title: The Role of Insulin-Like Growth Factor Binding Protein 2 (IGFBP2) in the Regulation of Corneal Fibroblast Differentiation.
abstract: OBJECTIVE
  Previously, we reported that keratocyte-conditioned medium (KCM) facilitates the differentiation of human mesenchymal stem cells (hMSCs) into corneal keratocyte-like cells. This study is designed to investigate the roles of insulin-like growth factor binding protein 2 (IGFBP2) for the regulation of corneal fibroblast differentiation as a newly unveiled component of KCM.
  
  
  METHODS
  Immunodot blot analysis was performed to identify the factors that are highly secreted, especially in KCM. Then, we investigated whether IGFBP2 differentiates hMSCs into keratocyte-like cells and whether maintains the phenotypes of keratocyte in human corneal fibroblasts (HCFs) by analyzing expression patterns of alpha-smooth muscle actin (α-SMA) and keratocyte markers including keratocan, lumican and aldehyde dehydrogenase 1 family member A1 (ALDH1A1). Furthermore, to specify the role of IGFBP2, the expression of α-SMA and keratocyte markers was determined in transforming growth factor β 1 (TGFβ1)-induced corneal myofibroblast and in HCFs after knockdown of IGFBP2.
  
  
  RESULTS
  The most prominent factor in both KCM and amniotic membrane extract was IGFBP2. Insulin-like growth factor binding protein 2 increased the expression of IGFBP2, keratocan, and ALDH1A1, and decreased α-SMA expression in hMSCs and HCFs. Insulin-like growth factor binding protein 2 inhibited TGFβ1-induced upregulation of α-SMA and increased expressions of keratocan and ALDH1A1 in HCFs. Furthermore, the knockdown of IGFBP2 increased α-SMA expression and decreased ALDH1A1 level in HCFs.
  
  
  CONCLUSIONS
  Insulin-like growth factor binding protein 2 is strongly associated with restoration of keratocyte phenotype in HCFs. Our results show an important novel role of IGFBP2 in regulation of corneal fibroblast differentiation and suggest that IGFBP2 can be a therapeutic candidate for corneal antifibrotic strategy.
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Kyoung Woo
authors.initials: KW
authors.lastname: Kim
authors.forename: Jae Chan
authors.initials: JC
authors.lastname: Kim
mesh_terms: D015153:Blotting, Western; D002454:Cell Differentiation; D002478:Cells, Cultured; D003315:Cornea / Q000166:cytology / Q000378:metabolism*; D060527:Corneal Keratocytes / Q000166:cytology / Q000378:metabolism*; D004247:DNA / Q000235:genetics*; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018971:Insulin-Like Growth Factor Binding Protein 2; D004247:DNA