Calcium dysregulation underlies phenotypic diversity in LQT2: Insights from induced pluripotent stem cell-derived cardiomyocytes of a KCNH2 p.Y427H family trio

Figure 2 Generation and characterization of family trio induced pluripotent stem cell-derived cardiomyocytes. A: Reprogramming process: Representative bright-field images of peripheral blood mononuclear cells and 10^th-passage induced pluripotent stem cells (iPSCs). G-banding karyotyping and short tandem repeat profiling confirm genomic stability. Immunofluorescence staining shows robust expression of pluripotency markers (NANOG, OCT4, SOX2) in green, with a DAPI counterstain in blue. Teratoma formation experiments in immunodeficient mice demonstrate iPSCs differentiation into all three germ layers: Endoderm (respiratory epithelium), mesoderm (adipocytes), and ectoderm (neuronal cells), confirming pluripotency. Scale bars: 100 μm; B: Differentiation process: Morphological progression during cardiac differentiation. Representative images show early, middle, and late stages of iPSC-derived cardiomyocytes formation, as well as single-cell and cell layer morphology. Immunostaining confirms cardiomyocyte identity and sarcomeric structure with cardiac troponin T in red, α-actinin in green, and DAPI in blue. Scale bars: 100 μm (overview), 10 μm (immunostaining). PBMCs: Peripheral blood mononuclear cells; iPSCs: Induced pluripotent stem cells; STR: Short tandem repeat; iPSC-CMs: Induced pluripotent stem cell-derived cardiomyocytes; cTNT: Cardiac troponin T.