title: Cell-seeded tubularized scaffolds for reconstruction of long urethral defects: a preclinical study.
abstract: BACKGROUND
  The treatment options for patients requiring repair of a long segment of the urethra are limited by the availability of autologous tissues. We previously reported that acellular collagen-based tubularized constructs seeded with cells are able to repair small urethral defects in a rabbit model.
  
  
  OBJECTIVE
  We explored the feasibility of engineering clinically relevant long urethras for surgical reconstruction in a canine preclinical model.
  
  
  METHODS
  Autologous bladder epithelial and smooth muscle cells from 15 male dogs were grown and seeded onto preconfigured collagen-based tubular matrices (6 cm in length). The perineal urethral segment was removed in 21 male dogs. Urethroplasties were performed with tubularized collagen scaffolds seeded with cells in 15 animals. Tubularized constructs without cells were implanted in six animals. Serial urethrography and three-dimensional computed tomography (CT) scans were performed pre- and postoperatively at 1, 3, 6, and 12 mo. The animals were euthanized at their predetermined time points (three animals at 1 mo, and four at 3, 6, and 12 mo) for analyses.
  
  
  METHODS
  Statistical analysis of CT imaging and histology was not needed.
  
  
  CONCLUSIONS
  CT urethrograms showed wide-caliber urethras without strictures in animals implanted with cell-seeded matrices. The urethral segments replaced with acellular scaffolds collapsed. Gross examination of the urethral implants seeded with cells showed normal-appearing tissue without evidence of fibrosis. Histologically, an epithelial cell layer surrounded by muscle fiber bundles was observed on the cell-seeded constructs, and cellular organization increased over time. The epithelial and smooth muscle phenotypes were confirmed using antibodies to pancytokeratins AE1/AE3 and smooth muscle-specific desmin. Formation of an epithelial cell layer occurred in the unseeded constructs, but few muscle fibers formed.
  
  
  CONCLUSIONS
  Cell-seeded tubularized collagen scaffolds can be used to repair long urethral defects, whereas scaffolds without cells lead to poor tissue development and strictures. This study demonstrates that long tissue-engineered tubularized urethral segments may be used for urethroplasty in patients.
authors.affiliation: Department of Urology and Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, NC 27157, USA.
authors.forename: Hazem
authors.initials: H
authors.lastname: Orabi
authors.forename: Tamer
authors.initials: T
authors.lastname: AbouShwareb
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: James J
authors.initials: JJ
authors.lastname: Yoo
authors.forename: Anthony
authors.initials: A
authors.lastname: Atala
mesh_terms: D000818:Animals; D017690:Cell Transplantation / Q000379:methods*; D003094:Collagen / Q000494:pharmacology; D004285:Dogs; D008297:Male; D023421:Models, Animal; D009130:Muscle, Smooth / Q000166:cytology / Q000601:surgery; D019651:Plastic Surgery Procedures / Q000379:methods*; D023822:Tissue Engineering / Q000379:methods; D054457:Tissue Scaffolds; D014057:Tomography, X-Ray Computed; D014182:Transplantation, Autologous; D014521:Urethra / Q000166:cytology* / Q000000981:diagnostic imaging / Q000601:surgery*; D014525:Urethral Stricture / Q000601:surgery; D001743:Urinary Bladder / Q000166:cytology / Q000601:surgery; D013521:Urologic Surgical Procedures, Male / Q000379:methods*; D019459:Urothelium / Q000166:cytology / Q000601:surgery
chemical_list: D003094:Collagen