Figure 2. Systemic AAV CRISPR therapy resulted in sustained skeletal muscle function improvement in mdx mice.

Systemic AAV-9 CRISPR therapy was performed in 6-week-old male mdx mice at the dose of 1 × 10¹³ vg/mouse and 3 × 10¹³ vg/mouse for the Cas9 and gRNA vectors, respectively. Mice were evaluated at 18 months of age. (A) Representative dystrophin immunostaining photomicrographs from WT, mdx and CRISPR-treated mdx mice. Scale bar: 100 μm (top); 200 μm (bottom). (B) Quantification of dystrophin-positive myofibers. (C) Representative dystrophin Western blot from WT and CRISPR-treated mice. (D) Quantification of dystrophin Western blot. (E) Quantification of total dystrophin transcripts. (F) Quantification of the AAV genome copy number. (G) Representative skeletal muscle H&E and Masson trichrome (MTC) staining. Scale bar: 100 μm. (H) Quantification of fibrosis in skeletal muscle. (I) Specific twitch (sPt) and tetanic force (sPo). (J) Eccentric contraction profile. Statistical analyses were done using following tests: B and D, 2-tailed Student’s t test; F, multiple t tests (statistical analysis was only performed between the Cas9 data and the gRNA data in each organs; we did not compare data from different organs); E, H, and I, 1-way ANOVA; and J, 2-way ANOVA. *P < 0.05. ^#Loading in this lane was at one-fourth the volume of that in other lanes. The quadriceps or gastrocnemius muscle was used to generate the skeletal muscle data shown in the figure.