title: Local application of rapamycin reduces epidural fibrosis after laminectomy via inhibiting fibroblast proliferation and prompting apoptosis.
abstract: BACKGROUND
  Epidural fibrosis is a common complication after laminectomy. It is associated with intractable lower back pain and additional complications. To date, no study has evaluated whether the local application of rapamycin (RAPA) can inhibit fibroblast proliferation and reduce epidural scar adhesion after laminectomy. The results of the present study showed that the local application of RAPA reduces epidural fibrosis after laminectomy in rats.
  
  
  METHODS
  In this study, 32 male Sprague-Dawley rats were randomly divided into four groups (0.2 mg/ml RAPA-treated group, 0.1 mg/ml RAPA-treated group, 0.05 mg/ml RAPA-treated group and physiological saline group). Laminectomy was performed at the level of lumbar segment 1 to 2, and different concentrations of RAPA or saline were applied to the laminectomy sites for 10 min. Four weeks after laminectomy, the rats were sacrificed, and the degrees of epidural adhesion in each group were evaluated. Macroscopic assessment, analysis of hydroxyproline content, and histological analysis were used to determine the therapeutic effect of the local application of RAPA on the inhibition of fibroblast proliferation and the reduction of epidural fibrosis after laminectomy. Next, we cultured fibroblasts from epidural scar tissues of rats that had undergone laminectomy. Fibroblasts were exposed to the indicated concentrations of RAPA, and western blotting and TUNEL assays were used to assess the effects of RAPA on inhibiting fibroblasts proliferation and promoting fibroblast apoptosis.
  
  
  RESULTS
  The results of macroscopic assessments, analysis of hydroxyproline content, and histological analyses indicated that RAPA significantly inhibited fibroblast proliferation and reduced epidural fibrosis in the treated groups in the rat model. The western blotting results indicated that the expression levels of the pro-apoptotic proteins cleaved-PARP and Bax were up-regulated, whereas those of Bcl-2 were reduced. TUNEL assay indicated that the apoptosis rates of fibroblasts were significantly increased after exposure to the indicated concentrations of RAPA.
  
  
  CONCLUSIONS
  The local application of RAPA reduced epidural fibrosis after laminectomy by inhibiting the proliferation of fibroblasts, stimulating their apoptosis, and decreasing collagen synthesis. This protocol may be used in new clinical treatment strategies to reduce epidural fibrosis after laminectomy.
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Department of Orthopedics, Xiangya Second Hospital, Central South University, Changsha, Hunan, 410012, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Department of Orthopedics, Xiangya Second Hospital, Central South University, Changsha, Hunan, 410012, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China. yanlianqi@126.com.|Department of Orthopedics, Xiangya Second Hospital, Central South University, Changsha, Hunan, 410012, China. yanlianqi@126.com.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China. yanlianqi@126.com.
authors.forename: Lianqi
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China. jingchengwyz@163.com.|Department of Orthopedics, Xiangya Second Hospital, Central South University, Changsha, Hunan, 410012, China. jingchengwyz@163.com.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China. jingchengwyz@163.com.
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Daxin
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Jihang
authors.initials: J
authors.lastname: Dai
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Nantong West Road 98, Yangzhou, Jiangsu, 225001, China.|Orthopedics Institute, Subei People's Hospital of Jiangsu Province, Yangzhou, Jiangsu, 225001, China.
authors.forename: Jun
authors.initials: J
authors.lastname: He
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D002921:Cicatrix / Q000378:metabolism / Q000473:pathology; D004824:Epidural Space / Q000187:drug effects / Q000473:pathology*; D005347:Fibroblasts / Q000187:drug effects*; D005355:Fibrosis / Q000188:drug therapy; D006909:Hydroxyproline / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D020287:In Situ Nick-End Labeling; D007796:Laminectomy; D008297:Male; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D020123:Sirolimus / Q000494:pharmacology*
chemical_list: D007166:Immunosuppressive Agents; D006909:Hydroxyproline; D020123:Sirolimus
keywords: Apoptosis; Epidural fibrosis; Fibroblast; Laminectomy; Proliferation; Rapamycin