Résumé de communication

Objectives: Wrinkled skin and hair loss are external reflections of morphological and physiological aging processes. Phototherapy using lasers and light emitting diodes (LEDs) is a non-invasive procedure that uses light energy to regenerate and repair aged skin. However, it has limitations owing to their dot-shaped emission characteristics and narrow spectral bandwidth. Because the action spectrum on tissue regeneration consists of more than one wavelength, applying a spectrum covering a wider spectral region may be advantageous. Introduction: In this study, we developed a new near-infrared LED (nNIR LED) with a broader spectrum than the existing NIR chip LED lighting and applied it to human skin cells and animal models to investigate its effects on skin improvement and hair growth. We investigated the effects of nNIR LEDs, compared to those of white LEDs, on cytotoxicity, adenosine triphosphate (ATP) synthesis, and reactive oxygen species (ROS) reduction in human skin cells. We also evaluated changes in skin thickness, collagen synthesis, and collagenase expression in a UV-induced photoaging mouse model. Materials / method: Additionally, the effect of NIR LED irradiation on hair follicle growth was observed by analyzing skin thickness, anagen induction, and follicle number. Results: Additionally, the effect of NIR LED irradiation on hair follicle growth was observed by analyzing skin thickness, anagen induction, and follicle number. nNIR and white LED did not show cytotoxicity in human skin cells, increased ATP and collagen synthesis, and decreased ROS levels. In a UV-induced photoaging mouse model, irradiation with nNIR LED and white LED decreased skin wrinkles and skin thickness, increased collagen synthesis, and downregulated collagenase expression. Moreover, these promoted hair growth, skin thickness, and hair follicle number. Conclusion: Our study findings could be used to develop novel therapy for skin and hair growth improvement using LED light.