Anisotropic Alginate Hydrogels Promote Axonal Growth Across Chronic Spinal Cord Transections after Scar Removal

We have previously reported that cell-seeded alginate hydrogels (AHs) with anisotropic capillaries can restore the continuity of the spinal cord and support axonal regeneration in a rat model of acute partial spinal cord transection. Whether similar effects can be found after transplantation into sites of complete chronic spinal cord transections without additional growth-promoting stimuli has not been investigated. We therefore implanted AHs into the cavity of a chronic thoracic transection following scar resection (SR) 4 weeks post-injury and examined electrophysiological and functional recovery, as well as regeneration of descending and ascending projections within and beyond the AH scaffold up to 3 months after engraftment. Our results indicate that both electrophysiological conductivity and locomotor function are significantly improved after AH engraftment. SR transiently impairs locomotor function immediately after surgery, but does not affect long-term outcomes. Histological analysis shows numerous...