Optogenetic Hyperpolarization of Cardiomyocytes Terminates Ventricular Arrhythmia

Funken, Maximilian; Malan, Daniela; Sasse, Philipp; Bruegmann, Tobias

doi:10.3389/fphys.2019.00498

Cited by 32 publications

(21 citation statements)

References 32 publications

(36 reference statements)

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“…Light activation of single 3T3 HR cells caused their V m to shift from ∼−35 to ∼−104 mV. While this degree of hyperpolarization eliminates resistive loading of CMCs by coupled 3T3 HR cells, the question arises whether light activation may in fact lead to a hyperpolarization of CMCs relevant for conduction (Funken et al, 2019). As reported before (Salvarani et al, 2017), CMC membrane potential changes induced by coupled NECs depend on the relative sizes of the membrane resistance of NECs (∼950 M ), the membrane resistance of CMCs [∼290 M , from Salvarani et al (2017)], and the gap junctional resistance [14 M , from Salvarani et al (2017)].…”

Section: Light Stimulation Of 3t3 Hr Cells: Effects At the Single-celmentioning

confidence: 99%

The Role of Membrane Capacitance in Cardiac Impulse Conduction: An Optogenetic Study With Non-excitable Cells Coupled to Cardiomyocytes

et al. 2020

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Non-excitable cells (NECs) such as cardiac myofibroblasts that are electrotonically coupled to cardiomyocytes affect conduction velocity (θ) by representing a capacitive load (CL: increased membrane to be charged) and a resistive load (RL: partial depolarization of coupled cardiomyocytes). In this study, we untangled the relative contributions of both loading modalities to NEC-dependent arrhythmogenic conduction slowing. Discrimination between CL and RL was achieved by reversibly removing the RL component by light activation of the halorhodopsin-based hyperpolarizing membrane voltage actuator eNpHR3.0-eYFP (enhanced yellow fluorescent protein) expressed in communication-competent fibroblast-like NIH3T3 cells (3T3 HR cells) that served as a model of coupled NECs. Experiments were conducted with strands of neonatal rat ventricular cardiomyocytes coated at increasing densities with 3T3 HR cells. Impulse conduction along preparations stimulated at 2.5 Hz was assessed with multielectrode arrays. The relative density of 3T3 HR cells was determined by dividing the area showing eYFP fluorescence by the area covered with cardiomyocytes [coverage factor (CF)]. Compared to cardiomyocytes, 3T3 HR cells exhibited a depolarized membrane potential (−34 mV) that was shifted to −104 mV during activation of halorhodopsin. Without illumination, 3T3 HR cells slowed θ along the preparations from ∼330 mm/s (control cardiomyocyte strands) to ∼100 mm/s (CF = ∼0.6). Illumination of the preparation increased the electrogram amplitudes and induced partial recovery of θ at CF > 0.3. Computer simulations demonstrated that the θ deficit observed during illumination was attributable in full to the CL represented by coupled 3T3 HR cells with θ showing a power-law relationship to capacitance with an exponent of −0.78 (simulations) and −0.99 (experiments). The relative contribution of CL and RL to conduction slowing changed as a function of CF with CL dominating at CF ≤ ∼0.3, both mechanisms being equally important at CF = ∼0.5, and RL dominating over CL at CF > 0.5.

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Section: Light Stimulation Of 3t3 Hr Cells: Effects At the Single-celmentioning

confidence: 99%

The Role of Membrane Capacitance in Cardiac Impulse Conduction: An Optogenetic Study With Non-excitable Cells Coupled to Cardiomyocytes

et al. 2020

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“…Since then several groups have successfully suppressed cardiomyocyte activity using a variety of inhibitory optogenetic tools, including eNpHR (Abilez, 2012; Park et al, 2015b) and archaerhodopsin (Arch/ArchT) (Nussinovitch et al, 2014). ArchT-mediated cardiomyocyte hyperpolarization has also been used to terminate ventricular arrhythmias in the intact hearts of transgenic mice (Funken et al, 2019). As expected from the chloride reversal potential in cardiomyocytes, recent work (Kopton et al, 2017, 2018) has highlighted that cardiomyocytes in culture demonstrate excitation in response to light stimulation with both naturally occurring and engineered chloride channels.…”

Section: Selecting An Opsin For Cardiac Optogenetics: Directionalitymentioning

confidence: 99%

“…Similar approaches also been used to generate mice expressing hyperpolarizing optogenetic tools specifically in cardiomyocytes, by crossing αMyHC-Cre mice with mice that conditionally express ArchT on exposure to Cre-recombinase (Ai40D mice). This has been used to study hyperpolarization as a mechanism for ventricular arrhythmia termination (Funken et al, 2019).…”

Section: Targeting Opsins To Cardiac Tissuementioning

confidence: 99%

“…Applications of optogenetic techniques have been explored for their localizable, potentially translationally important, anti-arrhythmic effects (Bingen et al, 2014; Bruegmann et al, 2016, 2018; Crocini et al, 2016; Nyns et al, 2017; Funken et al, 2019). Classical electrical cardioversion including implantable cardioverter defibrillator (ICD) applies generalized electrical discharges to the whole heart without reference to particular re-entrant conduction pathways.…”

Section: Anti-arrhythmic Interventions In Chr2-murine Heartsmentioning

confidence: 99%

“…Thus, the observed anti-arrhythmic effects might arise from accompanying increased electrical sink currents, suggestive of novel mechanisms by which the observed cardioversion took place. Such hypotheses might prompt further investigation and their possible application (Funken et al, 2019).…”

Section: Anti-arrhythmic Interventions In Chr2-murine Heartsmentioning

confidence: 99%

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Principles of Optogenetic Methods and Their Application to Cardiac Experimental Systems

2019

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Optogenetic techniques permit studies of excitable tissue through genetically expressed light-gated microbial channels or pumps permitting transmembrane ion movement. Light activation of these proteins modulates cellular excitability with millisecond precision. This review summarizes optogenetic approaches, using examples from neurobiological applications, and then explores their application in cardiac electrophysiology. We review the available opsins, including depolarizing and hyperpolarizing variants, as well as modulators of G-protein coupled intracellular signaling. We discuss the biophysical properties that determine the ability of microbial opsins to evoke reliable, precise stimulation or silencing of electrophysiological activity. We also review spectrally shifted variants offering possibilities for enhanced depth of tissue penetration, combinatorial stimulation for targeting different cell subpopulations, or all-optical read-in and read-out studies. Expression of the chosen optogenetic tool in the cardiac cell of interest then requires, at the single-cell level, introduction of opsin-encoding genes by viral transduction, or coupling “spark cells” to primary cardiomyocytes or a stem-cell derived counterpart. At the system-level, this requires construction of transgenic mice expressing ChR2 in their cardiomyocytes, or in vivo injection (myocardial or systemic) of adenoviral expression systems. Light delivery, by laser or LED, with widespread or multipoint illumination, although relatively straightforward in vitro may be technically challenged by cardiac motion and light-scattering in biological tissue. Physiological read outs from cardiac optogenetic stimulation include single cell patch clamp recordings, multi-unit microarray recordings from cell monolayers or slices, and electrical recordings from isolated Langendorff perfused hearts. Optical readouts of specific cellular events, including ion transients, voltage changes or activity in biochemical signaling cascades, using small detecting molecules or genetically encoded sensors now offer powerful opportunities for all-optical control and monitoring of cellular activity. Use of optogenetics has expanded in cardiac physiology, mainly using optically controlled depolarizing ion channels to control heart rate and for optogenetic defibrillation. ChR2-expressing cardiomyocytes show normal baseline and active excitable membrane and Ca2+ signaling properties and are sensitive even to ~1 ms light pulses. They have been employed in studies of the intrinsic cardiac adrenergic system and of cardiac arrhythmic properties.

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Nongenetic Optical Modulation of Pluripotent Stem Cells Derived Cardiomyocytes Function in the Red Spectral Range

Ronchi,

Galli,

Tullii

et al. 2023

Advanced Science

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Optical stimulation in the red/near infrared range recently gained increasing interest, as a not‐invasive tool to control cardiac cell activity and repair in disease conditions. Translation of this approach to therapy is hampered by scarce efficacy and selectivity. The use of smart biocompatible materials, capable to act as local, NIR‐sensitive interfaces with cardiac cells, may represent a valuable solution, capable to overcome these limitations. In this work, a far red‐responsive conjugated polymer, namely poly[2,1,3‐benzothiadiazole‐4,7‐diyl[4,4‐bis(2‐ethylhexyl)−4H‐cyclopenta[2,1‐b:3,4‐b’]dithiophene‐2,6‐diyl]] (PCPDTBT) is proposed for the realization of photoactive interfaces with cardiomyocytes derived from pluripotent stem cells (hPSC‐CMs). Optical excitation of the polymer turns into effective ionic and electrical modulation of hPSC‐CMs, in particular by fastening Ca2+ dynamics, inducing action potential shortening, accelerating the spontaneous beating frequency. The involvement in the phototransduction pathway of Sarco‐Endoplasmic Reticulum Calcium ATPase (SERCA) and Na+/Ca2+ exchanger (NCX) is proven by pharmacological assays and is correlated with physical/chemical processes occurring at the polymer surface upon photoexcitation. Very interestingly, an antiarrhythmogenic effect, unequivocally triggered by polymer photoexcitation, is also observed. Overall, red‐light excitation of conjugated polymers may represent an unprecedented opportunity for fine control of hPSC‐CMs functionality and can be considered as a perspective, noninvasive approach to treat arrhythmias.

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Optogenetic Hyperpolarization of Cardiomyocytes Terminates Ventricular Arrhythmia

Cited by 32 publications

References 32 publications

The Role of Membrane Capacitance in Cardiac Impulse Conduction: An Optogenetic Study With Non-excitable Cells Coupled to Cardiomyocytes

The Role of Membrane Capacitance in Cardiac Impulse Conduction: An Optogenetic Study With Non-excitable Cells Coupled to Cardiomyocytes

Principles of Optogenetic Methods and Their Application to Cardiac Experimental Systems

Nongenetic Optical Modulation of Pluripotent Stem Cells Derived Cardiomyocytes Function in the Red Spectral Range

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