First prize: ureteral segmental replacement revisited.

BACKGROUND AND PURPOSE: Long strictures of the proximal ureter are difficult to manage, and circumferential replacement with various natural and synthetic materials has been unsuccessful. We sought to use cultured autologous cells seeded onto graft material for proximal-ureteral replacement. Additionally, we wished to determine if urothelial cell-seeded de-epithelialized small bowel would generate adequate ureteral replacement. MATERIALS AND METHODS: Three sets of experiments were performed. First, autologous pig-bladder smooth-muscle and urothelial cells were expanded in culture on large sheets of multilayer small-intestinal submucosa (SIS). These sheets were then tubularized and used to replace a 5-cm segment of proximal ureter in pigs. Second, autologous cells harvested from the bladders of Beagle dogs were cultured and seeded on porcine ureteral acellular matrix, which was used to replace a 3-cm segment of ureter in dogs. Segments were wrapped in omentum to enhance vascularity. Third, a de-epithelialized small-bowel segment seeded with autologous bladder-epithelial cells was transversally retubularized (Monti) into a 4-cm ureteral replacement. Follow-up studies consisted of retrograde pyelography, serum chemistry assays, hematoxylin/eosin studies, and immunohistopathologic examination using antibodies against alpha-smooth-muscle actin and pancytokeratin AE1-AE3. RESULTS: Coculture of urinary-tract cells on large segments of SIS failed to create adequate ureteral replacement. All grafts were contracted and stenotic, with complete obstruction of the ipsilateral renal unit. Similar results were seen in the Beagles. Despite clinical obstruction and gross contraction of the graft, a circumferential muscular ureteral wall lined with multilayer transitional epithelium was present. Urotheliumseeded de-epithelialized Monti bowel segments resulted in patent ureteral replacement without hydroureteronephrosis and with normal renal function, serum electrolytes, and acid-base balance. However, bowel mucosa fully regenerated, with multilayer transitional epithelium growing adluminally in continuity with the proximal and distal anastomotic sites. CONCLUSIONS: Seeding of ureteral grafts with autologous bladder cells does not promote success in two largeanimal models using different xenogenic acellular matrices. However, muscle and urothelium regeneration occurs with ureteral acellular matrix in the dog. Urothelium-seeded de-epithelialized Monti bowel segments may be an acceptable substitute for long proximal ureteral segments. Further technical refinements are required to replace the bowel mucosa completely with normal urothelium.

Peritoneal and systemic inflammatory mediators of laparoscopic bowel injury in a rabbit model.

PURPOSE: Unrecognized bowel injury following laparoscopy has a subtle and delayed clinical presentation compared with that after open surgery. We determined peritoneal and systemic immune function in laparoscopic and open bowel injury cases. We propose that laparoscopy does not activate immune responses to the same extent as open surgery. MATERIALS AND METHODS: A total of 40 rabbits were divided into 4 groups. Two study groups were subjected to laparoscopic and open bowel injury, and 2 control groups underwent pneumoperitoneum and sham open surgery, respectively, without bowel injury. Animals were sacrificed 1 day, 3 days and 1 week postoperatively. Macroscopic and histological findings were analyzed. Peritoneal fluid, systemic white blood count (WBC) and differentials were done with a hemocytometer. Peritoneal fluid and serum interleukin (IL)-8 concentrations were measured by enzyme-linked immunosorbent assay. RESULTS: Macroscopic and histological findings were indistinguishable in the 2 study groups. However, study groups demonstrated higher peritoneal WBCs than their respective controls at 1 and 3 days (p <0.05). Peritoneal WBC was lower in the laparoscopy than in the open study group at 3 days (p <0.05). There was a significant decrease in peritoneal lymphocytes and monocytes in the laparoscopic vs the open study group at 3 days. No differences were found in systemic WBC or differentials among all groups. Peritoneal IL-8 concentrations were higher in the laparoscopic bowel injury than in the laparoscopic control group at 1 and 3 days (p <0.05). However, there were no differences in peritoneal or serum IL-8 concentrations between both study groups. CONCLUSIONS: Laparoscopic surgery seems to be unable to sustain peritoneal immune responses, which may mask reliable clinical signs and symptoms of peritonitis associated with bowel injury.