title: Mesenchymal stem cell-mediated suppression of hypertrophic scarring is p53 dependent in a rabbit ear model.
abstract: BACKGROUND
  Mesenchymal stem cells (MSCs) are considered to play important roles in wound repair and tissue remodeling. Hypertrophic scar (HTS) is a cutaneous condition characterized by deposits of excessive amount of collagen after an acute skin injury. However, currently there is little knowledge about the direct relationship between MSCs and HTS.
  
  
  METHODS
  The hypertrophic scar model was established on rabbit ears. MSCs were isolated from rabbit femur bone marrow and transplanted through ear artery injection. Hypertrophic scar formation was examined using frozen-section analysis, hematoxylin and eosin (HE) staining, Masson's trichrome staining, and scar elevation index. The role of p53 in the MSCs-mediated anti-scarring effect was examined by gene knockdown using p53 shRNA.
  
  
  RESULTS
  In this study, MSCs engraftment through ear artery injection significantly inhibited the hypertrophic scarring in a rabbit ear hypertrophic scar model, while this anti-scarring function could be abrogated by p53 gene knockdown in MSCs. Additionally, we found that MSCs down-regulated the expression of TGF-β receptor I (TβRI) and alpha-smooth muscle actin (α-SMA) at both mRNA and protein levels in a paracrine manner, and this down-regulation was rescued by p53 gene knockdown. Moreover, our results showed that MSCs with p53 gene knockdown promoted the proliferation of fibroblasts through increasing nitric oxide (NO) production.
  
  
  CONCLUSIONS
  These results suggest that MSCs inhibit the formation of HTS in a p53 dependent manner through at least two mechanisms: inhibition of the transformation of HTS fibroblast to myofibroblast; and inhibition of the proliferation of fibroblasts through inhibition of NO production.
authors.forename: Yi-Lun
authors.initials: YL
authors.lastname: Liu
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Liu
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.forename: Tuan-Jie
authors.initials: TJ
authors.lastname: Hou
authors.forename: Yue-Ming
authors.initials: YM
authors.lastname: Liu
authors.forename: Hai-Rong
authors.initials: HR
authors.lastname: Liu
authors.forename: Yong-Hui
authors.initials: YH
authors.lastname: Luo
authors.forename: Ning-Ning
authors.initials: NN
authors.lastname: Zhao
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.forename: Feng-Mei
authors.initials: FM
authors.lastname: Deng
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002921:Cicatrix / Q000628:therapy*; D004423:Ear / Q000293:injuries*; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D011817:Rabbits; D012867:Skin / Q000293:injuries; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53