The α7 integrin is prerequisite for Sca-1<sup>+</sup> stem cell accumulation in skeletal muscle following exercise.

<p>(<i>A</i>) Localization of stem cell antigen-1 (Sca-1) (arrows, TRITC-red) positive mononuclear cells and α7 integrin (FITC-green) in the interstitium of wild type (WT), α7 transgenic (α7Tg), and α7<sup>−/−</sup> skeletal muscle in the sedentary state (Sed) or 24 hr post-exercise (Ex) at 20×. (<i>B</i>) Localization of Sca-1 (TRITC-red) positive mononuclear cells and α7 integrin (FITC-green) in the myotendinous junction and in close proximity to vessels and nerves of WT and α7Tg skeletal muscle in the sedentary state (Sed) or post-exercise (Ex). (<i>C</i>) FACS analysis of Sca-1 and CD45 expression on mononuclear cells extracted from skeletal muscle in the sedentary state and post-exercise. (<i>D</i>) Quantitation of Sca-1<sup>+</sup>CD45<sup>−</sup> mononuclear cells in the sedentary state (Sed) and 24 hr post-exercise (Ex). (E) Representative images showing co-localization of Sca-1<sup>+</sup> cells with leukemia inhibitory factor (LIF) in the vascular niche of WT and α7Tg muscle. Scale bar = 10 µm. Data are means ± SEM, n = 4–6/group for <i>C</i> and <i>D</i>. * P<0.05 vs. WT Sed and § P<0.05 vs. all groups.</p>