1型カテコラミン誘発性多形性心室頻拍(CPVT)iPS細胞から作製した単一の心筋細胞の活動電位とカルシウムイオン濃度の変化を同時光学記録

2025-06-10

2025-06-10 京都大学iPS細胞研究所

京都大学iPS細胞研究所の研究チームは、1型カテコラミン誘発性多形性心室頻拍(CPVT)患者由来iPS細胞から作製した単一の心筋細胞において、活動電位とカルシウムイオン濃度の変化を同時に光学記録する新たなシステムを構築した。この技術により、CPVT特有のカルシウム異常と心室筋型活動電位の関連が明確になり、既存薬(カルベジロール、フレカイニド)の効果が限定的である一方、JTV519やKN-93がカルシウム異常を改善する可能性が確認された。本成果は、心疾患治療薬の評価・開発に新たな指標を提供する。

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1型CPVT-iPS細胞から分化した心臓単細胞における活動電位とカルシウム過渡変化の同時光学記録
Simultaneous optical recording of action potentials and calcium transients in cardiac single cells differentiated from type 1 CPVT-iPS cells

Tadashi Takaki,Norihisa Tamura,Kenichi Imahashi,Tomoyuki Nishimoto,Yoshinori Yoshida
Frontiers in Physiology Published:04 June 2025
DOI:https://doi.org/10.3389/fphys.2025.1579815

Numerous reports investigating channelopathies, including Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), have successfully reproduced using cardiomyocytes (CMs) differentiated from human induced pluripotent stem cells (hiPSCs). However, the relationship between action potentials (AP) and calcium transient waveforms—especially after drug treatment—remains unclear. In this study, we simultaneously loaded a membrane potential dye FluoVolt and the new calcium indicator Calbryte^TM 590 AM and optimized stimulation and detection of both dyes to successfully obtain a higher signal-to-noise (S/N) ratio than the conventional membrane potential dye-red fluorescence Ca²⁺ dye combination, thus enabling the simultaneous recording of both AP and calcium transient waveforms in single hiPSC-CMs, which continued even after gradual increases in drug concentration. In drug-loading experiments on CPVT1 (RyR2-I4587V) hiPSC-derived ventricular-like CMs, carvedilol and flecainide demonstrated some effectiveness, while JTV519 at 3 µM exhibited both efficacy and alterations in AP waveforms. The Ca²⁺/calmodulin-dependent serine-threonine protein kinase II (CaMKII) inhibitor KN-93 at 1 µM was highly effective (93%) at reducing Ca²⁺ transient abnormalities without altering AP waveforms.