Metabolic complications of urinary intestinal diversion

Regenerative medicine strategies for treatment of neurogenic bladder

Neurogenic bladder is a general term encompassing various neurologic dysfunctions in the bladder and external urethral sphincter caused by damage or disease. Therapeutic management options fall into the categories of conservative, minimally invasive or surgical. The current standard for surgical management is bladder augmentation using intestinal segments. However, because intestinal tissue possesses different functional characteristics to bladder tissue, numerous complications can ensue. Regenerative medicine uses combinations of cells and/or biomaterials to encourage regeneration of healthy tissue and offers an alternative approach for the replacement of lost or deficient organs, including the bladder. Promising results using the principles of regenerative medicine have already been obtained in children with neurogenic bladder caused by myelomeningocele. Human clinical trials, governed by the US FDA, are ongoing in the USA in both children and adults to further evaluate the safety and efficacy of this technology for regenerating bladders. More studies are in progress and additional advances in this field can be anticipated.

Updates on stem cells and their applications in regenerative medicine

Stem cells have the capacity for self-renewal and capability of differentiation to various cell lineages. Thus, they represent an important building block for regenerative medicine and tissue engineering. These cells can be broadly classified into embryonic stem cells (ESCs) and non-embryonic or adult stem cells. ESCs have great potential but their use is still limited by several ethical and scientific considerations. The use of bone marrow-, umbilical cord-, adipose tissue-, skin- and amniotic fluid-derived mesenchymal stem cells might be an adequate alternative for translational practice. In particular, bone marrow-derived stem cells have been used successfully in the clinic for bone, cartilage, spinal cord, cardiac and bladder regeneration. Several preclinical experimental studies are under way for the application of stem cells in other conditions where current treatment options are inadequate. Stem cells can be used to improve healthcare by either augmenting the body's own regenerative potential or developing new therapies. This review is not meant to be exhaustive but gives a brief outlook on the past, present and the future of stem cell-based therapies in clinical practice.

Feasibility study of a novel urinary bladder bioreactor

We have devised a bioreactor to simulate normal urinary bladder dynamics. The design permits a cell-seeded scaffold made from a modified porcine acellular matrix to be placed between 2 closed chambers filled with culture medium and be mechanically stimulated in a physiologically relevant manner. Specifically designed software increased hydrostatic pressure from 0 to 10 cm of water in a linear fashion in 1 chamber, resulting in mechanical stretch and strain on the scaffold. Pressure was increased over 55 min (filling) and then decreased to 0 over 10 s (voiding). Commercially available small intestinal submucosa scaffolds were used to test the mechanical capabilities of the bioreactor, and pressure waveforms were generated for up to 18 h. Scaffolds were seeded with bladder smooth muscle or urothelial cells and incubated in the bioreactor, which generated pressure waveforms for 6 h. Scaffold integrity was preserved as seen through Masson's trichrome staining. No obvious contamination of the system was noted. Hematoxylin and eosin staining showed presence of cells after incubation in the bioreactor, and immunohistochemistry and real-time reverse transcriptase polymerase chain reaction suggested continued cellular activity. Cellular orientation tended to be perpendicular to the applied pressure. Preliminary results suggest that our bioreactor is a suitable model for simulating normal physiological conditions of bladder cycling in an ex vivo system.

Bioengineered tissues for urogenital repair in children

The most common congenital abnormalities involve the genitourinary system. These include hypospadias, in which the urethral opening develops in an improper position, and bladder exstrophy, in which the bladder develops on the outer surface of the abdomen. Children with these conditions will require immediate and multiple reconstructive surgeries. Currently, reconstruction may be performed with native nonurologic tissues (skin, gastrointestinal segments, or mucosa), homologous tissues from a donor (cadaver or living donor kidney), heterologous tissues or substances (bovine collagen), or artificial materials (silicone, polyurethane, teflon). However, these materials often lead to complications after reconstruction, either because the implanted tissue is rejected, or because inherently different functional parameters cause a mismatch in the system. For example, replacement of bladder tissue with gastrointestinal segments can be problematic due to the opposite ways in which these two tissues handle solutes-urologic tissue normally excretes material, and gastrointestinal tissue generally absorbs the same materials. This mismatched state can lead to metabolic complications as well as infection and other issues. The replacement of lost or deficient urologic tissues with functionally equivalent ones would improve the outcome of reconstructive surgery in the genitourinary system. This goal may soon be attainable with the use of tissue engineering techniques.

A review of metabolic consequences and long-term complications of enterocystoplasty in children

This review summarizes the important metabolic consequences and long-term complications associated with enterocystoplasty, with a particular emphasis on the pediatric patient with genitourinary abnormalities. A directed Medline literature review for metabolic and long-term complications following enterocystoplasty was performed. Information gained through published literature and from our database was reviewed and summarized to provide the reader with a thorough review of the subject. Bowel is not a perfect tissue for substitution or augmentation, and its use to treat functionally and structurally compromised bladders is associated with several metabolic consequences and long-term complications. Metabolic acidosis is the most common metabolic abnormality seen. The rates and severity of these complications vary, though they may have a profound impact on a patient's quality of life after enterocystoplasty. The metabolic consequences and long-term complications associated with enterocystoplasty are important clinical features of this intervention, and careful consideration should be given to them before pursuing enterocystoplasty.

Regenerative Medicine: Applications and Development in Urology

Purpose

Congenital abnormalities and acquired disorders can lead to organ damage and loss. Nowadays, transplantation represents the only effective treatment option. However, there is a marked decrease in the number of organ donors, which is even yearly worsening due to the population aging. The regenerative medicine represents a realistic option that allows to restore and maintain the normal functions of tissues and organs. This article reviews the principles of regenerative medicine and the recent advances with regard to its application to the genitourinary tract.

Recent findings

The field of regenerative medicine involves different areas of technology, such as tissue engineering, stem cells and cloning. Tissue engineering involves the field of cell transplantation, materials science and engineering in order to create functional replacement tissues. Stem cells and cloning permit the extraction of pluripotent, embryonic stem cells offering a potentially limitless source of cells for tissue engineering applications. Most current strategies for tissue engineering depend upon a sample of autologous cells from the patient's diseased organ. Biopsies from patients with extensive end-stage organ failure, however, may not yield enough normal cells. In these situations, stem cells are envisaged as being an alternative source. Stem cells can be derived from discarded human embryos (human embryonic stem cells), from fetal tissue or from adult sources (bone marrow, fat, skin). Therapeutic cloning offers a potentially limitless source of cells for tissue engineering applications. Regenerative medicine and tissue engineering scientists have increasingly applied the principles of cell transplantation, materials science and bioengineering to construct biological substitutes that will restore and maintain normal function in urological diseased and injured tissues such as kidney, ureter, bladder, urethra and penis.

Conclusions

Regenerative medicine offers several applications in acquired and congenital genitourinary diseases. Tissue engineering, stem cells and, mostly, cloning have been applied in experimental studies with excellent results. Few preliminary human applications have been developed with promising results.

[Metabolic aspects of bowel use in urologic surgery]

Urinary diversion, pouches and orthotopic bladder replacement have been made possible by the use of bowel segments in urologic surgery. The most important complications at short and long-term are metabolic disorders due to the permanent contact of urine with the bowel segment or the exclusion of this segment from bowel continuity. Metabolic acid-base problems occur immediately after the derivation beginning and depend on the renal capacity to compensating. The metabolic disorder due to the exclusion of a bowel segment appears generally years later, after complete depletion of physiologic reserves (vitamin B12). Perfect knowledge of early and late metabolic complications of urinary diversion allows a more accurate indication, a more adequate selection of the derivation type, an improved patient followup, and better long-term results. Metabolic complications constitute the best selection criteria for urinary diversion; subsequently, only a few techniques are likely to persist in the future.

Increased urologic complications in children after kidney transplants for obstructive and reflux uropathy

In the cyclosporine era, reports on pediatric kidney transplant (KTx) patients with obstructive and reflux uropathy are limited by small numbers, short follow-up, and/or lack of control groups. Our single-center study evaluated long-term outcomes (patient and graft survival, urinary tract infections [UTIs], urologic complications) in a large cohort of KTx recipients (<20 years old). We matched our 117 study patients with obstructive and reflux uropathy with 117 controls whose KTx was needed for other reasons; all 234 underwent their KTx between April 25, 1984, and October 23, 2002. The mean age was 8.0 +/- 6.2 years; mean follow-up, 133 +/- 67 months. The urologic complication rate was higher in study patients (43%) than in controls (11%) (p < 0.0001), as was the UTI rate (45% vs. 2%; p < 0.0001). The metabolic acidosis and UTI rates were higher in study patients who did (vs. did not) undergo bladder augmentation (p < 0.0001). We found no significant difference between study patients and controls in patient or graft survival, acute or chronic rejection, or mean estimated glomerular filtration rates. Unique to our study is the finding of higher metabolic acidosis and UTI rates in study patients who underwent bladder augmentation.

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.

Time-Dependent Neovasculogenesis and Regeneration of Different Bladder Wall Components in the Bladder Acellular Matrix Graft in Rats

OBJECTIVES

To determine the time-dependent regeneration of different cellular components in the bladder acellular matrix graft (BAMG) and the involvement of hematopoietic stem cells in BAMG vascular regeneration.

METHODS AND MATERIALS

Thirty-three male Sprague Dawley rats underwent partial cystectomy and the acellular matrices were grafted to the remaining host bladder. At 4, 7, 14, 30, 60, 90, and 180 d after grafting, animals were sacrificed and their bladders were excised and paraffin-embedded. Tissue sections were stained for determination of CD3, CD20, CD34, CD31, CD68, smooth muscle cell (SMC) alpha-actin, and neurofilament protein as well as elastin fibers and collagen typing. Cystometric evaluation of grafted bladders was also performed 3 mo after procedure.

RESULTS

In acellular matrices, there was no expression of cellular markers and type-1 collagen fibers were predominant. One month after surgery, all grafted matrices were completely lined with urothelium. Polymorphonuclear cells and lymphocytes densely infiltrated BAMG during the first 2 wk after grafting; however the inflammation resolved by the first post-surgical mo. CD34+ endothelial progenitor cells (EPCs) were found in all grafts 4 d after surgery. The number of CD34+ cells increased continuously and peaked 2 mo after grafting. The increment in number of CD31+ microvessels in grafted matrices followed that of CD34+ cells and reached 144.5% of control values at third post-surgical mo. The mean number of CD34+ and CD31+ cells returned to control ranges by 6 mo after grafting. Expression of SMC alpha-actin was first visualized on day 4 and alpha-actin intensity reached to control values 6 mo after grafting. Neural elements appeared 1 wk after grafting and just 60% of normal intensity was achieved by the sixth post-surgical mo; however complete nerve bundles were found in all grafted matrices after 1 mo. Cystometric studies revealed higher bladder capacity and compliance but lower maximum intravesical pressure in grafted bladders in comparison with controls, 3 mo after surgery.

CONCLUSIONS

Our results demonstrate the effective cellular regeneration in BAMG and propose a considerable role for the CD34+ EPCs in the neo-vasculogenesis of the grafts.

Transplantation of Preserved Human Amniotic Membrane for Bladder Augmentation in Rats

Although gastrointestinal segments have been widely used for bladder reconstruction, they are not ideal because of the possible complications. Searches have therefore continued for an alternative material for augmentation. Here, we performed bladder augmentation in rats using human amniotic membrane (hAM). Morphologically, the hAM-augmented bladder revealed regeneration of urothelium, detrusor smooth muscle, and nerve fibers within 3 months post-operatively. In our functional evaluation of bladder strips, we compared hAM-augmented bladders with bladders augmented using small intestinal submucosa (SIS). For example, at 6 months post-operatively, contractions of the following size (as a percentage of the responses in the control-bladder group) were obtained in response to high potassium, carbachol, and electrical field stimulation, respectively: hAM 22% vs SIS 15%, hAM 15% vs SIS 7%, hAM 5.3% vs SIS 1.3% (no significant differences, hAM vs SIS). Both hAM- and SIS-augmented bladders displayed adequate capacity and compliance. The present results indicate that, for bladder augmentation, hAM can be used as a scaffold and is comparable in this respect with SIS. hAM can be more easily obtained than SIS and requires little preparation, and its use raises few ethical questions. Hence, hAM may represent a new therapeutic alternative for urological reconstructions.

Different Types of Scaffolds for Reconstruction of the Urinary Tract by Tissue Engineering

INTRODUCTION

Tissue engineering is an important and expanding field in reconstructive surgery. The ideal biomaterial for urologic tissue engineering should be biodegradable and support autologous cell growth. We examined different scaffolds to select the ideal material for the reconstruction of the bladder wall by tissue engineering.

MATERIALS AND METHODS

We seeded mouse fibroblasts and human keratinocytes in a co-culture model on 13 different scaffolds. The cell-seeded scaffolds were fixed and processed for electron microscopy, hematoxylin and eosin stain, and immunohistochemistry. Cell density and epithelial cell layers were evaluated utilizing a computer-assisted optical measurement system.

RESULTS

Depending on the growth pattern, scaffolds were classified into the following three distinct scaffold types: carrier-type scaffolds with very small pore sizes and no ingrowth of the cells. This scaffold type induces a well-differentiated epithelium. Fleece-type scaffolds with fibers and huge pores. We found cellular growth inside the scaffold but no epithelium on top of it. Sponge-type scaffolds with pores between 20 and 40 microm. Cellular growth was observed inside the scaffold and well-differentiated epithelium on top of it.

CONCLUSION

To our knowledge, this is the first time three distinct scaffold types have been reported. All types supported the cell growth. The structure of the scaffolds affects the pattern of cell growth.

Urinary Diversion

A consensus conference convened by the World Health Organization (WHO) and the Société Internationale d'Urologie (SIU) met to critically review reports of urinary diversion. The world literature on urinary diversion was identified through a Medline search. Evidence-based recommendations for urinary diversion were prepared with reference to a 4-point scale. Many level 3 and 4 citations, but very few level 2 and no level 1, were noted. This outcome supported the clinical practice pattern. Findings of >300 reviewed citations are summarized. Published reports on urinary diversion rely heavily on expert opinion and single-institution retrospective case series: (1) The frequency distribution of urinary diversions performed by the authors of this report in >7000 patients with cystectomy reflects the current status of urinary diversion after cystectomy for bladder cancer: neobladder, 47%; conduit, 33%; anal diversion, 10%; continent cutaneous diversion, 8%; incontinent cutaneous diversion, 2%; and others, 0.1%. (2) No randomized controlled studies have investigated quality of life (QOL) after radical cystectomy. Such studies are desirable but are probably difficult to conduct. Published evidence does not support an advantage of one type of reconstruction over the others with regard to QOL. An important proposed reason for this is that patients are subjected preoperatively to method-to-patient matching, and thus are prepared for disadvantages associated with different methods. (3) Simple end-to-side, freely refluxing ureterointestinal anastomosis to an afferent limb of a low-pressure orthotopic reconstruction, in combination with regular voiding and close follow-up, is the procedure that results in the lowest overall complication rate. The potential benefit of "conventional" antireflux procedures in combination with orthotopic reconstruction seems outweighed by the higher complication and reoperation rates. The need to prevent reflux in a continent cutaneous reservoir is not significantly debated, and this should be done. (4) Most reconstructive surgeons have abandoned the continent Kock ileal reservoir largely because of the significant complication rate associated with the intussuscepted nipple valve.

New era in health care: tissue engineering

Tissue engineering is a rapidly expanding field, which applies the principles and methods of physical sciences, life sciences and engineering to understand physiological and pathological systems and to modify and create cells and tissues for therapeutic applications. It has emerged as a rapidly expanding ‘interdisciplinary field’ that is a significant potential alternative wherein tissue and organ failure is addressed by implanting natural, synthetic, or semi synthetic tissue or organ mimics that grow into the required functionality or that are fully functional from the start. This review presents in a comprehensive manner the various considerations for the reconstruction of various tissues and organs as well as the various applications of this young emerging field in different disciplines.

Laparoscopic augmentation cystoplasty: a comparison between native ileum and small intestinal submucosa in the porcine model

OBJECTIVES

To determine the feasibility of laparoscopic augmentation cystoplasty (LAC) in the porcine model and to compare LAC using standard bowel vs a small intestinal submucosa (SIS) allograft.

MATERIALS AND METHODS

Fourteen female pigs underwent LAC; six had standard ileal AC and eight AC with SIS. All the pigs had limited cystometrogram studies before surgery to determine bladder capacity. At 6 weeks after surgery the pigs were anaesthetized, the bladder capacities were re-assessed and then the pigs were killed; the bladders were harvested and examined histologically.

RESULTS

In all, 12 of 14 pigs completed the 6-week survival period; two pigs from the SIS group died from urinary ascites secondary to anastomotic leaks at the cystoplasty site. There were no complications in the ileal augmentation group. The operative duration was similar in both groups. The bladder capacities increased significantly in both groups, although more reliably in the native ileum group. In two pigs in the SIS group there was no increase in bladder capacity.

CONCLUSIONS

LAC is feasible in the porcine model and results in a significant increase in bladder capacity. AC using SIS does not appear to increase bladder capacity as reliably as native ileum, and has a higher complication rate.

Effect of stanford pouch and ileal conduit urinary diversions on bone mineral density and metabolism

After urinary-intestinal diversions metabolic complications may occur in long term follow up. We aimed to evaluate bone metabolism changes in urinary diverted patients. Nineteen patients with urinary diversions (11 Stanford pouch and 8 ileal conduit) performed with diagnosis of locally invasive bladder cancer and 19 age-sex matched healthy subjects were enrolled in the study. Bone mineral density (BMD), arterial blood pH, bicarbonate and base excess as well as bone mineralisation parameters at urine and serum were evaluated for all groups. For statistical evaluation, nonparametric comparisons between groups were used. Comparison of ileal conduit and control groups displayed higher alkaline phosphatase and parathormone levels in the patient group though the difference was not significant. The mean BMD values of ileal conduit group were osteopenic, revealing a significant difference with the control group. Statistically significant differences between alkaline phosphatase, parathormone levels of Stanford pouch and control groups were apparent whereas BMD values were not significantly different. When the two patient groups were compared with each other, no difference in BMD or bone metabolism parameter values could be observed. Patients with urinary diversions are under risk of bone demineralisation and must be followed by BMDs, arterial blood analysis and bone mineral metabolism parameters.

Recent applications of regenerative medicine to urologic structures and related tissues

PURPOSE OF REVIEW

A severe shortage of donor tissues and organs exists, which is worsening yearly given the aging population. Currently, patients suffering from diseased and injured organs are treated with transplanted organs or cells. This paper reviews recent advances that have occurred in regenerative medicine and describes application of new technologies to treat diseased or damaged organs and tissues.

RECENT FINDINGS

Although most current strategies for tissue engineering depend upon a sample of autologous cells from the diseased organ of the patient, biopsies from patients with extensive end-stage organ failure may not yield enough normal cells. In these situations, stem cells are envisioned as being an alternative source. Stem cells can be derived from discarded human embryos (human embryonic stem cells), from fetal tissue, or from adult sources (bone marrow, fat, skin). Therapeutic cloning offers a potentially limitless source of cells for tissue engineering applications.

SUMMARY

Recently, scientists in the fields of regenerative medicine and tissue engineering have applied the principles of cell transplantation, material science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues.

Bladder Augmentation With Acellular Dermal Biomatrix in a Diseased Animal Model

PURPOSE

The use of bowel for bladder augmentation is associated with many complications. We have reported that acellular dermal biomatrix can be used successfully for directing the regeneration of each key bladder wall element in healthy domestic pigs. Before proposing that this material should be used in the human setting a final set of experiments using this scaffold to replace diseased bladder wall is necessary. We determined if acellular dermal biomatrix can be used to replace diseased bladder wall. We compared our findings to our previous results.

MATERIALS AND METHODS

Six domestic male pigs underwent urethral ligation and suprapubic tube placement. Five female pigs served as controls for bladder dynamics. Machined resistance valves of 5 and 10 cm H(2)O pressure were placed into the lumen of the cystostomy catheter for a mean of 3.3 weeks (range 3 to 4). Obstruction was then relieved and partial cystectomy was performed, followed by augmentation with a 4 x 4 cm segment of acellular dermal biomatrix of the markedly thickened and poorly compliant bladder. Animals were sacrificed 3 months following augmentation. Standard urodynamic studies were performed. Contractility and compliance were measured in freshly isolated regenerated and native bladder tissues. Histological evaluation was performed on hematoxylin and eosin, and Masson's trichrome stained sections.

RESULTS

Bladder compliance was markedly decreased after 3.3 weeks of obstruction. Mean compliance +/- SEM before obstruction was 16.28 +/- 9.21 cm H(2)O. After 3.3 weeks of obstruction average compliance was 4.13 +/- 0.98 cm H(2)O. One pig died 2 weeks following augmentation due to graft separation and sepsis. Gross examination of augmented bladders revealed the complete replacement of acellular dermal biomatrix with bladder tissue. Histological evaluation revealed extensive fibrosis with small islands of poorly organized muscle in contrast to the complete regeneration of mucosa, smooth muscle and serosa seen in augmentations previously performed in healthy animal bladders. Maximum contractile tension of the patch tissue was not different than that in the native tissue from the obstructed hypertrophied bladder but it was only approximately 10% of the tension produced by healthy tissue from nonobstructed augmented bladders. The obstructed bladder patch and native tissue was approximately 14 times stiffer than healthy bladder tissue.

CONCLUSIONS

While augmentation of healthy porcine bladder with acellular dermal biomatrix results in excellent functional bladder tissue regeneration, similar experiments in a porcine model of obstructed bladder disease failed to show favorable results. Therefore, acellular dermal biomatrix cannot be recommended at this time for human bladder dysfunction. Results support the contention that matrices designed for human bladder augmentation should be tested in a disease animal model before recommending them for human bladder dysfunction.

Percutaneous treatment of large upper tract stones after urinary diversion

OBJECTIVES

To present our experience in percutaneous management of large upper tract stones after urinary diversion.

METHODS

From October 1984 to March 2005, 20 percutaneous nephrolithotomy and 4 antegrade ureteroscopy procedures were performed in 17 men and 7 women, with a mean age of 53.5 years. The urinary diversions were an ileal W neobladder, hemi-Kock pouch, ileal conduit, and rectal bladder in 10, 7, 4, and 3 patients, respectively. The median interval between diversion and stone management was 1.5 years. Success was defined as a stone-free, nonobstructed renal unit at 3 months after the intervention. Follow-up was performed every 6 months with intravenous urography or noncontrast computed tomography for diagnosis of stone recurrence and evaluation of renal morphology.

RESULTS

Renal punctures were guided with ultrasonography in 18 patients (75%) and fluoroscopy in 6 patients. One intraoperative complication (4.16%) and two postoperative complications (8.3%) occurred. All patients with ureteral stones became stone free after one procedure. Auxiliary procedures were needed in 5 patients after percutaneous nephrolithotomy; 2 patients required a second session and 3 needed extracorporeal shock wave lithotripsy. The overall success rate was 87.5% (21 patients). One patient with treatment failure underwent open surgery, and two with small residual fragments were followed up. Long-term follow-up data were available for 15 patients. The stone recurrence rate was 33.3% (5 patients) after a median follow-up of 40 months (range 14 to 132). Recurrent stones were treated with extracorporeal shock wave lithotripsy.

CONCLUSIONS

The results of our study have demonstrated that percutaneous treatment of large upper tract stones after urinary diversion offers a high success rate with minimal morbidity. However, regular follow-up after treatment is recommended.

[In vitro three-dimensional reconstruction of human bladder mucosa]

OBJECTIVE

The purpose of this study is to apply the in vitro keratinocyte culture techniques and the tissue engineering principles to human urothelium, to reconstruct an in vitro three-dimensional human bladder mucosa, suitable for grafting.

MATERIAL AND METHODS

Biopsy specimens of human bladder mucosa were obtained from patients undergoing suprapubic prostatectomy, in vitro cultured and finally, an immunohistochemical study was made.

RESULTS

A three-dimensional in vitro tissue was obtained, composed of a bio-artificial submucosa (fibrin gel and fibroblast) where the uroepithelial cells were seeding. We used a biodegradable polyglycolic acid mesh to facilitate the tissue manipulation and implantation. An immature epithelium was obtained with a weak immunostaining to cytokeratins. The immunohistochemical study could not demonstrate the development of basement membrane.

CONCLUSIONS

In vitro keratinocyte culture techniques could be applied to other epithelial tissues like the urothelium. We obtained a three-dimensional in vitro tissue suitable for grafting in a relatively short time, which needs the matrix interactions in order to mature.

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.

Tissue-engineered autologous bladders for patients needing cystoplasty

BACKGROUND

Patients with end-stage bladder disease can be treated with cystoplasty using gastrointestinal segments. The presence of such segments in the urinary tract has been associated with many complications. We explored an alternative approach using autologous engineered bladder tissues for reconstruction.

METHODS

Seven patients with myelomeningocele, aged 4-19 years, with high-pressure or poorly compliant bladders, were identified as candidates for cystoplasty. A bladder biopsy was obtained from each patient. Urothelial and muscle cells were grown in culture, and seeded on a biodegradable bladder-shaped scaffold made of collagen, or a composite of collagen and polyglycolic acid. About 7 weeks after the biopsy, the autologous engineered bladder constructs were used for reconstruction and implanted either with or without an omental wrap. Serial urodynamics, cystograms, ultrasounds, bladder biopsies, and serum analyses were done.

RESULTS

Follow-up range was 22-61 months (mean 46 months). Post-operatively, the mean bladder leak point pressure decrease at capacity, and the volume and compliance increase was greatest in the composite engineered bladders with an omental wrap (56%, 1.58-fold, and 2.79-fold, respectively). Bowel function returned promptly after surgery. No metabolic consequences were noted, urinary calculi did not form, mucus production was normal, and renal function was preserved. The engineered bladder biopsies showed an adequate structural architecture and phenotype.

CONCLUSIONS

Engineered bladder tissues, created with autologous cells seeded on collagen-polyglycolic acid scaffolds, and wrapped in omentum after implantation, can be used in patients who need cystoplasty.

Working Capacity and Well-Being after Radical Cystectomy with Continent Cutaneous Diversion

OBJECTIVES

The primary aim was to compare the working capacity in patients with continent urinary diversion with a control group. Secondary aims were to assess the changes in electrolyte and acid-base homeostasis and the functional status during strenuous physical activity, and finally, the well-being in the two groups.

METHODS

Eleven patients who had undergone radical cystectomy and continent cutaneous diversion using an ileocolonic segment participated. The control group consisted of 12 men, matched for age and activity level. Working capacity was assessed by ergospirometry on an exercise bicycle. Venous blood samples were taken before the test, when the expiratory exchange ratio (RER) was about 1.0 and immediately after completion of the test. SF-36 was used to evaluate the subject's functional status and well-being.

RESULTS

The median working capacity in the patient group was 155 (85-190) W and 155 (125-215) W in the control group (n.s.) corresponding to 72 (43-97) % and 80 (59-97) % respectively of predicted values. Peak oxygen uptake was somewhat low in both groups when compared to P-O Astrands norms. Blood tests revealed that patients developed a slight metabolic hyperchloremic acidosis, not seen in the control group. There were no differences between the groups as assessed with SF-36.

CONCLUSION

Patients with a continent urinary diversion have a working capacity equal to a control group despite a slight metabolic hyperchloremic acidosis. Quality of life was similar in the two groups and corresponded well with the norms for the general Swedish population aged 65 to 74.

Recent developments in tissue engineering and regenerative medicine

PURPOSE OF REVIEW

Currently, patients suffering from diseased and injured organs are treated with transplanted organs or cells. There is, however, a severe shortage of donor tissues and organs that is worsening yearly given the aging population. This paper reviews recent advances that have occurred in regenerative medicine and describes applications of new technologies to treat diseased or damaged organs and tissues.

RECENT FINDINGS

Most current strategies for tissue engineering depend upon a sample of autologous cells from the diseased organ of the patient. Biopsies from patients with extensive end-stage organ failure, however, may not yield enough normal cells. In these situations, stem cells are envisioned as being an alternative source. Stem cells can be derived from discarded human embryos (human embryonic stem cells), from fetal tissue or from adult sources (bone marrow, fat, skin). Therapeutic cloning offers a potentially limitless source of cells for tissue engineering applications.

SUMMARY

Increasingly, scientists in the fields of regenerative medicine and tissue engineering have applied the principles of cell transplantation, material science and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues.

Urinary diversion in children and adolescents with neurogenic bladder: the Mainz experience. Part II: Continent cutaneous diversion using the Mainz pouch I

After failure of conservative treatment of neurogenic bladders (deterioration of the upper urinary tract/incontinence) continent cutaneous diversion has to be considered in those patients with irreparable urethral sphincter defects or those who are unable to perform trans-urethral self-catheterization. In this second part of the study we investigated the long-term safety of using the Mainz pouch I with regard to protecting the upper urinary tracts and to provide urine continence. Between 1985 and 2002, operations to form an ileocaecal pouch with umbilical stoma (Mainz pouch I) were performed on 70 children and adolescents of median age 15.3 years (range 5.7-20 years). During the follow-up period five patients died 2.4-14 years postoperatively of causes not related to urinary diversion. A follow-up period of 8.7 years (0.9-18) was achieved in 65 patients with 118 renal units (RUs). As compared to preoperatively, the upper urinary tracts had remained stable or improved in 113/118 RUs (95.8%) at the latest follow-up. Complete continence was achieved in 97% of patients with a continent cutaneous diversion. Surgical revisions were required for: incontinence of the outlet mechanism in 9%, stoma prolapse in 2%, stoma stenosis in 23%, pouch calculi in 15%, symptomatic reflux in 1%, ureter stenosis in 16% of the RUs with submucosal tunnel and in 3% of the RUs with an extramural tunnel. We conclude that, in patients with irreparable sphincter defect and those who are unable to perform urethral self-catheterization, continent cutaneous urinary diversion with the Mainz pouch I provides a high continence rate with preservation of the upper urinary tracts in the long run. In patients with dilated ureters, the extramural tunnel technique results in a lower complication rate.

Urinary diversion in children and adolescents with neurogenic bladder: the Mainz experience. Part III: Colonic conduit

After the failure of conservative treatment of neurogenic bladders, urinary diversion has to be considered. For patients with chronic renal failure, severe dilated upper urinary tracts with deterioration of the renal function and those who are not able to perform a self-catheterization, the colonic conduit diversion is our therapy of choice. In this part of the study, we investigate the long-term safety of our concept for these patients in regard to protecting the upper urinary tracts. Between 1968 and 2002, colonic conduit urinary diversion was performed in 88 patients, in most of them in the era before continent diversion. Overall, 11 patients with a colonic conduit were converted to bladder substitution or continent cutaneous diversion during the follow-up period. These patients are no longer included in the long-term follow-up of colonic conduit patients. Of the 77 patients with colonic conduit diversion, 21 patients were not available for follow-up: 11 were deceased and 10 were lost to follow-up. Three of the deaths were related to nephrological complications in patients who already had impaired renal function before conduit diversion. An average follow-up of 21.8 years (2-32.7; median 23.8 years.) is available in 56 patients with 99 RUs (6 solitary kidneys, 7 nephrectomies). Five non-functioning kidneys were removed after recurrent pyelonephritis and two kidneys with pyonephrosis. Ureter stenoses were corrected in 6% of the RUs. As compared to preoperatively, the upper urinary tracts remained stable or improved in 97/99 RUs at the latest follow-up. A revision of the stoma was necessary in 16% (conduit elongation n =2, stenosis n =7) and calculi formations were treated in 8% of the RUs. For patients with chronic renal failure or who are unable to perform a catheterization of a continent stoma, the colonic conduit is a safe alternative in the long run.

METABOLIC CONSEQUENCES AND LONG-TERM COMPLICATIONS OF ENTEROCYSTOPLASTY IN CHILDREN: A REVIEW

PURPOSE

We summarize important metabolic consequences and long-term complications associated with enterocystoplasty with particular emphasis on the pediatric patient with genitourinary abnormalities.

MATERIALS AND METHODS

A directed MEDLINE literature review for metabolic and long-term complications following enterocystoplasty was performed. Information gained through the published literature and from our database was reviewed and summarized to provide the reader with a thorough review of the subject.

RESULTS

Bowel is not a perfect tissue for substitution or augmentation and its use to treat functionally and structurally compromised bladders is associated with several metabolic consequences and long-term complications. Metabolic acidosis is the most common metabolic abnormality seen. The rates and severity of these complications vary, although they may have a profound impact on patient quality of life after enterocystoplasty.

CONCLUSIONS

The metabolic consequences and long-term complications associated with enterocystoplasty are important clinical features of this intervention. Careful consideration should be given to them prior to pursuing enterocystoplasty.

Bladder, bowel and bones--skeletal changes after intestinal urinary diversion

Impaired bone metabolism following urinary diversion through intestinal segments has always been a controversial subject of unclear clinical relevance. Whereas the perpetuated pathophysiological considerations seem conclusive in theory, the role of acidosis and malabsorption is less clear in animal experimentation and, even more so, in the clinical reality of modern continent diversion. In hardly any of the available contemporary case series was overt derangement of the acid-base balance, rickets or osteomalacia encountered. No consistent changes in osteotropic serum parameters could be found with normal calcium and phosphate in all patients. The assumption that colonic reservoirs have a higher risk of developing metabolic bone disease could not be confirmed by clinical data. As early correction of base excess is easy and probably a common policy in patients with intestinal urinary reservoirs, it will be virtually impossible to further study the natural history of bone metabolism after urinary diversion. While there is no need for a bone specific follow-up in asymptomatic adults with a normal acid-base balance, particular attention should be paid to children and to all patients with impaired renal function.

Acid-base and electrolyte disorders after urinary diversion

The use of bowel in urologic reconstructive procedures may result in numerous short and long-term complications, including well-described acid-base and electrolyte disorders. Many of these metabolic alterations are influenced by how solute absorption occurs across the particular bowel segment chosen for reconstruction. Solute absorption is impacted by: (1) the segment of bowel used, (2) the surface area of bowel used, (3) the time of retention of urine, (4) the concentration of solutes in the urine, (5) renal function, and (6) the pH and osmolality of the urine. These factors affect the type and amount of solutes absorbed, as well as the severity of metabolic complications that develop.

[Alkaline citrates in urology. A status report]

Alkaline citrates have been used as an efficient therapy in hypocitraturic calcium nephrolithiasis, uric acid lithiasis, cystinuria, and renal tubular acidosis. Furthermore, alkaline citrates are very effective in treating and preventing hyperchloremic metabolic acidosis in patients with urinary diversion. The main physiological effects during urolithiasis therapy have been significant increases in urinary pH, in citrate and potassium, and a decrease in calcium excretion. This paper reviews current indications, therapy modalities, and metaphylactic use reported in the literature and/or recommended by the Deutsche Gesellschaft für Urologie (DGU) and the European Association of Urology (EAU). It is intended to give useful advice for the urologist's daily practice.

Modified ileal neobladder for continent urinary diversion: functional results after 9 years of experience

PURPOSE

We report the continence status and urodynamic findings in 59 patients who underwent radical cystectomy and orthotopic bladder reconstruction using a modified S-ileal neobladder technique between January 1993 and July 2002.

MATERIALS AND METHODS

Continence status was assessed using patient interview, frequency-volume charts and the need for protective devices. Reservoir sensation, compliance, capacity and activity were assessed by enterocystometry. Post-void residual urine volume greater than 100 ml was the indication for clean intermittent self-catheterization.

RESULTS

Daytime continence was reported by 95.5% and 100% of our patients at 1 and 5 years, respectively. Overall, 77.7% of patients reported nighttime continence at 1 year and 96.5% at 5 years. The need for a protective device decreased with time and most of the patients would have undergone the operation again. Enterocystometric capacity and maximum reservoir pressure remained remarkably stable at 391.6 versus 440 ml, and 30 versus 20 cm H2O, 6 months and 5 years after surgery, respectively. Nevertheless, median post-void residual urine volume increased from 35 ml at 6 months to 55 ml at 5 years with an increase in prevalence of patients requiring intermittent self-catheterization due to post-void residual urine greater than 100 ml from 1.8% at 6 months to 10% at 5 years.

CONCLUSIONS

Orthotopic bladder substitution with the modified S-ileal neobladder technique has an excellent functional outcome over time, resulting in high daytime and nighttime continence levels as well as high acceptability rates from our patients.

An Evaluation of Quality of Life in Patients who Underwent Urinary Diversion after Radical Cistectomy: Comparison of Different Urinary Diversions, our Experience

The aim of the study was to compare health-related quality of life (HRQOL) in 3 groups of patients with different urinary diversions using the “36 Item Short-Form Healt Survey” questionnaire; metabolic changes related to urinary diversion were also evaluated. The study included 22 patients who underwent radical cystectomy for bladder cancer: 10 pts had an an ileal-conduit (Group I), 9 had a retto-sigmoid pouch sec. Mainz II (Group II), and 3 had an ileal orthotopic neobladder (Group III).

There were no significant differences among the 3 groups regarding the metabolic status. The SF -36 survey showed that patients with ileal-conduit (Group I) had a significant decrease of general health (GH) and of physical functioning (AF) scores compared to patients with continent urinary diversion (Groups II and III). This appeared to be related to a decreased emotional drive (RE) rather than to a loss of vitality (VT).

There were no significant differences in any scale score between Group II and III.

Kidney transplantation in children with reconstructed bladder

There is some controversy about the safety of renal transplantation in patients with an augmentation cystoplasty because of the possibility of urinary tract infection in immunosuppressed patients leading to pyelonephritis and graft loss. Nevertheless, it is now well known that in patients with a small volume and poorly compliant bladder, reconstructive bladder surgery (augmentation cystoplasty or continent reservoir) creates a low-pressure and compliant reservoir, which protects the upper urinary tract and restores a functional lower urinary tract. Graft survival is not adversely affected when a kidney transplant is drained into a reconstructed bladder. When bowel segments are used for augmentation, a voiding modality with clean intermittent self-catheterization does not increase the risk of urinary tract infections, even in immunosuppressed patients.

Use of Single Layer Small Intestinal Submucosa for Long Segment Ureteral Replacement: A Pilot Study

PURPOSE

Previous studies have demonstrated successful use of small intestinal submucosa (SIS) as a tube for replacing short segment (11 mm) proximal ureteral defects. However, such small segment ureteral defects could be managed by resection re-anastomosis. We evaluated the use of 1-layer SIS as a tube for the replacement of long segment ureteral defects.

MATERIALS AND METHODS

The ureters of 5 female mongrel dogs were accessed through a median laparotomy incision. A 4 cm segment of mid ureter was resected on the right side. The right ureteral segments were replaced by tubularized SIS segments using 6-zero polydioxanone interrupted sutures. Internal pigtail stents were left for 6 weeks. All animals were sacrificed at 12 weeks. Ureteral patency was assessed by excretory urography and magnetic resonance urography 7 and 12 weeks after the initial procedures. Inflammation and regeneration were assessed histologically.

RESULTS

At 12 weeks all ureters on the experimental side were completely occluded with significant hydroureteronephrosis and the subsequent deterioration of kidney function. At autopsy there was failure to calibrate any of the experimental ureters with a 3Fr catheter. Although histologically urothelium and muscular cells had proliferated over the graft, they were embedded in an intense fibrotic and inflammatory process.

CONCLUSIONS

Technically 1-layer SIS was easily modeled, providing the conditions for watertight anastomosis. The regeneration of urothelium and muscle was induced and supported by the graft. However, functional replacement was not successful. One-layer SIS is not a suitable material for replacing long segment (4 cm) ureteral defects.

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.

Engineering of muscle tissue

The loss or failure of an organ or tissue is one of the most frequent, devastating, and costly problems in health care. Tissue engineering and regenerative medicine is an emerging interdisciplinary field that applies the principles of biology and engineering to the development of viable substitutes that restore, maintain, or improve the function of human tissues and organs. Tissue engineering science has provided critical new knowledge that will deepen our understanding of the phenotype of an important category of cell types-the muscle cells-and this knowledge may enable meaningful advances in musculoskeletal tissue engineering. There are two principle strategies for the replacement of impaired muscle tissues. One approach uses the application of isolated and differentiated cells (in vivo tissue engineering), using a transport matrix for the cell delivery; the other uses in vitro-designed and pre-fabricated tissue equivalents (in vitro tissue engineering). Future developments and the decision regarding which approach is more promising depend on the elucidation of the relationships among cell growth and differentiation, the three-dimensional environment, the architecture of the cells, and gene expression of the developmental process and the survival of the cells and integration in the host in in vivo experiments. As the techniques of tissue engineering become more sophisticated and as issues such as vascularization and innervation are addressed, the usefulness of these methods for reconstructive surgery may grow significantly.

Follow-up strategies and management of recurrence in urologic oncology bladder cancer:

A surveillance program following cystectomy should consider a patient's individual risk for the development of local and distant recurrences and any specific needs related to the urinary tract reconstruction performed (Table 1). Well-documented recurrence patterns following cystectomy are available from many large surgical series and provide the background information needed for tailoring follow-up based on pathologic criteria. Economic issues also must be considered, given that the health care-related expenses of treating and following patients with bladder cancer is twice as much as that expended for the treatment of prostate cancer. Because of the ever-increasing fiscal constraints placed on clinicians, risk-adjusted follow-up strategies are reasonable, but will require prospective evaluation to validate their appropriateness.

Metabolic Evaluation of 94 Patients 5 to 16 Years After Ileocecal Pouch (Mainz Pouch 1) Continent Urinary Diversion

PURPOSE In continent urinary diversion metabolic disturbances may be encountered in long-term followup. We evaluated metabolic consequences in patients with a minimum followup of 5 years after Mainz pouch 1 urinary diversion.

MATERIALS AND METHODS

At our institution continent urinary diversion using the ileocecal segment was performed between 1983 and 1995 in 458 patients. A total of 94 patients with an ileocecal pouch for a minimum of 5 years were reevaluated for metabolic changes. Median followup was 9.0 years. Routine laboratory parameters, blood gas analysis, vitamin B12, vitamin D25, cross-laps, bone specific alkaline phosphatase, osteocalcin and propeptide of type I collagen were obtained. Bone density was measured in 18 patients. Vitamin B12 changes could be followed longitudinally in 24 patients.

RESULTS

Medians of all parameters were in normal ranges. Clinical examinations revealed no signs of megaloblastic anemia, funicular myelosis or osteoporosis. There was no significant decrease of vitamin B12 in the long run. After followup examination we recommended vitamin B12 supplementation in 32% of patients because levels were in the lower normal range or below. A total of 37% of patients continue to take Na+/K+-citrate for prevention of metabolic acidosis.

CONCLUSIONS

Patients with an ileocecal pouch and a followup of more than 5 years did not present with clinical symptoms caused by metabolic disturbances. Nevertheless, systematic followup of blood gases in particular and alkali supplementation may have prevented bone demineralization. Followup of vitamin B12 is of concern because about a third of these patients need supplementation.

Surface modification to improve in vitro attachment and proliferation of human urinary tract cells

OBJECTIVE

To evaluate the attachment and proliferation of cultured human urinary tract cells to culture plates surface-modified by photochemical immobilization of extracellular matrix (ECM) proteins.

MATERIALS AND METHODS

Human uroepithelial (UEC) and smooth muscle (SMC) cells were harvested from ureter and expanded in culture; 24-well culture plates surface-modified by photochemical covalent immobilization of ECM proteins were then seeded with UEC or SMC. To characterize cellular attachment, cells were incubated on surface-modified plates for 30 and 90 min. For proliferation assays the cells were incubated for 3-12 days. Standard tissue culture plates with no surface modification and sham-modified plates served as controls. Differential attachment and proliferation on the various surfaces were assessed using analysis of variance with Fisher's posthoc test for multiple comparisons.

RESULTS

Attachment at 30 and 90 min of both UEC and SMC on plates surface-modified with ECM proteins was significantly greater than in control plates. Surface-modification with collagen resulted in significantly greater cellular attachment than with either laminin or fibronectin. UEC proliferation was also significantly greater than in control plates by surface-modification with collagen and fibronectin, but not with laminin. SMC proliferation was significantly better after surface modification than on sham- modified plates, but was no better than standard plates.

CONCLUSIONS

Covalent photochemical immobilization of ECM proteins to potential growth surfaces enhances the attachment of cultured UEC and SMC and the proliferation of UEC. This technique might be useful in modifying surface properties of synthetic polymer-based materials in a controlled and defined manner, giving them the capacity to promote and sustain the growth of urinary tract cells. This may lead to development of alternative methods of tissue engineering in the urinary tract.