Active contribution of transplanted induced pluripotent stem cell-derived cardiomyocytes to left ventricular function in a guinea pig model ; Aktive Mitarbeit transplantierter induzierter pluripotenter Stammzell-abgeleiteter Kardiomyozyten zur linksventrikulären Funktion im Meerschweinchenmodell

Induced pluripotent stem cell (iPSC)-derived cardiomyocyte transplantation has evolved into a potential novel therapeutic option for heart failure patients in the past twenty years. It has shown efficacy in both small and large animal models. Because of these promising results, the first clinical studies have started in 2021. However, the mechanism of action is not understood. It is still unknown if the transplanted cardiomyocytes contribute to force generation of the left ventricle. In this work, I aimed to investigate if transplanted cardiomyocytes contribute to left ventricular function after transplantation. I hypothesized that selectively and reversibly switching off cardiomyocyte contractility only in engrafted cardiomyocytes will result in a drop in left ventricular function. Switching cardiomyocytes back on should result in recovery of cardiac function. This could indicate that the engrafted cells contribute to left ventricular force. For this, I created four novel iPSC lines using CRISPR/Cas9 expressing artificial ion channels, hypothesizing that their activation will lead to electrical silencing and thereby switching off contractility. The four approaches were divided into two groups by their mode of activation. Two cell lines expressed a chemogenetic construct, meaning that the artificial cation (PSAM 5HT3) or anion (PSAM GlyR) channels can be activated by the small molecular substrate PSEM89S. The other two cell lines were chemo- and optogenetic cation (LMO4) and anion (iLMO4) channels, consisting of a luciferase coupled to an optogenetic channel. Coelenterazine, the luciferase substrate, is converted, producing light that activates the fused optogenetic channel. Alternatively, direct activation by light can be used. In iPSCs and differentiated cardiomyocytes, the four transgenes were expressed and functional. PSAM GlyR cardiomyocytes, cast into EHTs, could be stopped with PSEM89S, while PSAM 5HT3 EHTs were not affected. In the optogenetic lines, iLMO4 EHTs could be stopped using light pulses while ...