Alain Labro, Gent University, Belgium

Alain Labro, PhD
Ghent University, Department of Basic and Applied Medical Sciences, Belgium

Abstract

During the development of drugs, compounds are evaluated for their effect on cardiac ion channels to prevent adverse drug effects later on during clinical evaluation. One of the first preclinical tests to detect pro-arrhythmic liabilities involves evaluating the impact of compounds on specific cardiac ion channels expressed in heterologous cell models. While testing procedures for assessing the acute effects of compounds are well-established, there is a lack of standardized protocols for evaluating delayed effects. The manifestations of these delayed effects occur after approximately 24 hours, or even longer, as they do not affect ion channels directly. Instead, these compounds affect the expression of ion channels at the plasma membrane and are mostly detected at later stages when the compound is evaluated on iPSC derived cardiomyocytes or in animal testing. The detection of these delayed effects in heterologous cell models remains challenging. The exclusion of fetal bovine serum (FBS) from culturing conditions might be a solution when investigating the effect of delayed-action compounds on current expression. FBS starvation induces cell-cycle synchronization, prompting cells to transition into G0 quiescence and consequently reducing cell variability. Furthermore, interaction of serum protein with the compound is eliminated. Additionally, FBS composition is poorly defined and batch-to-batch variability cannot be disregarded. Therefore, excluding FBS from cell culturing conditions may result in more consistent and reproducible results. Furthermore, in case of the slow delayed rectifier potassium current (IKs), serum starvation increased the sensitivity to detect delayed effects of the compound probucol after 24 hours of incubation.

Expertise

Electrophysiology
Ion channel biophysics
Ion channel pharmacology