Caffeic acid-vanadium nanozymes treat skin flap ischemia-reperfusion injury through macrophage reprogramming and the upregulation of X-linked inhibitors of apoptotic proteins

Ischemia-reperfusion (I/R) injury following skin flap transplantation is a critical factor leading to flap necrosis and transplant failure. Antagonizing inflammatory responses and oxidative stress are regarded as crucial targets for mitigating reperfusion injury and enhancing flap survival. In this study, caffeic acid-vanadium metal polyphenol nanoparticles (CA-V NPs) were prepared for the treatment of skin flap ischemia and reperfusion. This study was conducted using a one-step method to prepare new types of CA-V NPs with uniform sizes and stable structures. <i>In vitro</i>, the CA-V NPs exhibited CAT-like and SOD-like activities and could effectively scavenge ROS, generate oxygen, and alleviate oxidative stress. In the H₂O₂-induced cellular oxidative stress model, CA-V NPs effectively reduced ROS levels and inhibited apoptosis through the XIAP/Caspase-3 pathway. In the cellular inflammation model induced by LPS combined with IFN-<i>γ</i>, CA-V NPs reprogrammed macrophage polarization toward the M2 phenotype and reduced inflammatory responses by reducing the expression of the chemokines CCL4 and CXCL2. In addition, animal experiments have shown that CA-V NPs can alleviate oxidative stress in skin flap tissues, inhibit apoptosis, promote angiogenesis, and ultimately improve the survival rate of skin flaps. CA-V NPs provide a new target and strategy for the treatment of flap I/R injury.