Objective      To establish a rat model of human proliferative diabetic retinopathy (PDR)

and to assess its value in order to provide an ideal animal model for clinical neotype drug research.       Methods      Diabetic Sprague-Dawley (SD) rats were intravitreously injected with VEGF at 1 month after r

eceiving intra-peritoneal injection of 60 mg/kg body weight of streptozotocin (STZ) (C group). The fluorescence fundus angiographic (FFA) changes and CD105-positive retinal vascular endothelial cells were observed by light microscopy at different time points after VEGF injection. The results were compared with the SD rats only received intraperitoneal injection of 60 mg/kg body weight of STZ (B group).       Results      The FFA results showed that no abnormal fluorescence was observed in the normal rats and only enhanced background fluorescence was observed in the B group. However

not only the non-proliferative pathological changes such as enhanced background fluorescence

retinal great vessel buckling

angiotelectasis

retinal vascular leakages and hemorrhage

but also the proliferative pathological changes of diabetic retinopathy such as intraretinal new vessels were observed in the C group. Retinal vascular leakage of carbon granules and CD105-positive retinal vascular endothelial cells were not observed in the normal rats and the B group. In the C

1

group (two weeks after VEGF injection)

carbon granules leakage was only observed in the great vessels of ganglion cell layer

but there were no CD105-positive retinal vascular endothelial cells observed. In the C

2

group (four weeks after VEGF injection)

carbon granules leakage was observed in outer nuclear layer

and CD105-positive retinal vascular endothelial cells were also observed besides the pathological changes of the C

1

group. In the C

3

group (eight weeks after VEGF injection)

far-reaching carbon granules leakage was observed as well as macular edema and exudation

and CD105-positive retinal vascular endothelial cells were also observed besides the pathological changes of the C

2

group.       Conclusion      The PDR rat model is successfully established

which is proved to have good application value by FFA and CD105 immunohistochemistry. The CD105-positive vascular endothelial cells observed by ligh

t microscopy coincide with the intraretinal new vessels observed by FFA at the same time. Therefore

we provide an ideal animal model for clinical studies on drug screening.