Fig. 3

Time-dependent effect of C18:1AC on human vEHT and aEHT. Force of human a vEHT and b aEHT in response to exposure to 25 µM short-chain C3AC (vEHT n = 20–24/5, aEHT n = 7–11/3), 5 µM C18:1AC (vEHT n = 18–23/5, aEHT n = 9–14/3) and 25 µM C18:1AC (vEHT n = 18–24/5, aEHT n = 8–13/3) over 3 days. Exposure to 25 µM C18:1AC induced a decrease in contractile force in vEHT and aEHT in a distinct manner. Parameters normalised to corresponding vehicle control (dotted line). Two-way ANOVA plus Dunnett’s post-test for multiple comparisons vs. control, *p < 0.05, ***p < 0.001. Mean ± SEM. Segments of representative original contractility recording traces of c vEHTs and d aEHTs exposed to solvent only or 25 µM C18:1AC for 3 days (red line = force in mN, blue line = velocity in mN/s). The recording trace of the 25 µM C18:1AC exposed aEHT represents a “twitching” contractile phenotype. e Human EHTs were grouped according to contractile phenotype after two weeks of exposure to 25 µM of C18:1AC. Grouped as “contraction” (deflection of posts) and “twitching/wobbling” (convulsions with no deflection of posts). Only aEHTs, but not vEHTs displayed twitching phenotypes (vEHT n = 24/5, aEHT n = 13/3). Numbers in brackets show total number of EHTs/number of batches. f Graphical illustration of the protocol to trace C18:1AC in EHT. C18:1AC in g whole aEHTs (per whole EHT: 1 million cells and fibrin matrix, n = 3 EHTs) and h hiPSC-derived cardiomyocytes from dissociated aEHTs (per dissociated EHT: 1 million cells, n = 3 EHTs) after exposure to 25 µM of C18:1AC for 20 min or 3 days. Untreated aEHTs served as controls (n = 2 EHTs per group). i Relative C18:1AC amount from different sub-cellular fractions after isolation of cardiomyocytes from aEHT and vEHT followed by sub-cellular fractionation after 3 days of exposure to 10 µM of C18:1AC (aEHT n = 2 indicated by red circles, vEHT n = 3)