Abstract
Purpose :
Diabetic retinopathy (DR) is one of the leading causes of vision impairment worldwide. Unfortunately, DR research is hindered by a lack of disease models that faithfully reproduce the retinal phenotype of diabetes, in particular for type 2 diabetes. Previously, we have shown that a number of aspects of DR can be faithfully reproduced in early (P5) post-natal organotypic retinal explant cultures (Valdés et al., ALTEX 33:459-464, 2016). However, since the retina is not fully developed at this stage, it remains unclear whether the deleterious effects of diabetes-like conditions on the early postnatal retina are representative of mature retinal pathophysiology.
Methods :
Mouse retinas were explanted at P14 (around eye opening) and treated from P16 to different with different experimental conditions (i.e. no-insulin, high-glucose, no-insulin + high-glucose, 2-deoxyglucose; 2-DG) to simulate type 1 and 2 diabetic conditions. The treatment effects were assessed on histological preparations using photoreceptor row counts, TUNEL assay for cell death detection, and immunostaining for cone arrestin.
Results :
In the no-insulin, high-glucose, and no-insulin + high-glucose treatment paradigms the photoreceptor row counts, numbers of TUNEL, and cone arrestin-positive cells did not change significantly when compared to control. However, the 2-DG treatment significantly increased the numbers of dying TUNEL-positive cells in the outer nuclear layer (ONL; control: 1.22% ± 0.3 STD; 2-DG: 13.76% ± 0.8, p<0.001) and reduced the number of arrestin-positive cones per 100 µM of retinal circumference (control: 4.7 ± 0.7; 2-DG: 0.4 ± 0.3, p<0.001). Yet, the overall photoreceptor row count was not significantly altered (control: 8.0 ± 0.6; 2-DG: 8.1 ± 0.4).
Conclusions :
Compared to the early post-natal retina, older retinas responded less strongly to simulated diabetic conditions, yet, cone photoreceptors were highly vulnerable to type I diabetes-like conditions caused by 2-DG treatment. Taken together, we have further validated and extended an in vitro model of DR which may prove useful for studies into the etiopathology of DR and for DR-related drug screening.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.