Retinal pigment epithelial cells secrete urokinase-type plasminogen activator and its inhibitor PAI-1

Ophthalmic Res. 1992;24(4):203-12. doi: 10.1159/000267169.


Secretion of plasminogen activators and their inhibitors was examined in cultures of human retinal pigment epithelial (RPE) cells. The methods employed were zymography and reverse zymography, solid-phase immunocapture assay, metabolic labeling followed by immunoprecipitation, and immunofluorescence. The results showed that these cells produce urokinase-type plasminogen activator (u-PA) and a plasminogen activator inhibitor (PAI) which is immunologically and biochemically similar to PAI-1. Tissue-type plasminogen activator activity (t-PA) was not detected, but we detected small amounts of t-PA in an inactive complex with inhibitor in RPE cell-conditioned media. We conclude that RPE cells have the potential to utilize u-PA-catalyzed plasminogen activation which is subject to regulation by PAI-1. These results may have a bearing on the pathogenesis of proliferative retinal diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal
  • Cells, Cultured
  • Culture Media
  • Electrophoresis, Polyacrylamide Gel
  • Fluorescent Antibody Technique
  • Humans
  • Immunoenzyme Techniques
  • Pigment Epithelium of Eye / cytology
  • Pigment Epithelium of Eye / metabolism*
  • Plasminogen Activator Inhibitor 1 / metabolism*
  • Tissue Plasminogen Activator / analysis
  • Urokinase-Type Plasminogen Activator / metabolism*


  • Antibodies, Monoclonal
  • Culture Media
  • Plasminogen Activator Inhibitor 1
  • Tissue Plasminogen Activator
  • Urokinase-Type Plasminogen Activator