Lifetime Study in mice: radiation-induced cataract

Summary We did a lifetime study in irradiated and control mice with a follow up time until 24 months post irradiation with repeated in vivo analysis of the lens density and the retina. Mice of different genetic constitution (wild-type, Ercc2+/-) were acutely whole body irradiated with low doses of ionising radiation (0, 63, 125 and 500 mGy) and a low dose rate (63 mGy/min). Lens opacification was analysed monthly by Scheimpflug imaging and the retinal fundus and thickness was analysed by OCT. At different time points (4 and 24 hours, 12, 18 and 24 months post irradiation) mice were sacrificed and eyes were analysed by histology and immunohistochemistry. Mice of all groups, even the DNA repair helicase deficient mice (Ercc2+/−), did not develop clinically relevant radiation-dependent lens opacities. Only an age-dependent increase of lens density was identified. Consequently, no major morphological changes were visible in the eye histology of all mice. Immunohistochemical staining against DNaseIIb revealed no differences between the groups as well as 8-OHG staining resulted in similar ROS levels in all irradiation groups. However, non-irradiated Ercc2+/- mice showed an increased level of oxidative stress compared to wild-type mice.