Role of Vascular Endothelial Growth Factor and Placental Growth Factor in Glaucoma and Scar Formation After Glaucoma Filtration Surgery

Abstract

Purpose:: Filtering surgery is the most efficient treatment for glaucoma. However, in up to 30%, trabeculectomy fails due to excessive postoperative scarring. This study was designed to elucidate the role of the vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) in fibrosis after glaucoma filtration surgery.

Methods:: First, aqueous humor and plasma samples were collected from glaucomatous and non-glaucomatous (cataract) patients and the concentrations of VEGF and PlGF were measured by ELISA. Secondly, the expression of the VEGF receptors Flt-1 and KDR was determined in cultured human Tenon fibroblasts by quantitative real-time RT-PCR and Western blot. Finally, the effect of VEGF on Tenon fibroblasts was determined using a proliferation assay.

Results:: The mean concentration of VEGF and PlGF in aqueous humor of glaucoma patients was significantly higher than that in patients with cataract (P < 0.05). No differences, however, were found in the plasma from these patients. The expression of Flt-1 and KDR was detected successfully at the RNA as well as the protein level with quantitative real-time RT-PCR and Western blot in cultured human Tenon's capsule fibroblasts. Furthermore, cell proliferation test showed that VEGF was able to stimulate the growth of these fibroblasts.

Conclusions:: VEGF and PlGF are increased in the aqueous of glaucoma patients and may play a role in scarring after filtering surgery. Therefore, a therapy with anti-VEGF or anti-PlGF might open new perspectives for more successful filtering surgery, and thus considerably improve the visual prognosis of glaucoma patients.

Keywords: growth factors/growth factor receptors • wound healing • conjunctiva