title: Comparison of the in vitro toxicity of indocyanine green to that of trypan blue in human retinal pigment epithelium cell cultures.
abstract: OBJECTIVE
  To compare the in vitro toxicity of indocyanine green (ICG) to that of trypan blue (TB) in human retinal pigment epithelium cell cultures. The use of ICG and TB in macular hole surgery is discussed.
  
  
  METHODS
  In vitro cell biology experimental study.
  
  
  METHODS
  The ICG dye and TB were applied to ARPE-19, a commercially available human retinal pigment epithelium cell line. Cultures were established and maintained according to supplier protocols. The ICG dye, TB or Hank's balanced salt solution (controls) were then applied to the cells at varying concentrations and over various exposure periods. Fiberoptic light was also applied to cells to assess for the possibility of a potentiating phototoxic effect. Cell viability fractions were determined using a well-studied mitochondrial dehydrogenase assay.
  
  
  RESULTS
  The TB was not toxic to the retinal pigment epithelium cell cultures at any concentration or over any period of exposure, whereas ICG dye demonstrated dose-dependent and exposure-dependent toxicity. The ICG dye was found to be toxic to the cells at all tested concentrations between 5.0 mg/ml (stock concentration, 26.1% cell survival) and 0.5 mg/ml (92.8% cell survival) over a 3-minute exposure. No toxicity to TB was seen at the stock concentration of 1.5 mg/mL. Addition of light to the cultures did not significantly alter cell viability with either dye. Long periods of exposure, 2 hours, 24 hours, and 72 hours, to minute concentrations of either dye did not produce significant cell death.
  
  
  CONCLUSIONS
  Indocyanine green demonstrates more toxicity than TB to human retinal pigment epithelium cell cultures. This is independent of any phototoxic potentiating effect of fiberoptic light or solvent toxicity. A clinically useful concentration of 0.5-mg/ml ICG causes low cytotoxicity at 3 minutes' exposure (cell survival 92.8%) and shows no detectable toxicity at 1-minute exposure (cell survival 102%).
authors.affiliation: Ivey Eye Institute, 750 Commissioners Road E., London, Ontario, Canada N6A 4G5.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Gale
authors.forename: Alain A
authors.initials: AA
authors.lastname: Proulx
authors.forename: John R
authors.initials: JR
authors.lastname: Gonder
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Mao
authors.forename: Cindy M L
authors.initials: CM
authors.lastname: Hutnik
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007208:Indocyanine Green / Q000633:toxicity*; D008027:Light; D009994:Osmolar Concentration; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000528:radiation effects; D013997:Time Factors; D014343:Trypan Blue / Q000633:toxicity*
chemical_list: D004396:Coloring Agents; D014343:Trypan Blue; D007208:Indocyanine Green