Transient rise of cytosolic free calcium ion concentrations ([Ca2+ ]i) plays a pivotal role in cardiomyocyte contraction which in turn is the basis of the vital function of the heart. The rise and duration of the transients [Ca2+ ]i are carefully controlled by a mechanism called the calcium-induced calcium release during an action potential of cardiac myocytes. Any direct acute drug effect, including interference with ion channels, pumps, exchangers and hormone receptors involved in human cardiomyocyte action potential and heart rate control can be detected by monitoring [Ca2+ ]i transients which makes it a valuable tool in drug discovery and safety pharmacology.
Cor.4U® have been introduced into validation studies including the CiPA (Comprehensive in vitro Proarrhythmia Assay) initiative lead by HESI (Health and Environment Science Institute) in the USA and the CSAHi (Consortium of Safety Assessment using Human iPS Cells)/JiCSA (Japan iPS Cardiac Safety Assessment)3 in Japan. The aim of these studies is to validate human stem cell-derived cardiomyocytes for safety pharmacological studies in order to modify or substitute the existing guidelines ICHS7a/b and to eliminate the guideline E14. In the CiPA validation study calcium transient measurements are one of three methods to assess pro- arrhythmic effects on a subset of blinded compounds in Cor.4U® cardiomyocytes.
FDSS® plate reader accurately assesses drug-induced changes of Cor.4U® calcium transient parameters:
Cor.4U® are applicable on FDSS® plate readers to high throughput screening and represent a cost- effective, robust and fast assay to assess cardiotoxicity and drug efficacy early in the drug development process.
(2A) Astemizole (0.5 nM - 10 μM), (2B) Ivabradine (1 nM - 6.667 μM) and (2C) ATX-II (0.005 nM - 100 nM). Analyzed parameters are average peak width (80%) for Astemizole and ATX-II and beating frequency for all three compounds.