Low Level Laser Therapy (LLLT) Effects of He-Ne Laser with Different Irradiation Conditions on Proliferation in Various Cultured Cells

<p> Purpose: Our previous studies have shown the potential effect of He-Ne laser irradiation on the proliferation activity of cancers. This study investigated the effects of He-Ne Laser irradiation with various irradiation conditions on proliferation in cultured human gingival fibroblasts and cultured human oral squamous cell carcinomas.</p><p> Materials and Methods: The HGF-1 cell, which is a fibroblast cell line, and the H157 cell and H314 cell, which are oral squamous cell carcinomas, were used as cultured cells. The cells were irradiated with low-energy He-Ne laser with the following three different power and duration combinations: L1: 1.38 J/cm², 10 min, L2: 5.75 J/cm², 42 min, and L3: 5.75 J/cm², 10 min. L1 and L2 were irradiated at a distance of 20.2 mm; L3 was irradiated with the tip contacting at the bottom. Various cells were incubated in 24-multiwell plastic culture dishes with Dulbecco’s modified Eagle medium (D-MEM) containing 10% fetal bovine serum. After the laser irradiation, cell numbers were determined at 0, 3, 6, 12, 24, 36, 48, 72 and 120 hours, and the proliferation was examined using WST-8.</p><p> Results: In the case of L1, regarding initial growth compared with that in the non-irradiated control, HGF-1 and H314 showed enhanced proliferation by the He-Ne laser irradiation. In the case of L2, we demonstrated that the He-Ne laser used in the present study has a potential suppressive effect on HGF-1, H157 and H314. In the case of L3, cell proliferation was significantly higher in HGF-1 and H157 on initial growth and on H314 on late growth.</p><p> Conclusion: The present study showed that irradiation conditions are most important for the LLLT effects of He-Ne laser, and that He-Ne laser irradiation may contribute to the proliferation of various cultured cells. However, the degree of proliferation differs depending on the optimal condition of the cell.</p>