title: Progressive maturation in contracting cardiomyocytes derived from human embryonic stem cells: Qualitative effects on electrophysiological responses to drugs.
abstract: The field of drug testing currently needs a new integrated assay system, as accurate as systems using native tissues, that will allow us to predict arrhythmia risks of candidate drugs and the relationship between genetic mutations and acquired electrophysiological phenotypes. This could be accomplished by combining the microelectrode array (MEA) system with cardiomyocytes (CMs) derived from human embryonic stem cells (hESC) and induced pluripotential stem cells. CMs have been successfully induced from both types, but their maturation process is not systematically controlled; this results in loss of beating potency and insufficient ion channel function. We generated a transgenic hESC line that facilitates maintenance of hESC-CM clusters every 2 weeks by expressing GFP driven by a cardiac-specific alphaMHC promoter, thereby producing a compact pacemaker lineage within a ventricular population over a year. Further analyses, including quantitative RT-PCR, patch-clamp, and MEA-mediated QT tests, demonstrated that replating culturing continuously enhanced gene expression, ionic current amplitudes, and resistance to K(+) channel blockades in hESC-CMs. Moreover, temporal three-dimensional (3D) culturing accelerated maturation by restoring the global gene repressive status established in the adhesive status. Replating/3D culturing thus produces hESC-CMs that act as functional syncytia suitable for use in regenerative medicine and accurate drug tests.
authors.affiliation: Stem Cell and Drug Discovery Institute, Kyoto, Japan.
authors.forename: Tomomi G
authors.initials: TG
authors.lastname: Otsuji
authors.forename: Itsunari
authors.initials: I
authors.lastname: Minami
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kurose
authors.forename: Kaori
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Masako
authors.initials: M
authors.lastname: Tada
authors.forename: Norio
authors.initials: N
authors.lastname: Nakatsuji
mesh_terms: D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism; D055724:Electrophysiological Phenomena; D053595:Embryonic Stem Cells / Q000166:cytology*; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism; D011744:Pyrimidinones / Q000494:pharmacology
chemical_list: D000889:Anti-Arrhythmia Agents; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D015221:Potassium Channels; D011744:Pyrimidinones; D049452:Green Fluorescent Proteins; C076259:nifekalant; D009543:Nifedipine