Anti-inflammatory, Sensory, and Microbiome Effects of Implanted Scaffolds on Spinal Cord Injury in Rats

Introduction: Traumatic spinal cord injury is rapidly followed by a strong immune response within the spinal cord, consisting of activation of central nervous system resident immune cells and infiltration by peripheral immune cells. This local immune response persists chronically and is widely recognized to hold considerable sway over the progression of secondary tissue damage.

Methods: We conducted a characterization of the post-injury immune response in spinal cords of adult (10–12-week-old) female wild-type (Sprague-Dawley) rats, as well as microbiome, sensory, and autonomic measures, following the implantation of a biomaterial scaffold (FPLG) after a moderate (200 kdyn) spinal cord contusion at T9. Animals were divided into three groups: sham (T9 laminectomy only); SCI (T9 laminectomy and contusion, followed by myelotomy (1 dpi)); and SCI+FPLG (T9 laminectomy and contusion, followed by myelotomy and scaffold insertion (1 dpi)). All animals had all outcome measures recorded at baseline and at sacrifice. Sensory and autonomic measures were also collected at various time points throughout the eight-week survival period.

Results: Following implantation of the FPLG scaffold, spinal macrophage levels decreased by ~25% with no significant effect on T-cells and other myeloid cells. Heart rate, blood pressure, and sensory function remained unaffected.

Conclusion : The implanted FPLG scaffold can reduce macrophages detectable in the SCI site as early as day 7 following injury, with a further reduction in levels by day 60. These results suggest that FPLG may reduce immune dysfunction in the spinal cord following SCI at even more chronic time points, leading to superior recovery of function.