Preconditioning With TGF-β Inhibitors Enhances Therapeutic Efficacy of Endothelial Progenitor Cells for Wound Healing in Diabetic Mice

Diabetic wound (DW) represent a common complication of diabetes. Despite advances in regenerative repair utilizing endothelial progenitor cells (EPCs), challenges such as low survival and impaired angiogenic function of EPCs remain. Herein, we explored an effective method to induce injury-induced protection for EPCs and improves their function. This was achieved through cell preconditioning under conditions of nutrient deprivation and high glucose (NDHG), combined with sb431542, a transforming growth factor beta (TGF-β) signaling inhibitor. Specifically, after three generations of cell passage during preconditioning, umbilical cord-derived endothelial cells (ECs) exhibited characteristics resembling those of EPCs, with over 80% of the cells expressed CD34, a typical marker of EPCs. Notably, these preconditioned EPC-like cells (pEPCs) showed tolerance to pathological environment, as evidenced by robust cell viability, improved antioxidant capacity, and stable tube-forming ability under NDHG condition. The protective effect of preconditioning in pEPCs is partly achieved by activating the PI3K/AKT pathway to upregulate the expression of Nrf2 and HIF-1α. Importantly, pEPCs exhibited therapeutic potential in two diabetic mouse models-limb ischemia and skin wounds by enhancing blood vessel formation and facilitating tissue repair. Overall, this preconditioning method induced the generation of functionally enhanced pEPCs, providing an alternative source of cells for treating DWs.