title: Newly developed tissue-engineered material for reconstruction of vascular wall without cell seeding.
abstract: BACKGROUND
  We have developed a tissue-engineered patch for cardiovascular repair. Tissue-engineered patches facilitated site-specific in situ recellularization and required no pretreatment with cell seeding. This study evaluated the patches implanted into canine pulmonary arteries.
  
  
  METHODS
  Tissue-engineered patches are biodegradable sheets woven with double-layer fibers. The fiber is composed of polyglycolic acid and poly-L-lactic acid, and compounding collagen microsponges. The patches (20- x 25-mm) were implanted into the canine pulmonary arterial trunks. At 1, 2, and 6 months after implantation (n = 4), they were explanted and characterized by histologic and biochemical analyses. Commercially available patches served as the control. No anticoagulant therapy was administered postoperatively.
  
  
  RESULTS
  No aneurysm or thrombus was present within the patch area in all groups. The remodeled tissue predominantly consisted of elastic and collagen fibers, and the endoluminal surface was covered with a monolayer of endothelial cells and multilayers of smooth muscle cells beneath the endothelial layer. The elastic and collagen fibers and smooth muscle cells kept increasing with a maximum at 6 months, while a monolayer of endothelial cells was preserved. The expression levels of messenger RNA of several growth factors in the tissue-engineered patches were higher than those of native tissue at 1 and 2 months and decreased to normal level at 6 months. No regenerated tissue was found on the endoluminal surface in the control group.
  
  
  CONCLUSIONS
  The novel tissue-engineered patches showed in situ repopulation of host cells without prior ex vivo cell seeding. This is promising material for repair of the cardiovascular system.
authors.affiliation: Department of Surgery, Division of Cardiovascular Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Takenori
authors.initials: T
authors.lastname: Yokota
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Uchimura
authors.forename: Shigeru
authors.initials: S
authors.lastname: Miyagawa
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Ota
authors.forename: Kei
authors.initials: K
authors.lastname: Torikai
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Saito
authors.forename: Koichiro
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Katsukiyo
authors.initials: K
authors.lastname: Kitabayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Okada
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Sawa
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Okita
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001807:Blood Vessel Prosthesis / Q000639:trends*; D004195:Disease Models, Animal; D004285:Dogs; D005500:Follow-Up Studies; D007150:Immunohistochemistry; D008855:Microscopy, Electron, Scanning; D009131:Muscle, Smooth, Vascular / Q000648:ultrastructure*; D011474:Prosthesis Design; D011651:Pulmonary Artery / Q000601:surgery* / Q000648:ultrastructure; D013718:Tensile Strength; D023822:Tissue Engineering / Q000639:trends*