.

AIMS: TASK-1 (K2P3.1) two-pore-domain potassium channels are atrial-specific and significantly up-regulated in atrial fibrillation (AF) patients, contributing to AF-related electrical remodelling. Inhibition of TASK-1 in cardiomyocytes of AF patients was shown to counteract AF-related action potential duration shortening. Doxapram was identified as a potent inhibitor of the TASK-1 channel. In this study, we investigated the antiarrhythmic efficacy of doxapram in a porcine model of AF. METHODS AND RESULTS: Doxapram successfully cardioverted pigs with artificially induced episodes of AF. We established a porcine model of persistent AF in domestic pigs via intermittent atrial burst stimulation using implanted pacemakers. All pigs underwent catheter-based electrophysiological investigations prior to and after 14 days of doxapram treatment. Pigs in the treatment group received intravenous administration of doxapram once per day. In doxapram-treated AF pigs, the AF burden was significantly reduced. After 14 days of treatment with doxapram, TASK-1 currents were still similar to values of sinus rhythm animals. Doxapram significantly suppressed AF episodes and normalized cellular electrophysiology by inhibition of the TASK-1 channel. Patch-clamp experiments on human atrial cardiomyocytes, isolated from patients with and without AF could reproduce the TASK-1 inhibitory effect of doxapram. CONCLUSION: Repurposing doxapram might yield a promising new antiarrhythmic drug to treat AF in patients.

Novel Fatty Acid in Cordyceps Suppresses Influenza A (H1N1) Virus-Induced Proinflammatory Response Through Regulating Innate Signaling Pathways.

Influenza virus (IV) infections usually cause acute lung injury characterized by exaggerated proinflammatory responses. The paucity of therapeutic strategies that target host immune response to attenuate lung injury poses a substantial challenge in management of IV infections. In this study, we chemically synthesized a novel fatty acid (2Z,4E)-deca-2,4-dienoic acid (DDEA) identified from Chinese Cordyceps by using UHPLC-Q-TOF-MS techniques. The DDEA did not inhibit H1N1 virus replication but attenuated proinflammatory responses by reducing mRNA and protein levels of TNF-α, IFN-α, IFN-ß, IL-6, CXCL-8/IL-8, CCL-2/MCP-1, CXCL-10/IP-10, CCL-3/MIP-1α, and CCL-4/MIP-1ß in A549 cells and U937-derived macrophages. The anti-inflammatory effect occurred through downregulations of TLR-3-, RIG-I-, and type I IFN-activated innate immune signaling pathways. Altogether, our results indicate that DDEA may potentially be used as an anti-inflammatory therapy for the treatment of IV infections.

Association Between Mortality and Left Ventricular Ejection Fraction in Patients With Takotsubo Syndrome Versus Acute Coronary Syndrome.

BACKGROUND/AIM: The association between ejection fraction (EF) and mortality in TTS patients as compared to ACS is limited. This study aims to investigate the association between EF and clinical outcomes in patients with TTS as compared to ACS. PATIENTS AND METHODS: This study compared in-hospital, and long-term incidence of clinical outcomes for 5 years in patients with TTS and ACS. The study was composed of two groups EF≥35% and EF<35%. RESULTS: The long-term mortality of the EF≥35% for 5 years was significantly higher in TTS patients as compared to ACS (18.1% vs. 7.7%, log-Rank; p<0.01). Irrespective of EF, a non-cardiovascular death was significantly higher in TTS as compared to ACS patients with EF≥35 (6.4% vs. 2.1%; p=0.02) and with EF<35% (21.4% vs. 7.5%; p=0.03). CONCLUSION: The long-term mortality is significantly higher in TTS as compared to ACS dominated by a non-cardiovascular cause of death at 5-years-follow-up.

Improved Outcome of Cardiogenic Shock Triggered by Takotsubo Syndrome Compared With Myocardial Infarction.

BACKGROUND: Cardiogenic shock (CS) is a severe complication of myocardial infarction (MI) or of takotsubo syndrome (TTS). For both diseases, CS is related to a worse long-term outcome. The outcome of CS has not been studied in a direct comparison of patients with MI and patients with TTS. METHODS: Mortality and cardiovascular complications were compared in patients presenting with CS based on MI or TTS between 2003 and 2017 during a follow-up of 5 years. A total of 138 patients with TTS and 532 patients with MI were included. Of these, 66 patients with MI and 25 patients with TTS developed CS (12% vs 18%, P = 0.08). RESULTS: Patients with MI and CS had more often malignant arrhythmias (74% vs 28%, P < 0.01), and need for resuscitation (80% vs 24%, P < 0.01) or death (71% vs 24%, P < 0.01) than patients with TTS and CS during the first 30 days. Although the overall rate of death remained higher in MI than in TTS (75.8% vs 52%, log rank, P < 0.01), deaths occurred in TTS constantly throughout the follow-up time, but not in MI. The incidence of heart failure increased in MI but not in TTS (31.8% vs 4%, P < 0.01) during follow-up. CONCLUSIONS: Patients with MI and CS have a worse prognosis than patients with TTS and CS. This is driven by cardiovascular events or death during the first 30 days after the index event. However, patients with TTS and CS show high mortality as well, especially during long-term follow-up.

The Experimental TASK-1 Potassium Channel Inhibitor A293 Can Be Employed for Rhythm Control of Persistent Atrial Fibrillation in a Translational Large Animal Model.

BACKGROUND: Upregulation of the two-pore-domain potassium channel TASK-1 (hK2 P 3.1) was recently described in patients suffering from atrial fibrillation (AF) and resulted in shortening of the atrial action potential. In the human heart, TASK-1 channels facilitate repolarization and are specifically expressed in the atria. In the present study, we tested the antiarrhythmic effects of the experimental ion channel inhibitor A293 that is highly affine for TASK-1 in a porcine large animal model of persistent AF. METHODS: Persistent AF was induced in German landrace pigs by right atrial burst stimulation via implanted pacemakers using a biofeedback algorithm over 14 days. Electrophysiological and echocardiographic investigations were performed before and after the pharmacological treatment period. A293 was intravenously administered once per day. After a treatment period of 14 days, atrial cardiomyocytes were isolated for patch clamp measurements of currents and atrial action potentials. Hemodynamic consequences of TASK-1 inhibition were measured upon acute A293 treatment. RESULTS: In animals with persistent AF, the A293 treatment significantly reduced the AF burden (6.5% vs. 95%; P < 0.001). Intracardiac electrophysiological investigations showed that the atrial effective refractory period was prolonged in A293 treated study animals, whereas, the QRS width, QT interval, and ventricular effective refractory periods remained unchanged. A293 treatment reduced the upregulation of the TASK-1 current as well as the shortening of the action potential duration caused by AF. No central nervous side effects were observed. A mild but significant increase in pulmonary artery pressure was observed upon acute TASK-1 inhibition. CONCLUSION: Pharmacological inhibition of atrial TASK-1 currents exerts in vivo antiarrhythmic effects that can be employed for rhythm control in a porcine model of persistent AF. Care has to be taken as TASK-1 inhibition may increase pulmonary artery pressure levels.

Genetic Ablation of TASK-1 (Tandem of P Domains in a Weak Inward Rectifying K+ Channel-Related Acid-Sensitive K+ Channel-1) (K2P3.1) K+ Channels Suppresses Atrial Fibrillation and Prevents Electrical Remodeling.

BACKGROUND: Despite an increasing understanding of atrial fibrillation (AF) pathophysiology, translation into mechanism-based treatment options is lacking. In atrial cardiomyocytes of patients with chronic AF, expression, and function of tandem of P domains in a weak inward rectifying TASK-1 (K+ channel-related acid-sensitive K+ channel-1) (K2P3.1) atrial-specific 2-pore domain potassium channels is enhanced, resulting in action potential duration shortening. TASK-1 channel inhibition prevents action potential duration shortening to maintain values observed among sinus rhythm subjects. The present preclinical study used a porcine AF model to evaluate the antiarrhythmic efficacy of TASK-1 inhibition by adeno-associated viral anti-TASK-1-siRNA (small interfering RNA) gene transfer. METHODS: AF was induced in domestic pigs by atrial burst stimulation via implanted pacemakers. Adeno-associated viral vectors carrying anti-TASK-1-siRNA were injected into both atria to suppress TASK-1 channel expression. After the 14-day follow-up period, porcine cardiomyocytes were isolated from right and left atrium, followed by electrophysiological and molecular characterization. RESULTS: AF was associated with increased TASK-1 transcript, protein and ion current levels leading to shortened action potential duration in atrial cardiomyocytes compared to sinus rhythm controls, similar to previous findings in humans. Anti-TASK-1 adeno-associated viral application significantly reduced AF burden in comparison to untreated AF pigs. Antiarrhythmic effects of anti-TASK-1-siRNA were associated with reduction of TASK-1 currents and prolongation of action potential durations in atrial cardiomyocytes to sinus rhythm values. Conclusions Adeno-associated viral-based anti-TASK-1 gene therapy suppressed AF and corrected cellular electrophysiological remodeling in a porcine model of AF. Suppression of AF through selective reduction of TASK-1 currents represents a new option for antiarrhythmic therapy.

Drug Testing in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes From a Patient With Short QT Syndrome Type 1.

Short QT syndrome (SQTS) predisposes afflicted patients to sudden cardiac death. Until now, only one drug-quinidine-has been shown to be effective in patients with SQTS type 1(SQTS1). The objective of this study was to use human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from a patient with SQTS1 to search for potentially effective drugs for the treatment of SQTS1 patients. Patch clamp and single-cell contraction measurements were employed to assess drug effects. Ivabradine, mexiletine, and ajmaline but not flecainide, ranolazine, or amiodarone prolonged the action potential duration (APD) in hiPSC-CMs from an SQTS1 patient. Ivabradine, ajmaline, and mexiletine inhibited KCNH2 channel currents significantly, which may underlie their APD-prolonging effects. Under proarrhythmic epinephrine stimulation in spontaneously beating SQTS1 hiPSC-CMs, ivabradine, mexiletine, and ajmaline but not flecainide reduced the epinephrine-induced arrhythmic events. The results demonstrate that ivabradine, ajmaline, and mexiletine may be candidate drugs for preventing tachyarrhythmias in SQTS1 patients.

Impact of T-inversion on the outcome of Takotsubo syndrome as compared to acute coronary syndrome.

BACKGROUND: Previous studies revealed that patients with Takotsubo syndrome (TTS) have a higher mortality rate than the general population and a comparable mortality to acute coronary syndrome (ACS). Repolarisation abnormalities, namely T-wave amplitude, may provide incremental prognostic information, in addition to traditional risk factors in ACS. This study was performed to determine the short- and long-term prognostic impact of inverted T-waves in TTS patients, as compared to ACS patients. METHODS AND RESULTS: Our institutional database constituted a collective of 138 patients diagnosed with TTS from 2003 to 2017, as well as 532 patients suffering from ACS. Patients with TTS or with ACS (n = 138 per group) were matched for age and sex and assessed retrospectively and prospectively and divided into two groups, TTS with inverted T-waves (n = 123) and ACS with inverted T-waves (n = 80). In-hospital complications such as respiratory failure with the need of respiratory support (60.2% vs 6.3%; P < 0.01), thromboembolic events (13.8% vs 2.5%; P < 0.01) and cardiogenic shock (18.9% vs 8.8%; P = 0.05) were significantly more presented in TTS as compared to ACS patients. Among cardiovascular risk factors diabetes mellitus (23.6% vs 45.0%; P < 0.01) and arterial hypertension (57.7% vs 78.8%; P < 0.01) were more presented in ACS patients as compared to TTS patients. Short-term mortality was similar, however the long-term mortality of 5 years was significantly higher in the TTS group (25.2% vs 7.5%; P < 0.01). In univariate analysis were male gender, EF < 35%, GFR < 60 mL/min, cardiogenic shock, inotropic drugs and history of cancer predictors of 5-year mortality. The multivariate analysis showed only male gender (HR 2.7, 95% CI 1.1-6.5; P = 0.02), GFR < 60 mL/min (HR 2.8, 95% CI 1.2-6.0; P = 0.01) and history of cancer (HR 3.6, 95% CI 1.4-9.3; P < 0.01) as independent predictors of 5-year mortality. CONCLUSION: Rates of long-term mortality were significantly higher in TTS patients showing inverted T-waves compared with patients diagnosed with ACS with inverted T-waves. However, T-inversion was not an independent predictor of 5-year mortality in the multivariate analysis.

Impact of ST-segment elevation on the outcome of Takotsubo syndrome.

BACKGROUND: Recent studies have highlighted that Takotsubo syndrome (TTS), mimicking acute coronary syndrome (ACS), is associated with poor clinical outcome. TTS is associated with different repolarization disorders including ST-segment elevation. ST elevation myocardial infarction (STEMI) in ACS is associated with declined prognosis. However, the clinical and prognostic impact of ST-segment elevation on TTS remains lacking. AIM: The aim of this study was to determine the short- and long-term prognostic impact of ST-segment elevation on TTS patients as compared with STEMI patients. PATIENTS AND METHODS: Our institutional database constituted a consecutive cohort of 138 TTS patients and 138 ACS patients matched for age and sex. TTS patients (n=41) with ST-segment elevation were compared with ACS patients with ST-segment elevation (n=64). RESULTS: Chest pain was significantly more documented in STEMI patients as compared with TTS patients (48.8% vs 78.1%; P<0.01). Cardiovascular risk factors such as diabetes mellitus (12.2% vs 29.7%; P=0.02) were significantly more presented in STEMI patients. Although the initial left ventricular ejection fraction (LVEF) was more declined in TTS patients (39%±9% vs 45%±16%; P<0.01), the LVEF was more declined in STEMI patients at follow-up (54%±10% vs 45%±16%; P=0.04). Inhospital complications such as respiratory failure were significantly more presented in TTS patients (68.3% vs 20.3%; P<0.01). The short-term as well as the long-term morality was similar in both groups. In univariate analysis, male sex, ejection fraction (EF) <35%, glomerular filtration rate (GFR) <60 mL/min, cardiogenic shock, inotropic drugs, and history of cancer were predictors of 5-year mortality. CONCLUSION: Rates of the long-term mortality in TTS patients with ST elevations are comparable with STEMI patients.

Ion Channel Dysfunctions in Dilated Cardiomyopathy in Limb-Girdle Muscular Dystrophy.

BACKGROUND: Limb-Girdle muscular dystrophies (LGMD) are a heritable group of genetically determined disorders with a primary involvement of the pelvic or shoulder girdle musculature with partially cardiac manifestation, such as dilated cardiomyopathy (DCM) and life-threatening tachyarrhythmia. We report here that human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes from a patient with LGMD2I and DCM associated with recurrent ventricular tachycardia displayed ion channel dysfunction and abnormality of calcium homeostasis. METHODS: Dermal fibroblasts obtained from a patient with LGMD2I harboring a fukutin-related protein gene mutation (826C>A; Leu276Ile) and 3 healthy donors were reprogrammed to hiPSCs. The hiPSCs were differentiated into cardiomyocytes and used for biological and electrophysiological studies. RESULTS: Compared with hiPSC cardiomyocytes from the healthy donors, the hiPSC cardiomyocytes from the patient exhibited abnormal action potentials characterized by reduced amplitude and upstroke velocity. The peak and late Na channel currents (INa) as well as the peak L-type calcium channel currents were significantly reduced. The expression of SCN5A and CACNA1C was reduced in DCM cardiomyocytes, consistent with reduction of INa and L-type calcium channel currents. In addition, the rapidly activating delayed rectifier potassium current (IKr) was reduced, whereas the transient outward current (Ito) and slowly activating delayed rectifier potassium current (IKs) were similar in DCM and control cardiomyocytes. Finally, a significant reduction of systolic and diastolic intracellular Ca2+ concentrations was detected in DCM cardiomyocytes. CONCLUSIONS: This study demonstrates that patient-specific hiPSC cardiomyocytes can recapitulate some phenotypic properties of LGMD2I with DCM and provide a platform for studies on the cardiac events in LGMD.

Modeling Short QT Syndrome Using Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

BACKGROUND: Short QT syndrome (SQTS), a disorder associated with characteristic ECG QT-segment abbreviation, predisposes affected patients to sudden cardiac death. Despite some progress in assessing the organ-level pathophysiology and genetic changes of the disorder, the understanding of the human cellular phenotype and discovering of an optimal therapy has lagged because of a lack of appropriate human cellular models of the disorder. The objective of this study was to establish a cellular model of SQTS using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). METHODS AND RESULTS: This study recruited 1 patient with short QT syndrome type 1 carrying a mutation (N588K) in KCNH2 as well as 2 healthy control subjects. We generated hiPSCs from their skin fibroblasts, and differentiated hiPSCs into cardiomyocytes (hiPSC-CMs) for physiological and pharmacological studies. The hiPSC-CMs from the patient showed increased rapidly activating delayed rectifier potassium channel current (IKr) density and shortened action potential duration compared with healthy control hiPSC-CMs. Furthermore, they demonstrated abnormal calcium transients and rhythmic activities. Carbachol increased the arrhythmic events in SQTS but not in control cells. Gene and protein expression profiling showed increased KCNH2 expression in SQTS cells. Quinidine but not sotalol or metoprolol prolonged the action potential duration and abolished arrhythmic activity induced by carbachol. CONCLUSIONS: Patient-specific hiPSC-CMs are able to recapitulate single-cell phenotype features of SQTS and provide novel opportunities to further elucidate the cellular disease mechanism and test drug effects.

Ion Channel Expression and Characterization in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

BACKGROUND: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are providing new possibilities for the biological study, cell therapies, and drug discovery. However, the ion channel expression and functions as well as regulations in hiPSC-CMs still need to be fully characterized. METHODS: Cardiomyocytes were derived from hiPS cells that were generated from two healthy donors. qPCR and patch clamp techniques were used for the study. RESULTS: In addition to the reported ion channels, INa, ICa-L, ICa-T, If, INCX, IK1, Ito, IKr, IKs IKATP, IK-pH, ISK1-3, and ISK4, we detected both the expression and currents of ACh-activated (KACh) and Na+-activated (KNa) K+, volume-regulated and calcium-activated (Cl-Ca) Cl-, and TRPV channels. All the detected ion currents except IK1, IKACh, ISK, IKNa, and TRPV1 currents contribute to AP duration. Isoprenaline increased ICa-L, If, and IKs but reduced INa and INCX, without an effect on Ito, IK1, ISK1-3, IKATP, IKr, ISK4, IKNa, ICl-Ca, and ITRPV1. Carbachol alone showed no effect on the tested ion channel currents. CONCLUSION: Our data demonstrate that most ion channels, which are present in healthy or diseased cardiomyocytes, exist in hiPSC-CMs. Some of them contribute to action potential performance and are regulated by adrenergic stimulation.

Electrical dysfunctions in human-induced pluripotent stem cell-derived cardiomyocytes from a patient with an arrhythmogenic right ventricular cardiomyopathy.

Aims: Our aim is to investigate the arrhythmogenic mechanism in arrhythmogenic right ventricular cardiomyopathy (ARVC)-patients by using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Methods and results: Human-induced pluripotent stem cell-derived cardiomyocytes were generated from human skin fibroblasts of two healthy donors and an ARVC-patient with a desmoglein-2 (DSG2) mutation. Patch clamp, quantitative polymerase chain reaction, and calcium imaging techniques were employed for the study. The amplitude and maximal upstroke velocity (Vmax) of action potential (AP) in ARVC-cells were smaller than that in healthy donor cells, whereas the resting potential and AP duration (APD) was not changed. The reduced Vmax resulted from decreased peak sodium current. The reason for undetected changes in APD may be the counter-action of reduced transient outward, small conductance Ca2+-activated, adenosine triphosphate-sensitive, Na/Ca exchanger (INCX) currents, and enhanced rapidly delayed rectifier currents. Isoprenaline (Iso) reduced INCX and shortened APD in both donor and ARVC-hiPSC-CMs. However, the effects of Iso in ARVC-cells are significantly larger than that in donor cells. In addition, ARVC-hiPSC-CMs showed more frequently than donor cells arrhythmogenic events induced by adrenergic stimulation. Conclusion: Cardiomyocytes derived from the ARVC patient with a DSG2 mutation displayed multiple ion channel dysfunctions and abnormal cellular electrophysiology as well as enhanced sensitivity to adrenergic stimulation. These may underlie the arrhythmogenesis in ARVC patients.