Hepatocyte growth factor in vitreous and serum from patients with proliferative diabetic retinopathy

Background-Hepatocyte growth factor (HGF) is an endothelium specific growth factor that has been implicated in angiogenesis, a crucial event for the d evelopment of proliferative diabetic retinopathy (PDR). The aim of the stud y is to determine the intravitreous concentrations of HGF in diabetic patie nts with PDR, and to investigate whether its serum levels could contribute to its intravitreous concentration. Methods-17 diabetic patients and seven non-diabetic patients in whom a vitr ectomy was performed were studied. Both groups were matched by serum levels of HGF. Venous blood and vitreous samples were collected simultaneously at the time of vitreoretinal surgery. Vitreous and serum HGF were determined by ELISA. Results-Intravitreous concentrations of HGF (median and range) were higher in diabetic patients (17.04 ng/ml (9.98-80)) in comparison with non-diabeti c patients (5.88 ng/ml (2.57-14.20); p=0.003). Intravitreous HGF concentrat ions were strikingly higher than serum HGF concentrations both in diabetic patients (17.04 ng/ml (9.98-80) v 0.66 ng/ml (0.26-1.26); p<0.001) and in t he control group (5.88 ng/ml (2.57-14.20) v 0.68 ng/ml (0.49-0.96); p=0.003 ). No correlation was found between serum and vitreous levels of HGF in bot h groups (diabetic patients, r=-0.31; p=0.5 and control subjects r=-0.15; p =0.5). Conclusion-The high vitreous levels of HGF observed in diabetic patients wi th PDR cannot be attributed to serum diffusion across the blood-retinal bar rier. Therefore, intraocular synthesis appears to be the main contributing factor for the high vitreous HGF concentrations in diabetic patients, a cyt okine that seems to be directly involved in the pathogenesis of PDR.