Abstract
Abstract: :
Purpose: The surgical peeling of internal limiting membrane (ILM) has recently been advocated as an effective surgical approach for the treatment of idiopathic macular holes. Further the staining of ILM with indocyanine green (ICG) dye has significantly improved its visualization during the peeling procedure. The purpose of this study is to examine whether ICG dye induces apoptosis in human retinal pigment epithelial (RPE) cells. Methods: Pure cultures of human RPE cells were isolated. RPE cells were incubated with different concentrations of ICG dye (1mg/ml, 5mg/ml, or 20mg/ml) for 30 minutes. The morphology of the cells was assessed with phase contrast microscopy. The rate of RPE cell apoptosis was assessed with Annexin V–FITC staining and propidium iodide (PI) by flow cytometry after 24 and 72 hours of culture. Regular culture medium and ICG solvent without the dye served as controls. Results: RPE cells maintained their monolayer morphology after incubation with ICG dye. However, ICG induced a statistically significant amount of apoptosis in RPE cells at all the concentrations (1mg/ml, 5mg/ml, and 20mg/ml) after 30 minutes of incubation (p < 0.05). After 72 hours of culture, the ICG induced apoptosis was concentration dependent. The solvent solution alone (without the ICG dye) did not induce any significant apoptosis in RPE cells, when compared with culture medium. Conclusions: The incubation of RPE cells with ICG dye increased the number of apoptotic RPE cells in vitro (when compared to the culture medium). Whether this increase in the number of apoptotic RPE cells play a significant role in vivo is currently not known. Our findings indicate that the decision over the intravitreal application of ICG dye needs to be made with caution.
Keywords: macular holes • retinal pigment epithelium • apoptosis/cell death