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Marina Löscher, Evangelia Lilou, Karl Ulrich Bartz-Schmidt, Sven Schnichels, José Hurst; Potential therapy of neurodegenerative retinopathies via activation of the BDNF-TrkB signaling pathway by a specific aptamer. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5708.
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© ARVO (1962-2015); The Authors (2016-present)
Common to all retinal degenerative diseases, including diabetic retinopathy, retinitis pigmentosa, glaucoma and age related macular degeneration, is the deterioration of the retina caused by the progressive degeneration and death of the different retinal cells. Growth factor-based therapy is a widely studied approach for slowing down or arresting the onset of visual cell degeneration. BDNF is a promising neurotrophic growth factor that exerts its action via the activation of the TrκB signaling cascade. However, direct application of neurotrophic factors has several downsides. By using an already published aptamer, which binds specifically to the TrκB receptor, we want to mimic the neuroprotective effect of BDNF and develop a new treatment option for retinal diseases.
In a first step, the safety of the TrκB aptamer (200nM) was confirmed using ARPE-19 and primary retinal cells from dissociated porcine retinae. Furthermore, the expression of the specific neuronal markers (TUBB3, GFAP, Opsin, Rhodopsin) as wells a markers of the TrκB signaling cascade (bFGF GDNF, p21, HSP70, p-ERK) were investigated for 24h and 72h in a retinal organ model. In addition, residence time and binding efficiency were also examined in cell culture and on porcine retinal explants by using a fluorescence labeled TrκB-aptamer.
No loss of cell viability or amount was observed 24 hours after administering the aptamer on the ARPE-19 and primary retinal cells. Binding of the aptamer was confirmed by fluorescence microscopy. The TrκB aptamer induced a significant increase in tubb3 mRNA expression (2-fold; p<0.05) as well as significantly increased level of Opsin (7-fold; p<0.001) and Rhodopsin mRNA (3-fold; p<0.05) on retinal explants. Furthermore, a significant increase was also noted in the downstream targets of the TrκB receptor: GDNF (1.7-fold;p<0.05), HSP70 (28-fold;p<0.01) and bFGF ( 5-fold; p<0.01).
The biocompatibility of the TrκB aptamer was confirmed. Our data prove the functionality of the aptamer on retinal cells and retinal explants, as the downstream targets were activated. The observed increase in the tested photoreceptor and retinal ganglion cell markers is a sign for a neuroprotective effect of the aptamer. As a next step the neuroprotective effect of the aptamer will be tested on a retinal damage model.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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