SPECIAL ISSUE ARTICLE AFM nano‐mechanical study of the beating profile of hiPSC‐ derived cardiomyocytes beating bodies WT and DM1 S. Dinarelli 1 | M. Girasole 1 | P. Spitalieri 2 | R.V. Talarico 2 | M. Murdocca 2 | A. Botta 2 | G. Novelli 2 | R. Mango 3 | F. Sangiuolo 2 | G. Longo 1 1 Institute for the Structure of Matter, CNR, Rome, Italy 2 Department of Biomedicine and Prevention, University of Rome “Tor Vergata” , Rome, Italy 3 Department of Emergency and Critical Care, Polyclinic Tor Vergata, Rome, Italy Correspondence S. Dinarelli, Institute for the Structure of Matter, CNR via del Fosso del Cavaliere 100, Rome, Italy. Email: simone.dinarelli@ism.cnr.it Abstract Myotonic Dystrophy type 1 (DM1) is the most common form of muscular dystrophy in adults, characterized by a variety of multisystemic features and associated with cardiac anomalies. Among cardiac phenomena, conduction defects, ventricular arrhythmias, and dilated cardiomyopathy represent the main cause of sudden death in DM1 patients. Patient‐specific induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) repre- sent a powerful in vitro model for molecular, biochemical, and physiological studies of dis- ease in the target cells. Here, we used an Atomic Force Microscope (AFM) to measure the beating profiles of a large number of cells, organized in CM clusters (Beating Bodies, BBs), obtained from wild type (WT) and DM1 patients. We monitored the evolution over time of the frequency and intensity of the beating. We determined the variations between differ- ent BBs and over various areas of a single BB, caused by morphological and biomechanical variations. We exploited the AFM tip to apply a controlled force over the BBs, to carefully assess the biomechanical reaction of the different cell clusters over time, both in terms of beating frequency and intensity. Our measurements demonstrated differences between the WT and DM1 clusters highlighting, for the DM1 samples, an instability which was not observed in WT cells. We measured differences in the cellular response to the applied mechanical stimulus in terms of beating synchronicity over time and cell tenacity, which are in good agreement with the cellular behavior in vivo. Overall, the combination of hiPSC‐CMs with AFM characterization can become a new tool to study the collective movements of cell clusters in different conditions and can be extended to the characteri- zation of the BB response to chemical and pharmacological stimuli. KEYWORDS AFM, Cardiomyocytes, hiPSC‐derived CMs, stem cells, force measurements 1 | INTRODUCTION Myotonic Dystrophy (DM1) is an autosomal dominant disease with a frequency that can exceed 1 case over 8000. It is caused by an expan- sion of repetitive CTG sequences in the 3′ untranslated region of the Dystrophia Myotonica‐Protein Kinase (DMPK) gene. It can be progres- sive, neonatal, and can appear late during the life of a person. DM1 is a multisystemic disorder characterized by myotonia, muscular dystro- phy, cataracts, hypogonadism, frontal balding, and cardiac defects. 1,2 From a biophysical point of view, the main consequence of the lack of the DMPK gene is a reduction of the strength that the muscular cells can generate, that physiologically speaking has implication in the skeletal development, movement, and cardiac strength. 3 The study of DM1 commonly involves genetic testing or standard animal models, This article is published in Journal of Molecular Recognition as part of the virtual Special Issue ‘AFM BioMed Krakow 2017, edited by Malgorzata Lekka, IFJ PAN, and Pierre Parot, CEA, France, and Jean‐Luc Pellequer, IBS, France’ Received: 22 December 2017 Revised: 20 March 2018 Accepted: 13 April 2018 DOI: 10.1002/jmr.2725 J Mol Recognit. 2018;e2725. https://doi.org/10.1002/jmr.2725 Copyright © 2018 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/jmr 1 of 7