title: Biophysical properties of cardiomyocyte surface explored by multiparametric AFM.
abstract: PeakForce Quantitative Nanomechanical Mapping (PeakForce QNM) multiparametric AFM mode was adapted to qualitative and quantitative study of the lateral membrane of cardiomyocytes (CMs), extending this powerful mode to the study of soft cells. On living CM, PeakForce QNM depicted the crests and hollows periodic alternation of cell surface architecture previously described using AFM Force Volume (FV) mode. PeakForce QNM analysis provided better resolution in terms of pixel number compared to FV mode and reduced acquisition time, thus limiting the consequences of spontaneous living adult CM dedifferentiation once isolated from the cardiac tissue. PeakForce QNM mode on fixed CMs clearly visualized subsarcolemmal mitochondria (SSM) and their loss following formamide treatment, concomitant with the interfibrillar mitochondria climbing up and forming heaps at the cell surface. Interestingly, formamide-promoted SSM loss allowed visualization of the sarcomeric apparatus ultrastructure below the plasma membrane. High PeakForce QNM resolution led to better contrasted mechanical maps than FV mode and provided correlation between adhesion, dissipation, mechanical and topographical maps. Modified hydrophobic AFM tip enhanced contrast on adhesion and dissipation maps and suggested that CM surface crests and hollows exhibit distinct chemical properties. Finally, two-dimensional Fast Fourier Transform to objectively quantify AFM maps allowed characterization of periodicity of both sarcomeric Z-line and M-band. Overall, this study validated PeakForce QNM as a valuable and innovative mode for the exploration of living and fixed CMs. In the future, it could be applied to depict cell membrane architectural, mechanical and chemical defects as well as sarcomeric abnormalities associated with cardiac diseases.
authors.affiliation: ITAV, Université de Toulouse, CNRS, France; LAAS-CNRS, Université de Toulouse, CNRS, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Smolyakov
authors.affiliation: Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Université de Toulouse, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Cauquil
authors.affiliation: ITAV, Université de Toulouse, CNRS, France.
authors.forename: Childerick
authors.initials: C
authors.lastname: Severac
authors.affiliation: ITAV, Université de Toulouse, CNRS, France; LAAS-CNRS, Université de Toulouse, CNRS, France; Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Université de Toulouse, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Lachaize
authors.affiliation: Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Université de Toulouse, France; Centre de Microscopie Électronique Appliquée à la Biologie, Université de Toulouse, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Guilbeau-Frugier
authors.affiliation: Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Université de Toulouse, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Sénard
authors.affiliation: ITAV, Université de Toulouse, CNRS, France; Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Université de Toulouse, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France. Electronic address: celine.gales@inserm.fr.
authors.forename: Céline
authors.initials: C
authors.lastname: Galés
authors.affiliation: ITAV, Université de Toulouse, CNRS, France; LAAS-CNRS, Université de Toulouse, CNRS, France; Service de Pharmacologie, CHU de Toulouse, Université de Toulouse, Toulouse, France. Electronic address: edague@laas.fr.
authors.forename: Etienne
authors.initials: E
authors.lastname: Dague
mesh_terms: D000818:Animals; D002462:Cell Membrane; D005559:Formamides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods*; D008928:Mitochondria / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000648:ultrastructure*; D012518:Sarcomeres / Q000648:ultrastructure; D013499:Surface Properties
chemical_list: D005559:Formamides; C031066:formamide
keywords: AFM; Cardiomyocytes