title: Implantation of amniotic membrane as a vascular substitute in the external jugular vein of juvenile sheep.
abstract: OBJECTIVE
  Amniotic membrane, as a natural biomaterial, has many advantages, such as low immunogenicity, anti-inflammation, antifibrosis, and rich extracellular matrix components, which make it a promising source for vascular tissue engineering. This study assessed the feasibility of constructing a vein conduit from the amniotic membrane and implanting it in the external jugular vein of juvenile sheep.
  
  
  METHODS
  Human amniotic membrane was prepared using fresh human placenta. For construction of a tube such as a vein, the membrane was rolled around a tube and amniotic membrane-constructed conduits were interposed to the external jugular vein by end-to-end anastomosis. Grafts were assessed for patency at weeks 5 and 48 and explanted for evaluation with histologic and microscopic techniques.
  
  
  RESULTS
  At 5 weeks after implantation, the grafts were completely patent and displayed no signs of dilation. The internal surface was smooth and shiny, without any evidence of thrombus formation. After 48 weeks, grafts were still completely patent and displayed no signs of intimal thickening, dilation, or stenosis. No inflammation or fibrosis was evident. Histologic evaluation of the explanted grafts demonstrated a monolayer of endothelial cells. Scanning electron microscopy revealed a confluent layer of cells with normal endothelial cell morphology. A monolayer of cells positive for von Willebrand factor was detected in histology sections.
  
  
  CONCLUSIONS
  The findings of this study confirm that the amniotic membrane can be a proper substitute for vascular tissue engineering.
authors.affiliation: Nanomedicine and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Habibollah
authors.initials: H
authors.lastname: Peirovi
authors.forename: Navid
authors.initials: N
authors.lastname: Rezvani
authors.forename: Mostafa
authors.initials: M
authors.lastname: Hajinasrollah
authors.forename: Seied Sajjad
authors.initials: SS
authors.lastname: Mohammadi
authors.forename: Hassan
authors.initials: H
authors.lastname: Niknejad
mesh_terms: D000367:Age Factors; D000650:Amnion / Q000637:transplantation*; D000714:Anastomosis, Surgical; D000818:Animals; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation; D005240:Feasibility Studies; D006801:Humans; D007601:Jugular Veins / Q000601:surgery*; D023421:Models, Animal; D012756:Sheep; D014654:Vascular Patency