Abstract
Background: Cellular transplantation has emerged as promising approach for treating cardiac diseases. However, a poor engraftment rate limits our understanding on how transplanted cardiomyocytes contribute to cardiac function in the recipient’s heart. Methods: The CRISPR/Cas9 technique was employed for stable and constitutive gene expression in human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs). Myocardial infarction was induced in adult immunodeficient mice, followed by intramyocardial injection of hiPSC-CMs expressing either CCND2/channelrhodopsin 2 (hiPSC-CCND2OE/ChR2OECMs) or CCND2/luciferase (hiPSC-CCND2OE/LuciOECMs). Six months later, hemodynamics and intramural electrocardiogram were recorded upon blue light illuminations in anesthetized, open-chest mice. Results: Blue light resets automaticity of spontaneously beating hiPSC-CCND2OE/ChR2OECMs in culture, but not that of hiPSC-CCND2OE/LuciOECMs. Response to blue light was also observed in mice carrying large (>106 cells) intracardiac grafts of hiPSC-CCND2OE/ChR2OECM but not in mice carrying hiPSC-CCND2OE/LuciOECMs. The former exhibited single premature ventricular contractions upon light illumination or ventricular quadrigeminy upon second-long illuminations. At the onset of premature ventricular contractions, maximal systolic ventricular pressure decreased while ventricular volume rose concomitantly. Light-induced changes reversed upon resumption of sinus rhythm. Conclusions: We established an in vivo model for optogenetic-based modulation of the excitability of donor cardiomyocytes in a functional, reversible, and localized manner. This approach holds unique value for studying electromechanical coupling and molecular interactions between donor cardiomyocytes and recipient hearts in live animals.
Highlights
One of the major objectives of cell-based therapy for myocardial repair is to generate new muscle or mimics that can functionally replace damaged myocardium
The standard curve allowed us to determine the engrafted cell number from the bioluminescence signal obtained from the mice
We first generated a standard curve by plotting a linear regression curve of cell numbers vs. the respective radiance obtained from the bioluminescence assay for each cell density (Figure 3A)
Summary
One of the major objectives of cell-based therapy for myocardial repair is to generate new muscle or mimics that can functionally replace damaged myocardium. Towards this goal, many different cell types have been tested in the preclinical animal models and in patients [1–4]. Conclusions: We established an in vivo model for optogenetic-based modulation of the excitability of donor cardiomyocytes in a functional, reversible, and localized manner This approach holds unique value for studying electromechanical coupling and molecular interactions between donor cardiomyocytes and recipient hearts in live animals
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