title: Effect of indocyanine green and illumination on gene expression in human retinal pigment epithelial cells.
abstract: OBJECTIVE
  To investigate the biological effects of indocyanine green (ICG) and acute illumination on human retinal pigment epithelial (RPE) cells.
  
  
  METHODS
  Three concentrations (0, 0.25, and 2.5 mg/mL) of ICG were applied to ARPE19 cells for 1 minute. After isotonic rinsing, the cells were irradiated with a light beam with a wavelength spectrum from 400 to 800 nm and an output of 1850 lumens for 15 minutes. The cells were collected at timed intervals for the investigation of cell death and expression of stress-response genes by reverse transcription-polymerase chain reaction, immunofluorescence, and Western blot analysis.
  
  
  RESULTS
  After ICG incubation, photoreactive changes were observed in the RPE cells. A reduction in cellular viability and considerable shrinkage of the cells were observed. The expressions of the apoptosis-related genes p53 and bax and the cell cycle arrest protein p21 were upregulated in cells treated with both ICG and light. Of the early-response genes, the expression of c-fos was specifically enhanced by light, with additive effects from the presence of ICG. Such stimulatory effects on these gene expressions were greater at 2.5 mg/mL than at 0.25 mg/mL ICG.
  
  
  CONCLUSIONS
  ICG in the presence of acute illumination can elicit cell-cycle arrest and even apoptosis in RPE cells. The establishment of a safety level in the application of ICG in the region of 0.25 mg/mL is recommended.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Eye Hospital, The Chinese University of Hong Kong, 147K Argyle Street, Kowloon, Hong Kong.
authors.forename: Hin-Fai
authors.initials: HF
authors.lastname: Yam
authors.forename: Alvin Kwan-Ho
authors.initials: AK
authors.lastname: Kwok
authors.forename: Kwok-Ping
authors.initials: KP
authors.lastname: Chan
authors.forename: Timothy Yuk-Yau
authors.initials: TY
authors.lastname: Lai
authors.forename: Kwan-Yi
authors.initials: KY
authors.lastname: Chu
authors.forename: Dennis Shun-Chiu
authors.initials: DS
authors.lastname: Lam
authors.forename: Chi Pui
authors.initials: CP
authors.lastname: Pang
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D004396:Coloring Agents / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression / Q000187:drug effects* / Q000528:radiation effects*; D016762:Genes, fos / Q000235:genetics; D016758:Genes, jun / Q000235:genetics; D016158:Genes, p53 / Q000235:genetics; D006801:Humans; D007208:Indocyanine Green / Q000494:pharmacology*; D008027:Light; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D012313:RNA / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein
chemical_list: C494826:BAX protein, human; C493956:CDKN1A protein, human; D004396:Coloring Agents; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D005136:Eye Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D012313:RNA; D007208:Indocyanine Green