PDGFRα-positive cells in bone marrow are mobilized by high mobility group box 1 (HMGB1) to regenerate injured epithelia

c Dermatology, d Nutrition and Physiological Chemistry, and e The role of bone marrow cells in repairing ectodermal tissue, such as skin epidermis, is not clear. To explore this process further, this study examined a particular form of cutaneous repair, skin graft- ing. Grafting of full thickness wild-type mouse skin onto mice that had received a green fluorescent protein-bone marrow transplant after whole body irradiation led to an abundance of bone marrow- derived epithelial cells in follicular and interfollicular epidermis that persisted for at least 5 mo. The source of the epithelial pro- genitors was the nonhematopoietic, platelet-derived growth fac- tor receptor α-positive (Lin � /PDGFRα + ) bone marrow cell population. Skin grafts release high mobility group box 1 (HMGB1) in vitro and in vivo, which can mobilize the Lin � /PDGFRα + cells from bone mar- row to target the engrafted skin. These data provide unique in- sight into how skin grafts facilitate tissue repair and identify strategies germane to regenerative medicine for skin and, per- haps, other ectodermal defects or diseases. epidermolysis bullosa | skin injury | stem cells | keratinocyte | tissue regeneration