Microenvironment-responsive immunoregulatory electrospun fibers for promoting nerve function recovery.

The strategies concerning modification of the complex immune pathological inflammatory environment during acute spinal cord injury remain oversimplified and superficial. Inspired by the acidic microenvironment at acute injury sites, a functional pH-responsive immunoregulation-assisted neural regeneration strategy was constructed. With the capability of directly responding to the acidic microenvironment at focal areas followed by triggered release of the IL-4 plasmid-loaded liposomes within a few hours to suppress the release of inflammatory cytokines and promote neural differentiation of mesenchymal stem cells in vitro, the microenvironment-responsive immunoregulatory electrospun fibers were implanted into acute spinal cord injury rats. Together with sustained release of nerve growth factor (NGF) achieved by microsol core-shell structure, the immunological fiber scaffolds were revealed to bring significantly shifted immune cells subtype to down-regulate the acute inflammation response, reduce scar tissue formation, promote angiogenesis as well as neural differentiation at the injury site, and enhance functional recovery in vivo. Overall, this strategy provided a delivery system through microenvironment-responsive immunological regulation effect so as to break through the current dilemma from the contradiction between immune response and nerve regeneration, providing an alternative for the treatment of acute spinal cord injury.