Fig. 4

H & E staining of injured muscle tissue after transplantation of hydrogel. Mice were allocated into Col, Col + Cells, Col/Keratin, and Col/Keratin + Cells groups. Bright-field imaging indicated that in the group that received Col hydrogel alone, numerous inflammatory cells were recruited to the injury site (black arrows), leading to the digestion and scavenging of hydrogel remnants. These features were less in other groups that received the combination of cells with hydrogel. In Col + Cells, inflammatory cells (black arrows) are at the periphery of newly generated myofibers (blue arrows). The myofibers are not aligned in a regular pattern. In the Col + keratin group, the intensity of immune cells was reduced and newly generated myofibers exhibited a more aligned pattern (blue arrows). Maximum myofiber density was achieved in the group with the transplantation of Col/Keratin and Cells. The area was filled with aligned newly generated myofibers (blue arrows) and few immune cells can be evident in intermyocyte space (black arrows). Data analysis revealed the maximum myofiber formation in the Col/Keratin + Cells group compared to the other groups (10 high-power fields). One-way ANOVA analysis with Tukey test. **p < 0.01; ***p < 0.001; and ****p < 0.0001