Restoring electrical connection using a conductive biomaterial provides a new therapeutic strategy for rats with spinal cord injury

Spinal cord injury (SCI) involves damage to the central nervous system, and there is no effective treatment available currently. The injured spinal cord is unable to transmit physiological electrical signals caudal to the location of the injury after a complete transection. In this study, we attempted to use a conductive biomaterial as a novel scaffold to aid SCI repair. A composite biomaterial was fabricated by embedding conductive polypyrrole (PPy) in an electrospun polylactic acid (PLA) nanofibrous scaffold (PLA/PPy scaffold), and an electrospun PLA nanofibrous scaffold without the PPy component was used as a control. The scaffolds were implanted into rats having complete T9 spinal cord resection. Immunofluorescent staining, western blot analysis, and TUNEL assay were used to study histological changes in injured spinal cord tissues. Our data demonstrated that PLA/PPy scaffolds had beneficial effects, as evident from the motor evoked-potentials (MEPs) test and Basso, Beattie, and Bresnahan (BBB) locomotion rating scale. Implantation of the PLA/PPy scaffold significantly alleviated secondary tissue damage by reducing apoptosis and autophagy in neural cells in comparison with the implantation of the control PLA scaffold. Notably, six weeks after injury, the use of PLA/PPy scaffolds significantly reduced the activation of astrocytes and increased axonal regeneration, as indicated by immunofluorescent markers (GFAP and NF200) in the region of injury. Our present study suggests that restoring electrical conductivity using a biological scaffold is beneficial to the microenvironment and favorable for the regeneration and functional recovery of spinal cord tissue in an SCI rat model.