title: Irradiation at 636 nm positively affects diabetic wounded and hypoxic cells in vitro.
abstract: OBJECTIVE
  This study investigated the effect of low-intensity laser irradiation (LILI) on pro-inflammatory cytokines involved in wound healing processes in diabetes and hypoxia.
  
  
  BACKGROUND
  Diabetes is associated with impaired wound healing and a prolonged inflammatory phase. Pro-inflammatory cytokines such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6 are elevated in diabetes. LILI has been reported to accelerate wound healing and decrease inflammatory cytokines.
  
  
  METHODS
  A human skin fibroblast cell line (WS1) was used in vitro. Cells were exposed to various insults, namely, wounding, and a diabetic or hypoxic environment. Experimental cells were exposed to an energy density of 5  J/cm(2) using a continuous wave 636-nm diode laser at an average power of 95  mW, an illuminated area of 9.05  cm(2), and an irradiance of 11 mW/cm(2) (irradiation time, 476  sec). The effect of laser irradiation on cytokine expression was examined at 1 or 24  h post-irradiation. Cellular morphology, viability, proliferation, and cytokine expression (IL-1β, IL-6, and TNF-α) were investigated. Translocation of nuclear factor-kappa B (NF-κB) was also determined.
  
  
  RESULTS
  There was a higher rate of migration in irradiated wounded cultures, and irradiated hypoxic cells showed an improvement in cellular morphology. All cell models showed an increase in proliferation. Normal wounded cells showed a decrease in apoptosis, TNF-α, and IL-1β. Diabetic wounded cells showed an increase in viability and a decrease in apoptosis and IL-1β, whereas hypoxic cells showed an increase in viability and IL-6, and a decrease in apoptosis and TNF-α. NF-κB was translocated into the nucleus post-irradiation.
  
  
  CONCLUSIONS
  Phototherapy resulted in hastened wound closure, increased proliferation, and normalization of cellular function. The decrease in the different pro-inflammatory cytokines and NF-κB translocation was model and time dependent. Overall, laser irradiation resulted in a reduction in inflammatory cytokines and directed cells into the cell survival pathway.
authors.affiliation: Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, Doornfontein, South Africa.
authors.forename: Palesa R
authors.initials: PR
authors.lastname: Sekhejane
authors.forename: Nicolette N
authors.initials: NN
authors.lastname: Houreld
authors.forename: Heidi
authors.initials: H
authors.lastname: Abrahamse
mesh_terms: D000704:Analysis of Variance; D002460:Cell Line; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000502:physiology / Q000528:radiation effects; D003920:Diabetes Mellitus / Q000378:metabolism / Q000503:physiopathology*; D005347:Fibroblasts / Q000166:cytology / Q000473:pathology / Q000528:radiation effects*; D006801:Humans; D000860:Hypoxia; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism*; D028022:Low-Level Light Therapy / Q000379:methods*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology / Q000528:radiation effects*; D014947:Wounds and Injuries / Q000503:physiopathology / Q000628:therapy*
chemical_list: D007375:Interleukin-1; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha