Augmentation cystoplasty utilizing de-epithelialized sigmoid colon: a preliminary study

Bladder augmentation in children: current problems and experimental strategies for reconstruction

Bladder augmentation is a demanding surgical procedure and exclusively offered for selected children and has only a small spectrum of indications. Paediatric bladder voiding dysfunction occurs either on a basis of neurological dysfunction caused by congenital neural tube defects or on a basis of rare congenital anatomic malformations. Neurogenic bladder dysfunction often responds well to a combination of specific drugs and/or intermittent self-catheterization. However, selected patients with spinal dysraphism and children with congenital malformations like bladder exstrophy and resulting small bladder capacity might require bladder augmentation. Ileocystoplasty is the preferred method of bladder augmentation to date. Because of the substantial long-and short-term morbidity of augmentation cystoplasty, recent studies have tried to incorporate new techniques and technologies, such as the use of biomaterials to overcome or reduce the adverse effects. In this regard, homografts and allografts have been implemented in bladder augmentation with varying results, but recent studies have shown promising data in terms of proliferation of urothelium and muscle cells by using biological silk grafts.

Mucosectomy impairs ileal microcirculation and results in flap contraction after experimental ileocystoplasty

INTRODUCTION

Bladder augmentation with demucosalized ileal flap is a promising alternative approach for mucus free bladder augmentation; however, the contraction of the flap is still a major concern. It has been hypothesized that mucosectomy causes ischemic damage, but no direct histological evidence has been found and attention is now focused on the urothelium cover to prevent the exposure of the denuded surface to urine or the use of balloons to keep the flaps distended.

OBJECTIVE

Our aim was to study the effect of mucosectomy on the microcirculation of ileal flaps during reverse clam ileocystoplasty using direct intraoperative imaging of the ileum. Since the omentum is successfully used to revascularize ischemic tissue, we also examined whether omentopexy can prevent contraction.

STUDY DESIGN

Clam ileocystoplasty was performed in anesthetized minipigs with seromuscular (n = 3), seromusculo-submucosal (n = 3) reverse demucosalized ileal flaps. The velocity of the circulating red blood cells (RBCV) and the perfusion rate (PR) was measured with intravital videomicroscopy (Cytoscan A/R, Cytometrics, Philadelphia, PA, USA) before and after mucosectomy and the denuded surface of the ileum was covered with omentum after the reverse augmentation was complete (Figure). Animals were sacrificed after 8 weeks and the ileal flap dimensions were measured.

RESULTS

Significant reduction in RBCV and PR was detected after mucosectomy in both groups; however, no sign of acute flap necrosis or bladder perforation was seen. The omentum was found firmly attached to the ileal flaps, but contraction of the flaps was significant in both groups.

CONCLUSION

The disturbance in the microcirculation observed after mucosectomy may be responsible for flap contraction in ileocystoplasty with demucosalized ileum. Omentopexy did not help to prevent contraction.

DISCUSSION

Contraction of demucosalized intestinal flaps used for bladder augmentation has been frequently reported. This study provides direct evidence the first time for severely compromised microcirculation of the ileal flaps after mucosectomy. Limitation of the study is the relative low number of animals sacrificed.

Effects of augmentation cystoplasty on bladder contractility in rabbits

BACKGROUND/PURPOSE

An experimental study was conducted to investigate the effects of colocystoplasty and prefabricated cystoplasty on the bladder contractility in rabbits.

METHODS

Twenty-eight female New Zealand rabbits were randomly allocated into sham-operated controls, sigmoid enterocystoplasty (SECP), and prefabricated enterocystoplasty (PECP) groups. Augmentation cystoplasty with a 2-cm colon segment was performed in the SECP group. Mucosa was removed from the isolated sigmoid colon and covered with uroepithelial grafts from the bladder mucosa in the PECP group. Two weeks after the replacement of mucosa, enterocystoplasty was performed. Isometric contractions obtained by electrical field stimulation (EFS) and acetylcholine were evaluated in the bladder strips, 3 weeks after the operations.

RESULTS

Bladder strips obtained from the experimental groups displayed similar basal rhythmic activity. Electric field stimulation elicited a frequency-dependent contractile activity, which was lower between 1 to 20 Hz stimulation in the SECP- and PECP-operated animals. Acetylcholine elicited concentration-dependent contractions in all groups. Acetylcholine-induced contractile responses were greater in the PECP group.

CONCLUSIONS

This study demonstrated that an augmented bladder prepared either with a sigmoid colon or prefabricated seromuscular flap displayed contractile activity similar to normal bladder.

Bladder wall grafting in rats using salt-modified and collagen-coated polycaprolactone scaffolds: preliminary report

AIM

A rat model was used for the evaluation of collagen-coated and salt-modified polycaprolactone (PCL) scaffolds for bladder grafting after hemicystectomy.

METHODS

SD rats underwent partial cystectomy and cystoplasty with collagen-coated and salt-modified polycaprolactone scaffolds. The grafts of the regenerated bladder wall were harvested at different intervals and tissue regeneration was evaluated microscopically. Anatomic and functional characters were evaluated by cystography and urodynamics.

RESULTS

At harvesting, after 1 and 2 months, we found good preservation of the bladder shape and volume in all 16 rats receiving PCL cystorrhaphy. No stone formation was observed. Good epithelialization and ingrowth of smooth muscle cells were seen after 2 months grafting. Collagen-coated PCL scaffolds showed considerable encrustation, which appeared to be absorbed and disappear with time. The cystographic and urodynamic examinations revealed intact contour and a well-accommodated bladder with reservoir volume and contractility.

CONCLUSIONS

In the rat model, we have successfully demonstrated the applicability of collagen coated and salt-modified PCL in reconstruction of the partial cystectomized bladder.

Replacement of intestinal mucosa with urothelium in rat augmented bladders using intravesical photodynamic therapy with 5-aminolaevulinic acid

PURPOSE

We evaluated the efficacy of intravesical aminolevulinic acid (delta-aminolevulinic acid hydrochloride) (Frontier Scientific, Logan, Utah) and photodynamic therapy for the removal of small intestinal mucosa in augmented bladders in a rat model.

MATERIALS AND METHODS

Enterocystoplasty was performed in 70 female rats using a patch of terminal ileum. A total of 28 were used to determine the pharmacokinetics (0.3, 0.6 and 0.9 M) and dwell time (30, 60 and 90 minutes) of intravesically administered aminolevulinic acid to optimize intestinal mucosal absorption and minimize bladder mucosal absorption. The remaining augmented rats were treated with intravesical photodynamic therapy at light doses of 75, 100 and 125 J. Ileal and bladder tissues were evaluated by light microscopy. Cystometric studies to evaluate bladder volume were measured before and after photodynamic therapy.

RESULTS

The concentration of 0.3 M aminolevulinic acid with a dwell time of 30 minutes resulted in an average +/- SE bowel-to-bladder concentration of 2,156 +/- 269/749 +/- 62 ng/gm (ratio 2.9:1). After photodynamic therapy histology revealed uniform ablation and replacement of the intestinal mucosa with urothelium and minimal damage to the bladder wall at all light doses. Bladder cystometry revealed no significant change in bladder capacity after photodynamic therapy.

CONCLUSIONS

In the rat model intravesical aminolevulinic acid and photodynamic therapy resulted in the replacement of intestinal mucosa with urothelium, leaving the underlying muscular layer intact. This could potentially be a viable option for patients with a preexisting bladder augment.

Bladder wall replacement by tissue engineering and autologous keratinocytes in minipigs

OBJECTIVE

To develop a tissue-engineered bladder wall replacement with autologous cells and a biodegradable scaffold, as whenever there is a lack of native urological tissue the bladder is reconstructed with different bowel segments, which has inevitable complications.

MATERIAL AND METHODS

Skin biopsies were taken from six minipigs, and primary fibroblast and keratinocyte cell cultures established. A partial resection of the urinary bladder was reconstructed by a cell-seeded scaffold covered with completely differentiated epithelium and supported by a mucosa-free pedicled ileum graft. Each pig was assessed urodynamically and by cystography before operation and every month until explantation; the pigs were killed at 1, 2 and 3 months after augmentation. Control groups (of six pigs each) with bladder augmentation with complete or denuded ileum were used. The bladders were assessed histologically and by distensibility measurements

RESULTS

The differentiated keratinocyte epithelium was still present on the reconstructed bladder wall after 3 months. The overall shrinkage rate was 6.5%. The engineered bladder wall had lower distensibility than the native one. The inflammatory reaction present initially had disappeared after 3 months.

CONCLUSIONS

The implanted, tissue-engineered substitution of the bladder wall is not only a bridging graft, but also a complete reconstruction. With this model, extended bladder wall substitution seems feasible and should be investigated in further studies.

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.

Capsule induction technique in a rat model for bladder wall replacement: an overview

The search for a reliable technique for functional genitourinary tissue replacement remains a challenging task. The most recent advances in cell biology and tissue engineering have utilized various avascular and acellular collagen scaffolds with or without seeded cells. These techniques, however, are frequently complicated by tissue necrosis, contracture and resorption due to limited vascularization. We employed a new three-stage, evolving animal model with stage I optimizing the culture delivery vehicle, stage II employing a seeded vascularized capsule flap, and stage III adding a contractile matrix in the form of pedicled gracilis muscle prelaminated with autologous, in vitro-expanded urothelial cells to reconstruct an entire supratrigonal bladder-wall defect in rats.Specimens stained with hematoxylin and eosin (H&E), alpha(1)-actin staining, and a specific immunohistochemical staining (AE(1)&AE(3)-anticytoceratin monoclonal antibody stain) showed a continuous, multilayered, functioning urothelial lining along the transposed prelaminated gracilis flap in the animals of the final-stage experiment. Successful urinary reconstruction requires a contractile neoreservoir resistant to resorption over time and a stable, protective urothelial lining. We demonstrated that a gracilis muscle flap can be seeded with autologous cultured urothelial cells suspended in fibrin glue. This prelaminated flap can be safely transposed onto its pedicle and become successfully integrated into the remaining bladder wall, demonstrating urothelial lining and the potential to contract. Further studies in larger animals with urodynamic assessment is warranted to determine if this type of bladder-wall replacement technique is suitable for urinary reconstruction in humans.

Transplantable Urothelial Cell Sheets Harvested Noninvasively from Temperature-Responsive Culture Surfaces by Reducing Temperature

Augmentation cystoplasty using gastrointestinal flaps may induce severe complications such as lithiasis, urinary tract infection, and electrolyte imbalance. The use of viable, contiguous urothelial cell sheets cultured in vitro should enable us to avoid these complications. Transplantable urothelial cell sheets were obtained by utilizing a temperature-responsive cell culture method, and then examined by immunostaining and electron microscopy. Canine urothelium was produced on the surfaces of temperature-responsive culture dishes covalently bonded with the thermally sensitive polymer, poly(N-isopropylacrylamide). Stratified urothelial cell sheets were cultured and then harvested intact without enzymatic treatment from these dishes by reducing the temperature. Histological structure and cell-to-cell junctions were compared between these urothelial cell sheets and those harvested with dispase. All urothelial cell sheets were harvested from the bonded surfaces by reducing the culture temperature without the need for dispase. Electron microscopy revealed well-developed microridge, microvilli, and cell junction complexes. Conversely, these same cell features were destroyed by dispase treatment. Immunoblotting revealed that dispase fragmented occludin, whereas it remained unchanged in the intact urothelial cell sheets. Novel urothelial cell sheets obtained by culture on temperature-responsive culture surfaces were successfully harvested much less destructively than with dispase. This technology should prove useful in urinary tract tissue engineering in the near future.

The use of silver nitrate for chemical de-epithelialization and urothelialization of intestine in a rabbit model of augmentation cystoplasty

Urinary tract reconstruction using bowel segments can result in complications such as electrolyte abnormalities, infections, stones and cancer. Intestinal mucosa is the primary site responsible for these complications. De-epithelialization of the mucosa and subsequent urothelialization might alleviate these problems. We recently reported our success in de-epithelialization and subsequent uroepithelialization of intestinal segments using 10 g/100 ml AgNO(3) solution in a rat model of augmentation. In this study, chemical de-epithelialization of a colonic segment was attempted using 10 g/100 ml AgNO(3) solution in a rabbit model of augmentation. Sigmoid cystoplasty was performed in 20 male New Zealand rabbits using a 6 cm patch of sigmoid colon. There were two groups, including one group of five rabbits (control, group 1) that underwent augmentation alone, while another group (15 rabbits, treatment group or group 2) was treated with 10 g/100 ml AgNO(3 )solution before augmentation. Control rabbits were killed at the week 8 of experimentation. Treatment rabbits were killed at 2-, 4-, 6- and 8-week intervals. Immediately before augmentation and at the end of the 8 week experimental period each rabbit underwent cystometry. De-epithelialization of the bowel epithelium without urothelialization was apparent in the treatment rabbits killed at 2 and 4 weeks. Histological analysis revealed almost complete urothelialization of the augmented sections treated with 10 g/100 ml AgNO(3 )solution at the end of the 6 and 8 week of experimental periods. The preoperative and postoperative bladder capacities increased substantially in all groups. There was no obvious histologic difference in the amount of collagen present in the augmented tissues in any of the experimental groups. The present study confirmed that the treatment of intestinal segments with 10 g/100 ml AgNO(3 )solution led to chemical de-epithelialization and urothelialization of the augmented segments. This procedure could, theoretically, have applications to human surgery.

Advances in bladder augmentation

Over the past 20 years, rapid advances have been made in bladder augmentation due to the introduction of clean intermittent catheterization, the use of intestinal segments interposed into the urinary tract, and the development of tissue expansion. The particular augmentation method selected from the multiple methods currently available is an individualized process that takes into account both patient factors and potential complications. Exciting new techniques, such as tissue engineering, may change the face of lower urinary tract reconstruction.

The long-term culture of porcine urothelial cells and induction of urothelial stratification

OBJECTIVE

To assess porcine urothelial cell cultures and the in vitro induction of urothelial stratification in long-term cultures, to study their morphological, functional and genetic behaviour, and thus provide potential autologous urothelium for tissue-engineered substitutes for demucosalized gastric or colonic tissue.

MATERIALS AND METHODS

Primary cultures of porcine urothelium were established and the cells passaged thereafter. Cell specificity was confirmed by cytokeratin analysis, cell membrane stability assessed using lactate dehydrogenase leakage, cell de-differentiation by gamma-glutamyl transferase activity and genomic stability by karyotype investigations. Histology and scanning electron microscopy were performed to study the cultured cells and the stratified constructs. Furthermore, collagen matrices were tested as cell scaffolds.

RESULTS

The cells were cultured for 180 days; 10 subcultures were established during this period. Stratification was induced in a culture flask and on a collagen matrix. Cytokeratins 7, 8, 17 and 18 were expressed in all cultures, and cell membranes were stable, with no evident de-differentiation. The cultures were stable in their genotype and no chromosomal aberrations were found. The histology and immunohistochemistry of the stratified porcine constructs, and cell membrane stability and cell de-differentiation, were compared with those in the human system.

CONCLUSION

Pig and human urothelial cells can be cultured over a long period with no signs of senescence. Urothelial stratification can be induced in vitro. The collagen matrix seems to be an excellent scaffold, allowing cell adherence and growth.

Bladder augmentation with different forms of intestinal grafts: an experimental study in the pig

OBJECTIVE

To create an experimental animal model to examine changes in bladder volume and histology after bladder augmentation in growing individuals and from the model, evaluate a method using demucosalized intestinal grafts and short-term bladder drainage.

MATERIALS AND METHODS

The study comprised 21 piglets: in group 1, seven underwent a sham operation; in group 2, seven piglets underwent bladder augmentation with full-thickness caecum after a major bladder resection; in group 3 seven underwent the same procedure but with demucosalized caecum. The bladder volume and area of the intestinal segment were measured peroperatively and when the animals were killed 2 months later. Bladder specimens were taken for histological examination.

RESULTS

The mean preoperative bladder volumes were similar among the groups; in the control group, volumes increased from 58 to 165 mL and in group 2 from 63 to 255 mL, with an increase in area of the intestinal segment from 59 to 138 cm2. In group 3 the volume was unchanged, from 63 to 71 mL, with a decrease in area from 58 to 5 cm2. Control bladders showed normal urothelium with neutral mucins and sialomucins. In group 2, there was metaplasia in the border between urothelium and colonic epithelium, with enhancement of sialo- and sulphomucins. Demucosalization resulted in extensive fibrosis, with a monolayer of urothelial cells showing metaplasia.

CONCLUSIONS

The experimental model was successful; the observed changes in bladder volume correlated well with the fate of the intestinal implant, because the bladder resection was major. This is essential, as the bladder remnant has some growth potential. Full-thickness grafts grew faster than the normal bladder. Mechanical demucosalization, including submucosa, results in shrinkage despite short-term drainage. Glandular metaplasia, with production of sialomucins and sulphomucins, occurs at the junction between bladder and colon, irrespective of mucosal removal.

Bladder autoaugmentation in the rabbit using de-epithelialized segments of small intestine, stomach and lyophilized human dura mater

OBJECTIVE

To develop an animal model of partial detrusorectomy (autoaugmentation) and thus avoid the consequences of the direct contact of intestinal mucosa with the urinary tract in bladder augmentation.

MATERIALS AND METHODS

A diverticular urothelial bulge was created and patched with demucosalized segments of small bowel (group A), stomach (group B) and with lyophilized human dura mater (group C). The surgery was performed on 50 New Zealand rabbits which were compared with 10 control animals and killed at 2, 4 and 6 weeks after surgery. Urodynamic studies and cystography were performed before operation and at death, and the augmented bladders examined histologically.

RESULTS

Six weeks after the procedure, the mean (SD) bladder compliance was 22.7 (5.7) in group A (intestinal patch. n = 6). 2.3 (0.5) in group B (stomach patch, n = 3). 3.1 (1.9) in group C (lyophilized human dura, n = 3) and 9.4 (0.4) in the control group (n = 4). Histological studies showed residual enteric and gastric mucosa but an intact urothelium under the intestinal patch.

CONCLUSION

The results of this experimental study suggest that a demucosalized segment of small bowel is the best material to increase bladder compliance in detrusorectomy (autoaugmentation) as applied in this animal model.

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.

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.

Cultured urothelium in sheep bladder augmentation

In search of alternatives for urothelial-lined augmentation or reconstruction of the urinary bladder, this study combined the application of seromuscular gastrointestinal (GI) segments with the use of in-vitro cultured, autologous urothelial cells in a sheep model. A cell culture system was set up for establishment and expansion of urothelial cells out of small biopsies from bladder mucosa. A biodegradable carrier made of lactidcaprolactoncopolymer was introduced, allowing upside-down transplantation of cell cultures in vivo. Bladder mucosal biopsies were taken from 14 sheep (mean weight 13.3 kg) with an average yield of 3.5×10(5) viable cells/cm(2) after trypsinization. Primary low-density cultures grew to confluence within 5-7 days. Secondary cultures were established on the biodegradable film and were available a week later. They were transplanted onto demucosalized segments of stomach (group 1) or colon (group 2) in 5 animals each, followed by bladder incorporation in clam fashion. The earliest specimens, demonstrating survival and some proliferation of the cultured urothelium in both groups, were obtained 13 days postoperatively. To exclude urothelial regrowth, a temporary pouch grafted with cultured urothelium was created in 2 more sheep of each group. Biopsies were taken after 2 and 3 weeks, respectively, when the reopened pouch was integrated into the bladder (delayed augmentation). In these pouches, adherence and proliferation of urothelial cells could not be demonstrated. Limited radiologic and urodynamic investigations after 5-6-month follow-up revealed good shape, capacity, and compliance of the primarily augmented bladders only. The results indicate that urothelial cell cultures can be established and applied in vivo. Despite upside-down transplantation, they are able to survive on seromuscular segments in an autologous setting. The bladder environment is necessary to promote complete covering of the seromuscular segments. Based on our histologic findings, the share of both resident bladder urothelium and transplanted cells in the formation of the final urothelial lining remains uncertain. Morphologic and urodynamic follow-up data indicate that this process can be accelerated by the transplanted urothelial cells, reducing fibrotic changes of the GI segments. The functional quality of the augmented bladder seemed to improve compared to results after seromuscular augmentation alone.

Enzymatic treatment of ileal segments used for urinary tract reconstruction

Urinary tract reconstruction by using various gastrointestinal segments is not devoid of complications which may hamper to a great extent the beneficial effects of the procedure. Intestinal mucosa is the primary site responsible for these complications and any procedure aiming at the prevention of untoward effects of intestinal interposition should abolish the absorptive and secretory functions of the mucosa. Augmentation cystoplasties by ileal segments were performed on 24 male albino Wistar rats. In 12 animals de-epithelialization of the mucosa with an enzymatic cock-tail, consisting of type I and type V collagenases and trypsin, preceded the cystoplasty. The functional capacity of the epithelium was determined by a simplified glucose absorption test in the third postoperative week. Morphological examination before the absorption test did not reveal any fibrosis or shrinkage of the ileal segments. Complete elimination of the absorptive capability in enzyme treated mucosa was found during the glucose absorption test, while a rapid and highly effective absorption was observed in the control group (p < 0.05). As a result, it seems possible to obtain intestinal segments covered with a mucosa which acquired similar characteristics to uro-epithelium, therefore closely resembling the original urinary tissues.

Late follow up of autoaugmentation omentocystoplasty in a sheep model

Four male sheep were studied 12 months after an autoaugmentation omentocystoplasty (AAOC). The omentum was lined with urothelium, but continued inflammation and/or fibrosis were seen within the subepithelial tissues associated with a failure to achieve enlargement of the bladder when compared with a control group of six animals. The median compliance value was 5.9 mL/cm H2O for the AAOC animals and 9.8 mL/cm H2O for the control group, indicating that no improvement in bladder dynamic function had been achieved with the AAOC in sheep, and no significant improvement had occurred with time when the results were compared with those seen 6 months earlier.

Enterocystoplasty using modified pedicled, detubularized, de-epithelialized sigmoid patches in the mini-pig model

Enterocystoplasty and gastrocystoplasty have been developed to restore adequate bladder capacity but they still result in the undesired harmful contact of urine with the intestinal mucosa. In an attempt to prevent this nonphysiological interface we performed several modified enterocystoplasties in the mini-pig model using a pedicled, detubularized, de-epithelialized sigmoid patch. Five techniques of patch coverage were used to evaluate urothelial growth or survival on the sigmoid patch. All but 1 patch had intestinal mucosa remnants with mucocele formation. When no coverage was applied or a biodegradable polyglactin mesh was temporarily covering the pedicled, detubularized, de-epithelialized sigmoid patch, severe shrinkage occurred. Partial cover with autologous urothelium islets seemed to decrease shrinkage. Adequate urothelium survival and satisfactory elastic properties of the patch were observed when total cover of the sigmoid patch was achieved with a sheet of homologous urothelium recovering autologous urothelial islets or when the patch was applied to protruding urothelium obtained following sagittal posterior detrusor myotomy.

Intestinal de-epithelialization and augmentation cystoplasty: an animal model

OBJECTIVES

An animal model of augmentation cystoplasty was developed in New Zealand rabbits to study the effects of intestinal de-epithelialization on subsequent re-epithelialization by bladder urothelium.

METHODS

Twenty-four rabbits underwent augmentation cystoplasty using intestinal segments that were either treated with protamine sulfate and urea solution or else anastomosed with an intact epithelium. Half of the rabbits receiving the de-epithelialized intestinal segments were subjected to glycosaminoglycan replacement therapy by administration of intravesical heparin. Experimental and control rabbits were sacrificed at 1-, 2-, and 3-month intervals.

RESULTS

Histologic examination of the augmented sections showed small areas of urothelium growing over the intestinal epithelium (approximately 15%). The heparin-treated group demonstrated the greatest amount of re-epithelialization. There was no obvious histologic difference in the amount of collagen present in the augmented tissues in any of the experimental groups.

CONCLUSIONS

In a preliminary study, New Zealand rabbits appear to be satisfactory as an experimental animal for studying the augmentation cystoplasty procedure and for the development of therapeutic interventions for enhancing epithelial growth. Protamine and urea will de-epithelialize the bowel and heparin may promote epithelialization of augmented intestinal segment by transitional epithelium.

Nonsecretory sigmoid cystoplasty: experimental and clinical results

We report the results of experimental and clinical studies in which a de-epithelialized segment of sigmoid colon was used to cover the bladder dome where the mucosa was exposed (auto-augmentation) to increase bladder capacity. Experimentally, the technique was performed in 10 healthy female mongrel dogs and the intestinal segments established continuity perfectly over the exposed bladder mucosa. Histology 30 and 60 days postoperatively showed transitional epithelium lining the intestinal segment at the site of implantation. One island of intestinal mucosa was found. The technique was performed in 10 patients, including 9 with neurogenic bladder secondary to myelomeningocele and 1 with posterior urethral valves. Bladder capacity improved in all cases and intravesical pressure was reduced. Followup ranged from 6 to 43 months. The technique is proposed as a valuable alternative to traditional full-thickness patches of the digestive tract and auto-augmentation.

Reversed seromuscular flaps in the urinary tract in dogs

Reversed seromuscular flaps of ileum and standard bowel replacement procedures were performed in 16 dogs to evaluate their potential to decrease the likelihood of recognized complications in cases of standard bowel replacement. Of 12 dogs augmentation cystoplasty was done in 6 and ureteral replacement was done in 6. In each group 4 procedures were performed using reversed seromuscular flap, while the remaining 2 were done in the conventional manner (controls). All flap animals had partial to full re-epithelialization with transitional cells but they also had gross and microscopic evidence of flap contraction at the end of 6 months. In the flap augmentation group intravesical pressure measured preoperatively at bladder volumes of 30 cc and 60 cc averaged 25.8 and 45.8 mm. Hg compared to sacrifice pressures of 56.7 and 80.8 mm. Hg. Monthly serum blood urea nitrogen measurements were lower in reversed seromuscular flap animals compared to controls. An additional 4 dogs were studied to help elucidate the etiology of graft contraction, of which 2 underwent reversed seromuscular flap enterocystoplasty with no mucosal stripping while 2 had a procedure exposing intact intestinal serosa to the lumen of the bladder and urine. All of these animals demonstrated good re-epithelialization of the serosal surface with transitional cells as well as little or no evidence of flap fibrosis or contraction. Our results demonstrate that the use of reversed seromuscular flaps in the urinary tract in dogs results in good re-epithelialization of the serosal surface with transitional cells but also flap contraction. This fibrosis and scarring process is largely due to the trauma of mucosal stripping and not urine contact.

Photochemical ablation of intestinal mucosa for bladder augmentation

Complications associated with enterocystoplasty include mucus production, electrolyte abnormalities, infections, stones and cancer at the vesicoenteric anastomosis. Removal of the intestinal mucosa with subsequent urothelialization may obviate these problems. We describe a unique approach whereby photodynamic therapy is used to de-epithelialize an ileal segment before augmentation. Enterocystoplasty was performed in 32 female Fischer 344 rats using a 1.5 cm. patch of terminal ileum. Of the 32 rats 24 survived at least 6 weeks before euthanasia. The experimental group (10 rats) received hematoporphyrin derivative intravenously 24 hours before surgery. The ileal patch was treated with red light for 20 minutes and then used for augmentation. There were 3 control groups, including 1 group of 5 rats that underwent augmentation alone, while the other 2 groups were augmented but received either light treatment (4 rats) or hematoporphyrin derivative (5 rats). Histological analysis revealed urothelialization of the augments treated with hematoporphyrin derivative and light, which did not occur in the controls. The preoperative and postoperative bladder capacities increased substantially in all groups. Mucus production and bacterial colonization were reduced while stone formation increased in the treated animals.

Autoaugmentation gastrocystoplasty: early clinical results

OBJECTIVE

To assess the urodynamic and clinical outcome of five patients following an autoaugmentation gastrocystoplasty.

PATIENTS AND METHODS

Four patients, two boys and two girls aged between 8 and 16 years, with a neuropathic bladder and incontinence, and one boy, aged 16 years, with an ileal conduit were included in the study. The bladder augmentation technique combined autoaugmentation and the addition of a demucosalized patch of gastric muscle to the created bladder diverticulum.

RESULTS

All patients have improved bladder function, although one may require further surgery. Three had temporary difficulty tolerating full meals.

CONCLUSIONS

This new technique seems to have a place in the management of the neuropathic bladder, but further laboratory study and cautious clinical application is required to ascertain its role in bladder augmentation.

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.

Morphological analysis of ileal grafting following ileocystoplasty in the rat: a kinetic and ultrastructural study of the intestinal epithelium

Ileocystoplasty was performed in rats and the morphological and cell-kinetic changes occurring in the ileal grafts were determined at intervals up to 18 months postoperatively. The intestinal mucosa underwent no progressive changes but included villous and avillous regions associated with crypts of various sizes at all time intervals. Newly appearing and densely packed epithelial cells, shaped like petals, were always present in the lower parts of the villi associated with crypts showing no elongation, but seldom present in those with elongated crypts in the villous mucosa. Bromodeoxyuridine studies showed that the petal-shaped cells interfered with cell migration. No petal-shaped cells were observed in avillous mucosa in which the rate of cell turnover depended on crypt size. Fine-structural changes in absorptive epithelial cells in both types of mucosa included features of prematurity or hypermaturity in the cytoplasm and close adherence to the basal portions of adjacent cells and to the basal lamina. These changes may possibly contribute to the prevention of reabsorption of urine. However, some of the mechanisms responsible for adherence of the basal parts might incidentally interfere with the normal cell kinetics of the intestinal epithelium, resulting in dense packing of cells and the formation of multiple types of mucosa in ileal grafts.

Autoaugmentation omentocystoplasty in a sheep model

OBJECTIVE

To develop a sheep model of autoaugmentation omentocystoplasty and study the histologic appearance, and to compare the urodynamic results with a control group.

METHODS

Ten male lambs underwent a bladder autoaugmentation reinforced with an omental patch. Three were culled early, to study urothelial survival and inflammatory changes. One was sacrificed at six months to assess late histologic changes; five sheep had a urodynamic study at that stage and two died of unknown causes without further investigation. A group of seven six-month-old male sheep, of similar weights, formed the control urodynamic group.

RESULTS

The urothelial lining remained viable under the omentum, but marked inflammation and heterotopic calcification were seen within the subepithelial tissues in most of the animals. The histologic changes were reflected in the bladder dynamic data, which were no better than the control group; the average compliance value was 9.2 +/- 6.4 mL/cm H2O, compared to the control group figure of 11.8 +/- 5.2 mL/cm H2O.

CONCLUSIONS

It would appear that autoaugmentation alone does not usually produce bladder augmentation in the sheep.

Urothelial tissue culture for bladder reconstruction: an experimental study

An in vitro system for the growth of normal human urothelial cells has been developed. Urothelial cells were isolated from tissue samples in 38 patients and cultured in a defined serum-free medium. Confluent cell monolayers of 25 cm.2 were produced after 7 days in 32 cases. Subsequent subcultures at a 1:20 split ratio achieved confluency within another 7 days and a consistently high rate of growth was sustained for at least 7 passages. Characterization by immunofluorescence with a panel of antibodies demonstrated that the cultured cells were exclusively epithelial and retained the characteristic antigenic profile of normal urothelium, even after extended periods in culture. The only consistent cause of failure (6 of 38 cases) was bacterial contamination secondary to an underlying urinary tract infection in these patients.

Autoaugmentation gastrocystoplasty in a sheep model

Ten lambs had their bladders augmented with de-epithelialised stomach muscle added to an intact urothelium. They were assessed functionally and histologically up to 2 months post-operatively. The urothelium remained viable with minimal inflammation and a neo-bladder with good volume was formed.

Augmentation ureterocystoplasty

Augmentation cystoplasy using the gastrointestinal tract has disadvantages related to the intestinal resection and its incorporation into the urinary tract. To preclude both sets of complications, we performed augmentation ureterocystoplasty in a 5 1/2-year-old meningomyelocele patient with urinary incontinence, a low capacity bladder, severe vesicoureteral reflux and a poorly functioning kidney. After nephrectomy the ureter was incised longitudinally, folded over and placed onto the bladder as a patch. Bladder capacity, only 60 cc without the contribution from the refluxing upper tract, increased to 200 cc 6 months postoperatively. The patient is continent. Augmentation ureterocystoplasty is an option for bladder enlargement that obviates many of the risks associated with enterocystoplasty.

Seromuscular enterocystoplasty in rats

Enterocystoplasty is commonly used in clinical practice. Many of its undesirable effects, that is infections, stones, mucus production, absorption of urinary components into the blood stream and risk of cancer, result from the intestinal mucosa lining the urinary tract. We report on the feasibility of creating an enterocytoplasty with a seromuscular colonic segment that acquires a transitional epithelial lining. Augmentation enterocystoplasty was performed in 51 male, 500 gm., Sprague-Dawley rats with a 1.82 cm.2 patch of left colon from which the mucosa had been stripped. The serosal surface was used as lining for the enterocystoplasty. The intestinal patch and the bladder capacity at known pressure were measured at operation and at sacrifice. The histology of the enterocystoplasty was studied in detail following sacrifice. Of the animals 40 survived without significant complications and were sacrificed at a mean postoperative time of 30 days (range 5 to 80 days). In the remaining 11 rats a bladder stone developed but it did not seem to affect the outcome of the experiment. The size of the patch could be measured in 22 rats: it was 1.82 cm.2 (standard deviation +/- 0.86) at operation and 2.30 cm.2 (standard deviation +/- 1.1) at sacrifice. In none of the rats did the patch decrease in size. The bladder capacity at a known pressure (mean 17 cm. water) could be measured in 26 animals: it was 2.35 ml. (standard deviation +/- 0.65) at operation and 5.18 ml. (standard deviation +/- 1.19) at sacrifice. Histological analysis was done in 40 rats. In all cases the serosal surface was lined with transitional epithelium, there was no fibrosis or inflammation and the structure of the muscular layer of the bowel remained intact. The earliest growth of uroepithelium in the serosal surface of the bowel was noted at 5 days. This model suggests that the seromuscular enterocystoplasty can be constructed successfully in the rat model. The seromuscular intestinal patch does not shrink. The bladder capacity increases and histology shows a uroepithelial lining of the augmentation.