Transplantation of stem cell-derived cardiomyocytes with a chemogenetic off-on switch to improve cell engraftment and inhibit engraftment induced arrhythmias

• Applicant: Dr. Florian Weinberger
• Subject Area: Cardiology, Angiology ; Pharmacology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519663780

Ischemic heart disease is the main cause of death worldwide. Myocardial infarction results in a permanent loss of contractile myocardium and regularly leads to the development of heart failure. Transplantation of pluripotent stem cell-derived cardiomyocytes represents a regenerative therapeutic concept with great potential for the treatment of heart failure patients. It was successfully applied in preclinical studies and is currently evaluated in first clinical trials. This project aims to address two fundamental problems regarding this strategy: 1. The low transplantation efficiency 2. The transplantation induced arrhythmias We hypothesize that the transplantation of genetically engineered stem cell derived cardiomyocytes with an off-on switch will result in larger grafts and suppress the transplantation induced arrhythmias. This hypothesis is based on in vitro experiments with cardiomyocytes with an off-on switch. For this a so called Pharmacologically Selective Actuator Modul (PSAM), consisting of the chloride-selective ion pore domain of the glycine receptor and a mutated ligand-binding domain of the nicotinic acetylcholine receptor was knocked-into the AAVS1 locus of human induced pluripotent stem cells. Cardiomyocytes derived from this line could be stopped reversibly with a small molecular substance (PSEM89S). Engineered Heart Tissue (EHTs) generated from these cardiomyocytes, that were stopped with PSAM89S developed regularly, started to beat coherently after PSEM89S washed out and developed similar forces as control EHTs, indicating that maturation occurs even in the absence of active contraction. Yet, cell cycle activity was higher in the silenced cardiomyocytes. Stem cell derived cardiomyocyte transplantation resulted in ventricular arrhythmias in large animal models. This was caused by the cell`s immaturity and their automatism. Arrhythmias occurred within the first days and subsided after three weeks when the cells were further matured. We hypothesize that by electrically inactivating cardiomyocytes over the critical postoperative period it is possible to suppress the transplantation induced arrhythmias while the cardiomyocytes have time to mature. It also has been reported that the transplantation of cardiomyocytes that are not able to beat resulted in larger grafts. This finding led to the second hypothesis: cardiomyocyte inactivation will result in larger grafts. To address these two hypotheses a new stem cell line with an off-on switch optimized for an in vivo application has been generated and will be used in a small and large animal model.

• DFG Programme: Research Grants