HYPERICIN INHIBITS CHOROIDAL ENDOTHELIAL-CELL PROLIFERATION AND CORD FORMATION IN-VITRO

Purpose. To evaluate the effect of hypericin on bovine choroidal endot helial cell proliferation and cord formation and on protein kinase C a ctivity. Methods. The effect of hypericin (0.1-5 mu M) on bovine choro idal endothelial cell proliferation was determined by cell number coun ting and a H-3-thymidine uptake assay in media containing 1, 5 or 10% serum. For the cord formation assay, bovine choroidal endothelial cell s were seeded on basement membrane matrix, and the lengths of the capi llary-like structures (cords) formed were quantified by image analysis . The effect of hypericin on cord formation was evaluated in the prese nce of serum or vascular endothelial growth factor. The effect of hype ricin on protein kinase C activity was also measured in the presence o r absence of light. Results. Hypericin inhibited bovine choroidal endo thelial cell proliferation in a dose-dependent manner in the presence of light but not in the dark. Serum dose-dependently masked the inhibi tion of DNA synthesis by hypericin. Cord formation by bovine choroidal endothelial cells was stimulated by serum or vascular endothelial gro wth factor and inhibited by hypericin in the presence of light. Protei n kinase C activity was completely inhibited by hypericin in the prese nce of light but only mildly inhibited in the absence of light. Conclu sions. Hypericin inhibits bovine choroidal endothelial cell proliferat ion and cord formation and choroidal endothelial cell protein kinase C activity. These results suggest that hypericin should be further inve stigated in animal models for its potential to inhibit subretinal neov ascularization.