title: Fibrin induction of thrombospondin in corneal endothelial cells in vitro.
abstract: OBJECTIVE
  Fibrin deposition in the anterior chamber of the eye occurs in response to injury or inflammation and can permanently damage the corneal endothelium. Fibrin functions as a mediator of inflammation and wound healing by affecting cell morphology and function in a variety of cells, including corneal endothelial cells. We hypothesized that fibrin can directly induce corneal endothelial cells to express injury-related proteins (eg, thrombospondin [TSP]) necessary for corneal repair processes.
  
  
  METHODS
  Bovine corneal endothelial cells (BCECs) were pulse- or continuously labeled with 35S-methionine in the presence or absence of in situ polymerized fibrin (2 mg/ml). BCECs were harvested after 3-48 hr, and 35S-labeled proteins were analyzed by SDS-PAGE, autoradiography, and immunochemical techniques.
  
  
  RESULTS
  Fibrin selectively induced BCECs to express a high molecular weight (MW) protein that was present extracellularly in conditioned medium and fibrin matrix. This induction represented a 3-5 fold increase relative to nonfibrin-treated BCECs, was not accompanied by corresponding changes in 35S-labeled intracellular proteins, and was evident at early (3 hr) or late times (24 hr) post-fibrin treatment. The induced protein had an apparent MW of 180 kD (reduced) and > 420 kD (nonreduced), consistent with the characteristics of TSP. A polyclonal antibody to human TSP recognized the reduced form (180 kD) on Western blots and the native form (> 420 kD) in immunoprecipitation studies.
  
  
  CONCLUSIONS
  Fibrin induces BCECs to express TSP, a matrix protein involved in cell-cell and cell-matrix interactions and implicated in wound healing.
authors.affiliation: Department of Pathology, University of Connecticut Health Center, Farmington 06030.
authors.forename: M L
authors.initials: ML
authors.lastname: Ramsby
authors.forename: D L
authors.initials: DL
authors.lastname: Kreutzer
mesh_terms: D000818:Animals; D001345:Autoradiography; D015153:Blotting, Western; D002417:Cattle; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004728:Endothelium, Corneal / Q000187:drug effects / Q000378:metabolism*; D005136:Eye Proteins / Q000378:metabolism; D005337:Fibrin / Q000494:pharmacology*; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis*; D011233:Precipitin Tests; D013462:Sulfur Radioisotopes; D019699:Thrombospondins
chemical_list: D015815:Cell Adhesion Molecules; D005136:Eye Proteins; D010980:Platelet Membrane Glycoproteins; D013462:Sulfur Radioisotopes; D019699:Thrombospondins; D005337:Fibrin; D008715:Methionine