0134 : Using cardiomyocytes differentiated from urine-derived hiPSCs to recapitulate electrophysiological characteristics of LQT2 syndrome

RationaleHuman genetically inherited cardiac diseases have mainly been studied in heterologous systems or animal models, independently of the patients’ genetic background. Because sources for human cardiomyocytes are extremely limited, the use of urine samples to derive cardiomyocytes would be a non-invasive method to identify cardiac dysfunctions that lead to pathologies within the patients’ specific genetic background.ObjectiveCardiomyocytes differentiated from urine-derived pluripotent stem cells (UhiPS-CMs) were obtained from a patient with long QT syndrome and a mutation in hERG KCNH2 gene (p. A561P), and were characterized.Methods and ResultsCells obtained from urine samples from the A561P patient and his asymptomatic mother carrying no hERG mutation were reprogrammed using the episomal-based method. UhiPS cells were then differentiated into cardiomyocytes using a modified matrix sandwich method. UhiPS-CMs showed proper expression of ventricular cytoskeletal proteins and ion channels. They were electrically functional, with nodal-, atrial- and ventricular-like action potentials (APs) recorded using both high-throughput CellOptiq and patch-clamp techniques. Application of ajmaline, 4-aminopyridine, nifedipine, chromanol 293B or E-4031 to the UhiPS-CMs confirmed that INa, Ito, ICa, IKs and IKr currents, respectively, contributed to the APs. Comparing hERG expression from the patient's UhiPS-CMs to the mother's UhiPS-CMs showed that the mutation led to a trafficking defect that resulted in a reduced IKr current. This phenotype led to APs prolongation that sometimes resulted in arrhythmias (early afterdepolarizations).ConclusionUrine-derived pluripotent stem cells from patients carrying ion channels mutations can be used as novel models to differentiate functional cardiomyocytes that recapitulate cardiac arrhythmia phenotypes

Toward Personalized Medicine: Using Cardiomyocytes Differentiated From Urine-Derived Pluripotent Stem Cells to Recapitulate Electrophysiological Characteristics of Type 2 Long QT Syndrome

International audienceBackground-—Human genetically inherited cardiac diseases have been studied mainly in heterologous systems or animal models, independent of patients' genetic backgrounds. Because sources of human cardiomyocytes (CMs) are extremely limited, the use of urine samples to generate induced pluripotent stem cell–derived CMs would be a noninvasive method to identify cardiac dysfunctions that lead to pathologies within patients' specific genetic backgrounds. The objective was to validate the use of CMs differentiated from urine-derived human induced pluripotent stem (UhiPS) cells as a new cellular model for studying patients' specific arrhythmia mechanisms. Methods and Results-—Cells obtained from urine samples of a patient with long QT syndrome who harbored the HERG A561P gene mutation and his asymptomatic noncarrier mother were reprogrammed using the episomal-based method. UhiPS cells were then differentiated into CMs using the matrix sandwich method. UhiPS-CMs showed proper expression of atrial and ventricular myofilament proteins and ion channels. They were electrically functional, with nodal-, atrial-and ventricular-like action potentials recorded using high-throughput optical and patch-clamp techniques. Comparison of HERG expression from the patient's UhiPS-CMs to the mother's UhiPS-CMs showed that the mutation led to a trafficking defect that resulted in reduced delayed rectifier