Fig. 2.

Regenerative response of engineered muscle to in vitro cardiotoxin (CTX) injury. (A) Representative images of engineered muscle structure, and Pax7⁺ cells with time post-CTX injury (induced at 14 d of culture). (B) Pax7⁺, Ki67⁺/Pax7⁺ (% of Pax7⁺), MyoD⁺, and myogenin (MyoG)⁺ cell density, myofiber density, percent cross-striated myofibers, and twitch and tetanus force amplitudes shown relative to preinjury levels at 6 h, 5 d, and 10 d post-CTX addition. Mean ± SEM; n = 3–5 samples per group (6–10 images per sample); *P < 0.05 compared with 2-wk healthy controls; P < 0.05 between denoted groups.