Atrial fibrillation in a dish: insights into atrial arrhythmogenesis from induced pluripotent stem cell-derived cardiomyocytes

Abstract Background Pathogenic variants in Lamin A/C (LMNA) gene are the most common monogenic etiology in Familial Partial Lipodystrophy (FPLD) causing FPLD2. LMNA pathogenic variants have been previously associated with cardiomyopathy, familial arrhythmias or conduction system abnormalities independent of lipodystrophy. We aimed to assess cardiac impacts of FPLD, and to explore the extent of overlap between cardiolaminopathies and FPLD. Methods We conducted a retrospective review of an established cohort of 122 patients (age range: 13-77, M/F 21/101) with FPLD from Michigan (n = 83) and Turkey (n = 39) with an accessible cardiac evaluation. Also, functional syncytia of mature human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from a FLPD2 patient was studied for assessment of autonomous rhythm and action potential duration with optical mapping using a voltage sensitive dye. Results In the whole study cohort, 95 (78%) patients had cardiac alterations (25% ischemic heart disease, 36% arrhythmia, 16% conduction abnormality, 20% prolonged QT interval, 11% cardiomyopathy, and 15% congestive heart failure). The likelihood of having an arrhythmia (OR; 3.95, 95% CI: 1.49-10.49) and conduction disease (OR: 3.324, 95% CI: 1.33-8.31) was significantly higher in patients with LMNA pathogenic variants. Patients with LMNA pathogenic variants were at high risk for atrial fibrillation/flutter (OR: 6.77, 95% CI: 1.27- 39.18). The time to first arrhythmia was significantly shorter in the LMNA group with a higher hazard rate of 3.04 (95% CI: 1.29-7.17, p = 0.032). Non-482 LMNA pathogenic variants were more likely to be associated with cardiac events (vs. 482 LMNA: OR: 4.74, 95% CI: 1.41- 15.98 for arrhythmia; OR: 17.67, 95% CI: 2.44- 127.68 for atrial fibrillation/flutter; OR: 5.71, 95% CI: 1.37- 23.76 for conduction disease. hiPSC-CMs from a FPLD2 patient had higher frequency of autonomous activity, and shorter Fridericia corrected action potential duration at 80% repolarization compared to control cardiomyocytes. Furthermore, FPLD2 functional syncytia of mature hiPSC-CMs presented several rhythm alterations such as early after-depolarizations, spontaneous quiescence and spontaneous tachyarrhythmia; none of those were observed in the control cell lines. Finally, FPLD2 hiPSC-CMs presented significantly slower recovery in chronotropic changes induced by isoproterenol exposure; which indicates disrupted beta-adrenergic response. Conclusion Our results suggest the need for vigilant cardiac monitoring in FPLD, especially in patients with FPLD2 who have an increased risk to develop cardiac arrhythmias and conduction system diseases. In addition, study of human induced pluripotent stem cell-derived cardiomyocytes may prove useful to understand the mechanism of cardiac disease and arrhythmias and to create precision therapy opportunities in the future.

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Abstract 16472: Deciphering a Mechanistic Link Between Enhanced Late Sodium Current and Triggered Atrial Fibrillation Using Patient-specific and Gene-corrected Induced Pluripotent Stem Cell-derived Atrial Cardiomyocytes

Circulation ◽

10.1161/circ.142.suppl_3.16472 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Liang HONG ◽

Olivia T Ly ◽

Hanna Chen ◽

Arvind Sridhar ◽

Meihong Zhang ◽

...

Keyword(s):

Nitric Oxide ◽

Atrial Fibrillation ◽

Stem Cell ◽

Pluripotent Stem Cell ◽

Sodium Current ◽

Induced Pluripotent Stem Cell ◽

Patient Specific ◽

Gain Of Function ◽

Late Sodium Current ◽

Induced Pluripotent

Introduction: Gain-of-function mutations in SCN5A, which encodes the cardiac sodium channel, have been linked with familial atrial fibrillation (AF). However, the mechanistic link between the late sodium current (I Na,L ) and triggered arrhythmia remains unclear. Hypothesis: To characterize the electrophysiological (EP) phenotype of gain-of-function AF-linked SCN5A mutations, elucidate the underlying cellular mechanisms using patient-specific and gene-corrected (GC) induced pluripotent stem cell-derived atrial cardiomyocytes (iPSC-aCMs). Methods: We generated iPSC-aCMs from two families carrying SCN5A mutations (E428K and N470K) and control subjects. Whole-cell patch clamp and multi-electrode arrays were recorded to assess the EP phenotypes of the atrial iPSC-CMs. We corrected the E428K iPSC-aCMs using CRISPR/Cas9 gene editing approach (isogenic control). Results: The SCN5A mutation lines displayed abnormal EP properties including increased beating frequency and irregularity with triggered beats characteristic of AF ( Fig. 1 ). E428K iPSC-aCMs displayed spontaneous arrhythmogenic activity with beat-to-beat irregularity ( Fig. 1 A-D ) with the prolonged APD ( Fig. 1 E-H ) associated with enhanced I Na,L ( Fig. 1 I-L ). In contrast, expression of SCN5A -E428K in heterologous expression system failed to show enhanced I Na,L . The gene-corrected E428K iPSC-aCMs normalized the aberrant EP phenotype. Gene expression profiling revealed differential expression of calcium and potassium channel homeostasis and nitric oxide mediated signal transduction which could result in EP remodeling of atrial CMs. Conclusions: Patient-specific and gene-corrected iPSC-aCMs exhibited striking ex-vivo EP phenotype of an AF-causing SCN5A gain-of-function mutation that produced minimal changes in-vitro . We established a mechanistic link between enhanced I Na,L , ion channel remodeling and nitric oxide signaling pathways, and triggered AF.

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