The Effect of Indocyanine Green on Cultured Retinal Glial Cells

In Brief Background: Recently, indocyanine green (ICG) has been utilized to visualize inner limiting membrane in vitreous surgery. However, the safety of ICG injected into the vitreous has not been well established. The possible toxicity of ICG on Müller cells was investigated using cultured rat retinal glial cells (RGCs). Methods: Rat RGCs were cultured in Dulbecco modified Eagle medium supplemented with 20% fetal calf serum. The cytotoxicity of ICG was assayed with viable cell number and resazurin metabolic assay. The expression of the apoptosis-related gene bcl-2 was examined with real-time polymerase chain reaction analysis. Results: The effects of ICG on the viability of rat RGCs were tested at two different concentrations (0.05% and 0.5%). ICG significantly decreased the viable cell number of RGCs at 0.5%, while there was no significant effect at 0.05%. Similarly, the metabolic activity to resazurin was significantly decreased by exposure to 0.5% ICG. However, ICG showed little effects on resazurin metabolism at 0.05%. The expression levels of bcl-2 mRNA were higher in cells treated with 0.5% ICG than in those treated with 0.05% ICG and untreated control cells. Conclusion: The data suggest that ICG initiates the death of RGCs at high concentrations, in part, through apoptosis-related signal pathways. The cytotoxicity of indocyanine green (ICG) on cultured rat retinal glial cells (RGC) was examined. The high concentration (0.5 %) of ICG significantly reduces rat RGC viability and enhances the expression of bcl-2, suggesting that ICG initiate RCG death in part through apoptotic process.