Abstract
Purpose: :
In order to investigate the effect of laser photocoagulation on the secretion of vascular endothelial growth factor (VEGF) from RPE cells with different laser irradiation ranging from sublethal to superlethal powers.
Methods: :
RPE-choroid porcine tissue explants were irritated with a frequency-doubled Nd:YAG laser (wavelength 532 nm, exposure time 100ms, spot diameter 300µm) with laser powers of 0, 20, 40, 60, 80, and 100 mW. After laser irradiation, the tissues were maintained in perfusion culture system. Threshold power for cell viability was determined by Calcein-AM cell viability test. Following laser irradiation, media samples were obtained after 24 hours for quantification of vascular endothelial growth factor (VEGF) by enzyme-linked immunosorbent assay (ELISA).
Results: :
According to the calcein-AM viability test, the threshold power was determined around 50 mW for the 300 µm spot diameter. Following laser irradiation, VEGF concentration in the medium increased linear with laser power: exposure to 0-, 20-, 40-, 60-, 80, and 100 mW resulted in VEGF-concentrations of 275, 321, 352, 381,421 and 507 pg/ml, respectively (n=3 samples for each power).
Conclusions: :
Expression of VEGF was increased after laser irradiation in a power-dependent manner. Interestingly, significant concentrations were also found far below the threshold laser power for immediate cell death. The expression of VEGF following sublethal laser irradiation may be caused by intracellular temperature increase.
Keywords: laser • retinal pigment epithelium • vascular endothelial growth factor