Abstract: Objective To observe the effect of proanthocyanidins on miR-21, and explore the protective mechanism of proanthocyanidins on vascular endothelial function and retinal ganglion cells in diabetic retinopathy rats. 
Methods To observe the effect of proanthocyanidins on miR-21, and explore the protective mechanism of proanthocyanidins on vascular endothelial function and retinal ganglion cells in diabetic retinopathy rats. 
Results The effect of proanthocyanidins on the proliferation of human umbilical vein endothelial cells（HUVECs） was concentration-dependent. There was no significant difference between the 5 mg/L group and the control group(P＞0.05). Compared with the control group, the 25 mg/L, 50 mg/L, 75 mg/L and 100 mg/L groups had statistically significant differences(P＜0.05). The migration ability of 50 mg/L was weaker than that of the control group(P＜0.05), and the expression of miR-21 was down-regulated(P＜0.05). The expression of miR-21 in the retina of rats in the model control group and the procyanidin 250 mg/kg group were higher than that in the normal group, and the model control group was higher than the procyanidin 250 mg/kg group(P＜0.05).The apoptosis index of retinal ganglion cells in the model control group and the procyanidin 250 mg/kg group was greater than that of the normal group, and the model control group was greater than the procyanidin 250 mg/kg group. 
Conclusion  Proanthocyanidins can inhibit the proliferation and migration of vascular endothelial cells, and inhibit the apoptosis of retinal ganglion cells in diabetic retinopathy rats, and protect retinopathy. The mechanism may be related to down-regulation of miR-21 expression.

Key words: diabetic retinopathy, proanthocyanidins, miR-21