Role of lipotoxicity in triggering electrophysiologic changes in induced pluripotent stem cell-derived cardiomyocytes from patients with arrhythmogenic right ventricular cardiomyopathy

Mohamed Elsaied (Jena)1, S. Hübner (Jena)1, J. Bogoviku (Jena)1, J. G. Westphal (Jena)1, T. Kretzschmar (Jena)1, C. Schulze (Jena)1

1Universitätsklinikum Jena Klinik für Innere Medizin I - Kardiologie Jena, Deutschland


Introduction: Arrhythmogenic right ventricular cardiomyopathy (ARVC) remains a clinical challenge which leads to increased sudden cardiac death (SCD) in young people. We hypothesized that lipotoxic conditions could play an important role in early, concealed arrhythmogenesis associated with PKP2 mutations in patients in triggering ARVC events.

Methods and results: We used patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to recapitulate the pathological signatures of ARVC to study the disease development and progression. We generated three patient-specific iPSC lines from peripheral blood mononuclear cells obtained from two patients harboring a PKP2 heterozygous mutation and one a healthy control (WT) donor. By studying CMs differentiating from the PKP2-iPSCs and exposed to high fatty acid (HFA), we were able to identify (1) significant desmosomal abnormalities in the PKP2-hiPSC-CMs in both the electron microscopy studies and the PKP2 as well as plakoglobin protein/gene analysis; (2) demonstrate the effect of desmosomal remodeling on the associated intercalated disc structure gap junction; (3) reveal the accumulation of lipid droplets in the PKP2-CMs and the upregulation of the pro-adipogenic transcription factor PPARγ (2.7 ± 0.89 and 5.06±1.37 versus 1.0 ± 0.28, respectively; p < 0.001); (4) identify a clear correlation between the degree of desmosomal abnormalities in the PKP2-CMs and the probability for lipid accumulation in the same cells; and (5) a reduction in the mRNA levels of Wnt1 and Catenin-ß1 in the PKP2-hiPSC-CMs.

Further, our electrophysiological data showed that the CMs differentiated from iPSC are physiologically functional. Beating rate only decreased in both CMs derived from patients harbing PKP2 mutation following cultivated in HFA condition. In addition, clear alterations of CMs trace recorded and significant increase (p < 0.001) in a beat period as well as the field potential duration (FPD) of PKP2-CMs (290±70) after exposed to HFA (500±80) in compared to control (WT) CM (310±90).

Out of 630 measurable metabolites in plasma that were analyzed by LC-MS/MS and using MxP Quant 500 kit, 546 metabolites had valid values and showed 354 significant metabolites. Further, intracellular CMs metabolites showed 521 metabolites had valid values and showed 220 significant metabolites. As promising results to detect an early potential marker for ARVC, we can detect in PKP2-iPSC-CMs under HFA and in plasma of ARVC patient many marker such as, AC C14:1-OH, AC C3-DC (C4-OH), kynurenine, creatinine, and 1-Met-His, which have previously been identified as metabolic biomarkers in  patients with various forms of heart disease.

Conclusion:  The results of our study demonstrate the ability of lipogenic stress to worsen the ARVC phenotype and intramyocardial lipid accumulation may have at least a partial role in Wnt/β-catenin signaling in the molecular pathogenesis of ARVC disease. Elucidation of the precise regulatory mechanism of Wnt/β-catenin signaling in ARVC molecular pathogenesis could provide fundamental insights for new mechanism based therapeutic strategy to delay the onset or progression of this cardiac disease.

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