title: Antimicrobial photodynamic therapy: assessment of genotoxic effects on keratinocytes in vitro.
abstract: BACKGROUND
  Work has shown that cutaneous microbial species associated with skin conditions of microbial aetiology are susceptible to killing by antimicrobial photodynamic therapy (APDT) using visible light and methylene blue.
  
  
  OBJECTIVE
  To evaluate immediate and delayed genotoxicity of APDT on keratinocytes in vitro.
  
  
  METHODS
  A combination of methylene blue (100 microg mL(-1)) and visible light (42 mW cm(-2)), as used in studies of microbe and keratinocyte cytotoxicity, was employed to test a human keratinocyte cell line (H103) for genotoxic damage by comet assay.
  
  
  RESULTS
  The comet assay was able to detect genotoxic damage in H2O2-treated keratinocytes (positive control). APDT did not cause either immediate or delayed genotoxic damage in keratinocytes following APDT of up to 180 min.
  
  
  CONCLUSIONS
  APDT sufficient to reduce microbes by seven log cycles showed no detectable genotoxic effects on keratinocytes. APDT applied in vivo may represent a useful low-risk alternative to conventional antimicrobial treatment in dermatology.
authors.affiliation: Dermatology Department of Teshreen Hospital, Damascus, Syria.
authors.forename: B
authors.initials: B
authors.lastname: Zeina
authors.forename: J
authors.initials: J
authors.lastname: Greenman
authors.forename: D
authors.initials: D
authors.lastname: Corry
authors.forename: W M
authors.initials: WM
authors.lastname: Purcell
mesh_terms: D002460:Cell Line; D020552:Comet Assay / Q000379:methods; D004249:DNA Damage / Q000235:genetics; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000382:microbiology / Q000528:radiation effects*; D008751:Methylene Blue / Q000494:pharmacology; D010789:Phototherapy / Q000009:adverse effects*; D012874:Skin Diseases, Infectious / Q000188:drug therapy / Q000235:genetics
chemical_list: D006861:Hydrogen Peroxide; D008751:Methylene Blue