Multifunctional injectable hydrogel loaded with sheep placenta and copper-tannic acid nanozyme for facilitating spinal cord regeneration

Spinal cord injury (SCI) can lead to severe oxidative stress, inflammation, and impaired tissue regeneration in the local microenvironment, which hinders spinal cord regeneration. Injectable hydrogels have been investigated as potential therapeutic strategies for SCI. However, the microenvironment of an injured spinal cord is complex, as hemorrhage, ischemia, glial scar formation, and demyelination occur at different times and locations. In this study, a novel injectable functional hydrogel based on sheep placenta powder (SSP), hyaluronic acid methacrylate (HAMA) and copper-tannic acid (CuTA) nanozyme was developed to provide strong reactive oxygen species (ROS) scavenging ability, inhibition of macrophage polarization, and angiogenesis sequentially. After implantation, the multifunctional hydrogel alleviated local oxidative stress, inhibited the infiltration of M1 macrophages, accelerated the switching of M1 macrophages to the M2 type, and promoted local microvessel regeneration, thereby established a satisfactory foundation for spinal cord reconstruction and further improved behavioral phenotypes and motor abilities. Therefore, the multifunctional hydrogel offers a promising approach for SCI treatment.