Organ culture model
In order to understand the pathological changes in the retina, suitable models are required that simulate the condition of the eye diseases. Most models are based on laboratory animals. However, there are increasing efforts to reduce or replace these animal experiments with alternatives. Organ cultures from porcine retinae, which can be obtained from slaughtered animals from the food industry, offer a good alternative here, as they are anatomically, morphologically and physiologically very similar to the human eye.
Glaucoma organ culture models
To investigate glaucoma pathogenesis, an ex vivo degeneration model of the porcine retina has been established in recent years by our research group in collaboration with the Schnichels group (University Eye Hospital Tübingen) (Hurst et al., 2017; Kuehn et al., 2016; Kuehn et al., 2017). For this purpose, the porcine retina is cultured and degeneration is induced by adding various toxic substances. This simulates the various aspects of glaucoma pathogenesis and allows them to be investigated.
Both the use of hydrogenperoxide, as a trigger of oxidative stress, and of cobalt chloride, to induce hypoxic processes, led to degeneration of the porcine retina in our models. After successfully establishing the degeneration models, we have already used them to test various therapeutic approaches. For example, we were able to show that hypothermia treatment (Maliha et al., 2019) or special extremolytes (Tsai et al., 2020) protect ganglion cells from degeneration. Coenzyme Q10 also has a protective effect on retinal ganglion cells (Deppe et al., 2024) and it led to a reduction in the mitochondrial stress level (Figure 1).
Figure 1: Protection of retinal ganglion cells by coenzyme Q10. (A) Retinal ganglion cells (RGCs) were stained with antibodies against RBPMS (red) after eight days. The cell nuclei were labeled with DAPI (blue). (B) Hydrogen peroxide significantly reduced the number of RBPMS (p≤0.001). This effect was prevented by coenzyme Q10 (p≤0.001). (C) The relative mRNA expression of RBPMS was significantly reduced after oxidative damage (p=0.03). This reduction could be reversed with coenzyme Q10. The values are given as mean ± SEM for immunohistology and mean ± SEM for RT-qPCR. * p < 0.05; *** p < 0.001 vs. control. ### p < 0.001 vs. hydrogen peroxide (Deppe et al. 2024).
Age-related macular degeneration (AMD) organ culture models
To investigate the degeneration processes of AMD in more detail, the organ culture model of the porcine retina was adapted (Wagner et al., 2020). In the next step, we developed a coculture model by combining primary porcine RPE cells (ppRPE) and neuroretina, which leads to a better preservation of the photoreceptors (Wagner et al., 2022) and also better reflects the in vivo situation. To integrate oxidative stress as an aspect of AMD pathogenesis, ppRPE cells were treated with sodium iodate (NaIO3) and subsequently cocultured with Neuroretina explants. Significant damage was shown by NaIO3 to the ppRPE cells, which was reflected in decreased RPE65 and ZO-1 expression. In the neuroretina, NaIO3 led to a significant reduction in the number of cones (Wagner et al., 2024). These results underline the potential of our ex vivo AMD model for future investigation of AMD pathogenesis and evaluation of new therapeutic approaches.