title: Continuous irradiation with a 633-nm light-emitting diode exerts an anti-aging effect on human skin cells.
abstract: Accumulating evidence has indicated that the light source emitted from light‑emitting diode (LED) has a potential anti-aging effect on human skin. Studies using single and interval LED irradiation have documented such effects; however, to the best of our knowledge, the anti-aging effects of continuous LED irradiation have not yet been investigated. In the present study, we demonstrated that continuous irradiation with a 633±3-nm LED exerted anti-aging effects in both in vitro and ex vivo experiments. More specifically, irradiation with a 633-nm LED for 2 days increased the synthesis of type 1 procollagen and decreased the expression of matrix metalloproteinase (MMP)1 and MMP2 in skin fibroblasts. In addition, irradiation with a 633-nm LED decreased the expression levels of inflammatory genes, such has cyclooxygenase-2 (COX-2), and interleukin-1-α (IL-1α) in keratinocytes. Furthermore, a 14-day LED irradiation moderately increased keratinocyte proliferation. Using human skin explants, we confirmed the safety of this 633-nm LED irradiation, which resulted in unaltered morphology and allergy-free potential in human tissue. Overall, these data provide insight into the anti-aging effects of continuous LED irradiation on human skin.
authors.affiliation: Samsung Display Co., Ltd., Yongin, Gyeonggi-do 446-811, Republic of Korea.
authors.forename: Hak Sun
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Samsung Display Co., Ltd., Yongin, Gyeonggi-do 446-811, Republic of Korea.
authors.forename: Won Sang
authors.initials: WS
authors.lastname: Park
authors.affiliation: Samsung Display Co., Ltd., Yongin, Gyeonggi-do 446-811, Republic of Korea.
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Baek
authors.affiliation: R&D Center, ACT Co., Ltd., Suwon, Gyeonggi-do 443-734, Republic of Korea.
authors.forename: Bo-Sub
authors.initials: BS
authors.lastname: Lee
authors.affiliation: R&D Center, ACT Co., Ltd., Suwon, Gyeonggi-do 443-734, Republic of Korea.
authors.forename: Dae Sung
authors.initials: DS
authors.lastname: Yoo
authors.affiliation: R&D Center, ACT Co., Ltd., Suwon, Gyeonggi-do 443-734, Republic of Korea.
authors.forename: Si Jun
authors.initials: SJ
authors.lastname: Park
mesh_terms: D002460:Cell Line; D016922:Cellular Senescence / Q000528:radiation effects*; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000528:radiation effects; D006801:Humans; D053582:Interleukin-1alpha / Q000096:biosynthesis; D008027:Light; D020781:Matrix Metalloproteinase 1 / Q000096:biosynthesis; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D015595:Skin Aging / Q000528:radiation effects*
chemical_list: C508584:IL1A protein, human; D053582:Interleukin-1alpha; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1