Culturing hiPSCs in Defined FTDAC Medium

SFS.2 hiPSCs and the KCNQ1^{fs/fs_K.TET−ON} derivative line were routinely cultured in six-well plates on 1:75 diluted Matrigel™ HC (Corning # 354263), in defined FTDAC medium (Frank et al., 2012 (link)). FTDAC consisted of DMEM/F12, 1 × ITS (Corning # 354350), 0.1% human serum albumin (Biological Industries # 05-720-1B), 1 x defined lipids (Thermo), 1 × penicillin/streptomycin/L-glutamine (PSG), 10 ng/ml FGF2 (PeproTech # 100-18B), 0.2 ng/ml TGFβ1 (eBioscience # 34-8348-82), 50 nM Dorsomorphin (Santa Cruz # sc-200689), 5 ng/ml Activin A (eBioscience # 34-8993-85), and 1 nM C-59 (Tocris # 5148/10). Cells were routinely passaged at 700,000 single cells per six-well following Accutase™ digestion with 10 μM Y-27632 (abcamBiochemicals # ab120129). This way, hiPSCs were kept in culture for a maximum of 30 passages shown to preserve an intact karyotype (Zhang et al., 2015 (link)).