Induction of Skin Allograft Chimerism by Pharmacological Mobilization of Endogenous Bone Marrow-Derived Stem Cells

Skin substitutes including allografts remain a standard therapeutic approach to promote healing of both acute and chronic large wounds. However, none have resulted in the regrowth of lost and damaged tissues and scarless wound healing. Here, we demonstrate skin allograft chimerism and repair through the mobilization of endogenous bone marrow-derived stem and immune cells in rats and swine. We show that pharmacological mobilization of bone marrow stem cells and immune cells into the circulation promotes host repopulation of skin allografts and restoration of the skin's normal architecture without scarring and minimal contracture. When skin allografts from DA rats are transplanted into GFP transgenic Lewis recipients with a combination of AMD3100 and low-dose FK506 (AF) therapy, host-derived GFP-positive cells repopulate and/or regenerate cellular components of skin grafts including epidermis and hair follicles and the grafts become donor-host chimeric skin. Using AF combination therapy, burn wounds with skin allografts were healed by newly regenerated chimeric skin with epidermal appendages and pigmentation and without contracture in swine.