Engineered multifunctional silk fibroin/gelatin hydrogel conduit loaded with miR-29a@ZIF-8 nanoparticles for peripheral nerve regeneration

Peripheral nerve injury (PNI) is a common surgical disease. In recent years, with the development of tissue engineering materials, nerve guidance conduit (NGC) is expected to replace autologous nerve transplantation and become a new method for the treatment of PNI. In this work, we developed a multifunctional silk fibroin (SF)/gelatin-tyramine (GT) composite hydrogel conduit with flexible adjustable size by using a diffusion-driven cross-linking method. Furthermore, the ZIF-8 nanoparticles loaded with miR-29a (miR-29a@ZIF-8) delivery system was constructed and compounded into SF/GT hydrogel conduit to enhance its bioactivity and neural repair effects through sustained miR-29a release. In vitro cell experiments showed that SF/GT hydrogel conduit could significantly promote the myelination of Schwann cells (SCs), neuronal differentiation and axon extension of PC12 ​cells. In addition, it was worth mentioning that SF/GT hydrogel conduit could also regulate the immune microenvironment of nerve regeneration by promoting the transformation of macrophages from M1 phenotype to M2 phenotype, indicating a potential application as nerve guidance conduit in peripheral nerve repair.