title: Aging-related viscoelasticity variation of tendon stem cells (TSCs) characterized by quartz thickness shear mode (TSM) resonators.
abstract: Aging not only affects the whole body performance but also alters cellular biological properties, including cell proliferation and differentiation. This study was designed to determine the effect of aging on the mechanical properties of tendon stem cells (TSCs), a newly discovered stem cell type in tendons, using quartz thickness shear mode (TSM) resonators. TSCs were isolated from both old and young rats, and allowed to grow to confluency on the surface of TSM resonators. The admittance spectrums of TSM with TSC monolayer were acquired, and a series of complex shear modulusG' +jG″ as well as average thicknesshTSCwere calculated based on a two-layer-loading transmission line model (TLM) for TSM resonator sensor. The results showed an overall increase inG',G″ andhTSCduring aging process. Specifically, the storage modulusG' of aging TSCs was over ten times than that of young, revealing an important increase in stiffness of aging TSCs. Additionally, through phase-contrast and scanning electronic microscopy, it was shown that aging TSCs were large, flat and heterogeneous in morphologies while young TSCs were uniformly elongated. Increased cell size and irregular cell shape might be associated with the dense cytoskeleton organization, which could lead to an increase in both stiffness and viscosity. These results are in agreement with previously published data using different measurement methods, indicating TSM resonator sensor as a promising tool to measure the mechanical properties of cells.
authors.affiliation: Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Huiyan
authors.initials: H
authors.lastname: Wu
authors.affiliation: MechanoBiology Laboratory, Department of Orthopaedic Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Guangyi
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Hongfei
authors.initials: H
authors.lastname: Zu
authors.affiliation: MechanoBiology Laboratory, Department of Orthopaedic Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: James H-C
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Qing-Ming
authors.initials: QM
authors.lastname: Wang
keywords: Aging; TSC; TSM; Viscoelasticity