Designing multifunctionalized selenium nanoparticles to reverse oxidative stress-induced spinal cord injury by attenuating ROS overproduction and mitochondria dysfunction.

Spinal cord injury (SCI) remains a challenging clinical problem worldwide, due to the lack of effective drugs for precise treatment. Among the complex pathophysiological events following SCI, reactive oxygen species (ROS) overproduction plays a particularly significant role. As therapeutic agents for neurological diseases, tetramethylpyrazine (TMP) and monosialotetrahexosylganglioside (GM1) have been widely used in the clinical treatment of SCI. Our previous studies have reported that functionalized selenium nanoparticles (SeNPs) exhibit excellent antioxidant activity against oxidative stress-related diseases. Therefore, in this study, novel multifunctionalized SeNPs decorated with polysaccharide-protein complex (PTW)/PG-6 peptide and loaded with TMP/GM1 were rationally designed and synthesized, which exhibited a satisfactory size distribution and superior stability. Furthermore, the protective effects of SeNPs@GM1/TMP on PC12 cells against tert-butyl hydroperoxide (t-BOOH)-induced cytotoxicity and the underlying mechanisms were also explored. Flow cytometric analysis indicated that SeNPs@GM1/TMP showed strongly protective effects against t-BOOH-induced G2/M phase arrest and apoptosis. Moreover, we found that SeNPs@GM1/TMP could attenuate ROS overproduction to prevent mitochondria dysfunction via inhibiting the activation of p53 and MAPK pathways. Effects of SeNPs@GM1/TMP on functional recovery after SCI were evaluated by the Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test, and footprint analysis. The results of hematoxylin-eosin staining and Nissl staining also showed that SeNPs@GM1/TMP provided a neuroprotective effect in SCI rats. This finding suggests that SeNPs@GM1/TMP could be further developed as a promising nanomedicine for efficient SCI treatment.