[Expression of angiogenic factors by photodynamic therapy]

The purpose of this study was to evaluate the impact of photodynamic therapy (PDT) on the regulation of angiogenic factors such as vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF) in human eyes.

Eyes of patients with untreatable malignancy served as the study eyes (n = 2), age-matched donor eyes were used as controls (n = 2). Standard Verteporfin-PDT was applied to intact areas of the posterior pole. One week after PDT the eyes were examined by ophthalmoscopy as well as fluorescein (FA) and indocyanine green angiography (ICGA). After enucleation the eyes were processed for LM/EM histology. Immunolabeling using specific antibodies against VEGF and PEDF was performed in PDT-treated areas, untreated collateral areas of study eyes and untreated areas of control eyes.

All PDT-treated areas demonstrated a typical choroidal hypofluorescence on FA/ICGA. In LM/EM histology a selective damage of choriocapillary endothelial cells was found. VEGF expression was localized only to choriocapillary endothelial cells and focally in larger choroidal vessels of PDT-treated areas. Untreated areas of study eyes and controls were VEGF-negative. PEDF staining was observed in retinas and RPE of all eyes, but only choroidal endothelial cells of PDT-treated areas showed a PEDF-positive reactivity.

PDT not only induces structural and angiographic, but also biological effects in human eyes. VEGF and PEDF expression can be documented in choroidal endothelial cells following PDT and could have an impact on the recovery process after treatment.