Objective To explore the efficacy of postoperative topical preventive application of hydroxyurea (HU) in the rats with laminectomy.

Methods A total of 36 8-week SD rats were selected and randomly divided into group A (controls), group B (15 mg/mL HU) and group C (30 mg/mL HU). A laminectomy model was prepared; after exposing the dura mater, the surgical area was closed layer by layer after flushing with physiological saline in the group A, while in the group B and the group C, different concentrations of HU cotton pads were soaked and placed in the surgical area for 5 minutes before removal, and the surgical area was closed layer by layer. Change in spinal cord scores of rats before and after surgery was observed. At 4 weeks after surgery, the postoperative epidural adhesions were evaluated through macroscopic observation, hematoxylin eosin (HE) staining, fibroblast counting, Sirius red staining and immunohistochemical staining.

Results There was no significant difference in the spinal cord scores of rats before and after surgery among the three groups (P>0.05). Macroscopic observation and HE staining showed that compared with the group A, the degrees of epidural adhesion in the surgical area of rats in the group B and the group C were significantly reduced. Image J was used to count fiber cells in each group, and compared with the group A, the number of fibroblasts in the group B and the group C decreased significantly in a concentration dependent manner (P < 0.001 or P < 0.000 1); compared with the group B, the number of fibroblasts in the group C was significantly lower (P < 0.01). Sirius red staining showed a significant decrease in type Ⅰ collagen fibers expression and a significant increase in type Ⅲ collagen fiber expression in the group B and the group C.

Conclusion Postoperative topical application of HU in the rats with laminectomy can slow down the occurrence of epidural fibrosis.