title: Combining AFM and acoustic probes to reveal changes in the elastic stiffness tensor of living cells.
abstract: Knowledge of how the elastic stiffness of a cell affects its communication with its environment is of fundamental importance for the understanding of tissue integrity in health and disease. For stiffness measurements, it has been customary to quote a single parameter quantity, e.g., Young's modulus, rather than the minimum of two terms of the stiffness tensor required by elasticity theory. In this study, we use two independent methods (acoustic microscopy and atomic force microscopy nanoindentation) to characterize the elastic properties of a cell and thus determine two independent elastic constants. This allows us to explore in detail how the mechanical properties of cells change in response to signaling pathways that are known to regulate the cell's cytoskeleton. In particular, we demonstrate that altering the tensioning of actin filaments in NIH3T3 cells has a strong influence on the cell's shear modulus but leaves its bulk modulus unchanged. In contrast, altering the polymerization state of actin filaments influences bulk and shear modulus in a similar manner. In addition, we can use the data to directly determine the Poisson ratio of a cell and show that in all cases studied, it is less than, but very close to, 0.5 in value.
authors.affiliation: School of Materials, Faculty of Engineering and Physical Sciences, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom; Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Nadja
authors.initials: N
authors.lastname: Nijenhuis
authors.affiliation: School of Materials, Faculty of Engineering and Physical Sciences, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Xuegen
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Alex
authors.initials: A
authors.lastname: Carisey
authors.affiliation: Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Christoph
authors.initials: C
authors.lastname: Ballestrem
authors.affiliation: School of Materials, Faculty of Engineering and Physical Sciences, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom. Electronic address: brian.derby@manchester.ac.uk.
authors.forename: Brian
authors.initials: B
authors.lastname: Derby
mesh_terms: D000162:Acoustics; D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002470:Cell Survival; D002477:Cells / Q000737:chemistry* / Q000648:ultrastructure*; D055119:Elastic Modulus; D051379:Mice; D018625:Microscopy, Atomic Force; D041681:NIH 3T3 Cells; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D033081:Shear Strength
chemical_list: D000199:Actins