title: Development of a seeded scaffold in the great omentum: feasibility of an in vivo bioreactor for bladder tissue engineering.
abstract: OBJECTIVE
  Tissue engineering is very promising in bladder reconstruction. However, one of the main problems is to limit the development of ischaemic fibrosis during tissue maturation. We describe a model using the omentum as an in vivo bioreactor for a previously seeded scaffold.
  
  
  METHODS
  Bladder biopsies were taken from five female pigs, from which both urothelial and smooth muscle cells cultures were made. These cultured cells were used to seed a sphere-shaped small intestinal submucosa (SIS) matrix, which was transferred into the omentum after 3 wk of cell growth. The grafts were harvested 3 wk later and histologic, immunohistochemical, and functional studies were performed.
  
  
  RESULTS
  We obtained a highly vascularized tissue-engineered construct that contracted in response to acetylcholine stimulation. The wall thickness was 4mm, on average. Histologic and immunostaining analysis of the construct confirmed the presence of a multilayer urothelium on the luminal aspect and deeper fascicles organised tissue composed of differentiated smooth muscle cells and mature fibroblasts without evidence of inflammation or necrosis. Large- and small-diameter vessels were clearly identified histologically in the tissue obtained.
  
  
  CONCLUSIONS
  The omentum permitted in vivo maturation of seeded scaffolds with the development of a dense vascularisation that is anticipated to prevent fibrosis and loss of contractility. This in vivo maturation into the omentum could be the first step before in situ implantation of the construct.
authors.affiliation: Department of Urology, Paris Saint Joseph Hospital Trust, Paris, France. baumertherve@yahoo.fr
authors.forename: Hervé
authors.initials: H
authors.lastname: Baumert
authors.forename: Pascal
authors.initials: P
authors.lastname: Simon
authors.forename: Mehrak
authors.initials: M
authors.lastname: Hekmati
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Fromont
authors.forename: Maryline
authors.initials: M
authors.lastname: Levy
authors.forename: André
authors.initials: A
authors.lastname: Balaton
authors.forename: Vincent
authors.initials: V
authors.lastname: Molinié
authors.forename: Bernard
authors.initials: B
authors.lastname: Malavaud
mesh_terms: D000818:Animals; D019149:Bioreactors / Q000662:veterinary*; D017690:Cell Transplantation / Q000379:methods; D002478:Cells, Cultured; D005240:Feasibility Studies; D005260:Female; D007150:Immunohistochemistry; D009130:Muscle, Smooth / Q000166:cytology / Q000637:transplantation; D009852:Omentum; D013552:Swine; D023822:Tissue Engineering / Q000295:instrumentation*; D054457:Tissue Scaffolds / Q000662:veterinary*; D001743:Urinary Bladder / Q000166:cytology* / Q000502:physiology / Q000601:surgery; D019459:Urothelium / Q000166:cytology / Q000637:transplantation