title: Age-related changes in aortic valve hemostatic protein regulation.
abstract: OBJECTIVE
  Although valvular endothelial cells have unique responses compared with vascular endothelial cells, valvular regulation of hemostasis is not well-understood. Heart valves remodel throughout a person's lifetime, resulting in changes in extracellular matrix composition and tissue mechanical properties that may affect valvular endothelial cell hemostatic function. This work assessed valvular endothelial cell regulation of hemostasis in situ and in vitro as a function of specimen age.
  
  
  RESULTS
  Porcine aortic valves were assigned to 1 of 3 age groups: Young (YNG) (6 weeks); Adult (ADT) (6 months); or Elderly (OLD) (2 years). Histological examination of valves showed that secreted thrombotic/antithrombotic proteins localize at the valve endothelium and tissue interior. Gene expression and immunostains for von Willebrand factor (VWF), tissue factor pathway inhibitor, and tissue plasminogen activator in YNG porcine aortic valve endothelial cells were higher than they were for OLD, whereas plasminogen activator inhibitor 1 levels in OLD were higher than those for YNG and ADT. Histamine-stimulated YNG porcine aortic valve endothelial cells released higher concentrations of VWF proteins than OLD, and the fractions of VWF-140 fragments was not different between age groups. A calcific aortic valve disease in vitro model using valvular interstitial cells confirmed that VWF in culture significantly increased valvular interstitial cell nodule formation and calcification.
  
  
  CONCLUSIONS
  Hemostatic protein regulation in aortic valve tissues and in valvular endothelial cells changes with age. The presence of VWF and other potential hemostatic proteins increase valvular interstitial cell calcification in vitro. Therefore, the increased capacity of elderly valves to sequester the hemostatic proteins, together with age-associated loss of extracellular matrix organization, warrants investigation into potential role of these proteins in the formation of calcific nodules.
authors.affiliation: From the Department of Bioengineering, Rice University, Houston, TX.
authors.forename: Liezl R
authors.initials: LR
authors.lastname: Balaoing
authors.forename: Allison D
authors.initials: AD
authors.lastname: Post
authors.forename: Huiwen
authors.initials: H
authors.lastname: Liu
authors.forename: Kyung Taeck
authors.initials: KT
authors.lastname: Minn
authors.forename: K Jane
authors.initials: KJ
authors.lastname: Grande-Allen
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001021:Aortic Valve / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D001024:Aortic Valve Stenosis / Q000097:blood / Q000473:pathology; D001779:Blood Coagulation Factors / Q000235:genetics / Q000378:metabolism*; D002114:Calcinosis / Q000097:blood / Q000473:pathology; D025901:Carboxypeptidase B2 / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation; D006487:Hemostasis / Q000235:genetics; D006632:Histamine / Q000494:pharmacology; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D013552:Swine; D013927:Thrombosis / Q000097:blood / Q000473:pathology; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D001779:Blood Coagulation Factors; D017395:Plasminogen Activator Inhibitor 1; D014841:von Willebrand Factor; D006632:Histamine; D025901:Carboxypeptidase B2; D010959:Tissue Plasminogen Activator
keywords: aging; aortic valve; endothelial cells; hemostasis