Intravitreous hepatocyte growth factor in patients with proliferative diabetic retinopathy: a case-control study

The aim of the present study was to evaluate the vitreous levels of hepatocyte growth factor (HGF) in patients with proliferative diabetic retinopathy (PDR) and to investigate its relationship with vascular endothelial growth factor (VEGF) and retinopathy activity. In addition, the relationship between intravitreous HGF levels and the presence of epiretinal membranes (ERM), as well as the expression of c-Met in ERM were also investigated. In this case-control study, serum and vitreous samples as well as ERM specimens were obtained during vitrectomy from 28 diabetic patients with PDR and 30 non-diabetic control subjects. HGF and VEGF were determined by ELISA and c-Met expression by immunohistochemistry. Vitreal levels of both VEGF and HGF were higher in patients with PDR in comparison with the control group (p<0.0001). However, after correcting for total vitreous protein concentration, HGF (ng/mg of proteins) was lower in diabetic patients than in non-diabetic control subjects (p=0.02). No correlation was detected between the vitreal levels of HGF and VEGF. In addition, intravitreous VEGF but not HGF was found to be related to PDR activity. Both diabetic patients and non-diabetic patients in whom ERM had been excised presented higher HGF intravitreous levels. Finally, a significant expression of c-Met in ERM membranes were observed in both diabetic patients with PDR and in non-diabetic subjects. In conclusion, both HGF and VEGF increased, but were not related, in the vitreous fluid of diabetic patients with PDR. Our findings suggest that HGF is related to pathological conditions in which fibroproliferative processes or wound healing are involved rather than with angiogenesis itself.