Rosmarinic acid suppresses retinal neovascularization via cell cycle arrest with increase of p21(WAF1) expression.

Pathological angiogenesis is the most common cause of blindness at all ages including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration. Despite advances in therapy, retinopathy of prematurity remains the most sight-threatening vaso-proliferative retinopathy in children. Herein, we demonstrated that rosmarinic acid has an anti-angiogenic activity to retinal neovascularization in a mouse model of retinopathy of prematurity, which is related to cell cycle arrest with increase of p21(WAF1). Rosmarinic acid significantly inhibited the proliferation of retinal endothelial cells in a dose-dependent manner, and inhibited in vitro angiogenesis of tube formation. Interestingly, the anti-proliferative activity of rosmarinic acid on retinal endothelial cells was related to G2/M phase cell cycle arrest in a dose-dependent manner. With treatment of rosmarinic acid, retinal endothelial cells in G2/M phase increased whereas those in G0/G1 and S phases decreased, which was accompanied by increase of p21(WAF1) expression in a dose-dependent manner. Moreover, rosmarinic acid effectively suppressed retinal neovascularization in a mouse model of retinopathy of prematurity, and showed no retinal toxicity. These data suggest rosmarinic acid could be a potent inhibitor of retinal neovascularization and may be applied in the treatment of other vasoproliferative retinopathies.