title: Contractile properties of early human embryonic stem cell-derived cardiomyocytes: beta-adrenergic stimulation induces positive chronotropy and lusitropy but not inotropy.
abstract: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) provide the unique opportunity to study the very early development of the human heart. The aim of this study was to investigate the effect of calcium and beta-adrenergic stimulation on the contractile properties of early hESC-CMs. Beating clusters containing hESC-CMs were co-cultured in vitro with noncontractile slices of neonatal murine ventricles. After 5-7 days, when beating clusters had integrated morphologically into the damaged tissue, isometric force measurements were performed during spontaneous beating as well as during electrical field stimulation. Spontaneous beating stopped when extracellular calcium ([Ca²⁺](ec)) was removed or after administration of the Ca²⁺ channel blocker nifedipine. During field stimulation at a constant rate, the developed force increased with incremental concentrations of [Ca²⁺](ec). During spontaneous beating, rising [Ca²⁺](ec) increased beating rate and developed force up to a [Ca²⁺](ec) of 2.5 mM. When [Ca²⁺](ec) was increased further, spontaneous beating rate decreased, whereas the developed force continued to increase. The beta-adrenergic agonist isoproterenol induced a dose-dependent increase of the frequency of spontaneous beating; however, it did not significantly change the developed force during spontaneous contractions or during electrical stimulation at a constant rate. Force developed by early hESC-CMs depends on [Ca²⁺](ec) and on the L-type Ca²⁺ channel. The lack of an inotropic reaction despite a pronounced chronotropic response after beta-adrenergic stimulation most likely indicates immaturity of the sarcoplasmic reticulum. For cell-replacement strategies, further maturation of cardiac cells has to be achieved either in vitro before or in vivo after transplantation.
authors.affiliation: Pediatric Cardiology, Heinrich-Heine-University of Duesseldorf, Duesseldorf, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Pillekamp
authors.forename: Moritz
authors.initials: M
authors.lastname: Haustein
authors.forename: Markus
authors.initials: M
authors.lastname: Khalil
authors.forename: Markus
authors.initials: M
authors.lastname: Emmelheinz
authors.forename: Rewa
authors.initials: R
authors.lastname: Nazzal
authors.forename: Roland
authors.initials: R
authors.lastname: Adelmann
authors.forename: Filomain
authors.initials: F
authors.lastname: Nguemo
authors.forename: Olga
authors.initials: O
authors.lastname: Rubenchyk
authors.forename: Kurt
authors.initials: K
authors.lastname: Pfannkuche
authors.forename: Matthias
authors.initials: M
authors.lastname: Matzkies
authors.forename: Michael
authors.initials: M
authors.lastname: Reppel
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Bloch
authors.forename: Konrad
authors.initials: K
authors.lastname: Brockmeier
authors.forename: Juergen
authors.initials: J
authors.lastname: Hescheler
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002470:Cell Survival; D002478:Cells, Cultured; D018920:Coculture Techniques; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D053595:Embryonic Stem Cells / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D051379:Mice; D057507:Mice, 129 Strain; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D013268:Stimulation, Chemical; D016276:Ventricular Function / Q000187:drug effects
chemical_list: D000318:Adrenergic beta-Agonists; D002121:Calcium Channel Blockers; D002316:Cardiotonic Agents; D009543:Nifedipine; D007545:Isoproterenol; D002118:Calcium