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 development of proliferative diabetic retinopathy (PDR). The aim of the study is to determine the intravitreous concentrations of HGF in diabetic patients 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 vitrectomy 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-diabetic patients (5.88 ng/ml (2.57-14.20); p=0.003). Intravitreous HGF concentrations 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 the 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 both 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 with PDR cannot be attributed to serum diffusion across the blood-retinal barrier. Therefore, intraocular synthesis appears to be the main contributing factor for the high vitreous HGF concentrations in diabetic patients, a cytokine that seems to be directly involved in the pathogenesis of PDR.