(A) tdTomato (red) expression and DAPI (blue) nuclear staining were analyzed 21 days after the saline, Cas9 mRNA/Ai9 sgRNA or MC3 LNP Cas9 mRNA/Ai9 sgRNA injection in the striatum (Left), and the hippocampus (Right). Cas9 mRNA/Ai9 sgRNA or MC3 LNP Cas9 mRNA/Ai9 sgRNA was injected with two doses: 0.125 μg μL−1 (1X) or 0.250 μg μL−1 (2X). The scale bar represents 30 μm. (B, C) Quantification of the percentage of tdTomato+ cells among DAPI+ in the striatum (permutation one-way ANOVA: F(4,55) = 23.36, p < 0.001) (B), and the hippocampus (permutation one-way ANOVA: F(4,55) = 15.29, p < 0.001) (C). All data are presented as mean ± SEM. ** p < 0.01, *** p < 0.001 by post hoc permutation t-test. Post hoc p values were calculated between Cas9 mRNA/Ai9 sgRNA (0.125 μg μL−1 or 0.250 μg μL−1) and MC3 LNP Cas9 mRNA/Ai9 sgRNA (0.125 μg μL−1 or 0.250 μg μL−1) as well as between dosages 0.125 μg μL−1 vs. 0.250 μg μL−1 within Cas9 mRNA/Ai9 sgRNA or MC3 LNP Cas9 mRNA/Ai9 sgRNA. Saline (n = 15 images from 3 mice), Cas9 mRNA/Ai9 sgRNA low dose (0.125 μg μL−1; Cas9 mRNA 1X; n = 10 images from 2 mice), Cas9 mRNA/Ai9 sgRNA high dose (0.250 μg μL−1; Cas9 mRNA 2X; n = 10 images from 2 mice), MC3 LNP Cas9 mRNA/Ai9 sgRNA low dose (0.125 μg μL−1; MC3 Cas9 mRNA 1X; n = 10 images from 2 mice), and MC3 LNP Cas9 mRNA/Ai9 sgRNA high dose (0.250 μg μL−1; MC3 Cas9 mRNA 2X; n = 15 images from 3 mice).