title: Cellular Microbiaxial Stretching to Measure a Single-Cell Strain Energy Density Function.
abstract: The stress in a cell due to extracellular mechanical stimulus is determined by its mechanical properties, and the structural organization of many adherent cells suggests that their properties are anisotropic. This anisotropy may significantly influence the cells' mechanotransductive response to complex loads, and has important implications for development of accurate models of tissue biomechanics. Standard methods for measuring cellular mechanics report linear moduli that cannot capture large-deformation anisotropic properties, which in a continuum mechanics framework are best described by a strain energy density function (SED). In tissues, the SED is most robustly measured using biaxial testing. Here, we describe a cellular microbiaxial stretching (CμBS) method that modifies this tissue-scale approach to measure the anisotropic elastic behavior of individual vascular smooth muscle cells (VSMCs) with nativelike cytoarchitecture. Using CμBS, we reveal that VSMCs are highly anisotropic under large deformations. We then characterize a Holzapfel-Gasser-Ogden type SED for individual VSMCs and find that architecture-dependent properties of the cells can be robustly described using a formulation solely based on the organization of their actin cytoskeleton. These results suggest that cellular anisotropy should be considered when developing biomechanical models, and could play an important role in cellular mechano-adaptation.
authors.affiliation: Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail: winxx005@umn.edu.
authors.forename: Zaw
authors.initials: Z
authors.lastname: Win
authors.affiliation: Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail: buksa002@umn.edu.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Buksa
authors.affiliation: Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail: steu0057@umn.edu.
authors.forename: Kerianne E
authors.initials: KE
authors.lastname: Steucke
authors.affiliation: Department of Genetics, Cell Biology, and Development, University of Minnesota-Twin Cities, 420 Washington Avenue SE MCB 4-128, Minneapolis, MN 55455 e-mail: gwgl@umn.edu.
authors.forename: G W
authors.initials: GW
authors.lastname: Gant Luxton
authors.affiliation: Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail: baroc001@umn.edu.
authors.forename: Victor H
authors.initials: VH
authors.lastname: Barocas
authors.affiliation: Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail: pwalford@umn.edu.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Alford
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D016880:Anisotropy; D001696:Biomechanical Phenomena; D006801:Humans; D040542:Mechanotransduction, Cellular; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D059010:Single-Cell Analysis; D013314:Stress, Mechanical; D013816:Thermodynamics