Effects of phosphate glass fiber-collagen scaffolds on functional recovery of completely transected rat spinal cords.

Phosphate-based glass fibers (PGFs), due to characteristics such as biodegradability and directionality, could be effective as spatial cues for axonal outgrowth following nerve injury. In the present study, PGF-containing cylindrical scaffolds of 1.8mm diameter and 3mm length were developed and implanted into the gap between the proximal and distal stumps following complete transection of rat spinal cords at T9. The PGF-free collagen scaffolds were implanted into the transected spinal cords of the control group. The open-field Basso, Beattie and Bresnahan locomotor scale revealed that the locomotor function of the experimental group was better than in the control group from 8 to 12 weeks after implantation, and urodynamic analysis revealed additional improvements in the experimental group in some parameters. Twelve weeks after implantation, some axon growth from the proximal and distal stumps to the scaffold was observed in the experimental group but not in the control group. Macrophages surrounded the injured thoracic spinal cord at 1 and 4 weeks after implantation; however, 6h after implantation, the pro-inflammatory cytokines did not differ between the control and experimental groups. Anterograde corticospinal tract (CST) tracing with biotinylated dextran amine showed that, in the experimental group, some CST outgrowths could reach the lumbar enlargement. By 12 weeks, the mRNA levels of brain-derived neurotrophic factor in the bladder had increased more in the experimental group than in the controls. We conclude that PGFs can have a beneficial effect on functional recovery following complete transection of the thoracic spinal cord in rats.