title: Integration of collagen matrices into the urethra when implanted as onlay graft.
abstract: OBJECTIVE
  To assess the integration of decellularized heterologous collagen matrices into the urethra, when implanted with no cells or when seeded with autologous smooth muscle cells.
  
  
  METHODS
  Eighteen New Zealand rabbits were randomly assigned to two groups: Group I (n = 9) - animals undergoing urethral segment resection with interposition of a patch of heterologous collagen matrix seeded with autologous smooth muscle cells; Group II (n = 9) - animals undergoing resection of a urethral segment with interposition of a decellularized heterologous collagen matrix patch. Two animals from each group were sacrificed on postoperative days seven, fourteen and twenty-eight; three animals from each group were sacrificed at the end of three postoperative months. At the end of the third month one animal from each group underwent urethroscopy for urethral integrity assessment and one animal from each group had its microcirculation image captured by a SDF device (Side-stream Dark Field - Microscan Analysis Software). One animal from each group in each euthanasia period underwent cystourethrography so as the urethra could be viewed at flow time. The matrices integration was assessed through histological examination using hematoxylin and eosin (H & E), Masson trichrome (MT), Picrosirius red and Von Willebrand staining. In a blind study with two pathologists all the slides were studied.
  
  
  RESULTS
  The matrices whether seeded or not with autologous muscle cells were able to restore the architecture of the urethra, but were eliminated from the first week on, before incorporation. Microcirculation of the neourethra, at the end of the third month, showed the same characteristics as a normal urethra in both groups of animals.
  
  
  CONCLUSIONS
  Natural heterologous matrices implanted in the urethra as onlay graft were not incorporated into its walls but were able to fully restore the cell architecture of the organ, regardless of being seeded or not with autologous muscle cells.
authors.affiliation: Department of Surgery, Federal University of Sao Paulo, Brazil.
authors.forename: Kleber
authors.initials: K
authors.lastname: Sayeg
authors.forename: Luiz G
authors.initials: LG
authors.lastname: Freitas-Filho
authors.forename: Ângela Flávia Logullo
authors.initials: ÂF
authors.lastname: Waitzberg
authors.forename: Victor Eduardo Arrua
authors.initials: VE
authors.lastname: Arias
authors.forename: Marcus
authors.initials: M
authors.lastname: Laks
authors.forename: Fernanda Mattos
authors.initials: FM
authors.lastname: Egydio
authors.forename: Andréia Silva
authors.initials: AS
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism / Q000627:therapeutic use*; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000637:transplantation*; D011184:Postoperative Period; D011817:Rabbits; D011897:Random Allocation; D015203:Reproducibility of Results; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods; D014182:Transplantation, Autologous / Q000379:methods*; D016896:Treatment Outcome; D014521:Urethra / Q000473:pathology
chemical_list: D003094:Collagen