Diabetic retinopathy: VEGF, bFGF and retinal vascular pathology

Background Previous research indicated that the development of diabetic retinopathy (DR) is closely related to the excessive expression of growth factors. This paper was to study the relationship of DR with vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and the retinal vascular pathological change. Methods Fifty-five Wistar rats, weighing 100-200 g, were selected and randomly divided into four groups: control group (no streptozocin injection, n=10), M1 group (streptozocin induced diabetes for 1 month, n=15), M3 group (streptozocin induced diabetes for 3 months, n=15), and M5 group (streptozocin induced diabetes for 5 months, n=15). In situ hybridization and immunohistochemistry were used to investigate the expressions of bFGF and VEGF on retinal vascular, and retinal vessels were observed by transmission electron microscope. Results There was no difference in the number of pericytes between M1 and control group (P>0.05), but the number of pericytes decreased obviously in M3 and M5 groups compared with the control group (P<0.01, P<0.001, respectively). Capillary embolization and non-cell capillary were seen in M5 group. Positive expression of VEGF was found in M5 group using in situ hybridization and immunohistochemistry respectively. Positive expression of bFGF could be seen in M3 (78%) and M5 group (89%). Most remarkable changes of vessles were observed in M5 group including fragmental thickness, split of basement membrane, swelling and distortion of endothelial cells. Conclusions In retinal vascular of the streptozocin (STZ) rats, there shows the expression of bFGF at the third month and that of VEGF at the fifth month.