Figure 4.

Increased integrin promotes repair. To determine whether the satellite cells were used in repair, mice were injected with BrdUrd to label replicating cells. Seventy-two hours later muscle sections were analyzed by immunofluorescence for BrdUrd incorporation into DNA (green). Wheat germ agglutinin staining delineates fibers (red). Nuclei are stained with DAPI (blue). BrdUrd-labeled central nuclei (arrows) in 50 random fields were scored for each animal. Mean numbers (±SEM) are given for 11 animals for each genotype. For mdx/utr^−/− mice, the value is 32.0 ± 4.56 and for α7BX2-mdx/utr^−/− 55.0 ± 7.35 (P = 0.0152, unpaired t-test). Thus increased integrin expands the reservoir of satellite cells and the regenerative capacity of dystrophic muscle.