Epidural Fat Tissue Is More Effective for Scar Prevention Than Conventional Subcutaneous Fat Grafting After Laminectomy in a Mouse Model

Study Design.Basic science study.Objective.The aim of this study was to examine whether epidural fat tissue (EFT) transplantation can prevent epidural adhesion after laminectomy more efficiently than subcutaneous fat tissue (SFT) transplantation.Summary of Background Data.Epidural adhesion is almost inevitable after laminectomy. Although many materials have been used to prevent adhesion, none has been widely accepted. As EFT is an ectopic fat tissue located on the dura mater and there is no adhesion between EFT and the dura mater, we focused on the efficacy of EFT for adhesion prevention.Methods.We examined the differences in histology and gene expression between EFT and SFT of mice. We performed laminectomy at the 10th thoracic level and immediately transplanted EFT or SFT to the dura mater in mice. At 6weeks after transplantation, we performed histological and gene expression analyses and evaluated the adhesion tenacity. In addition, we examined the characteristic differences between human EFT and SFT.Results.The adipocytes of EFT were significantly smaller than those of SFT in mice and humans. The gene expression of inflammatory cytokine and fibrosis-related factors was significantly higher in SFT than in EFT. At 6weeks after transplantation, the percentage of the remaining fat area over the dura mater was significantly greater in the EFT group than in SFT group, and the adhesion tenacity score was significantly lower in the EFT group than that in the SFT group. An RNA sequencing analysis revealed 1921 differentially expressed genes (DEGs) between human EFT and SFT, and a Gene Ontology term associated with the inflammatory response was most highly enriched in SFT.Conclusion.EFT has different molecular and histological profiles from SFT and EFT grafting is more effective for epidural adhesion prevention than conventional SFT transplantation after laminectomy in a mouse model.