Book of Abstracts - New Frontiers 2022

Abstracts of oral presentations

MECHANISMS OF THE RyR2R420Q CPVT MUTATION. LESSONS HUMAN CARDIOMYOCYTES DERIVED FROM INDUCED-PLURIPOTENT STEM CELLS

A. Val Blasco 1 , L. Yin 1 , P. Gerbaud 1 , E. Zorio 2 , R. Perrier 1 , J. P. Benitah 1 , A. M. Gomez 1

1 Inserm, UMR- S 1180, Université Paris Saclay, Châtenay -Malabry, France; 2 Hospital La Fe, Valencia, Spain Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an inherited disease manifested as syncope or sudden death in apparently healthy children or young adults. The RyR2 R420Q mutation was identified in a 14-year-old boy who died suddenly due to emotional stress. Firsts analyses in RyR2 R420Q in heterologous systems, showed loss of function at high [Ca 2+ ]i and gain of function at low [Ca 2+ ]i, and when this mutation was present in mice, the Ca 2+ sparks in pacemaker cells were markedly prolonged. We propose to elucidate the [Ca 2+ ]i handling in cardiomyocytes derived from pluripotent stem cells from patients with CPVT. We differentiated human induced-pluripotent stem cells into cardiomyocytes (h-iPS-CM) from men and women of the mentioned family, ones exhibiting the mutation RyR2R420Q and others without the mutation used as control. First, we measured the action potentials (AP) with microelectrodes and found that woman CPVT h-iPS-CMs presented longer cycle length and increased AP amplitude whereas man CPVT h-iPS CMs showed smaller cycle length and similar AP characteristics. Then, we found that Ca 2+ transients amplitude were higher for woman CPVT cells compared to control cells, whereas no changes were found for man h-iPS-CMs; however, Ca 2+ transients were similar after ISO perfusion. SR Ca 2+ load presented no differences between woman groups but the time decay constant of caffeine-evoked Ca 2+ transients were significantly faster in woman CPVT h-iPS-CMs. In contrast, man CPVT h-iPS-CMs presented reduced SR Ca 2+ load compared to control cells. In addition, analysis of Ca 2+ pro-arrhythmogenic events were significantly augmented in CPVT h-iPS-CMs compared to wt h-iPS-CMs both in man and woman cells and it was accentuated after ISO perfusion. The RyR2 R420Q mutation in CPVT h-iPS-CMs represents well the Ca 2+ handling characteristics seen in patients and provides a reliable model to study CPVT in human context.

Keywords: arrhythmias, cardiomyocyte, calcium handling, iPS-CM, ryanodine Receptor, CPVT

Funding:ANR

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