title: A tissue engineered heart valve implanted in a juvenile sheep model.
abstract: BACKGROUND
  The tissue-engineered (TE) heart valve was developed to improve the durability of tissue heart valves. The aim of this study was to evaluate morphological and histological changes in a TE heart valve consisting of decellularized porcine matrices seeded with viable autologous vascular endothelial cells (AVEC).
  
  
  METHODS
  TE valves were implanted into the right ventricular outflow tract of eight juvenile sheep and explanted after 7 days, 3 and 6 months. The valves were evaluated visually, by invasive pressure measurements, X-ray, light microscopy, scanning, and transmission electron microscopy. The calcium content of the cusps was determined quantitatively by atomic absorption spectrometry.
  
  
  RESULTS
  After valve implantation, all animals showed fast recovery with no complications during the observation period. Invasive pressure measurements presented a mean TE valve pressure gradient of 1.5+/-0.5 mm Hg at 3 and the same at 6 months. Light microscopy showed a monolayer of AVEC on all explanted heart valves, confirmed by scanning electron microscopy and immunohistochemical staining. X-ray examination of explanted TE heart valves showed no cusp calcification, confirmed by atomic absorption spectrometry.
  
  
  CONCLUSIONS
  All explanted TE heart valves showed AVEC at the inner surface and ingrowth of fibroblast into the decellularized matrix, increasing during the observation period. The calcium contents were very low at explantation in these viable new heart valves.
authors.affiliation: Department of Cardiovascular Surgery, Charit , Humboldt University Berlin, Berlin, Germany. pascal.dohmen@charite.de
authors.forename: Pascal M
authors.initials: PM
authors.lastname: Dohmen
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Ozaki
authors.forename: Robert
authors.initials: R
authors.lastname: Nitsch
authors.forename: Jessa
authors.initials: J
authors.lastname: Yperman
authors.forename: Willem
authors.initials: W
authors.lastname: Flameng
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Konertz
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D002118:Calcium / Q000032:analysis; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000378:metabolism; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D007150:Immunohistochemistry; D023421:Models, Animal; D011664:Pulmonary Valve / Q000601:surgery / Q000648:ultrastructure; D012756:Sheep; D013054:Spectrophotometry, Atomic; D013997:Time Factors; D023822:Tissue Engineering
chemical_list: D002118:Calcium