title: Change in viability of C2C12 myoblasts under compression, shear and oxidative challenges.
abstract: Skeletal and epidermal loadings can damage muscle cells and contribute to the development of deep tissue injury (DTI) - a severe kind of pressure ulcers affecting many people with disability. Important predisposing factors include the multiaxial stress and strain fields in the internal tissues, particularly the vulnerable muscles around bony prominences. A careful study of the mechanical damage thresholds for muscle cell death is critical not only to the understanding of the formation of DTI, but also to the design of various body support surfaces for prevention. In this paper, we measured the mechanical damage thresholds of C2C12 myoblasts under prescribed compressive strains (15% and 30%) and shear strains (from 0% to 100%), and studied how oxidative stress, as caused potentially by reperfusion or inflammation, may affect such damage thresholds. A flat plate was used to apply a uniform compressive strain and a radially increasing shear strain on disks of Gelatin-methacrylate (GelMA) hydrogel with myoblasts encapsulated within. The percentages of cell death were estimated with propidium iodide (PI) and calcein AM staining. Results suggested that cell death depended on both the level and duration of the applied strain. There seemed to be a non-linear coupling between compression and shear. Muscle cells often need to function biomechanically in challenging oxidative environments. To study how oxidative stress may affect the mechanical damage thresholds of myoblasts, cell viability under compressive and shear strains was also studied after the cells were pre-treated for different durations (1h and 20h) with different concentrations (0.1mM and 0.5mM) of hydrogen peroxide (H2O2). Oxidative stress can either compromise or enhance the cellular resistance to shear damage, depending on the level and duration of the oxidative exposure.
authors.affiliation: Division of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR.
authors.forename: Ye
authors.initials: Y
authors.lastname: Hong
authors.affiliation: Division of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Division of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR.
authors.forename: Singwan
authors.initials: S
authors.lastname: Wong
authors.affiliation: Division of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR.
authors.forename: Liming
authors.initials: L
authors.lastname: Bian
authors.affiliation: Division of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR. Electronic address: arthurmak@cuhk.edu.hk.
authors.forename: Arthur F T
authors.initials: AFT
authors.lastname: Mak
mesh_terms: D000818:Animals; D016923:Cell Death; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D032446:Myoblasts / Q000187:drug effects / Q000502:physiology*; D018384:Oxidative Stress; D011312:Pressure; D013314:Stress, Mechanical
chemical_list: D006861:Hydrogen Peroxide
keywords: Damage mechanics; Deep tissue injury; Myoblasts; Oxidative stress; Shear