The Enlightened Heart: Cardiac Optogenetics to Investigate Cardiac Arrhythmia Initiation and Protection
Optogenetic methods use photosensitive proteins to manipulate cells and organs using light, with major advantages over electrical and pharmacological stimulation. Here we show our contributions to cardiac optogenetics to stimulate cardiomyocytes in vitro and mouse hearts in vivo to study and modulate cardiac arrhythmia mechanisms.
The expression of the light-sensitive ion channel channelrhodopsin-2 (ChR2) can be used to pace mouse and human cardiomyocytes in the culture dish as well as hearts of transgenic mice. We have shown that optogenetic methods are also very effective in terminating ventricular tachycardia and atrial fibrillation in mouse hearts, and that optogenetics may eventually provide an alternative to painful electric shocks. For translational applications, we developed a gene transfer strategy by adeno-associated virus injection for ChR2 expression and developed red-shored optogenetics.
To screen drug effects on cardiac ion channels in vitro, we have developed scalable technologies combining field potential measurements with optogenetic stimulation of human pluripotent cell-derived cardiomyocytes or established light-induced Ca2+ leak of the cardiac ryanodine-2 receptor. To determine input resistance, length constant and susceptibility to pro-arrhythmic extra beats, we have developed an optogenetic current clamp method in the intact heart by combining patterned and triggered light simulation with sharp microelectrode measurement.
For light stimulation of intracellular Gs, Gi and Gq signaling cascades, we have used the specific light-sensitive G protein-coupled receptors jellyfish opsin, coneopsin and neuropsin in cardiomyocytes and mouse hearts. For example, optical stimulation of transgenic hearts expressing the Gs-coupled jellyfish opsin increased cAMP levels and accelerated heart rate similarly to pharmacological stimulation, but with much faster on/off kinetics and very high spatial precision. Furthermore, optogenetic stimulation of coneopsin Gi signaling in the atria decreases refractoriness and increases atrial fibrillation vulnerability.
Thus, cardiac optogenetics can be used to develop systems for drug screening, better mechanistic understanding, and eventually treatment of potentially lethal cardiac arrhythmias.
This will be a hybrid seminar; prior registration is required.
Please contact info@sfb1425.uni-freiburg.de.
