Purpose:
Activated protein C (APC) has been demonstrated to reduce cell death associated with ischemia in the brain, lung, and kidney. The purpose of this study is to examine the ability of APC to rescue hypoxia-induced retinal cell death.
Methods:
Cultured mice retinal photoreceptor cells (661w) and human retinal pigment epithelial cells (ARPE-19) were placed in a hypoxic chamber. Immediately before placing in the ischemic condition, various concentrations of APC (0.3, 3 and 30 ug/ml for 661w and 3µg/ml for ARPE-19) were added to the culture medium. After incubation for 4, 8 or 12 hours, cells were subjected to the MTT assay to determine the number of viable cells.
Results:
When 661w and ARPE-19 cells were cultured in a hypoxic chamber, viable cells were decreased in a time-dependent manner (91.4, 78.3 and 62.7% compared to the baseline (0 hour)) and (82.8, 49.8 and 46.9%) at 4, 8 and 12 hours. In contrast, the viability of cells treated with APC were, for 661w cells, (0.3 ug/ml; 94.9, 93.7 and 83.5%), (3 ug/ml; 96.3, 97.9 and 90.0%), (30 ug/ml; 92.3, 103.3 and 95.7%) at 4, 8, and 12 hours, and for ARPE-19 cells, (3 ug/ml; 99.8, 100.8 and 102.0%), at 4, 8, and 12 hours. APC significantly protected 661w and ARPE-19 cells from hypoxia-induced cell death, and the level of cytoprotection did not differ between the doses tested.
Conclusions:
APC reduced the cytotoxicity to retinal cells induced by hypoxia in vitro. APC therefore is a promising candidate molecule for protecting the retina from ischemic retinal diseases.
Keywords: hypoxia • retina: distal (photoreceptors, horizontal cells, bipolar cells) • retinal pigment epithelium