Assessment of expression dynamics and v-SVZ targeting of the lead candidate AAV capsids
(A) Experimental outline to assess expression dynamics of AAV1_P5, AAV9_A2, and two WT capsids in vitro. (B) Representative images of NSCs in vitro transduced with different AAV capsids 7 days after injection (days post-injection [dpi]); scale bars, 20 μm. (C) Dynamics of tdTomato expression at different time points in primary-cultured NSCs. AAV9_WT_3 dpt (11.9% ± 5.04%) versus AAV9_A2_3 dpt (58.8% ± 8.24%) versus AAV1_P5_3 dpt (44.4% ± 6.94%) (Kruskal-Wallis test followed by Dunn’s post hoc test). (D) Dynamics of GFP expression at different time points in primary-cultured NSCs. (C and D) Cultured NSCs were used up to passage 7; n = 3 cell cultures from 3 different mice. (E) Schematic illustration of the experimental outline to in vivo validate different AAV capsids. (F and G) IHC of the v-SVZ with markers to discriminate the different cell types after (F) AAV9_WT and (G) AAV1_P5 transduction (scale bars, 100 μm and 50 μm, respectively). (H) Markers for IHC used to discriminate the different cell types (NSCs left; Ep cells right; scale bars, 30 μm). (I) Proportion of tdTomato-labeled cells located in the v-SVZ among all tdTomato-positive cells in a 25-μm-thick coronal brain section. A high proportion indicates regional specificity for the v-SVZ. AAV2_WT (31.5% ± 5.9%) versus AAV9_WT (3.84% ± 0.33%) versus AAV9_A2 (81.6% ± 10.1%) versus AAV1_P5 (98.9% ± 1.13%). (J) Dynamics of tdTomato expression at different time points in the full v-SVZ. Bars are partitioned by the mean proportion of cell types across mice. AAV2_WT_5 dpi (0.06 ± 0.06) versus AAV1_P5_5 dpi (4.67 ± 1.96) and AAV2_WT_7 dpi (0.22 ± 0.11) versus AAV9_A2_7 dpi (6.02 ± 0.71) versus AAV1_P5_7 dpi (4.17 ± 1.20).