Irradiation at 636 nm positively affects diabetic wounded and hypoxic cells in vitro

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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 data: 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/cm2 using a continuous wave 636-nm diode laser at an average power of 95 mW, an illuminated area of 9.05 cm2, and an irradiance of 11 mW/cm2 (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.

Original languageEnglish
Pages (from-to)521-530
Number of pages10
JournalPhotomedicine and Laser Surgery
Issue number8
Publication statusPublished - 1 Aug 2011

ASJC Scopus subject areas

  • Biomedical Engineering
  • Radiology, Nuclear Medicine and Imaging


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