Urinary bladder auto augmentation using INTEGRA and SURGISIS: an experimental model

Unusual cell-cell cooperative mechanical activity elucidates the process of tissue regeneration

We have studied wound contraction in three model wounds in animals: excised skin (guinea pig), transected peripheral nerve (rat) and the excised conjunctiva (rabbit). Wound contraction is driven by myofibroblasts bound together by adherens junctions (AJ) that confer cooperative activity to myofibroblasts during wound contraction and synthesis of scar. Grafting with the dermis regeneration template (DRT) cancels cell cooperativity by abolishing AJ connections in myofibroblasts, while also cancelling wound contraction, preventing synthesis of scar and inducing regeneration of excised tissues. The observed definitive prevention of scar synthesis suggests the exploration of DRT scaffolds to regenerate tissues in several other organs and to prevent fibrosis in humans.

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.

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

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

[Urodynamic changes after bladder augmentation surgery in paediatric patients with myelomeningocele due to neurogenic bladder]

BACKGROUND

Augmentation cystoplasty is a successful surgical procedure for the management of neurogenic bladder in children in order to improve urodynamic parameters. The aim of this article is to describe urodynamic changes after augmentation cystoplasty in children with myelomeningocele.

MATERIALS AND METHODS

A descriptive cross-sectional study including children aged 8-16 years with a myelomeningocele operated on for augmentation cystoplasty surgery with sigmoid colon segments due to a neurogenic bladder from the years 2003-2013. A urodynamic study was conducted before and after the surgical procedure. Non-probabilistic sample of consecutive cases. Descriptive statistics with frequencies and percentages, medians, and ranges. Inferential intra-group comparison with the Wilcoxon test and inter-group with Mann-Whitney U. SPSS 20.0 statistical package.

RESULTS

The study included 50 patients, of whom 25 were male and 25 were female, with a median age of 12 years (range, 6-15 years). Bladder capacity improved from 52.8% to 95.9% (p<0.001), uninhibited contractions 1.4-1.8, contraction intensity 47-8.5 (p<0.001), mean pre-surgical and post-surgical filling pressure 40.8cm H2O and 11.0cm H2O, respectively (p<0.001), mean emptying pressure 48.5 vs. 3.6cm H2O (p<0.001), and bladder accommodation 4.6 vs. 41.3cm H2O (p<0.001).

CONCLUSIONS

Augmentation cystoplasty with sigmoid colon significantly improved urodynamic parameters, such as bladder accommodation and filling pressure in children with myelomeningocele-associated neurogenic bladder.

Bladder autoaugmentation with protective autologous uterine flap. Experimental study in the rat

INTRODUCTION

Enterocystoplasties are associated to complications. We developed a surgical technique for bladder autoaugmentation using autologous uterine flap in the rat, to try and improve the post-surgical evolution.

METHODS

36 female Wistar rats were randomly allocated into following groups: Group 1: Control (n = 12) for analytical parameters, Group 2: Sham-operation hysterocystorrhaphy (n = 12) and Group 3: Bladder autoaugmentation with autologous uterine flap (n = 12). Two weeks after surgery ultrasound examination of the bladder was performed. At 8 weeks and 24 weeks, blood and urine samples were taken. Post-mortem evaluation was performed and urogenital apparatus removed for gross and microscopic examination. The statistical analysis was done using the Kruskall-Wallis and the extension of the Fisher's exact test. Significance was set at 5% (p < 0.05).

RESULTS

Serum chemistry, blood count and peripheral blood smears, electrolytes and urinary parameters were all within the normal range for the rat. No abnormal findings were observed during ultrasound examination. There was no mortality or other surgical complications. Post-mortem evaluation revealed no dilation of bladder, uterus or upper urinary tract. Uroliths were not observed. Histology of the augmented area demonstrated an excellent union between the bladder and the protective uterine flap. A normal urothelial layer was maintained.

CONCLUSIONS

The use of autologous uterine flap to perform bladder autoaugmentation in the rat proved a safe and suitable surgical technique to augment the bladder. The major advantage is the avoidance of the complications observed in other surgical techniques for bladder augmentation, like enterocystoplasties, where gastrointestinal tract epithelium is incorporated into the urinary tract.

An examination of regenerative medicine-based strategies for the urinary bladder

Patients that are afflicted with dysfunctional urinary bladders due to developmental defect, trauma or malignant transformation have limited treatment options that would allow for complete recapitulation of the urinary bladder. Hence, novel tissue engineering techniques that are successful in regenerating functional urinary bladder tissue for replacement therapy would be invaluable. Current tissue engineering techniques are hampered by several problems including choice of appropriate cell type, inadequate development of new blood vessels to the regenerated tissue, tissue innervation and primitive bioscaffold design. This article describes the recent advances in stem cell biology and the material sciences to address these problems, and attempts to improve upon current tissue engineering techniques to make successful regeneration of urinary bladder tissue a reality.