title: Repeated folding stress-induced morphological changes in the dermal equivalent.
abstract: OBJECTIVE
  Repeated mechanical stresses applied to the same region of the skin are thought to induce morphological changes known as wrinkle. However, the underlying mechanisms are not fully understood. To study the mechanisms, we examined effects of repeated mechanical stress on the dermal equivalent.
  
  
  METHODS
  We developed a novel device to apply repeated folding stress to the dermal equivalent. After applying the mechanical stress, morphological changes of the dermal equivalent and expression of several genes related to extracellular matrix turn over and cell contraction were examined.
  
  
  RESULTS
  The repeated folding stress induced a noticeable decrease in the width of the dermal equivalent. The mechanical stress altered orientations of collagen fibrils. Hydroxyproline contents, dry weights and cell viability of the dermal equivalents were not affected by the mechanical stress. On the other hand, Rho-associated coiled-coil-containing kinase (ROCK) specific inhibitor Y27632 completely suppressed the decrease in the width of the dermal equivalent.
  
  
  CONCLUSIONS
  The present results revealed that either degradation of collagen or changes in the number of cells were not responsible for the decrease in the width of the dermal equivalent and indicate that the repeated mechanical stress induces unidirectional contraction in the dermal equivalent through the RhoA-ROCK signaling pathway.
authors: Scleroprotein Research Institute, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors: Koji Y
authors: KY
authors: Arai
authors: Mami
authors: M
authors: Sugimoto
authors: Kanako
authors: K
authors: Ito
authors: Yuki
authors: Y
authors: Ogura
authors: Nobuko
authors: N
authors: Akutsu
authors: Satoshi
authors: S
authors: Amano
authors: Eijiro
authors: E
authors: Adachi
authors: Toshio
authors: T
authors: Nishiyama
mesh_terms: D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism*; D019245:Compressive Strength / Q000502:physiology; D055119:Elastic Modulus / Q000502:physiology; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D017768:Skin, Artificial; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology; D014783:Viscosity
chemical_list: D024042:Collagen Type I
keywords: dermal equivalent; fibroblast; mechanical stress; skin furrow/wrinkle