A. AT-MSCs or PBS were intradermally injected to WT or CD18-/- wounds and the wound tissues were harvested at days 2, 5, 7 post-wounding. Depicted are representative photographs of wound cryosections at days 2 and 5 post-wounding stained for human-specific β2M (green). Nuclei were stained with DAPI (blue). Scale bars: 100 µm. 