title: Gracilis muscle flap with a tissue-engineered lining for experimental bladder wall reconstruction.
abstract: OBJECTIVE
  To assess a pedicled gracilis muscle flap pre-laminated with autologous, in vitro-expanded urothelial cells to reconstruct an entire supratrigonal bladder-wall defect in rats.
  
  
  METHODS
  A gracilis muscle flap was harvested from 36 male Wistar rats, transposed into the abdomen and wrapped around a silicon-block space holder. Urothelial cells were harvested and expanded ex vivo. Cells were then suspended in fibrin glue and seeded into the gracilis muscle pocket. One week later this pre-laminated flap was transposed into a surgically created supratrigonal bladder-wall defect. All animals underwent such a pre-laminated gracilis flap bladder reconstruction and were categorized into three experimental groups. All surviving animals with urothelial-culture pre-laminated gracilis flap bladder reconstruction were killed 12 weeks (group 1) later. Control rats had gracilis flaps with no cell seeding and treated only with fibrin glue (group 2) or a standard culture medium (group 3) before reconstruction.
  
  
  RESULTS
  Specimens stained with haematoxylin and eosin, and a specific immunohistochemical staining (AE1 and AE3-anti-cytokeratin monoclonal antibody stain) showed a continuous, multilayered functioning urothelial lining along the transposed pre-laminated gracilis flap in group 1. All animals in group 1 with an intact urothelial lining on the gracilis muscle survived, in contrast to most animals in groups 2 and 3, where eight and all 12 animals died, respectively. The surviving four animals in group 2 had no detectable urothelial lining. CONCLUSION Successful urinary reconstruction requires a contractile neo-reservoir resistant to resorption over time and a stable, protective urothelial lining. A gracilis muscle flap can be seeded with autologous cultured urothelial cells suspended in fibrin glue. This pre-laminated flap can be safely transposed on its pedicle and be successfully integrated into the remaining bladder wall, with a urothelial lining and the potential to contract. Further studies in larger animals, with a urodynamic assessment, are warranted to determine if this type of bladder-wall replacement technique is suitable for urinary reconstruction in humans.
authors.affiliation: Department of Plastic and Reconstructive Surgery, University Hospital Innsbruck, Leopold-Franzens University, the Ludwig Boltzmann Institute for Quality Control in Plastic Surgery, Innsbruck, Austria. thomas.schoeller@uibk.ac.at
authors.forename: T
authors.initials: T
authors.lastname: Schoeller
authors.forename: S
authors.initials: S
authors.lastname: Lille
authors.forename: T
authors.initials: T
authors.lastname: Bauer
authors.forename: H
authors.initials: H
authors.lastname: Piza-Katzer
authors.forename: G
authors.initials: G
authors.lastname: Wechselberger
mesh_terms: D000818:Animals; D001698:Biomedical Engineering; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013524:Surgical Flaps; D001743:Urinary Bladder / Q000601:surgery*; D001745:Urinary Bladder Diseases / Q000473:pathology / Q000601:surgery*