Cardiomyocytes Derived From Pluripotent Stem Cells Recapitulate Electrophysiological Characteristics of an Overlap Syndrome of Cardiac Sodium Channel Disease

Abstract

Background-Pluripotent stem cells (PSCs) offer a new paradigm for modeling genetic cardiac diseases, but it is unclear whether mouse and human PSCs can truly model both gain-and loss-of-function genetic disorders affecting the Na ϩ current (I Na ) because of the immaturity of the PSC-derived cardiomyocytes. To address this issue, we generated multiple PSC lines containing a Na ϩ channel mutation causing a cardiac Na ϩ channel overlap syndrome. Method and Results-Induced PSC (iPSC) lines were generated from mice carrying the Scn5a 1798insD/ϩ (Scn5a-het) mutation. These mouse iPSCs, along with wild-type mouse iPSCs, were compared with the targeted mouse embryonic stem cell line used to generate the mutant mice and with the wild-type mouse embryonic stem cell line. Patch-clamp experiments showed that the Scn5a-het cardiomyocytes had a significant decrease in I Na density and a larger persistent I Na compared with Scn5a-wt cardiomyocytes. Action potential measurements showed a reduced upstroke velocity and longer action potential duration in Scn5a-het myocytes. These characteristics recapitulated findings from primary cardiomyocytes isolated directly from adult Scn5a-het mice. Finally, iPSCs were generated from a patient with the equivalent SCN5A 1795insD/ϩ mutation. Patch-clamp measurements on the derivative cardiomyocytes revealed changes similar to those in the mouse PSC-derived cardiomyocytes. Conclusion-Here, we demonstrate that both embryonic stem cell-and iPSC-derived cardiomyocytes can recapitulate the characteristics of a combined gain-and loss-of-function Na ϩ channel mutation and that the electrophysiological immaturity of PSC-derived cardiomyocytes does not preclude their use as an accurate model for cardiac Na ϩ channel disease. (Circulation. 2012;125:3079-3091.) Key Words: cell differentiation Ⅲ disease models, animal Ⅲ electrophysiology Ⅲ sodium channels Ⅲ pluripotent stem cells M ultiple cardiac arrhythmia syndromes, including long-QT syndrome type 3 (LQT3), Brugada syndrome (BrS), progressive cardiac conduction disease, and sinus node dysfunction, have been linked to mutations in SCN5A, the gene encoding the ␣-subunit of the cardiac sodium (Na ϩ ) channel. 1,2 Most SCN5A mutations associated with LQT3 act by disrupting fast inactivation of the Na ϩ channel, resulting in a persistent inward Na ϩ current (I Na ) during the action potential (AP) plateau phase, subsequently delaying ventricular repolarization and prolonging the QT interval (gain-of-function mutations). 3 In contrast, SCN5A mutations underlying BrS and conduction disease are loss-of-function mutations and are believed to reduce the total amount of available I Na as a result of expression of nonfunctional channels, impaired intracellular trafficking, and decreased membrane surface channel expression or through altered channel gating properties. 1,2 Editorial see p 3055 Clinical Perspective on p 3091Initially, it was believed that these arrhythmia syndromes constituted separate clinical entities, with individual SCN5A Received September 9...

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“…The green area defines the normal QT interval range for humans. Data are shown as mean ± SD: 1, (Malan et al , 2016); 2, (Rocchetti/Sala et al , unpublished); 3, (Zhang et al , 2014); 4, (Zhang et al , 2014); 5, (Davis et al , 2012); 6, (Rocchetti/Sala et al , unpublished); 7, (Bellin et al , 2013); 8, (Sala et al , 2016); 9, (Bizy et al , 2013); 10, (Ma et al , 2013); 11, (Ma et al , 2015); 12, (Ma et al , 2015); 13, (Gibson et al , 2014a); 14, (Itzhaki et al , 2011); 15, (Gibson et al , 2014c); 16, (Lu et al , 2014); 17, (Gibson et al , 2014b); 18, (Mehta et al , 2014). (B) and (C) Composition of extracellular buffers (B) and pipette solutions (C) for current clamp experiments.…”

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