Influence of photodynamic therapy on expression of vascular endothelial growth factor (VEGF), VEGF receptor 3, and pigment epithelium-derived factor.
OBJECTIVE
To evaluate the impact of photodynamic therapy (PDT) on expression and distribution of vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-3, and pigment epithelium-derived factor (PEDF).


METHODS
Eyes of patients scheduled for enucleation due to untreatable malignancy served as study eyes (n = 4), age-matched donor eyes were used as the control (n = 4). PDT using verteporfin with the recommended standard parameters was applied to intact areas of the perimacular region. Lesions were classified by ophthalmoscopy, fluorescein angiography (FA), and indocyanine green angiography (ICGA), as well as light and electron microscopic (LM/EM) histology. Immunolabeling using specific antibodies against VEGF, VEGFR-3, and PEDF was performed in PDT-treated areas, untreated collateral areas in study eyes, and untreated areas of control eyes. Specimens were fixed in 4% paraformaldehyde and 1% glutaraldehyde and embedded in paraffin. Four-micrometer-thick sections were stained using the peroxidase-labeled streptavidin-biotin method.


RESULTS
All PDT-treated areas demonstrated characteristic choroidal hypofluorescence by FA and ICGA. LM/EM histology revealed selective damage of choriocapillary endothelial cells. VEGF was expressed in the endothelial layer of choriocapillaries and focally within larger choroidal vessels in treated areas, but not in untreated areas. Sites with positive VEGF labeling also demonstrated upregulation of VEGFR-3. PEDF expression was localized to retinas in all eyes; however, PEDF staining of choroidal endothelial cells was specific for treated areas of study eyes.


CONCLUSIONS
PDT using verteporfin induces a reproducible angiogenic response in elderly human eyes. VEGF, VEGFR-3, and PEDF expression is enhanced after PDT. Choroidal endothelial cells appear to be the primary site of angiogenic stimulation.
D000368:Aged; D000369:Aged, 80 and over; D002829:Choroid / Q000098:blood supply* / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism; D015353:Eye Enucleation; D005134:Eye Neoplasms / Q000601:surgery; D005136:Eye Proteins; D005451:Fluorescein Angiography; D006801:Humans; D007124:Immunoenzyme Techniques; D007208:Indocyanine Green; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008222:Lymphokines / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D009414:Nerve Growth Factors; D009887:Ophthalmoscopy; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology; D011166:Porphyrins / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*; D015843:Serpins / Q000378:metabolism*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000378:metabolism*; D042442:Vascular Endothelial Growth Factors; D000077362:Verteporfin; D000099174:Pigment Epithelium-Derived Factor
D016228:Endothelial Growth Factors; D005136:Eye Proteins; D007208:Indocyanine Green; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D009414:Nerve Growth Factors; D017319:Photosensitizing Agents; D011166:Porphyrins; D011506:Proteins; D015843:Serpins; D042461:Vascular Endothelial Growth Factor A; D040321:Vascular Endothelial Growth Factor Receptor-3; D042442:Vascular Endothelial Growth Factors; D000077362:Verteporfin; D000099174:Pigment Epithelium-Derived Factor