Project description:Abnormalities of ventricular action potential (AP) cause malignant cardiac arrhythmias and sudden cardiac death. Here, we sought to identify microRNAs (miRNAs) that regulate the human cardiac AP and asked whether their manipulation allows for therapeutic modulation of AP abnormalities. Quantitative analysis of the miRNA targetomes in human cardiac myocytes identified miR-365 as a primary miRNA to regulate repolarizing ion channels. AP recordings in patient-specific induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) showed that elevation of miR-365 level significantly prolonged AP duration in hiPSC-CMs derived from a Short-QT syndrome (SQTS) patient, whereas specific inhibition of miR-365 normalized pathologically prolonged AP in Long-QT syndrome (LQTS) iPSC-CMs. Transcriptome analyses in human iPSC-CMs at bulk and single-cell level corroborated the key cardiac repolarizing channels as direct targets of miR-365, together with functionally synergistic regulation of additional AP-regulating genes by this miRNA. Whole-cell patch clamp experiments revealed miR-365-based regulation of repolarizing ionic currents. Finally, refractory period measurements in human myocardial slices substantiated the prolonging effect of miR-365 on AP duration also in adult human myocardial tissue. Our results delineate miR-365 to regulate human cardiac AP duration by targeting key factors of cardiac repolarization.
Project description:Abnormalities of ventricular action potential (AP) cause malignant cardiac arrhythmias and sudden cardiac death. Here, we sought to identify microRNAs (miRNAs) that regulate the human cardiac AP and asked whether their manipulation allows for therapeutic modulation of AP abnormalities. Quantitative analysis of the miRNA targetomes in human cardiac myocytes identified miR-365 as a primary miRNA to regulate repolarizing ion channels. AP recordings in patient-specific induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) showed that elevation of miR-365 level significantly prolonged AP duration in hiPSC-CMs derived from a Short-QT syndrome (SQTS) patient, whereas specific inhibition of miR-365 normalized pathologically prolonged AP in Long-QT syndrome (LQTS) iPSC-CMs. Transcriptome analyses in human iPSC-CMs at bulk and single-cell level corroborated the key cardiac repolarizing channels as direct targets of miR-365, together with functionally synergistic regulation of additional AP-regulating genes by this miRNA. Whole-cell patch clamp experiments revealed miR-365-based regulation of repolarizing ionic currents. Finally, refractory period measurements in human myocardial slices substantiated the prolonging effect of miR-365 on AP duration also in adult human myocardial tissue. Our results delineate miR-365 to regulate human cardiac AP duration by targeting key factors of cardiac repolarization.
Project description:Abnormalities of ventricular action potential (AP) cause malignant cardiac arrhythmias and sudden cardiac death. Here, we sought to identify microRNAs (miRNAs) that regulate the human cardiac AP and asked whether their manipulation allows for therapeutic modulation of AP abnormalities. Quantitative analysis of the miRNA targetomes in human cardiac myocytes identified miR-365 as a primary miRNA to regulate repolarizing ion channels. AP recordings in patient-specific induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) showed that elevation of miR-365 level significantly prolonged AP duration in hiPSC-CMs derived from a Short-QT syndrome (SQTS) patient, whereas specific inhibition of miR-365 normalized pathologically prolonged AP in Long-QT syndrome (LQTS) iPSC-CMs. Transcriptome analyses in human iPSC-CMs at bulk and single-cell level corroborated the key cardiac repolarizing channels as direct targets of miR-365, together with functionally synergistic regulation of additional AP-regulating genes by this miRNA. Whole-cell patch clamp experiments revealed miR-365-based regulation of repolarizing ionic currents. Finally, refractory period measurements in human myocardial slices substantiated the prolonging effect of miR-365 on AP duration also in adult human myocardial tissue. Our results delineate miR-365 to regulate human cardiac AP duration by targeting key factors of cardiac repolarization.
Project description:Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by MeCP2 mutation. However, the pathophysiological roles of MeCP2 mutation in the aetiology of QT prolongation and sudden death remain unclear. Here, we performed RNA sequencing-based transcriptome analysis in a pair of isogenic RTT female patient-specific induced pluripotent stem cell derived-cardiomyocytes (iPSC-CMs) that expresses either MeCP2wildtype or MeCP2mutant allele, and iPSC-CMs from a non-disease female control. The result revealed up-regulation of various WNT family genes in MeCP2mutant iPSC-CMs.
Project description:In this study, a comprehensive evaluation model for studying the cardiac toxicity of antipsychotic drugs was established by using iPSC-CMs. Six antipsychotic drugs, including aripiprazole, risperidone, quetiapine, haloperidol, clozapine, and olanzapine, all induced concentration-dependent QT prolongation in iPSC-CMs upon acute administration, and high concentrations of these drugs caused disorganized sarcomere arrangement in iPSC-CMs.
Project description:Cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs) or directly reprogrammed from non-myocytes (induced cardiomyocytes, iCMs) are promising sources for heart regeneration or disease modeling. However, the similarities and differences between iPSC-CM and iCM are still unknown. Here we performed transcriptome analyses of beating iPSC-CMs and iCMs generated from cardiac fibroblasts (CFs) of the same origin. Although both iPSC-CMs and iCMs establish CM-like molecular features globally, iPSC-CMs exhibit a relatively hyperdynamic epigenetic status while iCMs exhibit maturation status that more resemble adult CMs. Based on gene expression of metabolic enzymes, iPSC-CMs primarily employ glycolysis while iCMs utilize fatty acid oxidation as the main pathway. Importantly, iPSC-CMs and iCMs exhibit different cell cycle status, alteration of which influenced their maturation. Therefore, our study provides a foundation for understanding the pros and cons of different reprogramming approaches.
Project description:BACKGROUND: Brugada syndrome (BrS) is an inherited arrhythmia syndrome caused by loss-of-function variants in the cardiac sodium channel gene SCN5A (sodium voltage-gated channel alpha subunit 5) in ≈20% of subjects. We identified a family with 4 individuals diagnosed with BrS harboring the rare G145R missense variant in the cardiac transcription factor TBX5 (T-box transcription factor 5) and no SCN5A variant. METHODS: We generated induced pluripotent stem cells (iPSCs) from 2 members of a family carrying TBX5-G145R and diagnosed with Brugada syndrome. After differentiation to iPSC-derived cardiomyocytes (iPSC-CMs), electrophysiologic characteristics were assessed by voltage- and current-clamp experiments (n=9 to 21 cells per group) and transcriptional differences by RNA sequencing (n=3 samples per group), and compared with iPSC-CMs in which G145R was corrected by CRISPR/Cas9 approaches. The role of platelet-derived growth factor (PDGF)/phosphoinositide 3-kinase (PI3K) pathway was elucidated by small molecule perturbation. The rate-corrected QT (QTc) interval association with serum PDGF was tested in the Framingham Heart Study cohort (n=1893 individuals). RESULTS: TBX5-G145R reduced transcriptional activity and caused multiple electrophysiologic abnormalities, including decreased peak and enhanced “late” cardiac sodium current (INa), which were entirely corrected by editing G145R to wildtype. Transcriptional profiling and functional assays in genome-unedited and -edited iPSC-CMs showed direct SCN5A downregulation caused decreased peak INa, and that reduced PDGF receptor (PDGFRA [platelet-derived growth factor receptor α]) expression and blunted signal transduction to PI3K was implicated in enhanced late INa. Tbx5 regulation of the PDGF axis and increased arrhythmia risk with disruption of PDGF sigaling were both conserved in murine model systems. PDGF receptor blockade markedly prolonged normal iPSC-CM action potentials and plasma levels of PDGF in the Framingham Heart Study were inversely correlated with the QTc interval (P
Project description:Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) hold tremendous promise for in vitro modeling to assess native myocardial function and disease mechanisms as well as testing drug safety and efficacy. However, current iPSC-CMs are functionally immature, resembling in vivo CMs of fetal or neonatal developmental states. The use of targeted culture media and organoid formats have been identified as potential high-yield contributors to improve CM maturation. This study presents a novel iPSC-CM maturation medium formulation, designed using a differential evolutionary approach with oxidative capacity as an objective metric for iterative optimization. Relative to gold-standard reference formulations, our approach significantly matured morphology, Ca2+ handling, electrophysiology, and metabolism, which was further validated by multi-omic screening, for cells in either pure or co-cultured microtissue formats. Together, these findings not only provide a reliable workflow for highly functional iPSC-CMs for downstream use, but also demonstrate the power of high-dimensional optimization processes in evoking advanced biological function in vitro.
Project description:Our study aims to illustrate the potential use of atrial iPSC-CMs for modeling AF in a dish, elucidating the underlying cellular mechanisms, and identifying novel mechanism-based therapies custom-tailored for individual patients