Mouse muscle regeneration model and adenovirus injection

Muscle degeneration and regeneration in mice were induced by injecting cardiotoxin (CTX). Six week-old C57BL/6 mice were injected in their tibialis anterior muscles with 100 μl of 10 μM CTX. Adenoviruses expressing miR-20a or negative control (10¹⁰ to 10¹¹ p.f.u./ml) were injected into the tibialis anterior muscles 10 days prior to the CTX injection. Two tibialis anterior muscles from each mouse were collected at 0, 1, 3, 5 and 10 days post-CTX injury. One sample was fixed in 4% paraformaldehyde for histology and immunohistochemistry. The other sample was frozen in liquid nitrogen and stored at −80 °C for RNA and protein extraction.