Abstract

In pre-clinical drug development, cardiac contraction analysis of potential drug candidates is one of the crucial steps to ensure a successful and reliable transition to clinical stages. The use of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) continues to increase in the assessment of safety and toxicological side effects of newly developed compounds, due to their reproducibility and low ethical concern. However, their premature phenotype causes issues concerning non-physiological responses and acute testing within limited timescales (min to h) after compound application remains the primary application so far, partly due to the inability of common cell-based assays to analyze cellular behavior reliably over prolonged periods of time.
Here we describe the bio-compliant 96-well FLEXcyte technology with its pro-maturation effect on hiPSC-CM maturation as well as its applicability for chronic cardiotoxicological studies. Cells from commercial sources were cultured on freely-swinging and hyper-elastic silicone membranes. Rhythmic contraction of the hiPSC-CMs resulted in dynamic deflection changes quantified by means of capacitive distance sensing. The resulting beat patterns were analyzed for essential inotropic parameters including amplitude, frequency, slopes of contraction and relaxation, area under curve and arrhythmic events.
Treatment of hiPSC-CM with positive inotropic compounds S-Bay K8644, isoproterenol and omecamtiv mecarbil exhibited physiological responses when plated on FLEXcyte plates confirming the pro-maturation effect of the native-like environment given by the membranes.
Additionally, 15 kinase inhibitors and 3 anthracyclines with well-known cardiotoxic profiles were selected to evaluate the reproducibility of clinical data. For the assessment of chronic compound effects, inotropic properties of the cells were recorded daily for five days. Compounds considered as clinically cardio-safe showed negative inotropic effects only at micromolar doses, while compounds with demonstrated cardiotoxic profiles showed both time and dose dependent inotropic effects as well as arrhythmic events at nanomolar concentrations.
Our results indicate that the FLEXcyte technology enables the assessment of physiologically relevant inotropic effects on hiPSC-CMs at an acute and chronic level beyond the current perspective of preclinical cardiac risk assessment.