Irradiation at 636 nm positively affects diabetic wounded and hypoxic cells in vitro
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Updated: Jun 4, 2026
In Vivo Imaging of Reactive Oxygen Species in a Murine Wound Model
Published on: November 17, 2018
Palesa R Sekhejane1, Nicolette N Houreld, Heidi Abrahamse
1Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, Doornfontein, South Africa.
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/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.
