title: Clinical and histological effects of blue light on normal skin.
abstract: BACKGROUND
  Phototherapy with visible light is gaining interest in dermatological practice. Theoretically, blue light could induce biological effects comparable to ultraviolet A (UVA) radiation.
  
  
  OBJECTIVE
  To study the effects of blue light on normal skin in terms of photodamage, skin ageing and melanogenesis.
  
  
  METHODS
  Eight healthy volunteers were included and irradiation with visible blue light was given on five consecutive days. Skin biopsies were analysed with respect to photodamage (p53, vacuolization, sunburn cells), skin ageing (elastosis, MMP-1) and melanogenesis (Melan-A).
  
  
  RESULTS
  No inflammatory cells and sunburn cells were visible before or after irradiation. A significant increase in the perinuclear vacuolization of keratinocytes was demonstrated during treatment (P=0.02) with a tendency towards significance after cessation of treatment (P=0.09). No significant change in p53 expression was seen. Signs of elastosis and changes in MMP-1 expression were absent. Minimal clinical hyperpigmentation of the irradiated skin was confirmed histologically with a significant increase in Melan-A-positive cells (P=0.03).
  
  
  CONCLUSIONS
  Visible blue light, as given in the present study, does not cause deoxyribonucleic acid damage or early photo-ageing. The biological effects of blue light on normal skin are transient melanogenesis and inexplicable vacuolization without resulting apoptosis. In conclusion, the (short-term) use of visible blue light in dermatological practice is safe.
authors.affiliation: Department of Dermatology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. m.kleinpenning@derma.umcn.nl
authors.forename: Marloes M
authors.initials: MM
authors.lastname: Kleinpenning
authors.forename: Tim
authors.initials: T
authors.lastname: Smits
authors.forename: Marjolein H A
authors.initials: MH
authors.lastname: Frunt
authors.forename: Piet E J
authors.initials: PE
authors.lastname: van Erp
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van de Kerkhof
authors.forename: Rianne M J P
authors.initials: RM
authors.lastname: Gerritsen
mesh_terms: D000328:Adult; D000951:Antigens, Neoplasm / Q000378:metabolism; D005260:Female; D006801:Humans; D008027:Light / Q000009:adverse effects*; D058965:MART-1 Antigen; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010789:Phototherapy / Q000009:adverse effects*; D012867:Skin / Q000378:metabolism / Q000473:pathology*; D015595:Skin Aging / Q000473:pathology / Q000528:radiation effects*; D013471:Sunburn / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D016159:Tumor Suppressor Protein p53; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1