Diabetic foot ulcer (DFU) is one of diabetic complications,which is frequently present and tormented in diabetes mellitus.Most multipotent mesenchymal stromal cells (MSCs) are capable of immune evasion,providing an allogeneic,ready-to-use,cell product option for therapeutic applications.The beneficial effect of MSCs for the treatment of a variety of traumatic injuries,such as open wounds,has been extensively explored.In this study,a rat DFU model was used to simulate the pathophysiology of clinical patients and to investigate the localization of human umbilical cord mesenchymal stem cells (hUC-MSCs) after intravenous transplantation and its role in DFU healing,so as to evaluate the potential of hUC-MSCs in the treatment of DFU.The diabetic rat model was established by streptozotocin injection,which was used to create full-thickness foot dorsal skin wounds to mimic DFU by a 6-mm skin biopsy punch and a Westcott scissor.The hUC-MSCs were transplanted through femoral vein,and the ulcer cicatrization situation and the fate of hUC-MSCs were evaluated.Our data suggest that intravenously transplantated hUC-MSCs have the ability to migrate and locate to the wound tissue and are helpful to wound healing in DFU rats,partly by regulating inflammation,trans-differentiation and providing growth factors that promote angiogenesis,cell proliferation and collagen deposition.Herein,we demonstrate that hUC-MSC transplantation is able to accelerate DFU healing in rats and transplantation of exogenous stem cells may be a potential strategy for clinical application in DFUs.