Continuous irradiation with a 633-nm light-emitting diode exerts an anti-aging effect on human skin cells

Int J Mol Med. 2015 Feb;35(2):383-90. doi: 10.3892/ijmm.2014.2030. Epub 2014 Dec 9.


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.

MeSH terms

  • Cell Line
  • Cellular Senescence / radiation effects*
  • Cyclooxygenase 2 / biosynthesis
  • Fibroblasts / cytology
  • Fibroblasts / metabolism*
  • Gene Expression Regulation / radiation effects
  • Humans
  • Interleukin-1alpha / biosynthesis
  • Light*
  • Matrix Metalloproteinase 1 / biosynthesis
  • Matrix Metalloproteinase 2 / biosynthesis
  • Skin / cytology
  • Skin / metabolism*
  • Skin Aging / radiation effects*


  • IL1A protein, human
  • Interleukin-1alpha
  • Cyclooxygenase 2
  • PTGS2 protein, human
  • MMP2 protein, human
  • Matrix Metalloproteinase 2
  • MMP1 protein, human
  • Matrix Metalloproteinase 1