Metabolic complications of urinary intestinal diversion

Causes and management of urinary system problems in children on long-term home invasive mechanical ventilation

Many ventilator-dependent children have comorbid conditions including urinary tract disorders. We aimed to present a focused review of the literature describing the causes and management of urinary system problems in children with long-term home mechanical ventilation. We performed a literature search in PubMed/MEDLINE, Scopus, and Web of Science with keywords "children," "home mechanical ventilation," "urinary system," "urinary tract," "neurogenic bladder," "clean intermittent catheterization," "urinary tract infection," "urolithiasis," and "acute kidney injury." We included original articles, reviews, guidelines, and case reports published in English. Ventilator-dependent children may have neurogenic bladder/bowel dysfunction which renders them prone to urinary tract infection, high bladder pressure, vesicoureteral reflux, hydronephrosis, and renal dysfunction. These children require bladder catheterization, medications affecting parasympathetic/sympathetic nervous systems, or surgical procedures to prevent urinary infections, and to maintain continence and renal functions. However, bladder catheterization or surgical procedures like augmentation cystoplasty may also be complicated with urinary infections, urolithiasis, or urethral strictures. Urolithiasis frequency is also increased due to immobilization-related hypercalciuria, hypocitraturia caused by antiepileptic drugs, urinary stasis, and urinary infections. On the other hand, mechanical ventilation can impair renal function by reduction of cardiac output, redistribution of intrarenal blood flow and stimulation of sympathetic and hormonal pathways. Children requiring long-term invasive home mechanical ventilation may have other comorbid conditions, including urinary system diseases, which become manifest as these patients are being kept alive due to the advances in ventilation strategies. These children must be carefully observed for urological complications and managed accordingly to prevent kidney injury.

Multipotent bone marrow cell-seeded polymeric composites drive long-term, definitive urinary bladder tissue regeneration

To date, there are no efficacious translational solutions for end-stage urinary bladder dysfunction. Current surgical strategies, including urinary diversion and bladder augmentation enterocystoplasty (BAE), utilize autologous intestinal segments (e.g. ileum) to increase bladder capacity to protect renal function. Considered the standard of care, BAE is fraught with numerous short- and long-term clinical complications. Previous clinical trials employing tissue engineering approaches for bladder tissue regeneration have also been unable to translate bench-top findings into clinical practice. Major obstacles still persist that need to be overcome in order to advance tissue-engineered products into the clinical arena. These include scaffold/bladder incongruencies, the acquisition and utility of appropriate cells for anatomic and physiologic tissue recapitulation, and the choice of an appropriate animal model for testing. In this study, we demonstrate that the elastomeric, bladder biomechanocompatible poly(1,8-octamethylene-citrate-co-octanol) (PRS; synthetic) scaffold coseeded with autologous bone marrow-derived mesenchymal stem cells and CD34+ hematopoietic stem/progenitor cells support robust long-term, functional bladder tissue regeneration within the context of a clinically relevant baboon bladder augmentation model simulating bladder trauma. Partially cystectomized baboons were independently augmented with either autologous ileum or stem-cell-seeded small-intestinal submucosa (SIS; a commercially available biological scaffold) or PRS grafts. Stem-cell synergism promoted functional trilayer bladder tissue regeneration, including whole-graft neurovascularization, in both cell-seeded grafts. However, PRS-augmented animals demonstrated fewer clinical complications and more advantageous tissue characterization metrics compared to ileum and SIS-augmented animals. Two-year study data demonstrate that PRS/stem-cell-seeded grafts drive bladder tissue regeneration and are a suitable alternative to BAE.

Marked Metabolic Acidosis Due to a Transverse Stoma after Urethroplasty for Congenital Epispadias

A 58-year-old woman was admitted to our hospital. At 10 years old, she had undergone bilateral uretero-sigmoid anastomosis for congenital epispadias, and at 57 years old, she had received transverse colostomy. Biochemical tests showed marked metabolic acidosis. Computed tomography showed urine stagnation in the sigmoid colon, leading to a diagnosis of metabolic acidosis associated with transverse stoma after bilateral uretero-sigmoid anastomosis. Her bone mineral density was below normal, and the bone metabolic marker levels were high, indicating high-turnover osteoporosis. Both metabolic acidosis and bone metabolism were stabilized by treatment with a transanal urinary catheter, sodium bicarbonate, and vitamin D.

Advancing autologous urothelial micrografting and composite tubular grafts for future single-staged urogenital reconstructions

Urogenital reconstructive surgery can be impeded by lack of tissue. Further developments within the discipline of tissue engineering may be part of a solution to improve clinical outcomes. In this study, we aimed to design an accessible and easily assembled tubular graft with autologous tissue, which could be constructed and implanted as a single-staged surgical procedure within the premises of an ordinary operating room. The ultimate goals would be to optimize current treatment-options for long-term urinary diversion. Therefore, we evaluated the optimal composition of a collagen-based scaffold with urothelial micrografts in vitro, and followingly implanted the construct in vivo as a bladder conduit. The scaffold was evaluated in relation to cell regeneration, permeability, and biomechanical properties. After establishing an optimized scaffold in vitro, consisting of high-density collagen with submerged autologous micrografts and reinforced with a mesh and stent, the construct was successfully implanted in an in vivo minipig model. The construct assemblance and surgical implantation proved feasible within the timeframe of a routine surgical intervention, and the animal quickly recovered postoperatively. Three weeks post-implantation, the conduit demonstrated good host-integration with a multilayered luminal urothelium. Our findings have encouraged us to support its use in more extensive preclinical large-animal studies.

Insights into cellular behavior and micromolecular communication in urothelial micrografts

Autologous micrografting is a technique currently applied within skin wound healing, however, the potential use for surgical correction of other organs with epithelial lining, including the urinary bladder, remains largely unexplored. Currently, little is known about the micrograft expansion potential and the micromolecular events that occur in micrografted urothelial cells. In this study, we aimed to evaluate the proliferative potential of different porcine urothelial micrograft sizes in vitro, and, furthermore, to explore how urothelial micrografts communicate and which microcellular events are triggered. We demonstrated that increased tissue fragmentation subsequently potentiated the yield of proliferative cells and the cellular expansion potential, which confirms, that the micrografting principles of skin epithelium also apply to uroepithelium. Furthermore, we targeted the expression of the extracellular signal-regulated kinase (ERK) pathway and demonstrated that ERK activation occurred predominately at the micrograft borders and that ERK inhibition led to decreased urothelial migration and proliferation. Finally, we successfully isolated extracellular vesicles from the micrograft culture medium and evaluated their contents and relevance within various enriched biological processes. Our findings substantiate the potential of applying urothelial micrografting in future tissue-engineering models for reconstructive urological surgery, and, furthermore, highlights certain mechanisms as potential targets for future wound healing treatments.

Enfortumab Vedotin-induced Hyperglycemia and Ileal Conduit Reconstruction-induced Metabolic Acidosis

We report a 76-year-old man who was treated for hyperglycemia and metabolic acidosis after chemotherapy with enfortumab vedotin and pembrolizumab administered after his surgery for bladder cancer. He had an approximately 20-year history of diabetes. His body mass index was 18.6, and he received metformin 1000 mg/day, sitagliptin 50 mg/day, mitiglinide 30 mg/day, and voglibose 0.6 mg/day with hemoglobin A1c was approximately 7%. He underwent total cystectomy and ileal conduit reconstruction. After relapse, he received chemotherapy but later developed hyperglycemia and metabolic acidosis. His hyperglycemia was caused by enfortumab vedotin, and metabolic acidosis was attributable to the ileocecal canal. These symptoms should be remembered as important complications of this standard treatment, which prompted this case report.

Simultaneous Renal Transplantation With Bilateral Nephrectomy and Ureterocystoplasty

Bladder augmentation (BA) may be required before renal transplantation in children with end stage renal disease (ESRD). Herein we report a case of a 7-year-old boy with ESRD, contracted bladder and severe bilateral reflux secondary to posterior urethral valve (PUV), successfully managed by simultaneous bilateral nephrectomy, bilateral ureterocystoplasty and renal transplantation.

Tissue Engineering and Regenerative Medicine in Pediatric Urology: Urethral and Urinary Bladder Reconstruction

In the case of pediatric urology there are several congenital conditions, such as hypospadias and neurogenic bladder, which affect, respectively, the urethra and the urinary bladder. In fact, the gold standard consists of a urethroplasty procedure in the case of urethral malformations and enterocystoplasty in the case of urinary bladder disorders. However, both surgical procedures are associated with severe complications, such as fistulas, urethral strictures, and dehiscence of the repair or recurrence of chordee in the case of urethroplasty, and metabolic disturbances, stone formation, urine leakage, and chronic infections in the case of enterocystoplasty. With the aim of overcoming the issue related to the lack of sufficient and appropriate autologous tissue, increasing attention has been focused on tissue engineering. In this review, both the urethral and the urinary bladder reconstruction strategies were summarized, focusing on pediatric applications and evaluating all the biomaterials tested in both animal models and patients. Particular attention was paid to the capability for tissue regeneration in dependence on the eventual presence of seeded cell and growth factor combinations in several types of scaffolds. Moreover, the main critical features needed for urinary tissue engineering have been highlighted and specifically focused on for pediatric application.

Autologous regeneration of blood vessels in urinary bladder matrices provides early perfusion after transplant to the bladder

Large animal testing and clinical trials using bioengineered bladder for augmentation have revealed that large grafts fail due to insufficient blood supply. To address this critical issue, an in vivo staged implant strategy was developed and evaluated to create autologous, vascularized bioengineered bladder tissue with potential for clinical translation. Pig bladders were used to create acellular urinary bladder matrices (UBMs), which were implanted on the rectus abdominus muscles of rats and pigs to generate cellular and vascular grafts. Rectus-regenerated bladder grafts (rrBGs) were highly cellularized and contained an abundance of CD31-positive blood vessels, which were shown to be functional by perfusion studies. Muscle patterns within grafts showed increased smooth muscle formation over time and specifically within the detrusor compartment, with no evidence of striated muscle. Large, autologous rrBGs were transplanted to the pig bladder after partial cystectomy and compared to transplantation of control UBMs at 2 weeks and 3 months post-transplant. Functional, ink-perfused blood vessels were found in the central portion of all rrBGs at 2 weeks, while UBM grafts were significantly deteriorated, contracted and lacked central cellularization and vascularization. By 3 months, rrBGs had mature smooth muscle bundles and were morphologically similar to native bladder. This staged implantation technique allows for regeneration and harvest of large bladder grafts that are morphologically similar to native tissue with functional vessels capable of inosculating with host bladder vessels to provide quick perfusion to the central area of the large graft, thereby preventing early ischemia and contraction.

Efficacy of vesicostomy for refractory metabolic acidosis in persistent cloaca

Persistent cloaca involves fusion of the bladder, vagina, and rectum into a single duct called the common duct. Although its pathogenesis remains unclear, it has been associated with hyperchloremic metabolic acidosis. Herein, we present the case of a neonatal girl with high-confluence type variant of persistent cloaca treated with vesicostomy (Blocksom) for refractory metabolic acidosis. She was diagnosed with persistent cloaca before birth; colostomy was performed and a urinary catheter was placed in the bladder. Voiding cystourethrography on day 19 after birth showed that most of the contrast material leaked into the rectum; hence, the urinary catheter was removed. On day 27, hyperchloremic metabolic acidosis was detected and treatment with oral sodium bicarbonate was initiated; however, the infant showed no response. Because hyperchloremia occurred after removal of the urinary catheter, continuous urine retention in the colon through the common duct was believed to have caused the progression of hyperchloremic metabolic acidosis through transporters in the intestinal mucosa. As reinstallation of a urinary catheter was technically difficult, vesicostomy was performed on day 29, after which the metabolic acidosis improved. This report suggests vesicostomy as an effective treatment for refractory hyperchloremic metabolic acidosis associated with high-confluence type persistent cloaca.

Hyperchloremic Metabolic Acidosis with Hyperglycemic Hyperosmolar Syndrome after Robot-Assisted Radical Cystoprostatectomy with Ileal Conduit Urinary Diversion: A Case Report

Hyperchloremic metabolic acidosis can be a problem in urinary diversion using the ileum. A 73-year-old Japanese male was hospitalized in emergency due to anorexia and malaise 3 weeks after being discharged from the hospital after getting robot-assisted radical cystoprostatectomy and intracorporeal ileal conduit urinary diversion. The blood analysis revealed metabolic acidosis, elevated chloride ions, and marked hyperglycemia: he was diagnosed with hyperchloremic metabolic acidosis and hyperglycemic hyperosmolar syndrome. We started administering insulin and large amounts of fluid replacement; besides, we inserted a large-diameter open tip catheter into the ileal conduit in hopes of inhibiting urine reabsorption in the intestinal mucosa. His general condition gradually improved, and he was discharged 10 days after his hospitalization.

Impact of Intestinal Urinary Diversion on the Risk of Fracture and Loss of Bone Mass: A Systematic Review

BACKGROUND

Patients undergoing intestinal urinary diversion (IUD) may have a higher risk of osteoporosis and risk of fractures due to metabolic acidosis and decrease of intestinal absorption surface.

OBJECTIVE

We performed a systematic review of the available literature on the impact of IUD on bone demineralization.

METHODS

We systematically searched PubMed®, for original articles published before April 2020. Primary end points were the risk of fracture and loss of bone density. Secondary outcomes were the metabolic changes in biochemical and urine parameters related to calcium metabolism and histological changes.

RESULTS

Our electronic search identified a total of 2417 articles. After a detailed review, we selected 11 studies that addressed the impact of IUD on bone health in 10369 patients. The risk of bone fracture was studied in 3 articles, showing a higher risk in the IUD population. Of the 9 articles evaluating the relation between intestinal urinary diversion and bone density, 5 did find a positive association. One article evaluated the bone metabolism at a cellular level after IUD showing a decrease in bone turnover in this population. Three of the eight studies reporting data on serum parameters related to calcium and phosphate metabolism showed differences. Finally, a correlation between concentration of pyridolines in urine and loss of bone density was found in two of the three studies.

CONCLUSIONS

Although published data on BMD are contradictory, patients undergoing IUD seem to be at higher risk of bone fractures. Our finding support the need to implement accessible strategies on osteoporosis screening and prevention in IUD patients.

Presentation of mixed diabetic ketoacidosis and metabolic acidosis due to ileal neobladder reconstruction

Diabetic ketoacidosis (DKA) is one of the most serious acute metabolic complications of diabetes mellitus. It is characterised by the biochemical triad of hyperglycaemia, ketonemia/ketonuria, and an increased anion gap metabolic acidosis. In this case, a 40-year-old male patient presented to the emergency department, with vomiting, nausea, polydipsia, polyuria and weight loss. He was found to have an elevated plasma glucose, despite having no known history of diabetes mellitus. His medical history was significant for spina bifida and ileal neobladder reconstruction. The plasma glucose level was 38 mmol/L. Blood gas analysis showed normal anion gap metabolic acidosis with high chloride and low bicarbonate. His plasma ketone level was 4.5 mmol/L. No significant reason for hyperchloraemia was identified. On initiation of DKA regimen, his condition improved and serum ketones normalised. Due to persistent hyperchloraemic metabolic acidosis, bicarbonate infusion was administered and his metabolic acidosis resolved.

Renal transplantation in patients with an augmentation cystoplasty

Background

The effects of renal transplantation in patients with augmentation cystoplasty are still controversial. We retrospectively analyzed nine patients who underwent renal transplantation after augmentation cystoplasty.

Methods

A total of nine patients who underwent augmentation cystoplasty prior to renal transplantation between January 1990 and May 2020 were reviewed. Basic information on augmentation cystoplasty, transplant procedures, and long-term outcomes of renal transplantation were analyzed.

Results

The bowel segments utilized for augmentation cystoplasty were the stomach in two patients (one patient needed revision using the ileum), the ileum in four patients, the ileocolic pouch in one patient, the sigmoid in one patient, and the ureter in one patient. All the cystoplasties were performed prior to renal transplantation. The mean follow-up period after transplantation was 161 months (range, 2–341 months). Two patients had an episode of acute rejection each; however, their graft functions were well-maintained. Five patients had recurrent urinary tract infections, and three of these patients progressed to allograft failure. One patient died from bladder cancer with a functioning graft. Five of nine patients showed well-maintained graft function.

Conclusions

Renal transplantation after bladder augmentation surgery is a major operation requiring a high level of surgical skill. Based on our long-term experiences, we recommend diligent postoperative monitoring for urinary tract infections, optimal catheter use, and use of appropriate antibiotic prophylaxis to avoid severe complications.

[Bladder cancer - complications related to urinary diversion]

Even today, radical cystectomy with urinary diversion is one of the most complicated procedures in uro-oncology. Particularly in the long-term course, but also perioperatively, problems caused by urinary diversion play a significant role.Perioperatively, gastrointestinal problems such as an ileus, but also infections and early complications of the different anastomoses are most important. While ileus and perioperative infections can usually be treated conservatively, failure of the intestinal or ureteroileal anastomoses require regular surgical revisions.In the long-term follow-up, scarring can lead to chronic obstruction of urinary flow and, in the case of continental urinary diversions, to stone formation. These complications, as well as parastomal hernias in patients with poor conduits, may require further therapy. Functional bowel disorders may impair patients' quality of life significantly.Improved preoperative preparation and accompanying measures during the inpatient stay can significantly reduce non-surgical complications.Cystectomy with therapy-associated morbidity is a classical example of when surgery must be performed at specialised centers to reduce complications perioperatively as well as in follow-up.

Direct conversion of fibroblasts into urothelial cells that may be recruited to regenerating mucosa of injured urinary bladder

Urothelial cells play essential roles in protection of urine exudation and bacterial invasion at the urothelial mucosa, so that defect or damage of urothelial cells associated with urinary tract diseases may cause serious problems. If a sufficient number of functional urothelial cells are prepared in culture and transplanted into the damaged urothelial lesions, such technology may provide beneficial effects to patients with diseases of the urinary tract. Here we found that human adult dermal fibroblasts were converted into urothelial cells by transducing genes for four transcription factors, FOXA1, TP63, MYCL and KLF4 (FTLK). The directly converted urothelial cells (dUCs) formed cobblestone-like colonies and expressed urothelium-specific markers. dUCs were successfully expanded and enriched after serial passages using a specific medium that we optimized for the cells. The passaged dUCs showed similar genome-wide gene expression profiles to normal urothelial cells and had a barrier function. The FTLK-transduced fibroblasts were also converted into urothelial cells in vivo and recruited to the regenerating urothelial tissue after they were transplanted into the bladder of mice with interstitial cystitis. Our technology may provide a promising solution for a number of patients with urinary tract disorders.

Hyperchloremic normal gap metabolic acidosis

Metabolic acidosis is defined as a pathologic process that, when unopposed, increases the concentration of hydrogen ions (H+) in the body and reduces the bicarbonate (HCO3-) concentration. Metabolic acidosis can be of a kidney origin or an extrarenal cause. Assessment of urinary ammonium excretion by calculating the urine anion gap or osmolal gap is a useful method to distinguish between these two causes. Extrarenal processes include increased endogenous acid production and accelerated loss of bicarbonate from the body. Metabolic acidosis of renal origin is due to a primary defect in renal acidification with no increase in extrarenal hydrogen ion production. This situation can occur because either the renal input of new bicarbonate is insufficient to regenerate the bicarbonate lost in buffering endogenous acid as with distal renal tubular acidosis (RTA) or the RTA of renal insufficiency, or the filtered bicarbonate is lost by kidney wasting as in proximal RTA. In either condition, because of loss of either NaHCO3 (proximal RTA) or NaA (distal RTA), effective extracellular volume is reduced and as a result the avidity for chloride reabsorption derived from the diet is increased and results in a hyperchloremic normal gap metabolic acidosis. The RTA of renal insufficiency is also characterized by a normal gap acidosis, however, with severe reductions in the glomerular filtration rate an anion gap metabolic acidosis eventually develops.

Current Indications and Techniques for the Use of Bowel Segments in Pediatric Urinary Tract Reconstruction

Today, there are few indications for the use of bowel in pediatric urology. This is in large extent due to the successful conservative therapy in patients with neurogenic bladder and the improved success of primary reconstruction in patients with the bladder exstrophy-epispadias complex. Only after the failure of the maximum of conservative therapy or after failure of primary reconstruction, bladder augmentation, or urinary diversion should be considered. Malignant tumors of the lower urinary tract (e.g., rhabdomyosarcomas of the bladder/prostate) are other rare indications for urinary diversion. Replacement or reconstruction of the ureter with a bowel segment is also a quite rarely performed procedure. In this review, the advantages and disadvantages of the different options for the use of bowel segments for bladder augmentation, bladder substitution, urinary diversion, or ureter replacement during childhood and adolescence are discussed.

Appendicovesical fistula presenting as hypokalaemic hyperchloraemic metabolic acidosis: a case report

A 52-year-old man was admitted with diarrhoea and faecaluria and referred recurrent urinary tract infections for over 20 years. He also reported a two-week hospital admission more than 20 years ago for right iliac fossa pain, which was managed conservatively. Computed tomography showed a fistulous tract extending from the bladder with an unclear connection to the bowel. Cystoscopy confirmed the presence of a vesical fistula and biopsy of the tract confirmed colonic mucosa. Flexible sigmoidoscopy was negative. A cystogram was requested as an outpatient procedure and the patient was discharged after antibiotic treatment. A few days after discharge the patient was readmitted as an emergency to critical care for severe hyperchloraemic hypokalaemic acidosis and a Glasgow Coma Score of 6/15. He was intubated and ventilated and his metabolic derangement was treated. As soon as his conditions improved, he underwent emergency laparotomy, which revealed the presence of a fistula between the caecal fundus and the bladder. The fistula was repaired and the patient recovered swiftly and completely and was discharged on postoperative day 5. At 12-month follow up the patient was completely symptoms-free, his bowel habits were normal and he has not had any urinary infection. Appendicovesical fistula is a rare and potentially lethal condition due to its metabolic consequences. Past history of right iliac fossa pain treated conservatively, diarrhoea and recurrent urinary tract infection must raise suspicion.

Tissue Engineering in Pediatric Bladder Reconstruction-The Road to Success

Several congenital disorders can cause end stage bladder disease and possibly renal damage in children. The current gold standard therapy is enterocystoplasty, a bladder augmentation using an intestinal segment. However, the use of bowel tissue is associated with numerous complications such as metabolic disturbance, stone formation, urine leakage, chronic infections, and malignancy. Urinary diversions using engineered bladder tissue would obviate the need for bowel for bladder reconstruction. Despite impressive progress in the field of bladder tissue engineering over the past decades, the successful transfer of the approach into clinical routine still represents a major challenge. In this review, we discuss major achievements and challenges in bladder tissue regeneration with a focus on different strategies to overcome the obstacles and to meet the need for living functional tissue replacements with a good growth potential and a long life span matching the pediatric population.

Avoiding the Need for Bowel Anastomosis during Pelvic Exenteration-Urinary Sigmoid or Descending Colon Conduit-Short and Long Term Complications

OBJECTIVE

To educate surgeons of distal colon urinary diversion as an alternative to ileal conduit. To assess perioperative outcomes of distal colon conduit in pelvic exenteration including conduit-related, gastrointestinal, infectious, metabolic, and wound complications within 30 days, 31-89 days, and greater than 90 days from the time of surgery.

MATERIALS AND METHODS

Forty-one patients who underwent distal colon urinary diversion for malignancy, fistula, or neurogenic bladder were identified in our IRB approved database from 1/2007 to 7/2017.

RESULTS

Twenty-six (63.4%) were male with mean age of 54.1 years. Complications were stratified by early (≤30 days), intermediate (31-89 days), and late (≥90 days). Within 30 days, 2 (4.9%) had partial small bowel obstructions requiring nasogastric tube (NGT) placement and total parenteral nutrition (TPN); 8 (19.5%) prolonged ileus with 6 (14.6%) requiring TPN and 5 (12.2%) requiring NGT placement; 1 (2.4%) enterocutaneous fistula; 1 (2.4%) conduit hemorrhage, 10 (24.4%) treated urinary tract infections (UTIs). Between 31 and 89 days, 1 patient (2.4%) had urinary conduit leak and 3 (7.3%) treated UTIs. At ≥90 days, 2 (4.9%) had partial small bowel obstructions requiring NGT placement, 4 (9.8%) ureterocolonic strictures and 1 (2.4%) parastomal hernia, 3 (7.3%) treated UTIs. Readmission rate in ≤30 days was 10 (24.4%), 31-89 days was 13 (31.7%), and 90+ days was 16 (39%). Long-term metabolic complications at ≥90 days included 16 (39%) with hypokalemia, 10 (24.4%) with hyperchloremia, and 14 (34.1%) with metabolic acidosis.

CONCLUSION

Distal colon urinary conduit is a relatively safe and feasible option and obviates the need for small bowel anastomosis and possible associated complications.

Wnt-GSK3β/β-Catenin Regulates the Differentiation of Dental Pulp Stem Cells into Bladder Smooth Muscle Cells

Smooth muscle cell- (SMC-) based tissue engineering provides a promising therapeutic strategy for SMC-related disorders. It has been demonstrated that human dental pulp stem cells (DPSCs) possess the potential to differentiate into mature bladder SMCs by induction with condition medium (CM) from bladder SMC culture, in combination with the transforming growth factor-β1 (TGF-β1). However, the molecular mechanism of SMC differentiation from DPSCs has not been fully uncovered. The canonical Wnt signaling (also known as Wnt/β-catenin) pathway plays an essential role in stem cell fate decision. The aim of this study is to explore the regulation via GSK3β and associated downstream effectors for SMC differentiation from DPSCs. We characterized one of our DPSC clones with the best proliferation and differentiation abilities. This stem cell clone has shown the capacity to generate a smooth muscle layer-like phenotype after an extended differentiation duration using the SMC induction protocol we established before. We further found that Wnt-GSK3β/β-catenin signaling is involved in the process of SMC differentiation from DPSCs, as well as a serial of growth factors, including TGF-β1, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), hepatocyte growth factor (HGF), platelet-derived growth factor-homodimer polypeptide of B chain (BB) (PDGF-BB), and vascular endothelial growth factor (VEGF). Pharmacological inhibition on the canonical Wnt-GSK3β/β-catenin pathway significantly downregulated GSK3β phosphorylation and β-catenin activation, which in consequence reduced the augmented expression of the growth factors (including TGF-β1, HGF, PDGF-BB, and VEGF) as well as SMC markers (especially myosin) at a late stage of SMC differentiation. These results suggest that the canonical Wnt-GSK3β/β-catenin pathway contributes to DPSC differentiation into mature SMCs through the coordination of different growth factors.

Pseudo-Renal Tubular Acidosis: Conditions Mimicking Renal Tubular Acidosis

Hyperchloremic metabolic acidosis, particularly renal tubular acidosis, can pose diagnostic challenges. The laboratory phenotype of a low total carbon dioxide content, normal anion gap, and hyperchloremia may be misconstrued as hypobicarbonatemia from renal tubular acidosis. Several disorders can mimic renal tubular acidosis, and these must be appropriately diagnosed to prevent inadvertent and inappropriate application of alkali therapy. Key physiologic principles and limitations in the assessment of renal acid handling that can pose diagnostic challenges are enumerated.

Physiological stretch induced proliferation of human urothelial cells via integrin α6-FAK signaling pathway

AIMS

To test a kind of stretch pattern which is the optimum stress parameter to promote human urothelial cells (HUCs) proliferation, and to investigate the roles of integrin subunits and their pathway in the HUCs proliferation induced by physiological stretch.

METHODS

HUCs were seeded on silicone membrane, and subjected to four kinds of stretch (0,5%,10%,15% elongation) for 24 h, as controlled by a BioDynamic^® bioreactor. Cell proliferation, viability and cycle distribution were examined using Cell Counting Kit-8 and flow cytometry, respectively. The gene and protein expression of integrin subunits and focal adhesion kinase (FAK) in each group were assessed by Real-time PCR(RT-PCR) and western blot, respectively. Small interfering RNAs (siRNA) were applied to knockdown integrin α6 and FAK expression in HUCs, and FAK inhibitor was used to validate the role of α6 and FAK in cell proliferation under physiological stretch.

RESULTS

The proliferation of HUCs were highest in the 5% elongation group compared to static control, 10% and 15% elongation group. RT-PCR and western blot showed that 5% cyclic stretch significantly promoted the expression of integrin α6 and FAK. The stretch-induced cell proliferation and FAK expression was inhibited by siRNA of integrin α6. Further study with FAK inhibitor revealed that elongation promoted proliferation though integrin α6 and FAK signaling pathway.

CONCLUSIONS

Physiological stretch induced HUCs proliferation via integrin α6-FAK signaling pathway, and 5% elongation may be the optimal stress parameter to promote the cell proliferation.

Bioengineering Approaches for Bladder Regeneration

Current clinical strategies for bladder reconstruction or substitution are associated to serious problems. Therefore, new alternative approaches are becoming more and more necessary. The purpose of this work is to review the state of the art of the current bioengineering advances and obstacles reported in bladder regeneration. Tissue bladder engineering requires an ideal engineered bladder scaffold composed of a biocompatible material suitable to sustain the mechanical forces necessary for bladder filling and emptying. In addition, an engineered bladder needs to reconstruct a compliant muscular wall and a highly specialized urothelium, well-orchestrated under control of autonomic and sensory innervations. Bioreactors play a very important role allowing cell growth and specialization into a tissue-engineered vascular construct within a physiological environment. Bioprinting technology is rapidly progressing, achieving the generation of custom-made structural supports using an increasing number of different polymers as ink with a high capacity of reproducibility. Although many promising results have been achieved, few of them have been tested with clinical success. This lack of satisfactory applications is a good reason to discourage researchers in this field and explains, somehow, the limited high-impact scientific production in this area during the last decade, emphasizing that still much more progress is required before bioengineered bladders become a commonplace in the clinical setting.

Tissue-Engineered Neo-Urinary Conduit from Decellularized Trachea

Decellularized tissues have been increasingly popular for constructing scaffolds for tissue engineering applications due to their beneficial biological compositions and mechanical properties. It is therefore natural to consider decellularized trachea for construction of tissue-engineered trachea, as well as other tubular organs. A Neo-Urinary Conduit (NUC) is such a tubular organ that works as a passage for urine removal in bladder cancer patients who need a urinary diversion after their diseased bladder is removed. In this study, we report our findings on the feasibility of using a decellularized trachea for NUC applications. As a NUC scaffold, decellularized trachea provides benefits of having not only naturally occurring biological components but also having sufficient mechanical properties and structural integrity. We, therefore, decellularized rabbit trachea, evaluated its mechanical performance, and investigated its ability to support in vitro growth of human smooth muscle cells (hSMCs) and human urothelial cells (hUCs). The decellularized trachea had appropriate biomechanical properties with ultimate tensile strength of ∼0.34 MPa in longitudinal direction and ∼1.0 MPa in circumferential direction and resisted a radial burst pressure of >155 mm Hg. Cell morphology study by scanning electron microscopy further showed that hUCs grown on decellularized trachea adopted a typical flatten and interconnected network structure in the lumen of the scaffold, while they formed a round spherical shape and did not spread on the outer surfaces. SMCs, on the other hand, spread well throughout the scaffold. The gene expression analysis by real time quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence studies further confirmed scaffold's ability to support long-term growth of hSMCs. Since uroepithelium has been shown to regenerate itself over time in vivo, these findings suggest that it is possible to construct a NUC from decellularized trachea without any preseeding of UCs. In future, we plan to translate decellularized trachea in a preclinical animal model and evaluate its biological performance.

Ex vivo Functional Evaluation of Isolated Strips in BAMG Tissue-Engineered Bladders

Although gastrointestinal segments have been widely used for bladder augmentation, they are still not considered ideal sources due to the possibility of complications. In this study, with the aim of reducing complications, we performed bladder augmentation in pigs using bladder acellular matrix grafts (BAMG) as a scaffold. Three months after surgery, the BAMG tissue-engineered bladders revealed bladder reconstruction that morphologically resembled that of the normal bladder. Functional experiments were performed to evaluate the contractile characteristics of isolated strips from both normal and BAMG tissue-engineered bladders 3 months after augmentation. No significant differences between these two groups were found in spontaneous contraction and contraction after electric stimulation; in the relaxing effect of epinephrine on potassium chloride-induced twitch height; in the contracting effects of acetylcholin; or in the antagonistic effect of atropine on acetylcholine-induced contraction.

These results demonstrate that not only can BAMG tissue-engineered bladders be histologically reconstructed, they also possess electrophysiological and pharmacological characteristics similar to normal bladders. This further confirms BAMG as an ideal scaffold for bladder augmentation.

In Vitro Differentiation and Propagation of Urothelium from Pluripotent Stem Cell Lines

Bioengineering of bladder tissue, particularly for those patients who have advanced bladder disease, requires a source of urothelium that is healthy, capable of significant proliferation in vitro and immunologically tolerated upon transplant. As pluripotent stem cells have the potential to fulfill such criteria, they provide a critical cell source from which urothelium might be derived in vitro and used clinically. Herein, we describe the in vitro differentiation of urothelium from the H9 human embryonic stem cell (hESC) line through the definitive endoderm (DE) phase via selective culture techniques. The protocol can be used to derive urothelium from other hESCs or human-induced pluripotent stem cells.

Application of the allogenic mesenchymal stem cells in the therapy of the bladder tuberculosis

Urogenital tuberculosis (TB) often leads to contraction of the bladder, a reduction of the urinary reservoir capacity, and, in the latest stage, to real microcystitis up to full obliteration. Bladder TB Stage 4 is unsuitable for conservative therapy, and cystectomy with subsequent enteroplasty is indicated. In this study, using a model of bladder TB in New Zealand rabbits, the therapeutic efficacy of the interstitial injection of autologous bone-derived mesenchymal stem cells (MSCs) combined with standard anti-TB treatment in the restoration of the bladder function was demonstrated. For analysis of the MSC distribution in tissues, the latter were labelled with superparamagnetic iron oxide nanoparticles. In vitro studies demonstrated the high intracellular incorporation of nanoparticles and the absence of cytotoxicity on MSC viability and proliferation. A single-dose administration of MSCs into the bladder mucosal layer significantly reduced the wall deformation and inflammation and hindered the development of fibrosis, which was proven by the subsequent histological assay. Confocal microscopy studies of the bladder cryosections confirmed the presence of superparamagnetic iron oxide nanoparticle-labelled MSCs in different bladder layers of the treated animals, thus indicating the role of stem cells in bladder regeneration.

Is chronic alkali therapy in orthotopic ileal neobladders necessary? A prospective controlled study

PURPOSE

To evaluate the necessity of chronic alkali therapy in non-complicated orthotopic ileal neobladders with normal renal function.

MATERIALS AND METHODS

This is a prospective study that included 200 male patients who underwent radical cystectomy and ileal W neobladder for invasive bladder carcinoma between January 1993 and December 2013. The studied patients included 100 consecutive patients who were maintained on regular alkali therapy since surgery and 100 consecutive patients who stopped the use of alkali treatment after initial 3 months postoperative with minimum postoperative observation time of 1 year. All patients had satisfactory function of the reservoirs with normal upper tract. The patients were subjected to blood analysis for creatnine, electrolytes, pH and bicarbonate and urine chemical analysis. The study also included 40 healthy male age-matched volunteers who served as a control group.

RESULTS

Both groups were comparable as regard age, BMI, follow-up period and surgical technique. There were no significant differences between both groups as regard serum creatnine, electrolytes blood pH and bicarbonate and the mean values were within normal range; however, the neobladder patients are still toward the acidotic side in comparison to healthy volunteers. Also there were no significant differences between both groups of patients as regard urine pH and excretion of electrolytes, calcium, phosphorus and creatnine.

CONCLUSION

Patients with non-complicated ileal neobladders with normal upper tract who were not maintained on alkali prophylaxis for long period have a compensated acid base status. Therefore, the prolonged alkali prophylaxis is not mandatory.

Hyperammonemia: What Urea-lly Need to Know: Case Report of Severe Noncirrhotic Hyperammonemic Encephalopathy and Review of the Literature

Purpose. A 66-year-old man who presented with coma was found to have isolated severe hyperammonemia and diagnosed with a late-onset urea-cycle disorder. He was treated successfully and had full recovery. Methods. We report a novel case of noncirrhotic hyperammonemia and review the literature on this topic. Selected literature for review included English-language articles concerning hyperammonemia using the search terms “hyperammonemic encephalopathy”, “non-cirrhotic encephalopathy”, “hepatic encephalopathy”, “urea-cycle disorders”, “ornithine transcarbamylase (OTC) deficiency”, and “fulminant hepatic failure”. Results. A unique case of isolated hyperammonemia diagnosed as late-onset OTC deficiency is presented. Existing evidence about hyperammonemia is organized to address pathophysiology, clinical presentation, diagnosis, and treatment. The case report is discussed in context of the reviewed literature. Conclusion. Late-onset OTC deficiency presenting with severe hyperammonemic encephalopathy and extensive imaging correlate can be fully reversible if recognized promptly and treated aggressively.

Experimental bladder regeneration using a poly-l-lactide/silk fibroin scaffold seeded with nanoparticle-labeled allogenic bone marrow stromal cells

In the present study, a poly-l-lactide/silk fibroin (PL-SF) bilayer scaffold seeded with allogenic bone marrow stromal cells (BMSCs) was investigated as a potential approach for bladder tissue engineering in a model of partial bladder wall cystectomy in rabbits. The inner porous layer of the scaffold produced from silk fibroin was designed to promote cell proliferation and the outer layer produced from poly-l-lactic acid to serve as a waterproof barrier. To compare the feasibility and efficacy of BMSC application in the reconstruction of bladder defects, 12 adult male rabbits were divided into experimental and control groups (six animals each) that received a scaffold seeded with BMSCs or an acellular one, respectively. For BMSC tracking in the graft in in vivo studies using magnetic resonance imaging, cells were labeled with superparamagnetic iron oxide nanoparticles. In vitro studies demonstrated high intracellular incorporation of nanoparticles and the absence of a toxic influence on BMSC viability and proliferation. Following implantation of the graft with BMSCs into the bladder, we observed integration of the scaffold with surrounding bladder tissues (as detected by magnetic resonance imaging). During the follow-up period of 12 weeks, labeled BMSCs resided in the implanted scaffold. The functional activity of the reconstructed bladder was confirmed by electromyography. Subsequent histological assay demonstrated enhanced biointegrative properties of the PL-SF scaffold with cells in comparison to the control graft, as related to complete regeneration of the smooth muscle and urothelium tissues in the implant. Confocal microscopy studies confirmed the presence of the superparamagnetic iron oxide nanoparticle-labeled BMSCs in newly formed bladder layers, thus indicating the role of stem cells in bladder regeneration. The results of this study demonstrate that application of a PL-SF scaffold seeded with allogenic BMSCs can enhance biointegration of the graft in vivo and support bladder tissue regeneration and function.

Enterocystoplasty: The long-term effects on bone mineral density

BACKGROUND

Studies show that enterocystoplasty has a negative effect on bone mineral density (BMD). The aim of this study was to investigate the long-term impact of enterocystoplasty on BMD. We used dual energy x-ray absorptiometry (DEXA) scans to determine BMD and identify patients with osteopenia and osteoporosis who are at potential long-term risk for fracture.

MATERIALS AND METHODS

We reviewed our database of >200 individuals, who had undergone enterocystoplasty or continent diversion for both neurogenic and non-neurogenic reasons during childhood. We chose to study the non-neurogenic group first for a number of technical reasons, and identified 24 individuals who had undergone the procedure for non-neurogenic reasons, and had more than 15 years of follow-up. In addition we had a control group of 10 individuals born with bladder exstrophy, who had undergone primary closure before the year 2000, without enterocystoplasty. We used DEXA scan T- and Z-scores to identify patients with osteopenia and osteoporosis.

RESULTS

Eleven of 24 patients had normal DEXA scans with normal T- and Z-scores; seven had identifiable osteopenia and increased long-term risk for fracture. Six had osteoporosis; three of whom had reduced glomerular filtration rate (GFR). Eight of the 10 individuals in the control group had a normal DEXA scan.

CONCLUSIONS

Enterocystoplasty during childhood can lead to loss of BMD. This does not seem to be related to the enterocystoplasty alone. It is more pronounced in individuals who have other risk factors, such as reduced GFR. The identification of BMD loss makes it possible to intervene before osteoporosis occurs and leads to pathologic fracture.

Aerosol transfer of bladder urothelial and smooth muscle cells onto demucosalized colonic segments for bladder augmentation: in vivo, long term, and functional pilot study

BACKGROUND

Bladder augmentation technique has changed over the years and the current practice has significant adverse health effects and long-term sequelae. Previously, we reported a novel cell transfer technology for covering demucosalized colonic segments with bladder urothelium and smooth muscle cells through an aerosol spraying of these cells and a fibrin glue mixture.

OBJECTIVE

To determine the long-term durability and functional characteristics of demucosalized segments of colon repopulated with urothelial cells in the bladder of swine for use in augmentation cystoplasty.

STUDY DESIGN

Nine swine were divided into three groups. The first group (control) underwent standard colocystoplasty; the second group underwent colocystoplasty with colonic demucosalization and aerosol application of fibrin glue and urothelial cell mixture; in the third group detrusor cells were added to the mixture described in group two. The animals were kept for 6 months. Absorptive and secretory function was assessed. Bladders were harvested for histological and immunohistochemical evaluation.

RESULTS

All animals but one in the experimental groups showed confluent urothelial coverage of the colonic segment in the bladder without any evidence of fibrosis, inflammation, or regrowth of colonic epithelial cells. Ten percent of the instilled water in the bladder was absorbed within an hour in the control group, but none in experimental groups(p = 0.02). The total urine sediment and protein contents were higher in the control group compared with experimental groups (p < 0.05).

DISCUSSION

Both study groups developed a uniform urothelial lining. Histologically, the group with smooth muscle had an added layer of submucosal smooth muscle. Six months after bladder augmentation the new lining was durable. We were also able to demonstrate that the reconstituted augmented segments secrete and absorb significantly less than the control colocystoplasty group. We used a non-validated simple method to evaluate permeability of the new urothelial lining to water. To determine if the aerosol transfer of bladder cells would have behaved differently in the neurogenic bladder population, this experiment should have been performed in animals with neuropathic bladders.

CONCLUSION

Aerosol spraying of single cell suspension of urothelial and muscular cells with fibrin glue resulted in coverage of the demucosalized intestinal segment with a uniform urothelial layer. This new lining segment was durable without regrowth of colonic mucosa after 6 months. The new reconstituted segment absorbs and secretes significantly less than control colocystoplasty.

We can rebuild it: reconstructive solutions for structural urologic diseases

Bladder augmentation and urinary diversion have become standard of care as surgical treatments for structural and functional disorders affecting the bladder, both in children and adults. With improved medical care, long-term survival of these patients is expected. Common medical problems that can occur such as metabolic side effects including acid-base imbalances and nutritional issues need to be anticipated and addressed. In addition, surgical problems caused by impaired urinary drainage, namely stones and urinary tract infections, and mechanical factors related to catheterizable channels and continence also may compound postoperative management. The risk of malignancy after bladder augmentation and substitution, and appropriate surveillance for this, remains to be clearly defined.

Neurogenic bladder in spinal cord injury patients

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

Organ-specific matrix self-assembled by mesenchymal cells improves the normal urothelial differentiation in vitro

PURPOSE

Enterocystoplasty is the gold standard to perform bladder reconstruction. Since this technique has a high morbidity rate, several matrix scaffolds have been proposed to support the urothelial maturation. Unfortunately, epithelial cells failed to fully integrate the cell-matrix interactions and therefore appropriate signalling pathways of normal differentiation. Based on these observations, we proposed to culture bladder urothelial cells (BUC) onto a matrix self-assembled by bladder mesenchymal cells (BMC), to form a vesical model (VM).

METHODS

Different serum proportions were assessed to obtain a manipulable matrix deposited by BMC. The BUC were then seeded onto the BMC's matrix to evolve in a three-dimensional culture. Haematoxylin-eosin staining, immunolabeling, scanning electron microscopy, western blot and matrix metalloproteinases analysis were performed for the VM characterization.

RESULTS

We were able to obtain an original matrix made of collagen-I and presenting specific organization. Matrix remodelling was observed and led to a cellular compartmentalization. The reconstructed urothelium developed in a pseudostratified arrangement, displaying an adequate cellular polarity and apical membrane remodelling of superficial cells. Like native bladder, cytokeratin 14 immunolabeling was not observed in our VM, which indicate the conformity of the development sequence taken by BUC under the influence of the BMC's matrix.

CONCLUSION

Thus, it was possible to elaborate a VM without the use of exogenous matrices. The particular characteristics of the BMC's matrix permitted the development of an urothelium that shared the phenotype of native tissue. The autologous character of our VM, and its appropriate urothelial maturation, could potentially promote a better integration after grafting.

Bricker Conduit for Pediatric Urinary Diversion--Should we Still Offer It?

PURPOSE

We sought to evaluate long-term outcomes of the Bricker conduit urinary diversion in children.

MATERIALS AND METHODS

We retrospectively reviewed the database of a single tertiary center for children who had undergone ileal conduit between 1981 and 2011. Patients followed for less than 1 year were excluded. Patient files were reviewed for demographics, diversion indication, preoperative imaging, surgical details, hospital readmissions and followup data. Renal function at baseline and last followup was assessed by estimated glomerular filtration rate, calculated using the modified Schwartz or MDRD (Modified Diet in Renal Disease) formula. Growth charts elucidated patient growth patterns, while an internally designed quality of life questionnaire demonstrated patient and family satisfaction with the procedure.

RESULTS

We evaluated 29 children who underwent Bricker conduit at a median age of 10 years (range 2 to 18) and were followed for a median of 91 months (16 to 389). Neuropathic bladder was the underlying diagnosis in 72.4% of cases. Hydronephrosis improved or remained stable in 39 of 55 studied renal units (70.9%). Although no statistically significant difference was observed between mean ± SD baseline (64.5 ± 46 ml/minute/1.73 m(2)) and last followup estimated glomerular filtration rate (54.1 ± 44.9 ml/minute/1.73 m(2)), chronic kidney disease stage had worsened in 13 patients (44.8%), end-stage kidney disease had developed in 11 patients and 9 patients had died. Six patients underwent undiversion after stabilization of renal function. Linear growth was negatively affected in 12 patients (41.4%), and 85% reported poor quality of life. A total of 19 hospital readmissions were required in 14 patients to treat diversion related complications.

CONCLUSIONS

The Bricker conduit does not seem to halt renal deterioration in children. Negative impact on growth and quality of life, and the anticipated rate of complications are significant limitations of the procedure in the pediatric population.

Inosculation of blood vessels allows early perfusion and vitality of bladder grafts--implications for bioengineered bladder wall

Bioengineered bladder tissue is needed for patients with neurogenic bladder disease as well as for cancer. Current technologies in bladder tissue engineering have been hampered by an inability to efficiently initiate blood supply to the graft, ultimately leading to complications that include graft contraction, ischemia, and perforation. To date, the biological mechanisms of vascularization on transplant have not been suitably investigated for urologic tissues. To better understand the mechanisms of neovascularization on bladder wall transplant, a chimeric mouse model was generated such that angiogenesis and vasculogenesis could be independently assessed in vivo. Green fluorescence protein (GFP) transgenic mice received bone marrow transplants from β-galactosidase (LacZ) transgenic animals and then subsequent bladder wall transplants from wild-type donor mice. Before euthanization, the aorta was infused with fluorescent microbeads (fluorospheres) to identify perfused vessels. The contributions of GFP (angiogenesis) and LacZ (vasculogenesis) to the formation of CD31-expressing blood vessels within the wild-type graft were evaluated by immunohistochemistry at different time points and locations within the graft (proximal, middle, and distal) to provide a spatiotemporal analysis of neovascularization. The GFP index, a measure of angiogenic host ingrowth, was significantly higher at proximal versus mid or distal regions in animals 2-16 weeks post-transplant. However, GFP index did not increase over time in any area. Within 7 days post-transplant, perfusion of primarily wild-type, donor blood vessels in the most distal areas of the graft was observed by intraluminal fluorospheres. In addition, chimeric host-donor (GFP-wild type) blood vessels were evident in proximal areas. The contribution of vasculogenesis to vascularization of the graft was limited, as LacZ cells were not specifically associated with the endothelial cells of blood vessels, but rather found primarily in areas of inflammation. The data suggest that angiogenesis of host blood vessels into the proximal region leads to inosculation between host and donor vessels and subsequent perfusion of the graft via pre-existing graft vessels within the first week after transplant. As such, the engineering of graft blood vessels and the promotion of inosculation might prevent graft contraction, thereby potentiating the use of bioengineered bladder tissue for transplantation.

[Continent urinary diversion following anterior exenteration]

BACKGROUND

Quality of life after anterior or total exenteration is determined, among other factors, by the type of urinary diversion. There are two different types of urinary diversion: incontinent diversion (ureterocutaneostomy, ileal conduit, and colonic conduit) and continent diversions (continent cutaneous pouch, orthotopic neobladder, and rectal reservoir).

RESULTS

Invasive bladder cancer and advanced or recurrent gynecological tumors are the main indications for continent urinary diversion in women. In patients with non-irradiated bladder cancer, an orthotopic neobladder (except those with tumor invasion of the bladder neck or urethra) or a rectal reservoir is an option. In patients who had received preoperative radiotherapy, non-irradiated bowel segments should be used for urinary diversion (e.g., the transverse colon). In patients with planned postoperative radiation, the urinary diversion should be outside the radiation field.

CONCLUSION

Advantages and disadvantages of all types of urinary diversion should be objectively discussed with the patient. Especially exenteration for advanced or recurrent gynecological cancers should be performed in centers with a multidisciplinary team (gynecologist, urologist, radiotherapist, and in cases with complete exenteration the gastrointestinal surgeon).