Immunomodulatory effectiveness of tacrolimus in preventing epidural scar adhesion after laminectomy in rat model.

There was no previous study about topical application of tacrolimus (FK506) could inhibit fibroblast proliferation and prevent epidural scar adhesion after laminectomy. We intended to illustrate the effect of FK506 on inhibiting fibroblast proliferation and preventing epidural scar adhesion after laminectomy in rat model. In our study, seventy-two rats were randomly divided into four groups (0.1mg/ml group, 0.05 mg/ml group, 0.01 mg/ml group and control group). Laminectomy was performed at Lumbar-1 level, and then different concentrations of FK506 and saline were applied to the laminectomy sites. Four weeks later the rats were killed and the epidural adhesion was evaluated. Macroscopic assessment, hydroxyproline content analysis, histological analysis and mRNA measurements were used to evaluate the effect of FK506 on reducing epidural scar adhesion. The results showed that FK506 could prevent epidural scar adhesion in a dose-dependent manner. Little epidural adhesions were seen in the laminectomy sites treated with 0.1mg/ml FK506. The hydroxyproline content, the number of fibroblasts, the mRNA expression level of IL-2 and TGF-β1 in 0.1mg/ml FK506 group were significantly less than those of 0.05 mg/ml FK506 group, 0.01 mg/ml FK506 group and control group. However, dense epidural adhesions were found in 0.01 mg/ml FK506 group and control group. The hydroxyproline content and the number of fibroblasts in 0.01 mg/ml group showed no significant difference compared with those of control group. In conclusion, topical application of 0.1mg/ml FK506 could inhibit fibroblast proliferation and prevent epidural scar adhesion after laminectomy in rat model.