Background of the project: This position is integrated in the research consortium PERCOLATE. The overall aim of PERCOLATE is to establish a rapid and easy-to-use diagnostic test panel, based on detection of functional autoantibodies targeting G-protein coupled receptors (GPCR-fAAb) in combination with GPCR-fAAb mediated ischaemia-reperfusion parameters, accompanied by profiling of immune cells and viral reactivation in patients with Long-COVID (LC) and Post-Vaccination Syndrome (Post-VAC) for a personalized patients' stratification and care. Your task will be to advance the method of Wallukat et al., in which primary rat cardiomyocytes were used, to detect the functional active GPCR-AAbs from patients' sera utilizing hiPSC-derived cardiomyocytes and/or cardiac tissues. Aim 1. Establishment of a hiPSC-derived reporter cell line for fluorescence visualization of GPCR activation by GPCR-fAAbs in hiPSC-cardiomyocytes. Aim 2: Establishment of a hiPSC cell