Comprehensive analyses of the inotropic compound omecamtiv mecarbil in rat and human cardiac preparations

Abstract

Omecamtiv mecarbil (OM), a myosin activator, was reported to induce complex concentration- and species-dependent effects on contractile function and clinical studies indicated a low therapeutic index with diastolic dysfunction at concentrations above 1 µM. To further characterize effects of OM in a human context and under different preload conditions, we constructed a setup that allows isometric contractility analyses of human induced pluripotent stem cell (hiPSC)-derived engineered heart tissues (EHTs). The results were compared to effects of OM on the very same EHTs measured under auxotonic conditions. OM induced a sustained, concentration-dependent increase in time-to-peak under all conditions (maximally 2-3 fold). Peak force, in contrast, was increased by OM only in human, but not rat EHTs and only under isometric conditions, varied between hiPSC lines and showed a biphasic concentration-dependency with maximal effects at 1 µM. Relaxation time tended to fall under auxotonic and strongly increase under isometric conditions, again with biphasic concentration-dependency. Diastolic tension concentration-dependently increased under all conditions. The latter was reduced by an inhibitor of the mitochondrial sodium calcium exchanger (CGP-37157). OM induced increases in mitochondrial oxidation in isolated cardiomyocytes, indicating that OM, an inotrope that does not increase intracellular and mitochondrial Ca2+, can induce mismatch between an increase in ATP and ROS production and unstimulated mitochondrial redox capacity. Taken together, we developed a novel setup well suitable for isometric measurements of EHTs. The effects of OM on contractility and diastolic tension are complex with concentration-, time-, species- and loading-dependent differences. Effects on mitochondrial function require further studies.

Detection of soluble suppression of tumorigenicity 2 and N-terminal B-type natriuretic peptide in a rat model of aortic regurgitation: differential responses to omecamtiv mecarbil

“…In such circumstances, NT-proBNP remained unchanged, whereas sST2 increased markedly in our study suggesting that passive muscle tension with OM has distinct and subtle deleterious effects in the setting of AR, not reliably assessed by modifications in NT-proBNP. Furthermore the effects of OM are concentration, time, and species-dependent [25].…”

Chronic activation of tubulin tyrosination in HCM mice and in human iPSC-engineered heart tissues improves heart function

“…Auxotonic contractions were measured until day 60 as previously described. [22][23][24] We also used a patient-derived heterozygous MYBPC3 (MYBPC3het; UKEi070-A) and its isogenic control (MYBPC3ic; UKEi070-A-1) hiPSC lines that were previously created. 12 MYBPC3het and MYBPC3ic hiPSC-cardiomyocytes (3-4 batches of differentiation of triplicates) were transduced with AAV9-TTL or AAV9-Empty (MOI 100,000) for 10 days and treated with 100 nM endothelin-1 (ET1) or vehicle (H 2 O) the last 3 days as previously described.…”

Reproducibility of drug-induced effects on the contractility of an engineered heart tissue derived from human pluripotent stem cells

“…Engineered heart tissues (EHTs) are three-dimensional (3D) in vitro cellular platforms containing cardiomyocytes ( Schaaf et al, 2011 ) differentiated from human pluripotent stem cells (hPSC-cardiomyocytes) ( Yamanaka, 2007 ; Burridge et al, 2012 ) and have demonstrated potential to predict cardiac drug effects from variations in their assayable functional outputs ( Matsa et al, 2014 ; Denning et al, 2016 ; Ribeiro et al, 2019 ). In these culture platforms, interconnected hPSC-cardiomyocytes forming a beating tissue are aligned between load-bearing deflectable micropost force sensors ( Eschenhagen et al, 2012 ) and can be assayed to provide functional results on drug-induced cardiac contractile effects ( Jacob et al, 2016 ; Mannhardt et al, 2016 ; Mannhardt et al, 2017 ; Saleem et al, 2020 ; Rhoden et al, 2022 ). Despite being primarily developed to determine cardiac contractility from the deflection of microposts ( Hansen et al, 2010 ), other cardiac properties have been assayed with EHTs, such as electrophysiology ( Eder et al, 2014 ), calcium cycle ( Stoehr et al, 2014 ), and metabolism and mitochondrial function ( Rhoden et al, 2022 ).…”

“…In these culture platforms, interconnected hPSC-cardiomyocytes forming a beating tissue are aligned between load-bearing deflectable micropost force sensors ( Eschenhagen et al, 2012 ) and can be assayed to provide functional results on drug-induced cardiac contractile effects ( Jacob et al, 2016 ; Mannhardt et al, 2016 ; Mannhardt et al, 2017 ; Saleem et al, 2020 ; Rhoden et al, 2022 ). Despite being primarily developed to determine cardiac contractility from the deflection of microposts ( Hansen et al, 2010 ), other cardiac properties have been assayed with EHTs, such as electrophysiology ( Eder et al, 2014 ), calcium cycle ( Stoehr et al, 2014 ), and metabolism and mitochondrial function ( Rhoden et al, 2022 ). Since adverse cardiac events are among the main causes for drug attrition ( Batta et al, 2020 ), new in vitro models like the EHT are sorely needed to predict such events in the early stages of drug development ( Pang et al, 2019 ).…”