Histological and bacteriological findings in long-term ileocystoplasty and colocystoplasty in the rat

Ileocystoplasty in rats: metabolic, renal and enteropatch changes in a mid- and long-term follow-up

INTRODUCTION

Bladder augmentation predisposes humans to many metabolic, renal and enteropatch changes. Our aim was to evaluate in a rat model of ileocystoplasty mid- and long-term urinary, metabolic, renal and graft changes.

MATERIALS AND METHODS

We performed an ileocystoplasty and a sham operation in 30 rats. Seven augmented rats and 3 sham-operated animals were euthanized after 1, 3 and 6 months. We performed urinalysis, urine culture and blood sampling for serum electrolytes and urea. Histopathological changes of the ileal patch and kidneys were also evaluated.

RESULTS

The urine cultures were positive in 14.3, 57 and 71%, respectively, 1, 3 and 6 months after surgery. Urinary pH, serum chloride and urea of the augmented group were significantly higher. Bladder calculi were formed in 23.8% of ileocystoplasty. Histopathological examination showed urothelialization of the graft with hyperplastic/metaplastic changes. The kidneys showed glomerular depletion and a marked distal tubular ectasia.

CONCLUSIONS

Our data showed that, in a mid- and long-term follow-up, rat bladders subjected to ileocystoplasty displayed hyperchloremic metabolic acidosis, electrolyte imbalance, enhanced serum blood urea levels and glomerular/tubular changes. Hyperplastic and/or metaplastic changes at the junctional zone were observed. Our experimental results suggest that frequent monitoring of renal function and surveillance of humans who have undergone ileocystoplasty are recommended.

Malignancy associated with the use of intestinal segments in the urinary tract

Use of intestinal segments for urinary tract reconstruction has become widespread. In these patients, urologists are increasingly encountering malignancies that may be a direct result of this altered milieu. This review attempts to summarize the current literature on cancer in patients with intestinal segments in their urinary tracts. Although the exact etiology for this increased risk of malignancy is still unclear, several theories have been proposed. Many investigators now recommend annual screening in patients who have intestinal segments in contact with urine beginning 10 years after the initial surgery.

Long-term outcome of bladder augmentation using living-related partial bladder transplantation in rats

Long-term histopathologic changes after bladder augmentation (BA) in rats using living-related partial bladder transplantation (LPBTx) or conventional ileocystoplasty (ICP) were compared. In this study, BA (n = 37), LPBTx (n = 18), and ICP (n = 19) were performed in 16-wk-old Lewis rats. Five donors and seven nontransplanted normal Lewis rats (controls) were also studied. Rats that survived >10 mo after BA were killed after blood biochemistry and neobladder imaging. Harvested bladders were examined with hematoxylin and eosin and proliferating cell nuclear antigen (PCNA). When the rats were killed, there were 16 rats in the LPBTx group and 12 rats in the ICP group; ICP rats were significantly smaller than LPBTx rats (p < 0.05). Mean duration of follow-up for the LPBTX group was 17.3 mo, for the ICP group was 13.7 mo, for the donor group was 16.1 mo, and for the control group was 19.7 mo. Mean serum pH in the LPBTx group was 7.41 +/- 0.78 and in the ICP group was 7.25 +/- 0.38. Mean base excess in the ICP group was significantly lower than in the LPBTx group (p < 0.05). Incidence of bladder calculi in the LPBTx group (6.3%) was significantly lower than in the ICP group (33.3%; p < 0.05). There was no dysplasia/malignancy/increase in PCNA in the LPBTx group. PCNA increased in the ICP group, compared with controls (p < 0.05); two (16.7%) of 12 of ICP rats had dysplasia with mitosis. Bladder capacity increased in LPBTx and ICP compared with controls (both p < 0.05). We hope to show that BA using LPBTx may result in a neobladder with fewer complications than BA using ICP; LPBTx may also decrease the risk for malignancy.

SECONDARY MALIGNANCIES IN DIFFERENT FORMS OF URINARY DIVERSION USING ISOLATED GUT

PURPOSE

Tumor development following ureterosigmoidostomy is a worldwide accepted late complication. In contrast, tumor risk in other forms of urinary diversion with the separation of urine and feces is still unclear. We present a complete and detailed analysis of all reported tumors following urinary diversions using isolated gut segments in the literature. We estimated the tumor risk in comparison to ureterosigmoidostomies and to the general population.

MATERIALS AND METHODS

We reviewed the world literature up to April 2003 via MEDLINE for secondary tumors in urinary diversions using isolated intestinal segments.

RESULTS

We found 81 tumor case reports following urinary diversion using isolated intestinal segments. Tumors developed in 18 conduits, 45 cystoplasties, 5 rectal bladders, 3 neobladders, 6 colonic pouches and 4 ileal ureter replacements.

CONCLUSIONS

All urinary diversions using bowel with or without separation of urine and feces carry a significantly higher tumor risk for intestinal tumor development compared to the general population. The tumor spectrum and tumor location in isolated gut segments are different than tumors following ureterosigmoidostomies but the total tumor risk is probably similar. The latency period depends on the initial diagnosis with malignant diseases leading to a shorter induction time. Concerning etiology, many theories exist but the exact mechanism remains unclear. Regular endoscopic control beginning with postoperative year 3 for early detection of secondary malignancies is mandatory.

Tumour formation within intestinal segments transposed to the urinary tract

Patients and their urologists are quite rightly concerned about the possibility of neoplastic change within intestinal segments transposed to the lower urinary tract. This fear arises from the occurrence of latent adenocarcinoma arising from the urocolic anastomosis in approximately 10% of patients who underwent ureterosigmoidostomy in childhood. The present text provides an update of previous reviews and details work published since 1990 on epidemiological, experimental and clinical studies. Consideration of the collected evidence confirms the increased risk of colonic neoplasia following mixing of the faecal and urinary stream by ureterosigmoidostomy or its more recent variants. In contrast, the occurrence of tumours within transposed intestinal segments appears more likely to be related to the underlying urinary tract disease for which the surgery was performed rather than exposure of the intestinal mucosa to urine. This conclusion is, however, based on low level evidence and, despite the reassuring findings, caution is advised until more robust data are available to provide a confident risk assessment.

Increased urinary 8-hydroxy-2'-deoxyguanosine excretion after ileal neobladder replacement

OBJECTIVES

To examine whether orthotopic neobladder replacement using either ileum or colon segments results in increased oxidative stress, by measuring urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), one of the most commonly used markers for evaluating oxidative DNA damage.

PATIENTS, SUBJECTS AND METHODS

Urinary levels of 8-OHdG and creatinine, urine analysis, nutritional status, and acid-base and electrolyte balances, were assessed in 22 patients with an ileal neobladder, 28 with a colon neobladder, 37 with an ileal conduit and 22 healthy volunteers. The results from both types of orthotopic neobladder, the ileal conduit and in the healthy controls were compared.

RESULTS

The mean (sd) ratios of urinary 8-OHdG to urinary creatinine in patients with an ileal neobladder, colon neobladder, ileal conduit and in controls were 20.4 (7.8), 15.2 (4.3), 15.9 (5.1) and 15.2 (5.4) ng/mg, respectively. The urinary 8-OHdG ratio in the first group was significantly higher than in the other three groups. Among patients with a neobladder, the urinary 8-OHdG ratio was closely associated with the degree of pyuria, but not age, gender, the interval from surgery, body weight, height, serum creatinine or the degree of metabolic acidosis.

CONCLUSIONS

These findings suggest that creating an ileal neobladder caused significantly greater oxidative stress than a colon neobladder, ileal conduit, or that in healthy controls. Therefore, it is recommended to conduct a careful long-term follow-up considering the possible development of malignant disease after urinary diversion, especially by an ileal neobladder.

Flow cytometry analysis of proliferative lesions at the gastrocystoplasty anastomosis

PURPOSE

Proliferative epithelial metaplasia that develops in the anastomotic line after gastrocystoplasty has unknown malignant potential. Flow cytometry analysis of cell cycle profiles is used to predict the neoplastic progression of metaplastic lesions in other proliferative epithelium. We used this technique to evaluate transitional cell metaplasia in rat gastrocystoplasty specimens.

MATERIALS AND METHODS

A total of 50 prepubescent female Long-Evans rats were randomly assigned to an experimental group (gastrocystoplasty) or a control group (sham operation). At 21 to 27 months (mean 24.9) after operation 12 rats per group survived to sacrifice. Metaplastic lesions were microdissected to yield a minimum of 10(4) cells for DNA flow cytometry and cell cycle analysis. Transitional cell epithelium from sham specimens and gastric epithelium from experimental animals served as controls.

RESULTS

Transitional cell hyperplasia and metaplasia with cyst formation were found in the anastomotic line in all 12 augmented bladders (100%). No proliferative lesions developed in control animals. No nuclear pleomorphism or mitotic changes were identified on routine histological examination. The epithelial cell turnover rate was 10 times higher in the gastrocystoplasty junctional zone than in control bladders (mean 2.2% versus 0.1% S phase) but lower than in native stomach epithelium (mean 3.3% S phase). Of 12 experimental specimens 1 showed near diploid DNA aneuploidy. No DNA abnormalities were detected in control bladder or stomach specimens.

CONCLUSIONS

In this animal model histologically benign appearing proliferative lesions that develop in the anastomotic zone after long-term gastrocystoplasty harbor cell cycle and DNA ploidy abnormalities.

Changes in sodium transport in epithelial cells in a rat ileal-augmented bladder model

OBJECTIVE

To investigate changes in the morphology and sodium transport ability of intestinal epithelium diverted to the urinary tract, using an in vitro sodium-binding benzofuran isophthalate (SBFI) technique, as the effects of long-term urine exposure on the transport of electrolytes through intestine are incompletely understood.

MATERIALS AND METHODS

Ileal augmentation cystoplasty was conducted in female Sprague-Dawley rats; at 3 and 12 months after surgery the serum concentration of sodium, chloride and potassium were measured. Sodium transport in the ileal epithelial cells diverted to the urinary tract was evaluated using SBFI, as the value of the 340/380 nm excitation ratio measured with fluorescence spectrophotometry. The villous height and the number of villi per ileal length were obtained from haematoxylin and eosin-stained sections.

RESULTS

After 3 months the mean (sd) serum sodium concentrations in normal and augmented rats were 140.4 (2.5) and 140.7 (3.5) mmol/L, respectively; the chloride concentration in normal rats was 97.0 (2.9), and in augmented rats at 3 and 12 months it was 102.4 (2.9) and 99.0 (3.7) mmol/L, respectively. At 3 months, chloride concentrations were significantly higher in augmented than in normal rats (P < 0.05). The mean (sd) 340/380 nm ratio increased by 0.85 (0.09) in the normal ileum, and by 0.73 (0.15) and 0.49 (0.23) in the ileum of augmented rats at 3 and 12 months, respectively; the difference between normal and augmented ileum at 12 months was significant (P < 0.05). At 12 months the villous height in the augmented ileum, at 227.6 (16.0) micro m, was significantly less than in the normal ileum, at 803.4 (66.2) micro m (P < 0.05). However, the number of villi/mm ileum in normal and augmented rats at 12 months was 13.7 (1.5) and 15.0 (0.8), respectively, and not significantly different.

CONCLUSION

Sodium transport decreased significantly after long-term exposure to urine; the improvement in metabolic change was probably attributable to alterations of electrolyte transport and atrophic changes of the villus.

Increased serum carcinoembryonic antigen level in patients undergoing colon neobladder replacement compared with ileal neobladder replacement

OBJECTIVES

To compare the serum and urinary carcinoembryonic antigen (CEA) levels for assessment of possible risk of malignant transformation in patients with orthotopic neobladder.

METHODS

The serum and urinary levels of CEA, nutritional status, and acid-base and electrolyte balances were studied in 87 patients after radical cystectomy (22 with ileal neobladder, 28 with colon neobladder, and 37 with ileal conduit). The results of these groups were compared.

RESULTS

The serum CEA level in patients with colon neobladder, ileal neobladder, and ileal conduit was 5.4 +/- 3.0, 3.7 +/- 1.6, and 3.1 +/- 1.5 ng/mL, respectively. The serum CEA level in the colon neobladder group was significantly higher than the levels in the remaining two groups (P <0.05); 16 patients (57%) with colon neobladder had elevated serum CEA values (ie, greater than 5 mg/mL). Elevated serum CEA was observed in only 5 (23%) and 3 (8%) patients with ileal neobladder or ileal conduit, respectively. The serum CEA value in these patients was associated with the urinary CEA value (P <0.001), but not the other factors examined.

CONCLUSIONS

These findings suggest that colon bladder replacement caused significantly increased serum CEA values compared with ileal neobladder or ileal conduit; however, the elevated serum CEA level correlated with the urinary CEA level, irrespective of other clinical factors. Therefore, the elevated serum CEA in the colon neobladder group may have been due to reabsorption of CEA in urine rather than to an association with malignant changes in the bowel segments used for neobladder creation.

Cyclophosphamide-induced hemorrhagic cystitis in rats that underwent colocystoplasty: experimental study

PURPOSE

Cyclophosphamide and its derivatives induce hemorrhagic cystitis. A substantial number of patients receive bladder augmentation or replacements using bowel. If patients who have undergone colocystoplasty need treatment with cyclophosphamide before or after the operation, does hemorrhagic cystitis develop? We evaluated the histological changes produced in the colon wall and bladder related to cyclophosphamide and its derivatives in rats that underwent colocystoplasty.

MATERIALS AND METHODS

Sprague-Dawley rats of each sex were grouped according to whether they received a single 200 mg./kg. dose of cyclophosphamide, underwent colocystoplasty, underwent each technique or served as controls. The technique of colocystoplasty was the same in all groups. Results were analyzed according to previously reported criteria, by the gross appearance of the bladder and colon segment used for colocystoplasty, and by histological changes.

RESULTS

Two weeks after surgery colocystoplasty had not resulted in secondary changes in the implanted colon segment or original bladder, while there were only nonspecific changes of an inflammatory type in the anastomotic area. After cyclophosphamide administration the animals lost considerable weight and in the bladder area we observed hemorrhagic cystitis that was greater in males than in females, and greater in isolated bladder than when the bladder was sutured to the colon segment. In the colon there was no inflammation or hemorrhage damage of the hemorrhagic cystitis type in the bladder. A total of 12 days after colocystoplasty there were no secondary histological changes except in the anastomotic area. A single 200 mg./kg. dose of cyclophosphamide caused substantial weight loss and hemorrhagic cystitis. Cystitis was quantitatively greater in males than in females and greater in isolated bladder than in bladder anastomosed to the colon.

CONCLUSIONS

Administering a single dose of cyclophosphamide did not result in lesions in the colon segment used for colocystoplasty analogous to those of the bladder, such as hemorrhagic cystitis.

New concepts of histological changes in experimental augmentation cystoplasty: insights into the development of neoplastic transformation at the enterovesical and gastrovesical anastomosis

PURPOSE

To our knowledge the pathogenesis of malignancy associated with ileal cystoplasty, ureterosigmoidostomy and ileal conduits is currently unknown. To gain further insights into the mechanism of neoplastic transformation we studied histological changes in a canine augmentation cystoplasty model.

MATERIALS AND METHODS

Enterocystoplasty and gastrocystoplasty were performed using a 5 to 7 cm. patch of ileum in 8 dogs and gastric antrum in 6. Specimens were harvested 4 months postoperatively. Representative 3 microm sections of the enterovesical and gastrovesical junctions were stained with hematoxylin and eosin. Uroplakin expression was assessed using an indirect peroxidase method subjected to double staining with alcian blue and periodic acid-Schiffreagent.

RESULTS

The bladder portion of the augmentation cystoplasty had 3 to 4 stratified cell layers covered with a distinctive umbrella cell layer. Strong uroplakin staining was visible in all cell layers except the basal layer. At the enterovesical and gastrovesical junctions 6 to 10 layers of hyperplastic, urothelial appearing cells covered the glandular epithelium of the ileal and gastric segments. These cells expressed uroplakins. At this junction zone there was a marked decrease of underlying enteric glands, which had atrophied in proportion to the degree of urothelial hyperplasia. Double staining of uroplakin stained sections with alcian blue and periodic acid-Schiff reagent revealed mucosubstances in hyperplastic urothelial cells covering the enteral segments, indicating that the cells co-expressed uroplakins and mucins.

CONCLUSIONS

Histological changes in this experimental canine model of augmentation cystoplasty indicated that the overgrowth of hyperplastic transitional epithelium develops at the enterovesical and gastrovesical junctions. These cells express not only uroplakins, but also mucosubstances. Our results suggest that the migrated hyperplastic urothelial cells have undergone changes characteristic of the enteric and gastric epithelium, which may have important implications in the pathogenesis of malignancy in bladder augmentations.

The significance of the difference in bacterial adherence between bladder and ileum using rat ileal augmented bladder

OBJECTIVES

Intestinal segments are frequently used in the reconstruction of the urinary tract. Chronic bacteriuria is frequently observed in these patients, but the reason is not clearly understood. Therefore, we studied the difference in bacterial adherence between bladder and ileum using the rat ileal augmented bladder model to investigate the cause of chronic bacteriuria.

MATERIALS AND METHODS

Augmentation of the bladder using ileum and a sham operation were performed under sodium pentobarbital in 102 and 10 Sprague-Dawley rats, respectively. At three months after the operation, urinary pH and plasma concentration of sodium, chloride and potassium were measured and urinary culture was done. Urovirulence factors of Escherichia coli aspirated from augmented bladder were detected by polymerase chain reaction (PCR). Five to six rats with negative urinary cultures after the augmentation were used for each experimental cystitis. E. coli with type I pili aspirated from augmented rats and three clinically isolated strains of E. coli, C5 (type I pili, aerobactin), C92 (type I pili, aerobactin, P fimbriae), and C189 (type I pili, aerobactin, P fimbriae, CNF), were transurethrally inoculated into the augmented bladder of rats. Fourteen days after inoculation, rats were sacrificed and colony-forming units (CFU) per mg. of tissue of bladder and ileum were measured.

RESULTS

After operation, urinary pH and the serum level of chloride in all augmented groups were higher than those of the controls. Bacterial colonization was observed in 56 of 89 rats. Most of them were E. coli having only type I pili as a virulence factor. In contrast, the sham operated group revealed no bacterial colonization. In experimental cystitis, E. coli with only type I pili aspirated from augmented rats and E. coli C5 were clearly adhered to ileum rather than to bladder, but E. coli C92 and C189 showed no significant difference with respect to adherence to the two tissues. In experimental cystitis II, E. coli C5 with D-mannose were washed out in 3 of 5 rats by 14 days, while E. coli C5 without D-mannose were not washed out in all rats by 14 days.

CONCLUSIONS

These results suggested that the difference in bacterial adherence due to urovirulence factors, especially type I pili, is one of the main causes of asymptomatic bacteriuria after urinary reconstruction.

Effects of short-chain fatty acids on primary urothelial cells in culture: implications for intravesical use in enterocystoplasties

The presence of inflammatory changes and mucopus production in an enterocystoplasty may be similar to the condition of diversion colitis and starvation diarrhea caused by a lack of luminal short-chain fatty acids (SCFAs). We postulate a therapeutic role for intravesical SCFA. Because this treatment will also contact the urothelium, we have assessed the effect on cellular proliferation by utilizing primary urothelial cells in culture. Primary urothelial cells were grown from biopsy samples of normal urothelium obtained intraoperatively. A cocktail of SCFA used in the treatment of diversion colitis was incubated with these cells for time intervals ranging from 30 minutes to 72 hours at drug concentrations ranging from 0.04 to 20 mmol/L butyrate equivalent (BE). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to measure the residual viable biomass to assess growth inhibition. These experiments were repeated on cells grown on matrigel substrate. The human urothelial cancer line RT112 was likewise exposed to SCFAs to assess selectivity between primary and transformed cells. Primary urothelial cells in culture undergo growth inhibition when exposed to SCFAs. The concentration of SCFAs required to reduce the general biomass by 50% or more (IC> or =50) was 20 mmol/L BE when exposure was for 2 hours or less. When drug exposure was prolonged for 72 hours, the IC> or =50 was 2.5 mmol/L BE. Cells grown on matrigel had their growth similarly inhibited. The IC > or = 50 for the RT112 cell line was 2.5 mmol/L BE after 72 hours of drug incubation. Primary urothelial cells in culture undergo a time- and dose-dependent growth inhibition when exposed to SCFAs. This inhibition is particularly apparent at the higher doses similar to those in use in clinical practice. Cells grown on a matrigel substrate suffer growth attenuation similar to that affecting cells grown on polystyrene plates. In vivo assessment in a rodent intravesical model is advisable before considering instillations in patients.

Autologous transplantation of urothelium into demucosalized gastrointestinal segments: evidence for epithelialization and differentiation of in vitro expanded and transplanted urothelial cells

PURPOSE

Our study established a technique for in vitro expansion and subsequent transplantation of autologous urothelial cells into vascularized seromuscular segments from stomach and colon in sheep. The proof of proliferation and differentiation of the transplanted urothelium in the absence of resident urothelium is considered to be a prerequisite for use of this technique in bladder augmentation.

MATERIALS AND METHODS

Autologous sheep urothelial cells were expanded in vitro and grown on collagen membranes for sheet grafting. Using a vital stain, viability and confluency status of the urothelial graft were determined before transplantation into demucosalized segments isolated from the sheep stomach and colon gastrointestinal pouches. The gastrointestinal segments were sewn up and remained in the abdomen as small pouches stiched to the abdominal wall. Take and differentiation of transplanted cells within the pouch were assessed two and three weeks later using histological and immunohistological means.

RESULTS

Urothelial cells grew well on collagen membranes. A confluency status > 40% and co-culturing with 3T3 feeder cells favored successful transplantation. Two weeks after transplantation a multilayered urothelial-like epithelium was found to line the lumen of the pouch. The epithelium was characterized by a distinct urothelium-typical distribution of basal and luminal keratins and the expression of the umbrella cell-specific marker uroplakin III. Moreover, the epithelium had an underlying basal lamina which focally contained collagen type IV.

CONCLUSIONS

The data indicate that in vitro expanded urothelial cells are capable of epithelializing demucosalized gastrointestinal segments forming a genuine, differentiated "neo" urothelium.

Urological complications of pancreatic transplantation

PURPOSE

Pancreas transplantation is increasingly being used in the treatment of type I insulin-dependent diabetes mellitus. Because bladder drainage of the exocrine pancreatic secretion is the procedure of choice, urological complications are frequent. As the number of these procedures increases the urologist will have an extended role in the management of the postoperative complications, the majority of which are urological.

MATERIALS AND METHODS

The literature from 1985 on the complications related to pancreas transplants was reviewed.

RESULTS

Approximately 50 to 60% of bladder drained pancreas transplant recipients will have a urological complication postoperatively.

CONCLUSIONS

The increasing application of bladder drained pancreas transplantation in the treatment of type I insulin-dependent diabetes mellitus necessitates that the clinical urologist is familiar with the management of complications related to this procedure.

Inhibition of transport processes of intestinal segments following augmentation enterocystoplasty in rats

PURPOSE

Sodium and chloride transport was measured by using the Ussing chamber-voltage clamp technique to evaluate alterations occurring in ileal segments interposed in the urinary tract in a rat enterocystoplasty model.

MATERIALS AND METHODS

In adult male Sprague-Dawley rats which had undergone augmentation ileocystoplasties 3 months earlier, intestinal segments were explanted from the neobladders and native ileal segments were removed separately for electrolyte transport and morphometric analysis.

RESULTS

Basal ileal active sodium and chloride absorption and cyclic nucleotide-induced chloride secretion were attenuated in transplanted ileum in contrast to control tissue. Morphologically, there was villus epithelial hyperplasia, crypt hyperplasia and chronic inflammation in transplanted segments, but villus height:crypt length ratios were unchanged.

CONCLUSIONS

Pathophysiologic derangements in intestinal segments interposed in the urinary tract include inhibition of sodium and chloride transport processes and mucosal hyperplasia. The use of the Ussing chamber/voltage clamp technique described herein offers a new approach for additional studies of the metabolic consequences following urinary diversion.

Tumor induction and prophylaxis following different forms of intestinal urinary diversion in a rat model

Eighty Wistar rats were randomized into two groups. In group 1 vesicosigmoidostomy with proximal colostomy was performed, in group 2, vesicosigmoidostomy. The total tumor incidence did not significantly (group 1 10/40, 25%; group 2 13/40, 32.5%). The tumor spectrum differed, with more adenocarcinomas in group 2 (11/40, 27.5% vs 4/40, 10%; P = 0.047) and urothelial carcinomas only in group 1 (5/40, 2.5%). One hundred and ten other Wistar rats were randomized into three groups. Animals in group A received vesicoileosigmoidostomy, group B, two-step vesicosigmoidostomy with initial separation of urine and the urocolonic anastomosis, group C, vesicosigmoidostomy. Significantly fewer adenocarcinomas were observed in group A (2/40, 5%) than in group B (16/40, 40%; P < 0.002) and group C (9/30, 30%; P < 0.007). These results indicate a similar cancer risk in all continent forms of urinary diversion, at least via colon. Ileal interposition seems to be an effective carcinoma prophylaxis following ureterosigmoidostomy. The proliferative instability at the urointestinal anastomosis is crucial for the pathogenesis and prophylaxis of this form of carcinogenesis, whereas urine seems to play only a minor role.

Long-term histopathological changes observed in rats subjected to augmentation cystoplasty

Possible development of proliferative lesions in bladders subjected to augmentation cystoplasty is a matter of concern for many clinicians. We have previously reported on the development of bladder papillomas in 5 of 15 rats approximately 18 months after gastrocystoplasty. We now report a followup study designed to investigate histopathological changes occurring in rat bladders approximately 2 years after augmentation cystoplasty using various gastrointestinal segments. Prepubescent Long-Evans female rats were randomly divided into 4 groups and underwent either gastrocystoplasty, ileocystoplasty, colocystoplasty or a sham operation (controls). Animals were sacrificed 14 to 27 months (average 21.5) postoperatively and bladders were examined histologically. Metaplastic and/or hyperplastic changes were observed in the gastrointestinal patches or surrounding urothelium in all bladders having undergone augmentation cystoplasty. Tumors occurred on or adjacent to the lumenal surface of the augmented segment in 4 of 10, 3 of 11 and 2 of 11 rats that underwent gastrocystoplasty, ileocystoplasty or colocystoplasty, respectively. None of the tumors was observed to invade blood vessels, lymphatics or the underlying muscle layers. However, histological features of malignancy characterized by varying degrees of cellular pleomorphism occurred in some tumors. Control rats (10) had only minor changes related to reapposition of tissues and remnants of suture. Possible etiologies and the potential significance of these augmentation cystoplasty related proliferative lesions are discussed.

Grafting of cultured uroepithelium and bladder mucosa into de-epithelialized segments of colon in rabbits

Urinary tract reconstruction using bowel can result in acid-base and electrolyte abnormalities. We tested the feasibility of grafting bladder mucosa and urothelial cells grown on a biodegradable polyglactin 910 scaffold onto de-epithelialized segments of bowel in the rabbit. A segment of de-epithelialized colon was either grafted with cultured urothelium on a collagen mesh scaffold (12 rabbits) or with free bladder mucosa (11 rabbits). In 10 rabbits that served as a control group another segment of bowel was isolated and de-epithelialized. No urothelial or bowel epithelial growth was present 4 weeks later in 10 of the isolated de-epithelialized colonic segments grafted with the cultured urothelium. In 2 segments a minute focus of epithelium staining positively for anticytokeratin antibodies AE1 and AE3 was seen but this could not be histologically differentiated as either urothelium or native colonic epithelium. All 7 surviving animals that underwent a bladder mucosal graft had viable urothelium at sacrifice 30 days postoperatively. In 2 of the 7 rabbits microscopic nests of colonic epithelium were also found underneath the urothelial layer. Of the 7 internal controls 6 had no evidence of bowel epithelial regrowth 4 weeks after de-epithelialization. This study demonstrated that a confluent layer of urothelial cells could be grown in culture using a scaffold of biodegradable mesh and rat tail collagen. We also showed that bladder mucosal grafts can be grown on de-epithelialized bowel segments. We were unable to graft successfully cultured urothelial cells onto a de-epithelialized bowel segment. Further improvement in understanding the role of the submucosal matrix in cell growth may lead to future success in covering large segments of de-epithelialized bowel with autologous urothelium.