Key result
Brugada syndrome iPSC-derived cardiomyocytes display reduced sodium current density and increased arrhythmogenic triggered activity.
Why the study?
Understanding of the human cellular phenotype of Brugada Syndrome has lagged due to lack of adequate human cellular models of the disorder.
Does CRISPR/Cas9 genome editing of SCN5A variants correct the pro-arrhythmic electrophysiological phenotype in iPSC-CMs derived from patients with Brugada Syndrome?
Does CRISPR/Cas9 genome editing of SCN5A variants correct the pro-arrhythmic electrophysiological phenotype in iPSC-CMs derived from patients with Brugada Syndrome?
Patient-specific iPSC-CMs successfully recapitulate the single-cell electrophysiological abnormalities of Brugada Syndrome, which can be reversed by CRISPR/Cas9 genome editing of the causative SCN5A variant.
Background Brugada Syndrome is a disorder associated with characteristic ECG precordial ST elevation and predisposes afflicted patients to ventricular fibrillation and sudden cardiac death. Despite marked achievements in outlining the organ level pathophysiology of the disorder, the understanding of human cellular phenotype has lagged due to lack of adequate human cellular models of the disorder. Methods and Results We recruited two patients with Type 1 Brugada Syndrome (BrS) carrying two different SCN5A variants and two healthy controls. We generated induced pluripotent stem cells (iPSCs) from their skin fibroblasts by using integration-free Sendai virus. We utilized directed differentiation to create purified populations of iPSC-derived cardiomyocytes (iPSC-CMs). BrS iPSC-CMs showed reductions in inward Na+ current density and reduced maximal upstroke velocity of action potential compared to healthy control iPSC-CMs. Furthermore, BrS iPSC-CMs showed increased burden of triggered activity, abnormal Ca2+ transients, and beating interval variation. Correction of the causative variant by genome editing was performed and resultant iPSC-CMs showed resolution of triggered activity and abnormal Ca2+ transients. Gene expression profiling of iPSC-CMs showed clustering of BrS compared to controls. Furthermore, BrS iPSC-CM gene expression correlated with gene expression from BrS human cardiac tissue gene expression. Conclusions Patient-specific iPSC-CMs are able to recapitulate single cell phenotype features of BrS, including blunted inward sodium current, increased triggered activity and abnormal Ca2+ handling. This novel human cellular model creates future opportunities to further elucidate cellular disease mechanism and identify novel therapeutic targets.
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Liang et al. (2016) studied Brugada Syndrome (n=4). SCN5A variants vs. Healthy controls was evaluated on Peak INa density at -20 mV (pA/pF). iPSC-derived cardiomyocytes from Brugada Syndrome patients exhibited reduced inward sodium current density, increased triggered activity, and abnormal calcium transients compared to healthy controls.
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