Prevention of collagen sponge combined with dexamethasone on subdural scar adhesion after laminectomy in rats

Objective To evaluate the effect of different epidural covering objects and local usage of steroid hormone on scar formation after spinal operation and to explore its mechanism.Methods Wistar rats(80)were randomly divided into four groups:collagen sponge + Dexamethasone(Dex)group,pure collagen sponge group,gelatin sponge group,and control(no epidural covering)group.After anesthesia,incisions were made in the middle of rat back,L1-L5 laminectomy was performed to leave 0.5 cm × 1.5 cm defects on the dura matter.Epidural placement of collagen sponge and Dex(0.1 mL)was given to rats in collagen sponge + Dex group,epidural placement of collagen sponge in pure collagen sponge group,epidural placement of gelatin sponge in gelatin sponge group,and just directed suture in control group.Twelve weeks after operation,we observed the epidural scar formation and the dura adhesion.Application of immunohistochemistry and Western blotting analysis showed the expression of epidural scar and surrounding tissues in TGF-β1 and VEGF,and the differences between gelatin sponge group and control group were compared.Results Through macroscopic and microscopic observation,the epidural scar adhesion of collagen sponge + Dex group and pure collagen sponge group was obviously less than that in gelatin sponge group and the control group;while no significant difference was detected between collagen sponge + Dex group and pure collagen sponge group,and between gelatin sponge group and control group.Immunohistochemistry and Western blotting analysis showed the TGF-β1 and VEGF in epidural scar and surrounding tissues in collagen sponge + Dex group and pure collagen sponge group were significantly less than those of gelatin sponge group and control group;but no significance was detected between collagen sponge + Dex group and pure collagen sponge group and between gelatin sponge group and control group.Conclusion Collagen sponge could significantly reduce the formation of postoperative epidural scar adhesion in rats,while local injection of Dex could not enhance this effect;the local use of gelatin sponge could not reduce the formation of epidural scar adhesion.The expression of TGF-β1 and VEGF in the scar and surrounding tissue is significantly lower in the rats applied with collagen sponge,which should be an important mechanism for its prevention of epidural scars.