Effects of Hydrogel-Fiber on Cystic Cavity after Spinal Cord Injury.

Spinal cord injury (SCI) affects millions of people around the world, however, functional recovery is far from satisfying. The continuous emergence of biomaterials provides a new idea for the repair of SCI. Hydrogels can mimic the extracellular matrix (ECM), however, the unstable hydrogel shape limits its application. In this study, we evaluate the effect of hydrogel fiber (Polycaprolactone, PCL fiber was added to the hydrogel) on the recovery after SCI. 20 adult male Wistar rats were randomly divided into 4 groups: SCI+hydrogel group (H), SCI+hydrogel + PCL fiber group (HF), SCI group (SCI) and SHAM group (SHAM) and (N=5). SCI contusion injury was induced by a MASCIS Impactor (20g weight, 50cm high) at the T9 level in rats. Hydrogels or PCL fiber were administered into the SCI site one week after surgery. Periodical Basso, Beattie, and Bresnahan (BBB) locomotor score, spinal cord hematoxylin and eosin stain (HE) staining, and immunofluorescence staining were performed 28 days after the operation. HE staining showed that the average cystic cavity area in SCI (20.78 ±2.93 mm2) group was significantly higher than that in H group (6.54 ±0.85 mm2), HF group (5.06 ±0.76 mm2) and SHAM group (1.76 ±0.27 mm2) (P <; 0.001). There was no significant difference in BBB motor score among the HF group (16.80±1.10), SCI (14.20±1.09) and H group (15.00±1.23) (P > 0.05), except the sham group. Immunofluorescence showed higher NeuN positive cells in both the H group and the HF group. This preliminary result may indicate that PCL fiber optimized the strength of hydrogels, thus providing better support for the axon regeneration. Future investigation is needed to further characterize PCL fiber and elucidate related mechanisms.