title: Physiologic force-frequency response in engineered heart muscle by electromechanical stimulation.
abstract: A hallmark of mature mammalian ventricular myocardium is a positive force-frequency relationship (FFR). Despite evidence of organotypic structural and molecular maturation, a positive FFR has not been observed in mammalian tissue engineered heart muscle. We hypothesized that concurrent mechanical and electrical stimulation at frequencies matching physiological heart rate will result in functional maturation. We investigated the role of biomimetic mechanical and electrical stimulation in functional maturation in engineered heart muscle (EHM). Following tissue consolidation, EHM were subjected to electrical field stimulation at 0, 2, 4, or 6 Hz for 5 days, while strained on flexible poles to facilitate auxotonic contractions. EHM stimulated at 2 and 4 Hz displayed a similarly enhanced inotropic reserve, but a clearly diverging FFR. The positive FFR in 4 Hz stimulated EHM was associated with reduced calcium sensitivity, frequency-dependent acceleration of relaxation, and enhanced post-rest potentiation. This was paralleled on the cellular level with improved calcium storage and release capacity of the sarcoplasmic reticulum and enhanced T-tubulation. We conclude that electro-mechanical stimulation at a physiological frequency supports functional maturation in mammalian EHM. The observed positive FFR in EHM has important implications for the applicability of EHM in cardiovascular research.
authors.affiliation: Institute of Pharmacology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; Department of Biomedical Engineering, Columbia University, New York, NY 10032, USA; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany.
authors.forename: Amandine F G
authors.initials: AF
authors.lastname: Godier-Furnémont
authors.affiliation: Institute of Pharmacology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Tiburcy
authors.affiliation: Clinic of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Wagner
authors.affiliation: Institute of Pharmacology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Dewenter
authors.affiliation: Institute of Pharmacology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Lämmle
authors.affiliation: Institute of Pharmacology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany; Institute of Pharmacology and Toxicology, University of Technology Dresden, 01307, Germany.
authors.forename: Ali
authors.initials: A
authors.lastname: El-Armouche
authors.affiliation: Clinic of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany.
authors.forename: Stephan E
authors.initials: SE
authors.lastname: Lehnart
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10032, USA.
authors.forename: Gordana
authors.initials: G
authors.lastname: Vunjak-Novakovic
authors.affiliation: Institute of Pharmacology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August-University Göttingen, 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075, Germany. Electronic address: w.zimmermann@med.uni-goettingen.de.
authors.forename: Wolfram-Hubertus
authors.initials: WH
authors.lastname: Zimmermann
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004558:Electric Stimulation / Q000379:methods; D006339:Heart Rate; D055595:Mechanical Phenomena; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000166:cytology*; D051381:Rats; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D002118:Calcium
keywords: Biophysical properties; Calcium handling; Force frequency relationship; Force of contraction; Heart; Maturation; Myocardium; T-tubulation; Tissue engineering