title: Challenges in a larger bladder replacement with cell-seeded and unseeded small intestinal submucosa grafts in a subtotal cystectomy model.
abstract: OBJECTIVE
  To evaluate small intestinal submucosa (SIS), unseeded or seeded, as a possible augmentation material in a canine model of subtotal cystectomy.
  
  
  METHODS
  In all, 22 male dogs had a 90% partial cystectomy and were then divided into three groups. At 1 month after the initial cystectomy, dogs in group 1 (unseeded, six) and group 2 (seeded, six) received a bladder augmentation with a corresponding SIS graft. The dogs in group 3 (ten) received no further surgery and were considered the surgical control group. All dogs were evaluated before and after surgery with blood chemistry, urine culture, intravenous urography, cystograms and cystometrograms. After surgery (at 1, 5 and 9 months), the bladders were examined using routine histology and immunohistochemistry.
  
  
  RESULTS
  All 22 dogs survived the subtotal cystectomy, and 18 survived their intended survival period. One dog, in group 2 (seeded), was killed at 1 month after augmentation due to bladder perforation caused by a large piece of incompletely absorbed SIS. Three other dogs (group 1, two; and group 2, one) were killed within 2 months after augmentation due to bladder obstruction by stones. Group 1 and group 2 SIS grafts had moderate to heavy adhesion, graft shrinkage, and some had bone and calcification at the graft site. Histologically, there was limited bladder regeneration in both groups. Interestingly, dogs in group 3 at 1 month after cystectomy (when group 1 and 2 received their augmentations) had severely shrunken bladders and histologically had severe inflammation, fibroblast infiltration and muscle hypertrophy. These results verify the subtotal cystectomy model.
  
  
  CONCLUSIONS
  The use of seeded or unseeded SIS in a subtotal cystectomy model does not induce the same quality and quantity of bladder regeneration that is seen in the 40% non-inflammatory cystectomy model. This study provides important insights into the process of regeneration in a severely damaged bladder. The results led us to re-evaluate the critical elements required for a complete bladder replacement using tissue-engineering techniques.
authors.affiliation: Institute for Regenerative Medicine, Wake Forest University Health Science, Winston-Salem, NC, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Dominic
authors.initials: D
authors.lastname: Frimberger
authors.forename: Earl Y
authors.initials: EY
authors.lastname: Cheng
authors.forename: Hsueh-Kung
authors.initials: HK
authors.lastname: Lin
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Kropp
mesh_terms: D000818:Animals; D015653:Cystectomy / Q000379:methods*; D004285:Dogs; D007413:Intestinal Mucosa / Q000637:transplantation*; D007421:Intestine, Small / Q000637:transplantation*; D018919:Neovascularization, Physiologic; D012038:Regeneration / Q000502:physiology*; D023822:Tissue Engineering; D016896:Treatment Outcome; D001743:Urinary Bladder / Q000166:cytology / Q000502:physiology*