Transplanted mesenchymal stem cells are effective for skin regeneration in acute cutaneous wounds of pigs

INTRODUCTION: We investigated the effects of mesenchymal stem cells (MSCs) on cutaneous wound healing in pigs in order to develop new therapies to enhance wound healing in humans. METHODS: We cultured bone marrow cells from the femurs of male pigs, and the multipotency of these cells were then confirmed. The characteristics of the cultured cells were determined by flow cytometric analyses. The MSCs were injected intradermally into the skin of pigs as auto-transplantation, and linear full-thickness incisional wounds were made through the injected area immediately afterward. RESULTS: The MSCs were found to be positive for SWC3a, CD44, SLA class I, CD29, CD44H, and CD90. At 28 days post-surgery, wounds treated with MSCs had healed well, with only very fine scars visible macroscopically. Histologically, collagen architecture was thick and elastic fibers appeared in the wounds. Histomorphologic scale analysis demonstrated that the wounds treated with MSCs scored better than the controls. Significantly larger fibroblasts were observed in the wounds treated with MSCs than controls. CONCLUSION: These results indicate that transplantation of MSCs causes wounds to heal almost completely, possible indicating regeneration to normal skin. We hypothesize that the transplantation protocol described in this study may also be applicable to human wound healing.