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Masami Nakajima, Akiko Ishimori, Kazuhiro Umeyama, Hiroshi Nagashima; Diabetic retinopathy in transgenic pigs with induced diabetes mellitus.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5818.
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The transgenic pigs with induced diabetes mellitus were reported by Umeyama et al. in 2009 and 2013. Transgenic pigs have high blood glucose levels; i.e., greater than 200 mg/dl, after birth. Although histopathological analysis confirmed abnormal changes in the structure of the kidney, there has been no ophthalmological evaluation of potential diabetic retinopathy. Our aim was to investigate fundus changes in transgenic pigs that were exposed to continuous high blood glucose levels for at least 1 year and to evaluate whether human-like diabetic retinopathy developed.
Two transgenic pigs were set to have blood glucose levels from 350 mg/dl to 450 mg/dl for 1 year. In the case of extremely high blood glucose levels; i.e., greater than 450 mg/dl, 1-30 units of insulin (Lantus ®, Sanofi Aventis) were injected subcutaneously. Blood samples were taken and examined every week. A fundus examination was performed each month.
The mean blood glucose levels for the two animals were 394 mg/dl and 388 mg/dl. Both of the transgenic pigs showed retinal hemorrhaging and cotton-wool spots at 4 months after birth. Cataracts appeared at 2 months after birth and the fundus could no longer be observed at 5 months after birth. After cataract surgery, retinal hemorrhage and cotton-wool spots were observed as increased at 5 months after birth in one pig. Fundus examination after cataract surgery in the other pig showed vitreous hemorrhage in the vitreous cavity at 1 year after birth.
Transgenic pigs with induced diabetes mellitus developed various stages of diabetic retinopathy 1 year after birth. It is possible that retinal neovascular vessels were growing because vitreous hemorrhage was observed. Further histopathological analysis is needed. Transgenic pigs could be useful as a diabetic retinopathy animal model.
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