Abstract
Summary Statement
Collagen scaffolds modified with collagen-binding bFGF promotes the neural regeneration in the rat hemisected spinal cord injury model.
Objective
To investigate the effects of the collagen scaffolds (CS) combined with collagen-binding basic fibroblast growth factor (CBD-bFGF) on the neural recovery after spinal cord injury (SCI).
Methods
The left lateral 3 mm hemisection SCI of rat model (at T9 level) was made. A bundle of 2mm×2mm×3mm CS fused with CBD-bFGF (2μg/10μl/bundle, CS/bFGF) was implanted into hemi-transected gap. There were four groups in this experiment, the sham group without SCI, the control group with SCI, the CS-treated group with SCI and implanted CS, the CS/bFGF-treated group with SCI and implanted CS/bFGF. The 21-point Basso-Beattie-Bresnahan (BBB) scale was performed before the operation and at 1 week intervals after SCI for 8 weeks to assess the hindlimb locomotor function. 4 and 8 weeks after operation, footprint analysis was applied to evaluate the body weight support and limb coordination, respectively. H&E staining and immunohistochemistry for neurofilament (NF) and glial fibrillary acidic protein (GFAP) was administrated for histological evaluation at 4 and 8 weeks post injury, respectively.
Results
1). The survival curve showed that CS/bFGF-treated group had a significantly higher survival rate than that of the control group and CS-treated group, while the control group had the lowest one. 2). BBB score showed all the animals with SCI showed a gradual recovery in hindlimb locomotor function during the 8 weeks period. Moreover, the left hindlimb function in CS/bFGF-treated recovered faster and better than that of the control group and CS-treated group. Footprint analysis showed a significant improvement in interlimb coordination in the CS/bFGF-treated group contrast to the CS-treated and control groups at 4 and 8 weeks, respectively. The base of support was obviously reduced in CS/bFGF group and 8 weeks after SCI, the base of support of the CS/bFGF-treated group could closely approximate that of sham-operated group. Compared to the control and CS-treated groups, the CS/bFGF-treated group showed smaller angle of rotation. In addition, toe dragging was more serious in the control and CS-treated group than that in the CS/bFGF group. 3). At 4 and 8 weeks, spinal cord sections stained with H&E showed a significant increase in the density of linear fibrous tissues and cell infiltration in and around the scaffold of CS/bFGF-treated group compared to the control and CS-treated groups. The CS/bFGF-treated group showed highest NF-positive neural fiber density. Besides, the NF-positive neural fibers could extend into the scaffold and grow along with the direction of CS. GFAP+ astrocytes were present around the hemi-transected site in all SCI rats. But the CS/bFGF-treated group showed lower number of GFAP+ cells than that of the control and CS treated group at 4 and 8 weeks after the surgery, respectively, while in the control group the number of GFAP+ cells was highest.
Conclusions
The data suggested that implantation of CS/bFGF into a semi-transected SCI rat model can guide axon growth at the injury site and promote obvious improvement in functional recovery. As a result, CS/bFGF combination could be a promising alternative system for the clinical application of SCI repair.
