Abstract
Purpose: :
To establish the optimum dose and time of exposure for ICG and IFCG for use invivo using an invitro model of retinal ganglion cell culture.
Methods: :
10,000 cultured rat retinal ganglion cells (RGC-5) were plated in 24-well plates and after 24hours cells were exposed to two different concentrations (0.25 and 0.5 mg/ml) of ICG (dissolved in phosphate-buffered saline-PBS) and IFCG (dissolved in 5% dextrose) for various time intervals (1, 5, 15 and 30 minutes). Cultures containing PBS solution and 5 % dextrose served as controls. Cell cytotoxicity and cell viability were assessed using the Neutral red (NR) assay and Vi cell counts. Cell structural morphological changes were identified using phase contrast bright field microscopy.
Results: :
Using the NR assay, significant decrease in cell viability was detected in cells exposed to ICG for 5 minutes, irrespective of the concentration of the dye used (p<0.01) (Cell viability as a percentage of control were 57 and 46% for 0.25 and 0.5 mg/ml of ICG respectively). 0.25 mg/ml for 1minute was determined to be the optimum dose and time of exposure for ICG. IFCG was found to be cytotoxic at concentrations tested when the duration of exposure exceeded 15 minutes (Cell viabilities were 89.1 and 87.4% for 0.25 and 0.5mg/ml of IFCG, (p< 0.001). The results were validated by analysis of structural morphological changes noted using phase contrast bright field microscopy.
Conclusions: :
Infracyanine green is less cytotoxic when compared to Indocyanine green in invitro models using retinal ganglion cells. The optimum dose of ICG was found to be 0.25 mg/ml as long as the duration of exposure was less than one minute.
Keywords: retinal culture