Figure 4.

Fibrogenic Plasticity of Satellite Cells at Advanced Muscular Dystrophy Stages and in Response to TGFβ

(A) Representative FACS plots of α7-INTEGRIN expression in CTX-injured and CTX/TGFβ-injured Pax7-Cre^ER/YFP muscles (as in Figure S1F) and quantification of YFP⁺ cells that have reduced/lost α7-integrin expression. Values are mean ± SEM; n = 6 animals for each group. Non-parametric Mann-Whitney U test was used for comparison.

(B) Quantification of YFP⁺ cells that maintain or have reduced/lost α7-INTEGRIN expression in Pax7-Cre^ER/YFP/mdx (mdx) mice compared to Pax7-Cre^ER/YFP (WT) mice. Values are mean ± SEM; n = 6 animals for each group. Non-parametric Mann-Whitney U test was used for comparison.

(C and D) qRT-PCR of fibroblastic and myogenic markers in YFP⁺α7^low/− compared to YFP⁺α7^high cells from Pax7-Cre^ER/YFP/mdx muscle (C) and from CTX/TGFβ-injured Pax7-Cre^ER/YFP muscle (D). Values are mean ± SEM; n = 3 independent experiments (mice) for each group. Unpaired t test was used for comparison.

(E) Percentage of YFP⁺ cells that express myogenic and fibrogenic markers in single fibers from Pax7-Cre/YFP/mdx (mdx) mice compared to Pax7-Cre/YFP (WT) mice. Values are mean ± SEM; n = 5 animals each group. Non-parametric Mann-Whitney U test was used for comparison.

(F) Representative immunostaining shows YFP⁺ cells co-expressing fibrogenic markers in Pax7-Cre^ER/YFP/mdx mice. Scale bars, 25 μm.

(G) Myogenic potential of FACS-isolated YFP⁺α7^high cells from aged Pax7-Cre/YFP/mdx mice, compared to YFP⁺α7^low/− cells, after culture in DM for 4 days. The angiogenic potential of CD31^high versus CD31^low/− endothelial cells was similarly determined in angiogenic-promoting conditions (see Experimental Procedures). Scale bars, 50 μm.