(A) Representative immunostaining for dystrophin in tibialis anterior (TA) muscle cross sections of Dmd^mdx-4Cv; Prkdc^scid mice 4 weeks after transplantation with the indicated cell lines. Scale bars: 1 mm (top) and 100 μm (bottom). (B) Quantification of the transplantation trials shown in A. n = 5 transplantation recipients for intraspecies chimera–derived myoblasts and n = 9 transplantation recipients for interspecies chimera–derived myoblasts. Each dot represents an individual transplanted muscle, with different dot colors specifying 2 different chimera-derived myoblast lines used for transplantations. Data are presented as mean ± SD. Statistical analysis was performed using a Student’s 2-tailed t test. *P ≤ 0.05, ****P ≤ 0.0001. (C) Representative immunostaining images for dystrophin and fiber typing in TA muscle cross sections of Dmd^mdx-4Cv; Prkdc^scid mice 4 weeks after transplantation with the indicated myoblasts. Scale bars: 1 mm (left) and 100 μm (right). LUTs were individually adjusted. (D) A graph illustrating force measurements during repeated tetanic contractions, showing the decline in TA muscle force of Dmd^mdx-4Cv; Prkdc^scid mice 4 weeks after transplantation with mouse-mouse and rat-mouse chimera–derived myoblasts compared to PBS control. n = 8 mice measured per group. Data are presented as mean ± SD. Statistical analysis was performed using a mixed effects model. (E) Representative immunostaining of TA muscle cross section from Dmd^mdx-4Cv; Prkdc^scid mice stained for the indicated markers 4 weeks after transplantation with the specified cell lines. Arrowheads point to colocalization of PAX7 expression and the Pax7-nGFP reporter in rare cells. Scale bars: 100 μm (left) and 25 μm (right). (F) Schematic representation of myoblast re-isolation from transplanted muscles. (G) Representative FACS plots showing the percentage of Pax7-nGFP⁺ cells detected in digested TA muscles of Dmd^mdx-4Cv; Prkdc^scid mice at 4 weeks following myoblast transplantation. (H) Representative images of re-isolated myoblasts. Scale bar: 100 μm. (I) PCR for dystrophin in DNA extracted from re-isolated myoblasts. Note the presence of only an edited band in edited and re-isolated myoblasts.