NGF-releasing Prussian blue nanoparticles for nerve injury repair of lumbar disc herniation

Introduction Compression of the nerve root by a lumbar disc herniation can cause radiating pain in the lower limbs, and the nerve root decompression treatment may leave some patients with motor dysfunction and reduced sensory function. Studies have shown that nerve growth factor (NGF) can promote nerve growth and repair, but high doses, long duration, and immune response have become bottlenecks of its clinical application. Methods To overcome this obstacle, we developed Prussian blue (PBs) nanoparticles with the bio-delivery function and antioxidant effects of nanoenzymes. NGF was conjugated to the surface of PBs nanoparticles (PBs-NGF), which can be directly delivered to nerve cells. Results The results showed that free PBs showed great advantages in scavenging oxygen free radicals and antioxidants, while PBs-NGF showed good biocompatibility. At the cellular level, cell proliferation assay and fluorescence microscopy analysis confirmed that PBs-NGF significantly promoted the proliferation, differentiation, and neurite outgrowth of neuron-like PC12 cells compared with free NGF. In a nerve root compression (NRC) rat model, behavioral observations (paw withdrawal threshold, PWT, and paw withdrawal latency, PWL) confirmed that PBs-NGF eased the pain caused by nerve root compression. H&E staining showed that PBs-NGF could significantly reduce the inflammatory infiltration of nerve roots, and ELISA results showed that the concentrations of inflammatory markers (IL-6, IL-1β, and TNF-α) were also significantly reduced. Conclusion In summary, the developed functional nanoplatform provides a basis for the clinical application of NGF in lumbar nerve root injury with disc herniation compression and a new treatment strategy for patients.