In hearts, self-replicating reentrant spiral waves can cause deadly tachycardia. In vitro cardiac tissue models can benefit both fundamental research and patient-specific disease modeling. Here, cardiac optogenetics allows damage-free control of tissue activity. We present a system for digital control and observation of excitation wavefronts in human stem-cell-derived cardiomyocytes expressing f-ChRimson-YFP. Holographic light shaping enables patterned illumination, observing the 5x5 mm2 sample at 250Hz frame rate. A fast data evaluation scheme accesses spatially resolved stimulus-induced sample activity and the propagation of action potential wavefronts in in vitro cell cultures. Experiments with varied illumination patterns control wavefront direction and timing, paving the way for patient-specific disease modeling.
Cardiomyocytes form an electrically coupled syncytium, enabling synchronized action potential wavefronts. Optogenetics facilitates the study of cardiac excitation wavefronts in vivo and in vitro.
We demonstrate a laser-optical system utilizing computer-generated holograms to stimulate and inhibit light-sensitive human stem-cell-derived cardiomyocytes, allowing e.g. non-destructive modeling of myocardial scarring and exctiation wavefront control.
With rapid frame rates upt to 1.7 kHz, our system spatially positions multiple foci or complex illumination patterns, achieving defined 3D-distributed excitation wavefronts for quickly changing stimulation protocols. High-speed video microscopy assesses contractions in samples.
We show successful coupling of cardiomyocyte contraction to optical stimulation and stimulation-wavefront shape-dependencies, paving the way for patient-specific disease modeling using multi-photong holographic light shaping and red-shifted opsins in 3D cardiac organoids.
Cardiomyocytes form an electrically coupled syncytium which is the basis for the spatiotemporally synchronized propagation of macroscopic action potential wavefronts. Dysfunctional signal propagation patterns are a main cause of deadly tachycardia and are not yet fully understood. Optogenetics is a versatile toolset for the functional investigation of excitable cells and well-suited for the investigation of excitation wavefronts. We present a two-wavelength system using computer-generated holograms for the simultaneous stimulation and inhibition of induced stem-cell-derived human cardiomyocytes genetically sensitized to light, providing non-destructive models of myocardial scarring in vitro. The system is based on two beam paths, each comprising a binary ferroelectric SLM with frame rates reaching 1.7 kHz in a Fourier hologram configuration. To achieve near diffraction-limited spatial resolution, system-inherent aberrations are corrected digitally by superposing the light-pattern-generating holograms with sets of Zernike polynomials determined by an iterative optimization procedure. Thus, multiple foci or complex illumination patterns can be positioned three-dimensionally to illuminate multiple locations simultaneously to create defined excitation wavefronts. We show investigations on myocardial excitation control using different opsins like ChR2, ChRimson and BiPoles. This paves the way for future optogenetic heart rhythm control and the modeling of arrythmia induced by myocardial fibrosis using cardiac organoids in vitro.
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