Seromuscular colocystoplasty lined with urothelium: experimental study

Neurogenic bladder in spinal cord injury patients

Neurogenic bladder dysfunction due to spinal cord injury poses a significant threat to the well-being of patients. Incontinence, renal impairment, urinary tract infection, stones, and poor quality of life are some complications of this condition. The majority of patients will require management to ensure low pressure reservoir function of the bladder, complete emptying, and dryness. Management typically begins with anticholinergic medications and clean intermittent catheterization. Patients who fail this treatment because of inefficacy or intolerability are candidates for a spectrum of more invasive procedures. Endoscopic managements to relieve the bladder outlet resistance include sphincterotomy, botulinum toxin injection, and stent insertion. In contrast, patients with incompetent sphincters are candidates for transobturator tape insertion, sling surgery, or artificial sphincter implantation. Coordinated bladder emptying is possible with neuromodulation in selected patients. Bladder augmentation, usually with an intestinal segment, and urinary diversion are the last resort. Tissue engineering is promising in experimental settings; however, its role in clinical bladder management is still evolving. In this review, we summarize the current literature pertaining to the pathology and management of neurogenic bladder dysfunction in patients with spinal cord injury.

Dynamic reciprocity in cell-scaffold interactions

Tissue engineering in urology has shown considerable promise. However, there is still much to understand, particularly regarding the interactions between scaffolds and their host environment, how these interactions regulate regeneration and how they may be enhanced for optimal tissue repair. In this review, we discuss the concept of dynamic reciprocity as applied to tissue engineering, i.e. how bi-directional signaling between implanted scaffolds and host tissues such as the bladder drives the process of constructive remodeling to ensure successful graft integration and tissue repair. The impact of scaffold content and configuration, the contribution of endogenous and exogenous bioactive factors, the influence of the host immune response and the functional interaction with mechanical stimulation are all considered. In addition, the temporal relationships of host tissue ingrowth, bioactive factor mobilization, scaffold degradation and immune cell infiltration, as well as the reciprocal signaling between discrete cell types and scaffolds are discussed. Improved understanding of these aspects of tissue repair will identify opportunities for optimization of repair that could be exploited to enhance regenerative medicine strategies for urology in future studies.

The evolution of bladder augmentation: from creating a reservoir to reconstituting an organ

Bladder augmentation was first described in 1899. The goal at the time was to establish the ideal method to create a simple capacious reservoir for the safe storage of urine. That simple idea has over the last 100 years grown into one of the most dynamic areas in Pediatric Urology. Creative minds and hands from individuals in multiple disciplines have led us from creating a reservoir to the threshold of recreating a functional organ. In this review, we look at the historical evolution of bladder augmentation and how it exponentially grew in scope from those initial descriptions of intestinocystoplasty to the work being reported today in the field of tissue engineering.

Alternatives to conventional enterocystoplasty in children: a critical review of urodynamic outcomes

Alternatives to conventional enterocystoplasty have been developed in order to avoid the most common complications derived from contact of the urine with intestinal mucosa. In this article critically we review the literature on the topics: ureterocystoplasty, detrusorectomy, detrusorotomy, seromuscular gastroenterocystoplasty, use of off the shelf biomaterials, and bladder augmentation by bioengineering. Recognizing the difficulty of deciding when a child with a history of posterior urethral valves requires and augmentation and that the development of a large megaureter in cases of neurogenic dysfunction represents a failure of initial treatment, we conclude that ureterocystoplasty can be useful in selected cases when a large dilated ureter is available. Seromuscular colocystoplasty lined with urothelium (SCLU) has been urodynamically effective in several series when the outlet resistance is high and no additional intravesical procedures are necessary. Seromuscular gastrocystoplasty lined with urothelium seems to offer no distinct advantages and involves a much more involved operation. The use of seromuscular segments without urothelial preservation, with or without the use of an intravesical balloon has been reported as successful in two centers but strict urodynamic evidence of its effectiveness is lacking. The published evidence argues strongly against the use of detrusorectomy or detrusorotomy alone because of the lack of significant urodynamic benefits. Two recent reports discourage the use of small intestinal submucosa patches because of a high failure rate. Finally, research into the development of a bioengineered bladder constructed with cell harvested from the same patient continues but is fraught with technical and conceptual problems. In conclusion of the methods reviewed, only ureterocystoplasty and SCLU have been proven urodynamically effective and reproducible.

Augmentation ureterocystoplasty in boys with valve bladder syndrome

OBJECTIVE

Children with valve bladder syndrome represent the worst end of the posterior urethral valve spectrum. When conservative measures fail to control recurrent infections, prevent deterioration of the upper tract (in the form of increasing hydronephrosis and or worsening of kidney function) and improve incontinence, augmentation cystoplasty is considered. In most of these boys, renal insufficiency precludes the use of intestine for augmenting the bladder. Our aim was to evaluate the efficacy and safety of ureterocystoplasty in managing children with valve bladder syndrome.

PATIENTS AND METHODS

Eight boys (mean age 5 years) with valve bladder syndrome were included in this study. All boys had successful valve ablation at the time of presentation. When conservative treatment failed, ureterocystoplasty was scheduled. The entire ureter was folded and used in four boys after nephrectomy for a non-functioning kidney. The lower dilated ureter was used to augment the bladder, and transureteroureterostomy in two and re-implantation of the remaining ureter in two were performed. Radiological and urodynamic investigation was performed preoperatively and postoperatively at 3, 6 and 12 months. Improvement of hydroureteronephrosis was judged by ultrasound.

RESULTS

Bladder capacity (as measured during cystometry at 30 cmH(2)O) and compliance were significantly improved in all children following the procedure (P<0.001), and reached or exceeded the normal calculated capacity for age-matched boys. Hydroureteronephrosis improved in six boys (75%). The procedure avoids almost all the complications of enterocystoplasty. Clean intermittent self-catheterization was performed in all cases routinely after surgery, weaning off as judged by the voiding pattern of the child.

CONCLUSION

Ureterocystoplasty is an ideal option for augmenting the hypocompliant bladder in boys with valve bladder syndrome. The entire ureter or the dilated lower part can be used. This is a solution for boys with impaired renal function when enterocystoplasty cannot be performed.

In vivo bladder regeneration using small intestinal submucosa: experimental study

Significant side effects are correlated with bladder augmentation. Recently, small intestinal submucosa (SIS) has been proposed for clinical use. The efficacy of SIS bladder regeneration was studied in a porcine experimental model. Partial cystectomy (40-60% of bladder wall) was performed and replaced by SIS graft. Animals were planned to be killed at 2 weeks, 5 weeks and 3 months. Bladder capacity at 40 cmH(2)O pressure and macroscopic graft morphology were assessed before and after SIS implant. Histological examination was carried out with computer assisted morphometric analysis for collagen/smooth muscle ratio. Student's t test was adopted for statistical analysis. Two piglets died on the 9th and 10th post-operative day due to urinary peritonitis. The remaining piglets were killed after uneventful post-operative period at 5 weeks (two animals) and 3 months (two animals). The bladder capacity was reduced (-18%) at the 5 week follow-up and quite similar to the pre-operative volume (+2.5%) at the 3 months control. No diverticular formation, bladder calculi, mucus and urinary infection were found. The SIS graft resulted not significantly contracted. Histology at 10 days showed SIS membrane lined by transitional epithelium islands with some capillaries. At 5 weeks, transitional epithelium was fully covering the graft; new blood vessels and fibroblasts with smooth muscle cells were observed. At 3 months, the SIS was not evident. Two layers were defined: inner transitional epithelium, outer collagen with fibroblasts and muscular bundles. Computer assisted morphometric analysis showed collagen/muscle ratio 70/30% (normal bladder=56/44%, P<0.05). The SIS was effective as a scaffold for bladder wall regeneration in four out of six animals. Long-term studies are required to confirm the efficacy of the newly developed wall and for eventual clinical use.

Total bladder replacement with de-epithelialized ileum. Experimental study in dogs

OBJECTIVE

To assess the value of the silicone modeler in preventing graft retraction in dogs undergoing bladder replacement with de-epithelialized ileum.

MATERIALS AND METHODS

Twelve female dogs underwent total cystectomy and bladder replacement by neobladder made of demucosalized ileal segment, comparing the group with modeler (group I) and the group without modeler (group II). Cystometry data, graft epithelization and radiological assessment (cystography and excretory urography) were analyzed.

RESULTS

Neobladder capacity, at 2 months, ranged from 50 to 250 mL (mean 191 mL) and from 5 to 60 mL (mean 22 mL) and at 6 months, from 60 to 270 mL (mean 202.5 mL) and from 5 to 75 mL (mean- 30.5 mL), respectively in groups I and II, with a statistically significant difference between groups. After 30 days, postoperatively the presence of transitional epithelium was observed in all fragments obtained by biopsy.

CONCLUSION

The use of the intravesical silicone modeler prevented the retraction of the neobladder of de-epithelialized ileum.

Autoaugmentation gastrocystoplasty: further studies of the sheep model

OBJECTIVE

To report our experience with autoaugmentation gastrocystoplasty (AAGC, reported to result in an inconsistent augmentation effect in children) in a sheep model, specifically addressing issues of surgical techniques and postoperative bladder drainage that may affect the augmentation result, as many factors have been implicated in the poor outcome.

MATERIALS AND METHODS

Ten 6-month-old male lambs had a suprapubic catheter placed by an open laparotomy. Intraoperative urodynamics were evaluated before and after detrusorotomy for autoaugmentation and after completing AAGC. The bladder was drained with no distension for 1 week after surgery and the urodynamic evaluation repeated on control and experimental animals 6 months after surgery. The animals were then killed and the bladders evaluated for gastric flap survival and histological changes in the native bladder and augmentation segments. The results were analysed using a one-sided Student's t-test.

RESULTS

The median (range) native bladder volume at leak-point pressure was 110 (40-490) mL. Intraoperative bladder volumes after completing AAGC confirmed adequate augmentation segments in all animals. The urodynamic evaluation at 6 months after AAGC showed increases in bladder volumes in nine of 10 animals (0-1336 mL), significantly greater than the increase in volume in the control sheep (median 337.5 vs 115.3 mL; P < 0.05). The bladder compliance (volume/pressure at leak capacity) 6 months after AAGC was slightly better but not significantly higher than in controls (median 17.3 vs 10.8 mL/cmH(2)O; P > 0.05). The median (range) ratio of surviving gastric flap to native bladder circumferences was 34.5 (31-53)%. Histology showed scarring of the submucosal layer in one of 10 augmentation segments and normal urothelium in all bladders.

CONCLUSION

AAGC produces reliable bladder augmentation and excellent bladder compliance in a sheep model of a non-neurogenic bladder. The gastric flap survived well and there was no bladder wall separation with simple postoperative catheter drainage.

Bladder augmentation with an omental pedicled gastric seromuscular flap without the necessity of gastric resection

Bladder augmentation using gastrointestinal segments requires gastric or intestinal resection. This has several risks. In a rat model, we aimed to test the efficacy of a new procedure in which a gastric seromuscular (GSM) flap is separated from the gastric mucosa without the necessity of gastric resection, and this GSM flap, based on an omentum pedicle, is transferred to the bladder. A GSM flap based on an omental leaf was dissected from the gastric mucosa and rotated 180 degrees counter-clockwise, after ligation of the vessels relating to the omentum, until the mid-duodenum. After urodynamic analysis for control levels of bladder capacity and pressure, the GSM flap was anastomosed to the bladder with a continuous suture. Because four rats died due to bladder calculi, only 21 of 25 rats were killed at 1 month (n = 10) and 4 months (n = 11) for histopathological and urodynamic evaluations of the augmented bladder. Bladder capacity increased significantly in the augmented bladders compared to preaugmentation (P < 0.001). There was no significant difference between end-filling pressures of the augmented bladders and preaugmentation. Histopathological findings demonstrated that the muscular surface of the flap was completely re-epithelialized in all rats. Squamous metaplasia was detected in 30% (3/10) of the 1 month group rats, and in 55% (6/11) of 4 month rats (P > 0.05). Gross calculi formation appeared in 20% (2/10) of the 1 month group rats, and in 34% (4/11) of 4 month rats (P > 0.05). Our data show that the use of the GSM flap in the bladder of a rat resulted in the complete re-epithelialization of the flap and sufficient bladder capacity. Despite significant complications such as death, metaplasia and calculi, this technique may be considered as an alternative experimental model to traditional full-thickness patching, which needs gastric or intestinal resection.

A surgical model of composite cystoplasty with cultured urothelial cells: a controlled study of gross outcome and urothelial phenotype

OBJECTIVES

To study the outcome of composite cystoplasty using cultured urothelial cells combined with de-epithelialized colon or uterus in a porcine surgical model, using appropriate controls, and to characterize the neo-epithelium created by composite cystoplasty.

MATERIALS AND METHODS

Urothelial cells were isolated and propagated in vitro from open bladder biopsies taken from nine female minipigs. Cohesive sheets of confluent urothelial cells were transferred to polyglactin carrier meshes and sutured to de-epithelialized autologous colon in four animals and de-epithelialized autologous uterus in five. These composite segments were then used for augmentation cystoplasty. Conventional colocystoplasty, de-epithelialized colocystoplasty and sham operations were carried out in six control animals. After killing the animals at approximately 90 days the bladders were removed for examination and immunohistochemical analysis, using a panel of antibodies against cytokeratins and urothelial differentiation-associated antigens.

RESULTS

Macroscopically, the bladders augmented with composite segments derived from uterine muscle had no evidence of shrinkage or contracture. Histological analysis showed that in four of five composite uterocystoplasties, the neo-urothelium was stratified and had a transitional morphology, although in some areas coverage was incomplete. Immunohistochemical analysis showed evidence of squamous differentiation in both native and augmented segments. All composite and de-epithelialized colonic segments showed significant contraction with poor urothelial coverage, reflecting the unsuitability of the thin-walled porcine colon for de-epithelialization.

CONCLUSIONS

The functional and macroscopic outcome of bladder augmentation with a composite derived from cultured urothelium and de-epithelialized smooth muscle of uterine origin endorses the feasibility of composite cystoplasty.

Engineering tissues and organs

Genitourinary tissues can be engineered in-vitro and in-vivo for reconstruction using selective cell transplantation in combination with acellular matrices. This technology involves an interdisciplinary approach combining techniques of cell biology and materials sciences towards the development of functional tissues or organs. Tissues and organs in urology, such as the bladder, clitoris, corpus cavermosum, kidney, testis, ureter and urethra have been created in the laboratory, with varying degrees of functionality. Cells have also been recently used in patients as bulking agents for the treatment of vesicoureteral reflux and urinary incontinence. As the science of tissue engineering evolves, one can expect a wider application of this technology to the armamentarium of urologic surgery.

A new approach to bladder augmentation in children: seromuscular enterocystoplasty

OBJECTIVE

To report the use of seromuscular enterocystoplasty (SE) combined with detrusorectomy, in children.

PATIENTS AND METHODS

Between 1993 and 1998, SE was performed in 10 children (aged 10-17 years) with a spastic neurogenic bladder resulting from spinal trauma. Before surgery all children were incontinent and despite anticholinergic medication and clean intermittent catheterization, their bladder capacity was 60-100 mL and their intravesical pressure 40-60 cmH2O.

RESULTS

Before surgery, the mean end-filling intravesical pressure was 47.7 cmH2O and the mean bladder capacity 82.9 mL. At 3 months after surgery the mean end-filling intravesical pressure was decreased to 21.1 cmH2O and the mean bladder capacity increased to 319.6 mL. One patient (a 14-year-old girl) had urinary retention soon after surgery and has since used clean intermittent catheterization. The other children were able to void successfully using the Valsalva manoeuvre; none were incontinent. All patients were followed and there were no changes in intravesical pressure and bladder capacity.

CONCLUSION

In providing most of the desired features of an ideal augmentation segment, SE is a good and effective method of bladder augmentation.

Bladder augmentation. Options, outcomes, future

Remarkable progress has been made in lower urinary tract reconstruction in children. Nowhere is this more valuable than in augmentation cystoplasty, where there are several available options. This article discusses the current techniques and the benefits and limitations of these procedures. A section on tissue regeneration techniques and the author's current recommendations are included.

Future perspectives in reconstructive surgery using tissue engineering

Whenever there is a lack of native urologic tissue, reconstruction usually is performed with native nonurologic tissues, such as gastrointestinal segments, skin, or mucosa from multiple body sites. The use of native nonurologic tissues in the genitourinary tract is associated with adverse effects. Tissue engineering efforts currently are underway for almost every type of tissue and organ within the urinary system including bladder, ureter, urethra, and genitalia. Most of the efforts expended to engineer genitourinary tissues have occurred within the last decade. Tissue engineering techniques require a cell culture facility designed for human application. Personnel who have mastered the techniques of cell harvest, culture and expansion, and polymer design are essential for the successful application of this technology. The first human application of cell-based tissue engineering technology for urologic applications recently occurred with the injection of autologous cells for the correction of vesicoureteral reflux in children and urinary incontinence in adults. Trials involving bladder replacement using tissue engineering techniques currently are being arranged. Recent progress suggests that engineered urologic tissues may have clinical applicability.

In vitro assessment of a collagen sponge for engineering urothelial grafts

OBJECTIVE

To investigate the deposition of urinary crystals and the growth characteristics of urothelial cells on a collagen sponge, as a preliminary step in engineering urothelial autologous grafts.

MATERIALS AND METHODS

Collagen sponges were exposed to a continuous flow of urine at pH 5.3 and 6.3 for 1 week. The sponges were examined microscopically for crystal deposition and analysed for their calcium content. Two cell lines, RT112, derived from a well-differentiated transitional cell carcinoma, and UROtsa, an immortalized urothelial cell line, were seeded on the collagen sponges. Cells were cultured for 6, 12 and 21 days. The pattern of growth was analysed by histology and immunostaining with a pan-cytokeratin antibody. Growth was assayed to quantify cell proliferation on the sponges.

RESULTS

No crystals were evident on any of the collagen sponges. Calcium deposition was negligible at pH 5.3. Although calcium levels were measurable at pH 6.3, the levels were very low. Both cell lines attached and grew in a stratified manner on the collagen sponge, RT112 forming a layer 6-8 cells thick, and UROtsa a layer 4-6 cells thick; cell proliferation was maximal at 5-10 days. The sponge remained easy to handle after 3 weeks in culture.

CONCLUSION

These findings show that collagen sponges support the growth and stratification of urothelial cells, and indicate that the collagen sponge is a suitable substrate for developing urothelial autologous grafts.

In vitro functional properties of the rat bladder regenerated by the bladder acellular matrix graft

PURPOSE

To assess the response of rat urinary bladder regenerated by the homologous bladder acellular matrix graft (BAMG) to in vitro electrical and pharmacologic stimuli.

MATERIALS AND METHODS

In Sprague-Dawley rats, partial cystectomy (>50%) was performed, followed by BAMG augmentation cystoplasty. After 4 months, organ bath studies of tissue strips in 10 were used to compare the contractility of the BAMG regenerates and the corresponding host detrusor smooth muscle.

RESULTS

The BAMG regenerates exhibited contractile activity to electrical field stimulation and a qualitatively identical pattern of response to muscarinic, purinergic, alpha- and beta-adrenergic drug administration and nitric oxide. At 4 months after surgery, the maximum forces of contraction of the BAMG regenerates to carbachol stimulation amounted to close to 80% of the host bladder response. With electrical field stimulation, they equaled 44% and 62% of the host bladder response after 2.5 and 4 months, respectively. Histological and immunohistochemical studies confirmed the presence of receptors for neurotransmitters that these functional in vitro studies implied.

CONCLUSIONS

The present study provides further evidence that augmentation cystoplasty with the BAMG leads to functional regeneration of the rat bladder detrusor smooth muscle.

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.

Seromuscular colocystoplasty lined with urothelium protects dogs from acidosis during ammonium chloride loading

PURPOSE

We compared the metabolism of intravesical ammonium chloride in dogs in which the bladder had been enlarged by seromuscular colocystoplasty lined with urothelium, dogs that had undergone conventional colocystoplasty and control dogs.

MATERIALS AND METHODS

Eight adult female mongrel dogs were divided into control (2), colocystoplasty (3) and seromuscular colocystoplasty (3) groups. Serum creatinine, bicarbonate, sodium, chloride, and potassium levels were measured every 2 weeks during the 6-week recovery period. Six weeks after augmentation the dogs were placed under general anesthesia, the bladder was instilled with a hyperosmolar solution of 400 mmol/l. ammonium chloride, the femoral artery and portal vein were cannulated to obtain blood samples and the ureters were divided with the proximal ends diverted to allow serial urine measurements. Blood and urine electrolyte analysis was performed at 0, 60, 120, 180 and 240 minutes after the intravesical instillation of ammonium chloride.

RESULTS

During acid loading dogs that had undergone conventional colocystoplasty had a progressive decrease in serum carbon dioxide and arterial pH as well as increased levels of serum chloride and a significant increase in plasma ammonia concentration in the portal vein compared to controls and dogs that had undergone seromuscular colocystoplasty. In contrast, there were no differences in seromuscular colocystoplasty compared to control animals.

CONCLUSIONS

Increased ammonia in the portal vein and hyperchloremic acidosis in dogs that underwent conventional colocystoplasty suggest intravesical absorption of ammonium chloride. Dogs that underwent augmentation with seromuscular colocystoplasty lined with urothelium seemed to respond to acute intravesical ammonium in a way similar to that of control dogs and they are protected from these metabolic anomalies.

Reconstitution of human urothelium from monolayer cultures

PURPOSE

We established a 3-dimensional organ culture model of urinary tract tissue in which to study the effects of seeding cultured urothelial cells onto de-epithelialized urothelial stroma.

MATERIALS AND METHODS

Normal human urinary tract tissues were placed in organ culture or used to establish urothelial cell cultures. At passage 2 cell cultures were harvested and used to reconstitute autologous organ cultures by seeding onto de-epithelialized stroma. Organ cultures were harvested at intervals and analyzed by immunohistology with a panel of antibodies against differentiation associated antigens, cytokeratins, cell adhesion molecules, extracellular matrix components and proliferation associated antigens.

RESULTS

Human urothelial tissues were maintained in organ culture for at least 18 weeks and they retained a transitional epithelial morphology with expression of normal in situ antigenic characteristics. Within 2 weeks of reconstitution recombined organ cultures formed a stratified, polarized, transitional-like neo-epithelium that expressed many of the phenotypic and differentiated characteristics of normal tissue. Basement membrane formed at sites of direct contact between urothelial cells and stroma. After an initial stabilization period the proliferation rate of the urothelium of intact and reconstituted organ cultures decreased to the low turnover rate characteristic of normal urothelium in situ, indicating that the cells were responsive to normal growth regulatory controls.

CONCLUSIONS

Normal human urothelial cells, which express a proliferative nondifferentiated phenotype in monolayer culture, retain the capacity to differentiate and reform a slow turnover, stratified transitional epithelium.

Methods to enhance in vivo urothelial growth on seromuscular colonic segments in the dog

PURPOSE

We demonstrated survival and expansion in vivo of urothelial free autografts on demucosalized seromuscular segments.

MATERIALS AND METHODS

Four methods of in vivo urothelial expansion were investigated on demucosalized colonic segments in the canine model. Group 1 underwent colonic mucosal removal by manual stripping, group 2 underwent removal of colonic mucosa and submucosa, and group 3 underwent manual stripping of the colonic mucosa followed by treatment with protamine sulfate and urea. In the 3 groups urothelial autografts were then placed on the seromuscular segment and tubularized over a balloon splint. In group 4 the colonic mucosa was removed but the grafts were not tubularized. Instead the colonic segment was sutured to the parietal peritoneum.

RESULTS

Group 4 grafts had no epithelial growth and shrinkage of the bowel segment. Group 1 grafts had minimal growth with no expansion and colonic mucosal regrowth. Group 2 grafts demonstrated growth and expansion, although these colonic segments had a significant inflammatory response and fibrosis. Group 3 grafts had the best growth and expansion with the least inflammatory response, and 1 colonic segment was almost completely covered with urothelium.

CONCLUSIONS

We demonstrated in vivo expansion of urothelial autografts grown on seromuscular colonic segments. Preservation of the submucosa is essential to prevent fibrosis of the seromuscular colonic segment and a balloon stent is crucial to prevent graft contraction. Treatment of the demucosalized segment with protamine sulfate and urea results in better urothelial expansion and less colonic mucosal regrowth.

Enteric mucosal regrowth after bladder augmentation using demucosalized gut segments

PURPOSE

Regrowth of the enteric mucosa on a denuded muscular flap enterocystoplasty is an undesirable complication of demucosalized enterocystoplasty. This study was performed to understand how regrowth can be prevented and, thus, a complete urothelial lined enterocystoplasty can be achieved.

MATERIALS AND METHODS

We performed bladder augmentation on 30 sheep using demucosalized seromuscular gastric or colonic flaps with or without autoaugmentation. The epithelium and muscularis mucosae were completely removed from the gastric flap. Initial attempts to remove the muscularis mucosae and most of the submucosal layer from the colonic flap by cautery caused bleeding and muscle damage. Thus, demuscosalization was done by stripping with forceps, in which the muscularis mucosae and submucosa remained largely intact on the colonic flap. Sheep were sacrificed 4 to 12 months postoperatively and bladders were inspected for mucosal regrowth. Subsequently autoaugmentation with demucosalized seromuscular gastric or colonic flaps was performed clinically in 10 children in whom the enteric epithelium and muscularis mucosae were removed completely with part of the submucosa by dissection through the submucosal plane. These children were followed with urodynamic studies and mucin staining of urine up to 39 months postoperatively.

RESULTS

Regrowth of islands of enteric mucosa occurred in 4 of the 5 animals in which the muscularis mucosae and submucosal layers were preserved on a colonic flap. In all animals with mucosal regrowth the bowel was prepared by stripping the mucosa. Mucosal regrowth did not occur in any animal after complete removal of the muscularis mucosae and the inner portion of the submucosa from the stomach or colon. All patients had satisfactory urodynamic results and no evidence of enteric mucosal regrowth.

CONCLUSIONS

Removal of the muscularis mucosae with the inner portion of the submucosa appears necessary to prevent enteric mucosal regrowth on the muscular flap of a demucosalized enterocystoplasty. In addition, this level of dissection does not seem to interfere with the success of bladder augmentation in children.

Regenerative urinary bladder augmentation using small intestinal submucosa: urodynamic and histopathologic assessment in long-term canine bladder augmentations

PURPOSE

To evaluate small intestinal submucosa (SIS) as a possible bladder augmentation material.

MATERIALS AND METHODS

Nineteen male dogs underwent 35 to 45% partial cystectomy with immediate augmentation with SIS grafts. All dogs were evaluated pre- and postoperatively with blood chemistries, urine cultures, intravenous urograms, cystograms and cystometrograms. Postoperatively (1 to 15 months), bladders were examined with routine histology and image analysis.

RESULTS

All dogs survived their intended survival period without morbidity. All results were normal. Histologically, all 3 layers (mucosa, smooth muscle, serosa) of the normal bladder showed evidence of regeneration.

CONCLUSIONS

Small intestinal submucosa acts as a scaffold for bladder augmentation through regeneration and could be a potential option for bladder reconstruction.

Experimental assessment of small intestinal submucosa as a bladder wall substitute

OBJECTIVES

This study determined the feasibility of promoting urinary bladder regeneration with porcine-derived small intestinal submucosa (SIS).

METHODS

Twenty-two Sprague-Dawley rats underwent partial cystectomy with immediate bladder augmentation with SIS. Bladders were harvested for histologic evaluation at 2, 4, 8, 12, 24, and 48 weeks.

RESULTS

Histologically at 2 weeks, there was infiltration of the graft material with viable host cells consisting of fibroblasts, macrophages, and blood vessels covered by complete mucosal urothelium comprised of transitional cells. During the next 10 weeks, collagen formation and maturation were noted, and by the end of 12 weeks, the SIS graft was comprised of a mature collagen matrix admixed with thinly scattered disorganized smooth muscle bundles and covered by normal urothelium. At 48 weeks, all three layers of the normal bladder (urothelium, smooth muscle, and serosa) were present and were grossly and microscopically indistinguishable from the normal rat urinary bladder.

CONCLUSIONS

This study further supports the concept of bladder regeneration and suggests that SIS may be a viable material for bladder augmentations.

Effect of seromuscular colocystoplasty lined with urothelium and partial detrusorectomy on a new canine model of reduced bladder capacity

We developed a canine model of reduced bladder capacity by spraying talc on the outer surface of the detrusor after peeling the peritoneum from the bladder. This method was effective to reduce bladder capacity to almost a third of normal and this reduction persisted for the 6-month followup. On this model we performed detrusorectomy (auto-augmentation) and seromuscular colocystoplasty, and compared the results. Following detrusorectomy in talc bladder dogs bladder capacity failed to increase significantly at 3 months and 6 months. In contrast, seromuscular colocystoplasty caused a significant increase in bladder capacity in talc bladder dogs that was sustained for the 6-month followup. We also performed detrusorectomy in dogs with normal bladders and observed a progressive decrease in bladder capacity, which became significant at 6 months. Histology of the bladders after sacrifice revealed that talc induces a desmoplastic reaction around the detrusor that limits bladder distensibility and reduces its capacity. With detrusorectomy the perivesical fibrotic layer induced by talc and the detrusor were effectively removed but a thin layer of fibrosis developed between the bladder mucosa and the peritoneum that may account for the lack of improvement in bladder capacity. Identical observations were made after detrusorectomy in normal bladders. In contrast, following seromuscular colocystoplasty the bladder mucosa was adjacent to the submucosa of the colonic patch without fibrosis, a finding that may account for the restoration of bladder capacity. These experiments confirm previous experimental and clinical observations about seromuscular colocystoplasty, and suggest that it may result in better long-term results than simple auto-augmentation.

Seromuscular colocystoplasty lined with urothelium: experience with 16 patients

OBJECTIVES

Report of initial clinical experience with seromuscular colocystoplasty lined with urothelium (SCLU), a new operation to increase bladder capacity and compliance without incorporating intestinal mucosa into the urinary tract. We have previously reported the technique and results of this procedure in a canine model.

METHODS

Sixteen patients underwent SCLU at two institutions. Their charts were reviewed retrospectively. The patients have been observed for a mean of 12 months.

RESULTS

Postoperatively, the bladder capacity increased an average of 2.4-fold from a mean of 139 mL (+/- 23.7 SEM) to 335 mL (+/- 38.9 SEM) in 14 patients (P < 0.001). Two patients required reaugmentation. Preoperative and postoperative bladder end filling pressures were available in 13 patients and decreased from a mean of 51.6 cm H2O (+/- 4.2 SEM) to 27.7 cm H2O (+/- 2.4 SEM) (P < 0.001). Of the 16 patients, 13 were incontinent preoperatively; 5 had renal insufficiency. Three patients have undergone renal transplantation following SCLU. After SCLU, 13 patients were dry day and night, 1 incontinent at night only, and 2 remained incontinent. Ten patients have undergone postoperative bladder biopsy. Seven demonstrate urothelium covering the augmented portion of the bladder, 2 have regrowth of colonic mucosa, and 1 shows a mixture of colonic mucosa and urothelium.

CONCLUSIONS

The results presented suggest that SCLU is a viable alternative to the more conventional forms of bladder augmentation in selected patients.