Figure 6.
Long-term HTT silencing with tetra-siRNAHtt in porcine retina
(A) Retinal cross-section stained for expression of the HTT protein (purple signal). Top row shows uninjected or NTC-injected eyes at 1 and 4 months postinjection with 300 μg of siRNA. Bottom row shows tetra-siRNAHtt-injected eyes with same dose. Silencing in PR ISs (arrows and vertical bars marking height of IS in last column) is still clearly visible at 4 months postinjection. Images are representative images from 3 pigs per time point and siRNA. Scale bar: 50 μm. (B) Percentage quantification of remaining retinal HTT protein at 1 and 4 months postinjection when compared to the NTC. Top image shows examples of bands on western blot gel. Quantification represents the average of the 4 quadrants of 3 eyes. N = 12; error bars: SD. ∗∗∗∗p < 0.0001. (C) Pharmacokinetics of remaining siRNA in different eye tissues at 1 and 4 months postinjection. A PNA hybridization assay was performed with 1 quadrant per eye. N = 3, error bars: SD. Analyses of the retina, RPE, vitreous, lens, and cornea show that most of the siRNA is taken up by the retina and RPE and is cleared from the vitreous. In addition, very little migrates to the lens and cornea. Eye tissues from NTC-injected eyes did not show any signal and were therefore omitted from the figure. Boxed area shows vitreous, lens, and cornea graphs with adjusted y scales.