The PPAR-γ inhibitor T0070907 normalizes impaired electro-mechanical properties of human-induced pluripotent stem cell-derived cardiomyocytes in DSC2 arrhythmogenic cardiomyopathy

Abstract

Arrhythmogenic cardiomyopathy (ACM) primarily involves right ventricle impairment and lethal arrhythmias. Hereditary forms of ACM are mostly caused by mutations in genes coding for desmosomal proteins. Histopathological hallmark includes fibrofatty replacement of myocardial tissue, which may involve transdifferentiation of cardiomyocytes into adipocyte cells through the PPAR-γ pathway. Comprehensive investigation of cardiomyocytes electro-mechanical properties during this process has never been undertaken. We aimed to assess the implication of the PPAR-γ pathway inhibition using T0070907 inhibitor. We used cardiomyocytes (hiPSC-CM) differentiated from an ACM patient-derived pluripotent stem cells (hiPSC) harbouring a mutation (R132 C) in the DSC2 gene. The control and DSC2 hiPSC were reprogrammed and differentiated into hiPSC-CM to examine gene expression, electro-mechanical properties (patch-clamp and video analysis) and calcium handling (fluorescence imaging) profiles. The DSC2 hiPSC-CM were cultured for 40 days in presence or absence of 1 μM T0070907. The RT-qPCR of both DSC2 patient's heart samples and hiPSC-CM showed an increase of PPAR-γ expression when compared to control cells. When compared to control hiPSC-CM, the DSC2 hiPSC-CM exhibited a shorter action potential duration, due to an increase of K+ current density. Culture of DSC2 hiPSC-CM with the PPAR-γ inhibitor normalized both the action potential duration and K+ current density. Differences were also found in both the calcium transient and mechanical properties between control, DSC2 and DSC2 with PPAR-γ hiPSC-CM. PPAR-γ pathway inhibition by T0070907 normalized the disrupted electro-mechanical properties in DSC2 hiPSC-CM. This result opens interesting perspectives for further studies of the adipogenesis pathway to prevent appearance of fibro-fatty adipose tissue in the ACM patient's heart.