title: Maximum diastolic potential of human induced pluripotent stem cell-derived cardiomyocytes depends critically on I(Kr).
abstract: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) hold promise for therapeutic applications. To serve these functions, the hiPSC-CM must recapitulate the electrophysiologic properties of native adult cardiomyocytes. This study examines the electrophysiologic characteristics of hiPSC-CM between 11 and 121 days of maturity. Embryoid bodies (EBs) were generated from hiPS cell line reprogrammed with Oct4, Nanog, Lin28 and Sox2. Sharp microelectrodes were used to record action potentials (AP) from spontaneously beating clusters (BC) micro-dissected from the EBs (n = 103; 37°C) and to examine the response to 5 µM E-4031 (n = 21) or BaCl(2) (n = 22). Patch-clamp techniques were used to record I(Kr) and I(K1) from cells enzymatically dissociated from BC (n = 49; 36°C). Spontaneous cycle length (CL) and AP characteristics varied widely among the 103 preparations. E-4031 (5 µM; n = 21) increased Bazett-corrected AP duration from 291.8±81.2 to 426.4±120.2 msec (p<0.001) and generated early afterdepolarizations in 8/21 preparations. In 13/21 BC, E-4031 rapidly depolarized the clusters leading to inexcitability. BaCl(2), at concentrations that selectively block I(K1) (50-100 µM), failed to depolarize the majority of clusters (13/22). Patch-clamp experiments revealed very low or negligible I(K1) in 53% (20/38) of the cells studied, but presence of I(Kr) in all (11/11). Consistent with the electrophysiological data, RT-PCR and immunohistochemistry studies showed relatively poor mRNA and protein expression of I(K1) in the majority of cells, but robust expression of I(Kr.) In contrast to recently reported studies, our data point to major deficiencies of hiPSC-CM, with remarkable diversity of electrophysiologic phenotypes as well as pharmacologic responsiveness among beating clusters and cells up to 121 days post-differentiation (dpd). The vast majority have a maximum diastolic potential that depends critically on I(Kr) due to the absence of I(K1). Thus, efforts should be directed at producing more specialized and mature hiPSC-CM for future therapeutic applications.
authors: Stem Cell Research and Genomics, Masonic Medical Research Laboratory, Utica, New York, United States of America.
authors: Michael Xavier
authors: MX
authors: Doss
authors: José M
authors: JM
authors: Di Diego
authors: Robert J
authors: RJ
authors: Goodrow
authors: Yuesheng
authors: Y
authors: Wu
authors: Jonathan M
authors: JM
authors: Cordeiro
authors: Vladislav V
authors: VV
authors: Nesterenko
authors: Héctor
authors: H
authors: Barajas-Martínez
authors: Dan
authors: D
authors: Hu
authors: Janire
authors: J
authors: Urrutia
authors: Mayurika
authors: M
authors: Desai
authors: Jacqueline A
authors: JA
authors: Treat
authors: Agapios
authors: A
authors: Sachinidis
authors: Charles
authors: C
authors: Antzelevitch
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D017609:Barium Compounds / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D017609:Barium Compounds; D002712:Chlorides; D010880:Piperidines; D026902:Potassium Channel Blockers; D024661:Potassium Channels, Inwardly Rectifying; D011725:Pyridines; D012333:RNA, Messenger; C024986:barium chloride; C063968:E 4031