Journal
JOURNAL OF PHARMACOLOGICAL AND TOXICOLOGICAL METHODS
Volume 99, Issue -, Pages -Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.vascn.2019.106612
Keywords
Methods; Stem cell-derived cardiomyocyte; Action potential; Comprehensive in vitro proarrhythmia assay (CiPA); Safety pharmacology; ICH S7B; Torsades de pointes (TdP) arrhythmia; hERG; Cardiac electrophysiology; Voltage-sensitive optical sensors
Categories
Funding
- Fundacion Alfonso Martin Escudero, Spain
- NIH [F32 HL128079]
- HESI
- Division of Cancer Treatment and Diagnosis of the National Cancer Institute
- National Cancer Institute, National Institutes of Health [HHSN261200800001E, R24 HL117756]
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Introduction: Voltage-sensitive optical (VSO) sensors offer a minimally invasive method to study the time course of repolarization of the cardiac action potential (AP). This Comprehensive in vitro Proarrhythmia Assay (CiPA) cross-platform study investigates protocol design and measurement variability of VSO sensors for preclinical cardiac electrophysiology assays. Methods: Three commercial and one academic laboratory completed a limited study of the effects of 8 blinded compounds on the electrophysiology of 2 commercial lines of human induced pluripotent stem-cell derived cardiomyocytes (hSC-CMs). Acquisition technologies included CMOS camera and photometry; fluorescent voltage sensors included di-4-ANEPPS, FluoVolt and genetically encoded QuasAr2. The experimental protocol was standardized with respect to cell lines, plating and maintenance media, blinded compounds, and action potential parameters measured. Serum-free media was used to study the action of drugs, but the exact composition and the protocols for cell preparation and drug additions varied among sites. Results: Baseline AP waveforms differed across platforms and between cell types. Despite these differences, the relative responses to four selective ion channel blockers (E-4031, nifedipine, mexiletine, and JNJ 303 blocking I-Kr, I-CaL, I-Na, and I-Ks, respectively) were similar across all platforms and cell lines although the absolute changes differed. Similarly, four mixed ion channel blockers (flecainide, moxifloxacin, quinidine, and ranolazine) had comparable effects in all platforms. Differences in repolarisation time course and response to drugs could be attributed to cell type and experimental method differences such as composition of the assay media, stimulated versus spontaneous activity, and single versus cumulative compound addition. Discussion: In conclusion, VSOs represent a powerful and appropriate method to assess the electrophysiological effects of drugs on iPSC-CMs for the evaluation of proarrhythmic risk. Protocol considerations and recommendations are provided toward standardizing conditions to reduce variability of baseline AP waveform characteristics and drug responses.
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