Altered Electrical, Biomolecular, and Immunologic Phenotypes in a Novel Patient-Derived Stem Cell Model of Desmoglein-2 Mutant ARVC

Abstract

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive heart condition which causes fibro-fatty myocardial scarring, ventricular arrhythmias, and sudden cardiac death. Most cases of ARVC can be linked to pathogenic mutations in the cardiac desmosome, but the pathophysiology is not well understood, particularly in early phases when arrhythmias can develop prior to structural changes. Here, we created a novel human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of ARVC from a patient with a c.2358delA variant in desmoglein-2 (DSG2). These DSG2-mutant (DSG2Mut) hiPSC-CMs were compared against two wildtype hiPSC-CM lines via immunostaining, RT-qPCR, Western blot, RNA-Seq, cytokine expression and optical mapping. Mutant cells expressed reduced DSG2 mRNA and had altered localization of desmoglein-2 protein alongside thinner, more disorganized myofibrils. No major changes in other desmosomal proteins were noted. There was increased pro-inflammatory cytokine expression that may be linked to canonical and non-canonical NFκB signaling. Action potentials in DSG2Mut CMs were shorter with increased upstroke heterogeneity, while time-to-peak calcium and calcium decay rate were reduced. These were accompanied by changes in ion channel and calcium handling gene expression. Lastly, suppressing DSG2 in control lines via siRNA allowed partial recapitulation of electrical anomalies noted in DSG2Mut cells. In conclusion, the aberrant cytoskeletal organization, cytokine expression, and electrophysiology found DSG2Mut hiPSC-CMs could underlie early mechanisms of disease manifestation in ARVC patients.

Autophagy and Endoplasmic Reticulum Stress during Onset and Progression of Arrhythmogenic Cardiomyopathy

“…The altered expression of calcium handling proteins is in accordance with changes in intracellular Ca 2+ dynamics, which are a known hallmark of AC. They were studied and visualized in murine cardiomyocytes [ 89 , 90 ] as well as in human iPSC-derived cardiomyocytes [ 91 , 92 , 93 , 94 ]. Alterations included arrhythmogenic events such as early after depolarizations (EAD) and delayed after depolarizations (DAD) [ 89 , 93 ], reduced time to peak of intracellular Ca 2+ [ 94 ] and a reduced conduction velocity in affected myocardium [ 92 ].…”

“…They were studied and visualized in murine cardiomyocytes [ 89 , 90 ] as well as in human iPSC-derived cardiomyocytes [ 91 , 92 , 93 , 94 ]. Alterations included arrhythmogenic events such as early after depolarizations (EAD) and delayed after depolarizations (DAD) [ 89 , 93 ], reduced time to peak of intracellular Ca 2+ [ 94 ] and a reduced conduction velocity in affected myocardium [ 92 ]. In the case of murine cardiomyocytes, an increased frequency of spontaneous Ca 2+ release events was observed [ 89 , 90 ].…”

PDMS–PEG Block Copolymer and Pretreatment for Arresting Drug Absorption in Microphysiological Devices

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What’s New in Arrhythmogenic Cardiomyopathies

“…Furthermore, cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) have proven to be an effective In-vitro model for studying cardiac disease and have the potential to find possible therapeutic targets. A recently published study by Hawthorne RN et al presented a hiPSC-CM model of ARVC obtained from a patient with a new pathogenic DSG2 variant ( c.2358del (p.Asp787fs)), and showed an unique phenotype with altered DSG2 expression, increased inflammatory signaling and electrophysiological abnormalities in comparison to controls [ 7 ]. Patient-specific hiPSC experiments may enable researchers to discover specific pathophysiological pathways and assist to develop more precisely targeted therapies for various pathogenic situations including ACM.…”