title: Photodynamic inactivation of primary human fibroblasts by methylene blue and toluidine blue O.
abstract: BACKGROUND
  An important determinant of the clinical applicability and value of antimicrobial photodynamic inactivation (PDI) is the cytotoxicity of the treatment to human cells. We evaluated the in vitro cytotoxicity of PDI to primary human fibroblasts using methylene blue (MB) and toluidine blue O (TBO) as the photosensitizers.
  
  
  METHODS
  The primary human fibroblasts were exposed to PDI regimes that were used for the inactivation of methicillin-resistant Staphylococcus aureus (MRSA) and multi-drug resistant Escherichia coli (MDR E. coli). Mitochondrial activity subsequent to exposure was evaluated after 24h using the methylthiazoletetrazolium assay and compared to pretreatment values.
  
  
  RESULTS
  Mitochondrial activity of primary human fibroblasts was reduced by 27% after exposure to light (163.8 J/cm(2)) and MB (50 μg/ml). At a TBO concentration previously demonstrated to induce 99.91% and 83.2% reduction in a viable count for MRSA and MDR E. coli, respectively, 39.6% of the fibroblasts were photo-inactivated.
  
  
  CONCLUSIONS
  Our findings showed that MB/TBO-PDI did not induce significant cytotoxic effects on human fibroblasts in culture.
authors.affiliation: Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran. Kashefn@khayam.ut.ac.ir
authors.forename: Nasim
authors.initials: N
authors.lastname: Kashef
authors.forename: Gita
authors.initials: G
authors.lastname: Ravaei Sharif Abadi
authors.forename: Gholamreza Esmaeeli
authors.initials: GE
authors.lastname: Djavid
mesh_terms: D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000528:radiation effects*; D005347:Fibroblasts; D006801:Humans; D054023:Lasers, Semiconductor; D028022:Low-Level Light Therapy / Q000379:methods*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000528:radiation effects*; D008751:Methylene Blue / Q000494:pharmacology*; D008928:Mitochondria / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000494:pharmacology*; D014048:Tolonium Chloride / Q000494:pharmacology*
chemical_list: D017319:Photosensitizing Agents; D014048:Tolonium Chloride; D008751:Methylene Blue