Fig. 3: Modulation of miR-365 in human models of QT syndromes.

a Experimental design for AP recordings in patient-specific SQT1 and LQT1 hiPSC-CMs upon manipulation of miR-365 (scheme prepared using BioRender.). Representative immunostainings of SQT1 and LQT1 hiPSC-CMs (>60 days) showing the expression of cardiac markers ACTN2 and MYL2 (scale bar = 25 μm). b Average of 15 representative AP traces (F655/F560) from SQT1 hiPSC-CMs that were transfected with mimic-365 (red) or mimic-Ctrl (black) and were loaded 48 h later with di-8-ANEPPS (left panel). Quantification of optical AP recordings in SQT1 hiPSC-CMs (right panel). Median beating rate-corrected APDs at 90% of repolarization (cAPD90) were 290 ms in mimic-Ctrl and 431 ms in mimic-365-treated cells (data from 3 independent experiments). c Representative field potential (FP) traces recorded from SQT1 hiPSC-CMs upon treatment with mimic-365 (red) or -Ctrl (black) using a multielectrode array (MEA) system (left panel). Quantification of FP duration corrected for beating frequency (cFPD, right panel). d cAPD90 measured from SQT1 hiPSC-CMs upon manipulation of miR-365 using sharp microelectrodes for intracellular AP recording. e Averaged F665/F560 traces from 5 to 10 recorded APs (left panel) in representative LQT1 hiPSC-CMs treated with either antimiR-Ctrl (black) or antimiR-365 (green). Quantification of optical AP recordings in the LQT1 hiPSC-CMs (right panel). Data are from 3 independent experiments. Median cAPD90 in control- and antimiR-365 treated cells were 534 ms and 401 ms, respectively. f Representative FP traces of LQT1 hiPSC-CMs transfected with antimiR-365 or -Ctrl (left panel) and quantification of cFPD recorded post-transfection. g Intracellular AP recordings from LQT1 hiPSC-CMs treated with antimiR-Ctrl or -365 using sharp microelectrodes. h Scheme representing the effects of miR-365 manipulation on AP duration in QT syndromes. All quantitative data are plotted as box (25% and 75% quartiles) and whisker (min to max) showing the median and individual values. Source data and detailed statistical analyses for (b–g) are provided as a Source Data file.