Abstract
The SGLT2 inhibitor empagliflozin improved cardiovascular outcomes in patients with diabetes. As the cardiac mechanisms remain elusive, we investigated the long-term effects (up to 2 months) of empagliflozin on excitation-contraction (EC)-coupling in human cardiomyocytes derived from induced pluripotent stem cells (iPSC-CM) in a blinded manner. IPSC from 3 donors, differentiated into pure iPSC-CM (4 differentiations), were treated with a clinically relevant concentration of empagliflozin (0.5 μmol/l) or vehicle control. Treatment, data acquisition, and analysis were conducted externally blinded. Epifluorescence microscopy measurements in iPSC-CM showed that empagliflozin has neutral effects on Ca2+ transient amplitude, diastolic Ca2+ levels, Ca2+ transient kinetics, or sarcoplasmic Ca2+ load after 2 weeks or 8 weeks of treatment. Confocal microscopy determining possible effects on proarrhythmogenic diastolic Ca2+ release events showed that in iPSC-CM, Ca2+ spark frequency and leak was not altered after chronic treatment with empagliflozin. Finally, in patch-clamp experiments, empagliflozin did not change action potential duration, amplitude, or resting membrane potential compared with vehicle control after long-term treatment. Next-generation RNA sequencing (NGS) and mapped transcriptome profiles of iPSC-CMs untreated and treated with empagliflozin for 8 weeks showed no differentially expressed EC-coupling genes. In line with NGS data, Western blots indicate that empagliflozin has negligible effects on key EC-coupling proteins. In this blinded study, direct treatment of iPSC-CM with empagliflozin for a clinically relevant duration of 2 months did not influence cardiomyocyte EC-coupling and electrophysiology. Therefore, it is likely that other mechanisms independent of cardiomyocyte EC-coupling are responsible for the beneficial treatment effect of empagliflozin.Key messagesThis blinded study investigated the clinically relevant long-term effects (up to 2 months) of empagliflozin on cardiomyocyte excitation-contraction (EC)-coupling.Human cardiomyocytes derived from induced pluripotent stem cells (iPSC-CM) were used to study a human model including a high repetition number of experiments.Empagliflozin has neutral effects on cardiomyocyte Ca2+ transients, sarcoplasmic Ca2+ load, and diastolic sarcoplasmic Ca2+ leak.In patch-clamp experiments, empagliflozin did not change the action potential.Next-generation RNA sequencing, mapped transcriptome profiles, and Western blots of iPSC-CM untreated and treated with empagliflozin showed no differentially expressed EC-coupling candidates.
Highlights
Extended author information available on the last page of the articleThe antidiabetic drug empagliflozin, which inhibits the sodium-dependent glucose cotransporter 2 (SGLT2) in the kidney, has been shown to reduce cardiovascular mortality, all-cause mortality, and hospitalization rates for heart failure (HF) in patients at high cardiovascular risk and type 2 diabetesJ Mol Med (2020) 98:1689–1700[1]
After 8 weeks of treatment, which corresponds to the time of onset of the clinical effects of empagliflozin, Ca2+ transient amplitude in control induced pluripotent stem cell cardiomyocytes (iPSC-CM) (F340/380: 0.54 ± 0.03, n = 136 cells) was not significantly different compared with the empagliflozin-treated group (0.61 ± 0.04, n = 125 cells) at 0.25 Hz and during increasing frequencies up to 1 Hz (Fig. 2a–b and e)
This study investigated the direct long-term and thereby clinically relevant effects of empagliflozin on cardiomyocyte EC
Summary
Extended author information available on the last page of the articleThe antidiabetic drug empagliflozin, which inhibits the sodium-dependent glucose cotransporter 2 (SGLT2) in the kidney, has been shown to reduce cardiovascular mortality, all-cause mortality, and hospitalization rates for heart failure (HF) in patients at high cardiovascular risk and type 2 diabetesJ Mol Med (2020) 98:1689–1700[1]. The question arises whether empagliflozin has direct cardiac effects. Direct myocardial effects of empagliflozin on cardiac metabolism [6], contractility [7, 8], and cardiomyocyte Ca2+ and Na+ homeostasis [9, 10] have been proposed. The evaluation whether empagliflozin may affect cardiomyocyte ECcoupling is of importance to understand its potential cardiac effects and for further translational investigation. Isolated adult cardiomyocytes (CM), as investigated previously [7, 9, 10], are not suitable for chronic culture and treatment protocols according to the clinical setting, where the beneficial effects of empagliflozin became apparent after ~ 2 months of treatment [1]
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