Effect of charred Radix et Rhizoma Rhei in a laser-induced choroidal neovascularization murine model.

ABSTRACT

A pharmaceutical composition (patent no. WO2012079419) exhibited favorable outcomes in a clinical trial of wet age­related macular degeneration. The aims of the present study were to explore the effects of one composition component, charred Radix et Rhizoma Rhei (CRRR), in a laser­induced choroidal neovascularization (CNV) murine model. A total of 30 eight­week­old C57BL/6 mice were subjected to diode laser treatment, and CNV was induced by rupturing the Bruch's membrane. The mice were then randomly divided into two groups the CRRR­treated group that was administered CRRR water extract (concentration, 0.6 g/100 ml; dose, 1 ml/0.1 kg twice a day for 21 days); and the control group that was treated with saline (dose, 1 ml/0.1 kg twice a day for 21 days). The retinal tissue was subjected to quantitative polymerase chain reaction (qPCR) and western blot analysis to determine the expression levels of interleukin­10 (IL­10) and vascular epithelial growth factor (VEGF) at day seven following laser treatment. At weeks 2 and 3 after laser treatment, fundus fluorescein angiography was performed and graded to assess the severity of lesion leakage. Retinal flat mounts were prepared for three­dimensional confocal microscopy at day 22 after laser treatment. At days 14 and 21 after laser treatment, no statistically significant differences were observed between the clinically relevant lesions of the CRRR­treated and control mice. CNV volumes were not found to be significantly different between the CRRR­treated and control mice. The expression levels of IL­10 were significantly increased in the CRRR­treated mice (P<0.05). However, no statistically significant differences were observed between the VEGF expression levels of the CRRR­treated and control mice. In conclusion, CRRR did not appear to significantly inhibit CNV in this murine model. The function of CRRR in the pharmaceutical composition may be due to the effects of IL­10 and a synergistic effect with other components of the composition. However, further investigation is required.