Currently, several antiangiogenic agents for CNV treatment have been identified, but all remain unsatisfactory due to undesired side effects.
1,2 In this study, we used Dex, a synthetic glucocorticoid, as the positive control in vivo. Corticosteroids are the most commonly used and effective drugs in the therapy of ocular inflammation. Our recent results showed that Dex can inhibit angiogenesis mainly by down-regulation of VEGF.
18 Therefore, Dex was set as an effective control group in this study to evaluate the antiinflammation and antiangiogenic effects of ARS. However, many adverse effects identified in clinical treatment and in preclinical research limit the use of corticosteroids, including drug-induced ocular hypertension and glaucoma, tear-film instability, epithelial toxicity, crystalline keratopathy, decreased wound strength, orbital fat atrophy, ptosis, and limitation of ocular movement.
19 It has been reported that Dex retarded corneal epithelial healing in rabbit alkali-burning corneal wounding and carried a 7% to 8% risk of producing a significant rise of IOP, which may result in corneal glaucoma.
20–22 Consistent with the mentioned side effects of Dex, our results showed that 0.1% Dex resulted in corneal ulcer, although it could significantly inhibit corneal inflammation and revascularization. By CD31-TUNEL double staining, we found ARS can significantly induce apoptosis of vascular endothelial cells in vivo. Moreover, ARS specifically inhibited proliferation and induced apoptosis of endothelial cells in vitro, while corneal epithelial cells were unaffected. The selective inhibition of endothelial cells may be responsible for the decreased rate of adverse effects. Furthermore, we use fluorescein sodium to stain and quantify the area of epithelial defects in damaged corneas on the first day after operation, according to the previous report.
23 The data showed ARS treatment can decrease corneal defect area compared with PBS treatment group (
Supplementary Fig. S1B), which at least suggested ARS inhibited corneal inflammation and neovascularization without significant side effects on corneal wound healing. These results suggested that ARS could be an ideal agent for CNV treatment as it is highly effective, presents few adverse effects, and is inexpensive. We chose the concentration of ARS in the animal experiments according to the IC
50 of ARS on proliferation of vascular endothelial cells, which is approximately 25 μM (9.6 mg/L). It was reported that ARS had a maximal concentration (C
max) of 35.6 μM (13.7 mg/L) in patients who suffered from vivax malaria and were treated with intravenous injection of ARS.
24 As artemisin and derivatives have an elimination half-life time, another clinical study demonstrated that the range of C
max of ARS was from 2.7 μM (1.02 mg/L) to 426.6 μM (164 mg/L) in Ugandan adults with severe malaria.
25 Therefore, the concentration of ARS in our animal work is not over the C
max. To achieve an effective concentration of ARS in the cornea, we chose local administration of artesuante by using eye drops in this study. We made artesuante eye drops and treated the animals for 11 days immediately following the operation and 4 times per day until our experiment endpoint. The results suggested that eye drop may be the best way to deliver ARS in patients with CNV.