Influence of broad-spectrum and infrared light in combination with laser irradiation on the proliferation of wounded skin fibroblasts

Objective: This study aimed to establish if broad-spectrum or infrared (IR) light in combination with laser therapy can assist phototherapy and accelerate cell proliferation to improve the rate of wound healing. Background Data: The effect of laser light may be partly or completely reduced by broad-spectrum light. There are few studies that investigate the benefit or detriment of combining laser irradiation with broad-spectrum or IR light. Methods: Wounded human skin fibroblasts were irradiated with a dose of 5 J/cm² using a helium-neon laser, a diode laser, or a Nd:YAG laser in the dark, in the light, or in IR. Changes in cell proliferation were evaluated using optical density at 540 nm, alkaline phosphatase (ALP) enzyme activity, cytokine expression, and basic fibroblast growth factor (bFGF) expression. Results: The optical density and ALP enzyme activity indicate that 5 J/cm² using 1064 nm in the light is more effective in increasing cell proliferation or cell growth than 830 nm in the light, but not as effective as 632.8 nm in the light. bFGF expression shows that the response of wounded cells exposed to 5 J/cm² in IR light is far less than the biological response of wounded cells exposed to 5 J/cm² in the dark or light. The results indicate that wounded cells exposed to 5 J/cm² using 632.8 nm in the dark results in a greater increase in IL-6 when compared to cells exposed to 5 J/cm² in the light or in IR. Conclusion: Results indicate that 5 J/cm² (using 632.8 nm in the dark or 830 nm in the light) is the most effective dose to stimulate cell proliferation, which may ultimately accelerate or improve the rate of wound healing.