Effect of Cysteamine on Oxidative Stress-induced Cell Death of Human Corneal Endothelial Cells

Purpose: The principal objective of this study was to evaluate the protective effect of cysteamine against the oxidative stress-induced cell death of human corneal endothelial cells. Methods: In this study, human corneal endothelial cells (HCECs) were cultured according to a previously published method. With treatment of 0 mM or 5 mM of tert-butyl hydroperoxide (tBHP) with various concentrations (0-50 mM) of cysteamine, reactive oxygen species (ROS) production was measured using an oxidation-sensitive fluorescent probe, and dichlorofluorescein diacetate (DCFH-DA) methods. Cell viability was assayed via the Cell Counting Kit-8 method. The levels of cellular glutathione were also assessed enzymatically with glutathione reductase using a commercial glutathione assay kit (Cayman Chemical, USA). Results: This study showed that cysteamine reduced 2', 7'-dihydrodichlorofluorescein oxidation and increased glutathione. Cysteamine significantly inhibited tBHP-induced ROS production. Cysteamine-treated cells evidenced higher viability relative to the controls at 5 mM tBHP, and cysteamine also effectively protected HCECs against ROS-induced cell death via an increase in intracellular glutathione. Conclusions: Our data indicate that cysteamine was not toxic at low concentrations and, at high concentrations, protects HCECs against oxidative injury-mediated cell death via the inhibition of ROS production, although cysteamine is toxic in cells at high concentrations without oxidative stress.