Figure 5.

siSmad4-treated or miR-431-treated old muscles showed enhanced regenerative capacity. (A) Scheme of the experimental procedures. CTX (20 µM) was injected into TA muscle tissues of old mice at day 0. Two days and 5 d later, injured muscle tissues were injected with siSmad4 or miR-431 mimic, and contralateral muscle tissues were injected with control siRNA or miRNA mimic. At 14 d after injury, muscle tissues were analyzed by immunohistochemistry. (B,C) Representative immunohistochemistry images (left panels) of laminin (red) and DAPI (blue) staining of siSmad4-treated (B) and miR-431 mimic-treated (C) regenerating fibers (n = 4) on day 14 after injury. Each cross-section area (CSA) was measured by ImageJ software, and six different views were randomly selected for measurement of CSA; (*) P < 0.05. Bar, 100 µm.