Aims/hypothesis. Kallikrein-binding protein (KBP) is a serine proteinase inhibitor (serpin). It specifically binds to tissue kallikrein and inhibits kallikrein activity. Our study was designed to test its effects on retinal neovascularization and vascular permeability. Angiogenesis in the retina is controlled by a delicate balance between angiogenic stimulators (e.g., vascular endothelial growth factor, VEGF) and angiogenic inhibitors (e.g., pigment epithelium-derived factor, PEDF) [1,2,3]. Under certain pathological conditions such as diabetic retinopathy and retinopathy of prematurity (ROP), the retinal cells increase the production of angiogenic stimulators while decreasing angiogenic inhibitors in response to local hypoxia [4,5]. These changes break the balance in angiogenesis control and consequently, resulting in over-proliferation of capillary endothelial cells and retinal neovascularization which is a common cause of blindness [2,3,6]. The molecular mechanism leading to retinal neovascularization is presently not known.
Methods. Endothelial cell proliferation was deter