The effects of GelMA hydrogel on nerve repair and regeneration in mice with spinal cord injury

BACKGROUND: To determine the effects of gelatin methacryloyl (GelMA) hydrogel on nerve repair and regeneration in mice with spinal cord injury (SCI). METHODS: A total of 30 ICR mice (6–8 weeks old) were randomly assigned into the control group, the model group, and the experimental group via the random digits table method. There were 10 mice in each group. All mice underwent a T8 laminectomy. For mice in the experimental group and the model group, after the T8 laminectomy, SCI models were constructed by clamping the mice spinal cord tissue for 1 minute using an aneurysm clip (25 g). Additionally, the SCI area of each mouse in the experimental group was locally injected with 0.05–0.7 mL GelMA hydrogel [10% (w/v)] and photocrosslinking was initiated under a blue light source with a wavelength of 405 nm. The exercise performance of each mouse was tested via the bedside mobility scale (BMS) on post-operative days 1, 3, 7, and 14. After 14 days, mice were sacrificed and the dorsal root ganglion (DRG) sensory neurons were isolated and cultured for 3 days in vitro. The axon lengths of the neurons were then evaluated. Immunohistochemical staining was performed to assess the development of syringomyelia in the area. Western blots (WB) and immunofluorescence staining were performed to quantify the expression of glial fibrillary acidic protein (GFAP), growth associated protein (GAP)43, and nestin in the DRG neurons from each group of mice. RESULTS: Compared with mice in the control group, mice in the SCI model group showed a notable decrease in exercise ability, while the exercise ability of mice in the experimental group recovered markedly after treatment with GelMA hydrogel. Administration of GelMA hydrogel lengthened the axon of DRG neurons in mice and reduced the area of syringomyelia. Furthermore, GelMA hydrogel inhibited scar formation and promoted the recovery of neurological function by upregulating GAP43 and nestin expression and downregulating GFAP expression. CONCLUSIONS: In mice with SCI, local injection of GelMA hydrogel strongly inhibited scar formation, reduced the area of syringomyelia, and promoted nerve regeneration and recovery of limb movement function.