title: Multi-Imaging Method to Assay the Contractile Mechanical Output of Micropatterned Human iPSC-Derived Cardiac Myocytes.
abstract: BACKGROUND
  During each beat, cardiac myocytes (CMs) generate the mechanical output necessary for heart function through contractile mechanisms that involve shortening of sarcomeres along myofibrils. Human-induced pluripotent stem cells (hiPSCs) can be differentiated into CMs (hiPSC-CMs) that model cardiac contractile mechanical output more robustly when micropatterned into physiological shapes. Quantifying the mechanical output of these cells enables us to assay cardiac activity in a dish.
  
  
  OBJECTIVE
  We sought to develop a computational platform that integrates analytic approaches to quantify the mechanical output of single micropatterned hiPSC-CMs from microscopy videos.
  
  
  RESULTS
  We micropatterned single hiPSC-CMs on deformable polyacrylamide substrates containing fluorescent microbeads. We acquired videos of single beating cells, of microbead displacement during contractions, and of fluorescently labeled myofibrils. These videos were independently analyzed to obtain parameters that capture the mechanical output of the imaged single cells. We also developed novel methods to quantify sarcomere length from videos of moving myofibrils and to analyze loss of synchronicity of beating in cells with contractile defects. We tested this computational platform by detecting variations in mechanical output induced by drugs and in cells expressing low levels of myosin-binding protein C.
  
  
  CONCLUSIONS
  Our method can measure the cardiac function of single micropatterned hiPSC-CMs and determine contractile parameters that can be used to elucidate mechanisms that underlie variations in CM function. This platform will be amenable to future studies of the effects of mutations and drugs on cardiac function.
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco.
authors.forename: Alexandre J S
authors.initials: AJS
authors.lastname: Ribeiro
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco.
authors.forename: Olivier
authors.initials: O
authors.lastname: Schwab
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Mandegar
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco.
authors.forename: Yen-Sin
authors.initials: YS
authors.lastname: Ang
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Conklin
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco.
authors.forename: Deepak
authors.initials: D
authors.lastname: Srivastava
authors.affiliation: From the Department of Mechanical Engineering (A.J.S.R., O.S., B.L.P.), Department of Molecular and Cellular Physiology (by courtesy) (B.L.P.), Department of Bioengineering (by courtesy) (B.L.P.), and Stanford Cardiovascular Institute (A.J.S.R., B.L.P.), Stanford University, CA; Gladstone Institute of Cardiovascular Disease, San Francisco, CA (A.J.S.R., M.A.M., Y.-S.A., B.R.C., D.S.); Roddenberry Stem Cell Center at Gladstone, San Francisco, CA (Y.-S.A., D.S.); Departments of Pediatrics and Biochemistry & Biophysics (D.S.), Department of Cellular and Molecular Pharmacology (B.R.C.), California Institute for Quantitative Biosciences, QB3 (B.R.C.), and Department of Medicine and Cellular and Molecular Pharmacology (B.R.C.), University of California, San Francisco. pruitt@stanford.edu.
authors.forename: Beth L
authors.initials: BL
authors.lastname: Pruitt
mesh_terms: D002478:Cells, Cultured; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000502:physiology*; D064847:Multimodal Imaging / Q000379:methods*; D009200:Myocardial Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*
keywords: cardiac myocyte; contractility; sarcomere length; single cell; stem cell