Effect of low-power red light laser irradiation on the viability of human skin fibroblast.
Human skin fibroblast monolayers (S-126 cell line) were exposed to laser radiation (wavelength 670 nm, power density 40 mW/cm2). The energy densities were 2 J/cm2 and 12 J/cm2, respectively, and the irradiation was carried out at a temperature of 22 degrees C. For fibroblast viability evaluation, the colorimetric assay (conversion of thiazolyl blue to formazan) was used. The experiments were carried out at 37 degrees C, in the presence of 5% CO2, and at different time periods of incubation after irradiation (2, 4, 8 h and 1, 2, 3, 4, 5 days). The results indicated that there was a certain stimulating effect on the long-term proliferation of skin fibroblasts and that the stimulation proceeded in two stages, the first one 2 h and the second one 3 days post-irradiation.