BACKGROUND: the cytoskeleton is a dynamic arrangement of actin filaments that maintain cell shape and are vital in mediating the mechanobiological response of the cell. METHODS: to determine the cytoskeletal response to varying in vitro, biaxial stretch amplitudes, rat-tail tendon cells were paired into control and cyclically strained groups of 4.75, 9.5, or 12% strain at 1 Hz for 2 hours and the actin cytoskeleton stained. The cells were analyzed for actin staining intensity as a measure of relative depolymerization and for cell shape. Collagenase gene expression was measured in cells undergoing 12% cyclic strain at 1 Hz for 24 hours. RESULTS: there was no significant difference in the degree of actin staining intensity between the control group and cells strained at either 4.75 or 9.5%. However, cells strained at 12% demonstrated a significant decrease in actin staining intensity (depolymerization) compared to control cells, increased collagenase expression by 81%, and a clear shift towards a more rounded cell shape. CONCLUSION: the results of this study demonstrate that the previously reported induction of collagenase activity associated with the application of high magnitude, in vitro, tensile strains may actually be a result of cytoskeletal depolymerization, which causes loss of tensional homeostasis and alteration of cell shape.
BACKGROUND: the cytoskeleton is a dynamic arrangement of actin filaments that maintain cell shape and are vital in mediating the mechanobiological response of the cell. METHODS: to determine the cytoskeletal response to varying in vitro, biaxial stretch amplitudes, rat-tail tendon cells were paired into control and cyclically strained groups of 4.75, 9.5, or 12% strain at 1 Hz for 2 hours and the actin cytoskeleton stained. The cells were analyzed for actin staining intensity as a measure of relative depolymerization and for cell shape. Collagenase gene expression was measured in cells undergoing 12% cyclic strain at 1 Hz for 24 hours. RESULTS: there was no significant difference in the degree of actin staining intensity between the control group and cells strained at either 4.75 or 9.5%. However, cells strained at 12% demonstrated a significant decrease in actin staining intensity (depolymerization) compared to control cells, increased collagenase expression by 81%, and a clear shift towards a more rounded cell shape. CONCLUSION: the results of this study demonstrate that the previously reported induction of collagenase activity associated with the application of high magnitude, in vitro, tensile strains may actually be a result of cytoskeletal depolymerization, which causes loss of tensional homeostasis and alteration of cell shape.
Authors: Steven P Arnoczky; Michael Lavagnino; Monika Egerbacher; Oscar Caballero; Keri Gardner; Marisa A Shender Journal: Clin Orthop Relat Res Date: 2008-05-06 Impact factor: 4.176
Authors: Christian Gammelgaard Olesen; Christian Pablo Pennisi; Mark de Zee; Vladimir Zachar; John Rasmussen Journal: J Tissue Viability Date: 2013-03-18 Impact factor: 2.932
Authors: Michael Lavagnino; Steven P Arnoczky; Monika Egerbacher; Keri L Gardner; Meghan E Burns Journal: J Biomech Date: 2005-10-26 Impact factor: 2.712
Authors: E Knörzer; W Folkhard; W Geercken; C Boschert; M H Koch; B Hilbert; H Krahl; E Mosler; H Nemetschek-Gansler; T Nemetschek Journal: Arch Orthop Trauma Surg Date: 1986