Figure 6: Wild-type fibroblast grafting rescues SC self-renewal and muscle stiffness in Col6a1^–/– muscles.

(a) Representative confocal z-stack image of immunofluorescence analysis of Col6a1^–/– TA muscles 2 and 4 days after transplantation with wild-type fibroblasts. Sections were labeled with antibodies against collagen VI (light pink) and laminin (red). Scale bar, 100 μm. (b) Representative confocal z-stack images of immunofluorescence for collagen VI (green) and Pax7 (red) in Col6a1^–/– TA sections 4 days after grafting with wild-type fibroblasts. The arrowhead points at one Pax7⁺ cell, shown at higher magnification in the inset. Scale bar, 25 μm. (c) Quantification of the elastic modulus of Col6a1^–/– TA under untreated conditions (−) and 12 days after grafting with wild-type fibroblasts or Col6a1^–/– fibroblasts. Data are shown as mean±s.d. of two independent replicates (**P<0.01; n.s., not significant; unequal variance Student’s t-test; n=10 animals, each group). (d) Quantification of SCs in Col6a1^–/– TA in untreated conditions (−) and in the graft region 12 days after grafting with wild-type fibroblasts or Col6a1^–/– fibroblasts. Data are shown as mean±s.e.m. of three independent replicates (**P<0.01; unequal variance Student’s t-test; n.s., not significant; n=6 animals, each group). (e) Representative confocal z-stack image of immunofluorescence for collagen VI (green) and laminin (gray) in Col6a1^–/– TA cross-sections 30 days after injury and grafting with wild-type fibroblasts. Scale bar, 100 μm. (f) Ratio of SCs between Col6a1^–/– and wild-type mice under untreated conditions (−) or 30 days after cardiotoxin injury either in the absence or in the presence of a single grafting with wild-type fibroblasts. Data are shown as mean±s.e.m. of three independent replicates (**P<0.01; unequal variance Student’s t-test; n=6 animals, each group). Nuclei were stained with Hoechst (blue). KOFB, Col6a1^–/– fibroblasts; WTFB, wild-type fibroblasts.