title: Structural modification and cryopreservation of porcine heart valves for xenotransplantation with reduced immunity.
abstract: OBJECTIVE
  In order to provide valved xenografts with reduced immunity, yet durability comparable with that of homografts, a method for endothelial cell removal was developed.
  
  
  METHODS
  Adult porcine valved pulmonary conduits were isolated, washed and incubated in trypsin-EDTA solution. The endothelial cells were flushed free with a stream of culture medium, and the xenografts cryopreserved. Grafts were thawed after three months, and evaluated structurally.
  
  
  RESULTS
  Macroscopic inspection of the grafts revealed no cracks or other morphological damage. Light microscopy revealed mildly edematous changes, and the elastic layers appeared to be preserved. Incubation with trypsin-EDTA solution consistently removed the entire endothelial layer, without obvious damage to the underlying tissues.
  
  
  CONCLUSIONS
  With care and appropriate timing, the xenograft endothelium can be selectively removed, leaving the underlying tissue intact. This process may allow further structural manipulations to improve the durability of these grafts.
authors.affiliation: Department of Cardiothoracic Surgery, Rabin Medical Center, Petah-Tikva, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Erez
authors.forename: J
authors.initials: J
authors.lastname: Sandbank
authors.forename: A
authors.initials: A
authors.lastname: Stamler
authors.forename: E
authors.initials: E
authors.lastname: Raanani
authors.forename: E
authors.initials: E
authors.lastname: Sharoni
authors.forename: B A
authors.initials: BA
authors.lastname: Vidne
authors.forename: J
authors.initials: J
authors.lastname: Barak
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D015925:Cryopreservation; D004730:Endothelium, Vascular / Q000276:immunology / Q000473:pathology; D006350:Heart Valve Prosthesis; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D007124:Immunoenzyme Techniques; D011474:Prosthesis Design; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*