title: In vitro endothelialization of bioprosthetic heart valves provides a cell monolayer with proliferative capacities and resistance to pulsatile flow.
abstract: OBJECTIVE
  Degeneration of bioprosthetic heart valves has been suggested to be at least partly an immunogenic reaction toward the xenogeneic tissue. An autologous endothelial lining has been proposed to overcome this problem. We examined in vitro endothelialization of such tissue and retention of endothelial cells after exposure to flow resembling the in vivo situation.
  
  
  METHODS
  Cultured human saphenous vein endothelial cells were used to in vitro endothelialize photo-oxidized bioprosthetic heart valves. The endothelialized valves were mounted in a specially designed flow device, creating a pulsatile flow through the valve. Maintenance of a confluent cell layer and deposition of basement membrane markers were determined with immunohistochemical labeling.
  
  
  RESULTS
  Labeling of the main components of the basement membrane, laminin and collagen type IV, was verified within 6 hours after in vitro endothelialization. Under static conditions, 4-mm wide denudations were completely re-endothelialized in 4 days, which was similar to the growth rate on gelatin-coated cell culture plastic, which served as a control material. After exposure of endothelialized valves to pulsatile flows for 24 hours (80 beats/min, 3.4 L/min), there were minimal cell losses from the bioprostheses. The cell layer adapted to the pulsatile flow, as verified by rearrangement of morphology and intracellular stress fibers.
  
  
  CONCLUSIONS
  This study shows the feasibility of in vitro endothelialization of photo-oxidized bioprosthetic heart valves. The cells are able to withstand a pulsatile flow in vitro, to develop basement membrane-like structures, and to re-endothelialize denuded areas. This technology may be used to enhance the performance of bioprosthetic heart valve prostheses.
authors.affiliation: Karolinska Institute, Department of Surgical Sciences, Karolinska Hospital, Stockholm, Sweden. katarina.jansson@kirurgi.ki.se
authors.forename: K
authors.initials: K
authors.lastname: Jansson
authors.forename: L
authors.initials: L
authors.lastname: Bengtsson
authors.forename: J
authors.initials: J
authors.lastname: Swedenborg
authors.forename: A
authors.initials: A
authors.lastname: Haegerstrand
mesh_terms: D001485:Basement Membrane / Q000378:metabolism / Q000648:ultrastructure; D001705:Bioprosthesis; D002455:Cell Division; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D005240:Feasibility Studies; D006350:Heart Valve Prosthesis; D006801:Humans; D007797:Laminin / Q000378:metabolism / Q000648:ultrastructure; D011673:Pulsatile Flow; D012501:Saphenous Vein / Q000166:cytology
chemical_list: D007797:Laminin; D003094:Collagen