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Updated: Apr 10, 2026
Electromechanical Assessment of Optogenetically Modulated Cardiomyocyte Activity
Published on: March 5, 2020
Sensing Cardiac Electrical Activity With a Cardiac Myocyte--Targeted Optogenetic Voltage Indicator
Mei-Ling Chang Liao1, Teun P de Boer1, Hiroki Mutoh1
1From the Institute of Pharmacology (M.-L.C.L., S.D., E. Wettwer, W.-H.Z.), Clinic for Cardiology and Pulmonology (N.R., E. Wagner, B.U., K.S.-B., K.G., S.W., S.E.L., L.S.M.), and Microarray and Deep-Sequencing Facility (B.R.D.), University Medical Center Göttingen, Göttingen, Germany; DZHK (German Center for Cardiovascular Research), partner site Göttingen, Göttingen, Germany (M.-L.C.L., N.R., E. Wagner, K.S.-B., S.L., K.G., S.E.L., W.S., W.-H.Z.); Institute of Biomechanics, Technical University Hamburg-Harburg, Hamburg, Germany (M.-L.C.L., M.M.M.); Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands (T.P.d.B., I.A., T.v.V.); Laboratory of Neuronal Circuit Dynamics, RIKEN Brain Science Institute, Saitama, Japan (H.M., T.K.); Max-Planck-Institutes for Dynamics and Self Organization (N.R., C.R., S.L.) and Experimental Medicine (W.S.), Göttingen, Germany; Department of Internal Medicine II, University Hospital of Regensburg, Regensburg, Germany (B.U., S.W., L.S.M.); Department of Medicine and Centre for Neurotechnology, Imperial College London, United Kingdom (T.K.).
Rationale:
Monitoring and controlling cardiac myocyte activity with optogenetic tools offer exciting possibilities for fundamental and translational cardiovascular research. Genetically encoded voltage indicators may be particularly attractive for minimal invasive and repeated assessments of cardiac excitation from the cellular to the whole heart level.
Objective:
To test the hypothesis that cardiac myocyte-targeted voltage-sensitive fluorescence protein 2.3 (VSFP2.3) can be exploited as optogenetic tool for the monitoring of electric activity in isolated cardiac myocytes and the whole heart as well as function and maturity in induced pluripotent stem cell-derived cardiac myocytes.
Methods And Results:
We first generated mice with cardiac myocyte-restricted expression of VSFP2.3 and demonstrated distinct localization of VSFP2.3 at the t-tubulus/junctional sarcoplasmic reticulum microdomain without any signs for associated pathologies (assessed by echocardiography, RNA-sequencing, and patch clamping). Optically recorded VSFP2.3 signals correlated well with membrane voltage measured simultaneously by patch clamping. The use of VSFP2.3 for human action potential recordings was confirmed by simulation of immature and mature action potentials in murine VSFP2.3 cardiac myocytes. Optical cardiograms could be monitored in whole hearts ex vivo and minimally invasively in vivo via fiber optics at physiological heart rate (10 Hz) and under pacing-induced arrhythmia. Finally, we reprogrammed tail-tip fibroblasts from transgenic mice and used the VSFP2.3 sensor for benchmarking functional and structural maturation in induced pluripotent stem cell-derived cardiac myocytes.
Conclusions:
We introduce a novel transgenic voltage-sensor model as a new method in cardiovascular research and provide proof of concept for its use in optogenetic sensing of physiological and pathological excitation in mature and immature cardiac myocytes in vitro and in vivo.
