Wnt7a-loaded satellite cells have an enhanced engraftment potential. (A) Schematic of the isolation, ex vivo treatment, and transplantation of satellite cells from Pax7-zsGreen mice. (B) Representative pictures showing engraftment of zsGreen- and Pax7-expressing donor-derived cells that were either Wnt7a or vehicle treated. Bar, 20 µm. (C) Quantification of engraftment of Wnt7a- or vehicle-treated donor satellite cells (Pax7⁺/zsGreen⁺, arrowheads in B). Error bars represent means ± SEM; n = 3. **, P < 0.01. (D) Representative images showing dystrophin-expressing myofibers (asterisks) derived from transplanted Wnt7a or vehicle-treated satellite cells. Bar, 20 µm. (E) Quantification of myofibers expressing dystrophin after transplantation of Wnt7a- or vehicle-treated satellite cells. Error bars represent means ± SEM; n = 3. **, P < 0.01. (F) Engrafted satellite cells form clusters of dystrophin-expressing myofibers in host mdx muscles. The photographs show the tibialis anterior muscle that was injected with Wnt7a- or vehicle-treated cells. The distance between the two maximally spaced clusters of dystrophin-expressing myofibers (highlighted in red) is indicated with a magenta line. (G) Quantification of the maximal cluster distance in muscles injected with Wnt7a- or vehicle-treated cells. Error bars represent means ± SEM; n ≥ 4. **, P < 0.01. (H) Minimal feret measurements of dystrophin-expressing myofibers in host muscles. Myofibers that had fused with a Wnt7a-treated cell become hypertrophic. Error bars represent means ± SEM; n = 3. *, P < 0.05. (I) Quantification of the twitch force tension of mdx muscles injected with Wnt7a- or vehicle-treated cells. Error bars represent means ± SEM; n ≥ 7. **, P < 0.01. (J) Maximal specific force generated by mdx muscles injected with Wnt7a- or vehicle-treated cells. Error bars represent means ± SEM; n ≥ 7. *, P < 0.05.