GDNF-Loaded Polydopamine Nanoparticles-Based Anisotropic Scaffolds Promote Spinal Cord Repair by Modulating Inhibitory Microenvironment.

Spinal cord injury (SCI) is a devastating injury that causes permanent loss of sensation and motor function. SCI repair is a significant challenge due to the limited regenerating ability of adult neurons and the complex inflammatory microenvironment. After SCI, the oxidative stress induced by excessive reactive oxygen species (ROS) often leads to prolonged neuroinflammation that results in sustained damage to the spinal cord tissue. Polydopamine (PDA) shows remarkable capability in scavenging ROS to treat numerous inflammatory diseases. In this study, glial cell-derived neurotrophic factor (GDNF)-loaded PDA nanoparticle-based anisotropic scaffolds for spinal cord repair are developed. It is found that mesoporous PDA nanoparticles (mPDA NPs) in the scaffolds efficiently scavenge ROS and promote microglia M2 polarization, thereby inhibiting inflammatory response at the injury site and providing a favorable microenvironment for nerve cell survival. Furthermore, the GDNF encapsulated in mPDA NPs promotes corticospinal tract motor axon regeneration and its locomotor functional recovery. Together, findings from this study reveal that the GDNF-loaded PDA/Gelatin scaffolds hold potential as an effective artificial transplantation material for SCI treatment.