Heat-induced Apoptosis in Cultured Human Retinal Pigment Epithelial Cells and Vascular Endothelial Cells

Abstract

Abstract: : Purpose:To investigate and compare the effect of heat on cultured human retinal pigment epithelial (RPE) cells and vascular endothelial cells. Methods:Human RPE cell culture and vascular endothelial cell culture were exposed to mild (42°C) and moderate (47°C) hyperthermia for 1, 4, 8, and 24 hours. 24 hours after heat exposure, morphological analysis was conducted using the inverted phase contrast microscope. The DNA fragmentation in cell apoptosis was detected by TUNEL staining. The extent of cell damage and portion of apoptosis were estimated through flow cytometry after Annexin V-fluorescein isothiocyanate (FITC) labeling. Results:Apoptosis of cultured human RPE cells and vascular endothelial cells was induced by hyperthermia. After mild hyperthermia (42°C) apoptosis was dominant whereas in moderate hyperthermia (47°C) necrosis was dominant. Vascular endothelial cell was more damaged than RPE after mild hyperthermia at any duration. In moderate hyperthermia, necrosis and apoptosis of vascular endothelial cells occurred after short exposure, and were more pronounced than RPE. Conclusion:Results indicate that mild and moderate hyperthermia can induce extensive apoptosis in cultured human RPE cells and vascular endothelial cells and that the vascular endothelial cell is more susceptible to heat than the retinal pigment epithelial cell. This result may shed light on the mechanism of tanspupillary thermotherapy for choroidal neovasculrization, and therefore help to determine the proper level of power and application of laser treatment.

Keywords: 567 retinal pigment epithelium • 323 apoptosis/cell death • 614 vascular cells