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. 2009 Sep 24;106(41):17475–17480. doi: 10.1073/pnas.0908641106

Fig. 5.

Fig. 5.

Evaluation of regenerating skeletal muscles in βΔCre mice. (A and B) Trichrome staining of +/+ (A) and βΔCre (B) tibialis anterior muscle shows similar necrosis in both genotypes 2 days after CTX injection. (C and D) Recovery of the injured muscles and regenerating myofibers (containing centralized nuclei) at day 5 postinjury in +/+ (C) and βΔCre (D) muscle. Myofibers with eosinophil cytoplasm are indicated with arrowheads in (D). (E and F) At day 10 postinjury, the existence of numerous small fibers (arrowheads) is evident in the βΔCre injured muscle (F) compared to +/+ muscle (E). Note that, in contrast to control regenerating muscles, βΔCre muscles contained many calcified fibers (arrows). (G) Morphometric analysis of muscle regeneration in +/+ and βΔCre mice. The data show the frequency distribution in the tibialis anterior fiber cross-sectional area (CSA) within the regenerating muscle. (H) Measurement of the total regenerating (marked by centralized nuclei) fiber area in mutant injured muscles. Data are presented as the mean ± SD (+/+ n = 6; βΔCre n = 6). Significant differences (P < 0.05; Student's t-test) are indicated by asterisks (*). (J and K) Regenerated tibialis anterior muscle of +/+ (J) and BMKO (K) mice 10 days after CTX injection. No impairment of regeneration was evident in BMKO muscle compared to +/+ muscle. (L) BM cells from βΔCre mutant or wild-type mice (CD45.1−CD45.2+ allotype) were transferred to lethally irradiated recipient mice (CD45.1+CD45.2+ allotype). Plots show representative FACS analysis of peripheral blood in recipient mice at 4 weeks after transplantation to measure the engraftment of donor (CD45.1−CD45.2+) and recipient (CD45.1+CD45.2+) cells. (M and N) The mice transplanted in (L) were subjected to the CTX injury protocol. Trichrome staining of injured TA muscle sections at day 10 postinjury is shown. Note that the observed defect in muscle regeneration in βΔCre mice was recapitulated in wild-type mice transplanted with βΔCre mutant BM cells (N) while control wild-type mice transplanted with wild-type BM cells showed normal regeneration (M).