Low-level Laser Irradiation on Col-I and VEGF Expression In Vitro

Low-level Laser (LLL) therapies have been used for treatment of several oral diseases, especially to improve tissue repair. Epithelial cells play an important role on healing events promoting coating of damaged tissues and stimulating underlying cells. Therefore, the application of therapies capable to increase the metabolism of epithelial cells may improve healing of wounds. Objectives: To evaluate the effects of the LLL irradiation on culture of keratinocytes. Methods: Human epithelial cells (HaCaT) were seeded (30,000 cells/cm²) in wells of 24-well dishes for 48 hours. Then, the cells were irradiated by an irradiation device - LASERTable (780 ± 3nm wavelength; 40mW). Three laser irradiation of cultured cells were performed every 24 hours by application of the following energy doses: 0.5; 1.5; 3; 5; or 7J/cm². Evaluation of gene expression of collagen type I (Col-I) and vascular endothelial growth factor (VEGF) was performed 24 hours after the last irradiation by quantitative RT-PCR, using specific primers and probes and Taqman^® reagents. Tukey test was used for pairwise comparisons and Kruskal-Wallis complemented by Mann-Whitney test was used for non-parametric data (α=0.05). Results: LLLT promoted significantly increased gene expression for Col-I and VEGF, especially for 1.5J/cm² (p<0.05). The other considered doses showed gene expressions similar to control. Conclusion: Specific parameters of LLL irradiation, used on this study, applied on cultured epithelial cells increased the expression of important factors involved in tissue regeneration.