Fs22024

EHM was generated as described previously^{18 (link)}. In brief, iPSC-derived CMs and human foreskin fibroblasts (HFF) (HFF-1, ATCC, SCRC-1041) were mixed at a ratio 70:30, resuspended in Collagen type I (Collagen Solutions, FS22024) diluted into RPMI 2x (Thermo Fisher Scientific, 51800-035) and then cast into wells of an EHM multi-well plate (Myriamed GmbH, myrPlate-TM5). After 45 min, EHM medium freshly supplemented with TGFβ1 (Peprotech, AF-100-21C) was added, and refreshed daily for the first 3 days. Subsequently, the tissue medium was replaced daily with EHM medium for the entirety of the experimental duration.

EHM was generated according to the protocol published by Tiburcy et al.^{58 (link)}. In brief, patient-derived iPS-cell-derived CMs (purity >90%) were mixed together with HFFs (HFF-1, ATCC, SCRC-1041) at a ratio of 70:30. The cell mixture was resuspended in an appropriate volume of Collagen type I (Collagen Solutions, FS22024) diluted into RPMI 2× (Thermo Fisher Scientific, 51800-035). A total of 185 μl of the cell–collagen mixture was cast in each well of a 48 EHM multi-well plate (myrPlate-TM5; myriamed GmbH). The cast mixture was incubated for approximately 45 min at 37 °C and subsequently EHM medium freshly supplemented with TGFβ1 (Peprotech, AF-100-21C) was added. During the initial 3 days following the casting process, tissue medium was refreshed daily with EHM medium supplemented with TGFβ1. Subsequently, the tissue medium was replaced daily with EHM medium for the entirety of the experimental duration.