Dopamine-modified hyaluronic acid hydrogel's role in spinal cord injury.

Spinal cord injury (SCI) is one of the most severe diseases in the world caused by violence or accidents, often leading to the loss of sensation, movement, and autonomic nervous function, resulting in a high rate of disability. Current clinical treatment strategies often fail to meet expectations. Here, we designed a dopamine (DP)-modified hyaluronic acid (HA) hydrogel combined with neurotrophic factors (NGF) to improve the adverse microenvironment after spinal cord injury (SCI) and promote axonal regeneration. HA, as a "scaffolding molecule," utilizes the reaction between 1-ethyl-(3-dimethylaminopropyl) (EDC) carbodiimide and N-hydroxysuccinimide (NHS) to modify the crosslinker DP onto HA, thereby obtaining an HA-DP solution. Finally, after adding NGF and mixing evenly, the HA-DP-NGF hydrogel is obtained. Cellular experiments analysis indicated that the neurite length of PC-12 cells co-cultured with HA-DP-NGF (1.02 ± 0.21 cm), (1.08 ± 0.23) and the protein level of Tuj1 were significantly higher than those of the control group (0.83 ± 0.08 cm), (0.95 ± 0.21). Furthermore, implanting HA-DP-NGF hydrogel into the damaged spinal cord of rats, compared with the injury group (6.98 ± 0.47), helped to reduce the CSPGS level in the injury area (5.10 ± 0.55), and promoted axonal regeneration in the severely damaged spinal cord area. The hydrogel designed in this study has high mechanical properties and good cytocompatibility, providing new insights for SCI repair.