P244 : A comparative study of red and yellow light emitting diodes for skin photorejuvenation in vivo and in vitro

Background: Red-colored light-emitting diodes (LEDs) can improve skin photorejuvenation and regeneration by increasing cellular metabolic activity. Objectives: To evaluate the effectiveness of LEDs with specific wavelengths for skin photorejuvenation in vitro and in vivo. Methods: Normal human dermal fibroblasts (HFs) were cultured and irradiated in vitro by LEDs at different wavelengths (410-850К) and doses (0-10J/Р). In vivo experiments were performed on the skin of hairless mice. Collagen (COL) and matrix metalloproteinases (MMPs) expression were evaluated via semi-quantitative RT-PCR, Western blotting, and a procollagen type I C-peptide enzyme immunoassay (EIA). Hematoxylin-eosin and Masson’s trichrome stains were performed to evaluate histological changes. Results: In HFs, COL I was up-regulated and MMP-1 was down-regulated in response to LED irradiation at 595【2Кand 630【8К. In EIA, a peak result was achieved at a dose of 5J/Рwith a LED at 595【2К. In vivo, COL I synthesis was up-regulated in response to both 595Кand 630КLED irradiation and this impact prolonged to 21 days after irradiation after a single 100J/Рdose. The histological changes were consistent with RT-PCR and western blot results. Conclusion: Treatment with 595【2К, 630【8КLEDs up-regulated COL I expression and down-regulated MMPs expressions, and the effects persisted at least 21 days after irradiation. These findings suggest that yellow and red-colored LEDs might be useful for skin photorejuvenation.