title: uPA, tPA and PAI-1 mRNA expression in periretinal membranes.
abstract: OBJECTIVE
  Formation of periretinal membranes occurs in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR) and includes cell migration, proliferation, extracellular matrix formation and tissue contraction, processes in which plasminogen activation (PA) system is involved.
  
  
  METHODS
  Twenty PVR, PDR or pucker membranes were examined to identify the cells with cell specific markers and to detect the expression of urokinase (uPA), tissue-type plasminogen activator (tPA) or plasminogen activator inhibitor-1 (PAI-1) by in situ hybridization and by immunohistochemistry.
  
  
  RESULTS
  In PVR, uPA, tPA and PAI-1 were expressed by retinal pigment epithelial (RPE) cells, macrophages or retinal glial cells. In PDR, PA components were also expressed by endothelial cells. Semiquantitative analysis in in situ hybridization and immunohistochemistry results demonstrated no notable differences in uPA, tPA or PAI-1 expression between PDR and PVR membranes.
  
  
  CONCLUSIONS
  We conclude that local proteolytic activation is involved in extracellular matrix production both in diabetic and non-diabetic membranes.
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland. vappu.siren@helsinki.fi
authors.forename: Vappu
authors.initials: V
authors.lastname: Sirén
authors.forename: Ilkka
authors.initials: I
authors.lastname: Immonen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D002648:Child; D003930:Diabetic Retinopathy / Q000378:metabolism / Q000473:pathology; D004730:Endothelium, Vascular / Q000378:metabolism; D019773:Epiretinal Membrane / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009457:Neuroglia / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000235:genetics*; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics*; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism / Q000473:pathology
chemical_list: D015415:Biomarkers; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator