Optical modulation of excitation-contraction coupling in human induced pluripotent stem cell-derived cardiomyocytes

Non-genetic photostimulation is a novel and rapidly growing multidisciplinary field of research that aims to induce light sensitivity in living systems by exploiting exogeneous phototransducers. Here we propose a recently synthetized intramembrane photo-transducer, based on an azobenzene derivative (Ziapin2), for optical pacing of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The light-mediated photostimulation process has been studied by applying a number of characterization techniques to detect the effect on the cell properties. In particular, we recorded changes in membrane capacitance, in membrane potential (Vm), and modulation of intracellular Ca2+ dynamics. Finally, cell contractility was analyzed using a custom MATLAB algorithm. Photostimulation of intra-membrane Ziapin2 causes a transient Vm hyperpolarization followed by a delayed depolarization and action potential firing. The observed initial electrical modulation nicely correlates with changes in Ca2+ dynamics and contraction rate. This work represents the proof of principle that Ziapin2 is able to modulate electrical activity and contractility in hiPSC-CMs, opening up a future development in cardiac electrophysiology.