Purpose  To analyze the regulation of microRNA-126 (miR-126) on function of retinal endothelial cells in oxygen-induced retinopathy (OIR) mouse model.
Methods To identify miR-126 level change in OIR condition, we used real-time reverse transcription-PCR assay to prove the down-regulated miR-126 level in retina and vitreous from OIR mice on postnatal day 12 (P12). With the analysis of bioinformatics, we predicted the target genes through the 3'-untranscriptional region (3'-UTR) binding to miR-126 sequence incompletely. To increase the down-regulated level of miR-126, the recombinant plasmid vector pCMV-MIR-126 was delivered into vitreous of OIR mice on P12 with intravitreous injection. Using the enzyme linked immunosorbent assay (ELISA), we then detected the target genes expression changes in retina and vitreous from OIR mice on P17, treated with intravitreous injection, which are including proinflammatory factor- vascular cell adhesion molecule 1 (VCAM-1) and apoptosis facilitator- bcl-2 Like 11 (Bcl-2L11). After maintaining the level of miR-126 in eyes from OIR mice, we analyzed the changes of retinal endothelial cells dysfunction with detecting Albumin leakage in retina and vitreous using Immuno-histochemistry and Immuno-blotting, and retinal endothelial cells apoptosis with TUNEL apoptosis assay.
Results We identified the down-regulated level of miR-126 in eyes from OIR mice obviously. After pCMV-MIR-126 intravitreous injection to recovery the level of miR-126, the over-expression of VCAM-1 and Bcl-2L11 were inhibited, Albumin leakage in retina/vitreous and the apoptotic retinal endothelial cell numbers were obviously reduced.
Conclusions Our results explore that miR-126 plays a central role in  maintaining the function of retinal endothelial cells via regulating its related genes expression in OIR condition. It suggests once more that miR-126 might be a crucial transcriptional regulator in eye diseases especially diabetic retinopathy, retinopathy of prematurity.