title: Regulation of cell-mediated collagen gel contraction in human retinal pigment epithelium cells by vascular endothelial growth factor compared with transforming growth factor-β2.
abstract: BACKGROUND
  To explore the potential role of vascular endothelial growth factor compared with transforming growth factor-β2 in the regulation of human retinal pigment epithelium cell-mediated collagen gel contraction.
  
  
  METHODS
  The retinal pigment epithelium cell mediated type I collagen gel contraction assay was performed to evaluate and compare the effect of vascular endothelial growth factor and transforming growth factor-β2. The number of viable retinal pigment epithelium cells in the gel and the expression of α-smooth muscle actin were analysed.
  
  
  RESULTS
  Both vascular endothelial growth factor and transforming growth factor-β2 caused a time dependent gel contraction, associated with over expression of α-smooth muscle actin in retinal pigment epithelium cells undergoing a fibroblast like transformation. The decrease in volume of the collagen gel and increase in α-smooth muscle actin expression were more significant in the transforming growth factor-β2-treated group than in vascular endothelial growth factor-treated group beginning at day 2, and the growth of retinal pigment epithelium cells was significantly more inhibited in the transforming growth factor-β2-treated group compared with the vascular endothelial growth factor-treated group after day 1 (P < 0.05). Transforming growth factor-β2 stimulation increased both vascular endothelial growth factor mRNA expression and secretion. The α-smooth muscle actin expression and the change in volume of collagen gel were significantly positively correlated in both experimental groups.
  
  
  CONCLUSIONS
  Both vascular endothelial growth factor and transforming growth factor-β2 can cause induction of retinal pigment epithelium cell-mediated collagen gel contraction in vitro via partial upregulation of α-smooth muscle actin expression.
authors.affiliation: Eye Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. zj2majin@yahoo.com.cn
authors.forename: Jin
authors.initials: J
authors.lastname: Ma
authors.forename: Qianru
authors.initials: Q
authors.lastname: Zhang
authors.forename: Morten C
authors.initials: MC
authors.lastname: Moe
authors.forename: Tiepei
authors.initials: T
authors.lastname: Zhu
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002452:Cell Count; D002469:Cell Separation; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D053781:Transforming Growth Factor beta2 / Q000235:genetics / Q000494:pharmacology*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000494:pharmacology*
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D024042:Collagen Type I; D012333:RNA, Messenger; D053781:Transforming Growth Factor beta2; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A