Urethral Tissue Reconstruction Using the Acellular Dermal Matrix Patch Modified with Collagen-Binding VEGF in Beagle Urethral Injury Models.

OBJECTIVES: Urethral tissue reconstruction for hypospadias is challenging for urologists. In this study, bovine acellular dermal matrix (ADM) patch loading with collagen-binding vascular endothelial growth factor (CBD-VEGF) was used to repair the urethral injury in beagles. METHODS: The safety and effectiveness of the scaffold implantation were carefully evaluated by comparing among the urethral injury control group, ADM implantation group, and ADM modified with CBD-VEGF implantation group during 6 months. Urodynamic examination, urethral angiography, and pathological examination were performed to evaluate the recovery of urethral tissue. RESULTS: Stricture, urethral diverticulum, and increased urethral closure pressure were observed in the control group. Fistula was observed in one animal in the ADM group. By contrast, no related complications or other adverse situations were observed in animals treated with ADM patch modified with CBD-VEGF. The average urethra diameter was significantly smaller in the control animals than in scaffold implantation groups. Pathological examination revealed more distribution of proliferative blood vessels in the animals treated with ADM modified with CBD-VEGF. CONCLUSIONS: Overall, ADM patches modified with CBD-VEGF demonstrated an optimized tissue repair performance in a way to increase tissue angiogenesis and maintain urethral function without inducing severe inflammation and scar formation.

Fiber density of collagen grafts impacts rabbit urethral regeneration.

There is a need for efficient and "off-the-shelf" grafts in urethral reconstructive surgery. Currently available surgical techniques require harvesting of grafts from autologous sites, with increased risk of surgical complications and added patient discomfort. Therefore, a cost-effective and cell-free graft with adequate regenerative potential has a great chance to be translated into clinical practice. Tubular cell-free collagen grafts were prepared by varying the collagen density and fiber distribution, thereby creating a polarized low fiber density collagen graft (LD-graft). A uniform, high fiber density collagen graft (HD-graft) was engineered as a control. These two grafts were implanted to bridge a 2 cm long iatrogenic urethral defect in a rabbit model. Histology revealed that rabbits implanted with the LD-graft had a better smooth muscle regeneration compared to the HD-graft. The overall functional outcome assessed by contrast voiding cystourethrography showed patency of the urethra in 90% for the LD-graft and in 66.6% for the HD-graft. Functional regeneration of the rabbit implanted with the LD-graft could further be demonstrated by successful mating, resulting in healthy offspring. In conclusion, cell-free low-density polarized collagen grafts show better urethral regeneration than high-density collagen grafts.

Radial Forearm.

The radial forearm free flap phalloplasty provides a thin, potentially sensate, minimally hair-bearing cutaneous flap. Since its initial description, several modifications of the technique have emerged. The earliest dimensions described needed to be increased because of the increase amount of subcutaneous fat in the Western population. Incorporating a centrally placed neo-urethra with a distal extension that gets folded over to create a semblance of a neoglans eliminates the distal/meatal stenosis. Performing a urethral extension at a preliminary surgery and extending the neourethra proximally has improved the position of the neophallus and minimized proximal urethral strictures and fistulas in transgender men.

Width proportion of the urethral plate to the glans can serve as an appraisal index of the urethral plate in hypospadias repair.

OBJECTIVES: To find a new appropriate evaluation for urethral plate quality in hypospadias repair, with particular interest in the width proportion of the urethral plate to the glans, serving as an appraisal index. METHODS: Data were prospectively collected from prepubertal boys who underwent primary tubularized incised plate hypospadias repair between January 2014 and April 2016 in one center. Intrinsic parameters of the penis (meatal location, glans width, urethral plate width and curvature degree) were measured during the operation. Urethroplasty complications were recorded during follow up. The correlation between width proportion of the urethral plate to the glans and urethroplasty complications was analyzed. RESULTS: Primary tubularized incised plate repair was carried out in 442 patients (mean age 2.8 years, range 0.5-12 years). At mean follow up of 26 months (range 12-38 months), urethroplasty complications occurred in 59 (13.3%) patients. The width proportion of the urethral plate to the glans was weakly correlated to both the glans width and meatal location. The width proportion of the urethral plate to the glans ranged from 0.18 to 0.73, with a mean of 0.39. The cut-off value of width proportion of the urethral plate to the glans was determined to be 0.36 by the receiver operating characteristic curve. Urethroplasty complications occurred in 17 out of 254 patients (6.7%) with width proportion of the urethral plate to the glans >0.36, and 42 out of 188 patients (22.3%) with width proportion of the urethral plate to the glans ≤0.36. The width proportion of the urethral plate to the glans ≤0.36 showed an increased odds of 4.819-fold (95% confidence interval 2.548-9.112, P < 0.001) risk of urethroplasty complications compared with width proportion of the urethral plate to the glans >0.36. Midshaft and proximal meatal location also increased the risk of urethroplasty complications. CONCLUSIONS: The present study highlights the value of the width proportion of the urethral plate to the glans for objectivity and accuracy in urethral plate evaluation, which in turn serves as an independent factor influencing outcomes in tubularized incised plate repair.

Substitution urethroplasty using oral mucosa graft for male anterior urethral stricture disease: Current topics and reviews.

Male anterior urethral stricture is scarring of the subepithelial tissue of the corpus spongiosum that constricts the urethral lumen, decreasing the urinary stream. Its surgical management is a challenging problem, and has changed dramatically in the past several decades. Open surgical repair using grafts or flaps, called substitution urethroplasty, has become the gold standard procedure for anterior urethral strictures that are not amenable to excision and primary anastomosis. Oral mucosa harvested from the inner cheek (buccal mucosa) is an ideal material, and is most commonly used for substitution urethroplasty, and lingual mucosa harvested from the underside of the tongue has recently emerged as an alternative material with equivalent outcome. Onlay augmentation of oral mucosa graft on the ventral side (ventral onlay) or dorsal side (dorsal onlay, Barbagli procedure) has been widely used for bulbar urethral stricture with comparable success rates. In bulbar urethral strictures containing obliterative or nearly obliterative segments, either a two-sided dorsal plus ventral onlay (Palminteri technique) or a combination of excision and primary anastomosis and onlay augmentation (augmented anastomotic urethroplasty) are the procedures of choice. Most penile urethral strictures can be repaired in a one-stage procedure either by dorsal inlay with ventral sagittal urethrotomy (Asopa technique) or dorsolateral onlay with one-sided urethral dissection (Kulkarni technique); however, staged urethroplasty remains the procedure of choice for complex strictures, including strictures associated with genital lichen sclerosus or failed hypospadias. This article presents an overview of substitution urethroplasty using oral mucosa graft, and reviews current topics.

Future Prospects for Human Tissue Engineered Urethra Transplantation: Decellularization and Recellularization-Based Urethra Regeneration.

To evaluate the histological characteristics of decellularized human urethra after transplantation into the rat omentum and compare in vivo cell seeding with perfusion-based and cell sheet urethral regeneration. Eight adult human male urethras accompanied with the surrounding corpus spongiosum were obtained. The tissues were decellularized with detergent-based method. The efficacy of decellularization and extracellular matrix preservation was evaluated by several techniques. Decellularized scaffolds were transplanted into the omentum of 12 male rats and located into the scrotum. Biopsies were taken 1, 3, and 6 months postoperatively to assess the natural recellularization. Mesenchymal stem cells obtained from preputial tissue were seeded with perfusion-based and cell sheet techniques as well. Immunohistochemical staining with α-actin, cytokeratin AE1/AE3, synaptophysin, and CD31 antibodies were performed. Removal of nuclear components and preservation of biomechanical properties was confirmed. In-vivo recellularization revealed promising results in progressive angiogenesis and cell seeding of epithelium-like cells in the lining of the urethra as well as smooth muscle cells in the wall structure. In-vitro urethral regeneration revealed that cell sheet engineering was the technique of choice compared to perfusion-based technique. This study may paw the road for clinical application of acellular urethral matrix with the surrounding corpus spongiosum in urological reconstructive surgery.

Tissue Engineering of the Urethra: A Systematic Review and Meta-analysis of Preclinical and Clinical Studies.

CONTEXT: Urethra repair by tissue engineering has been extensively studied in laboratory animals and patients, but is not routinely used in clinical practice. OBJECTIVE: To systematically investigate preclinical and clinical evidence of the efficacy of tissue engineering for urethra repair in order to stimulate translation of preclinical studies to the clinic. EVIDENCE ACQUISITION: A systematic search strategy was applied in PubMed and EMBASE. Studies were independently screened for relevance by two reviewers, resulting in 80 preclinical and 23 clinical studies of which 63 and 13 were selected for meta-analysis to assess side effects, functionality, and study completion. Analyses for preclinical and clinical studies were performed separately. Full circumferential and inlay procedures were assessed independently. Evaluated parameters included seeding of cells and type of biomaterial. EVIDENCE SYNTHESIS: Meta-analysis revealed that cell seeding significantly reduced the probability of encountering side effects in preclinical studies. Remarkably though, cells were only sparsely used in the clinic (4/23 studies) and showed no significant reduction of side effects. ln 21 out of 23 clinical studies, decellularized templates were used, while in preclinical studies other biomaterials showed promising outcomes as well. No direct comparison to current clinical practice could be made due to the limited number of randomized controlled studies. CONCLUSIONS: Due to a lack of controlled (pre)clinical studies, the efficacy of tissue engineering for urethra repair could not be determined. Meta-analysis outcome measures were similar to current treatment options described in literature. Surprisingly, it appeared that favorable preclinical results, that is inclusion of cells, were not translated to the clinic. Improved (pre)clinical study designs may enhance clinical translation. PATIENT SUMMARY: We reviewed all available literature on urethral tissue engineering to assess the efficacy in preclinical and clinical studies. We show that improvements to (pre)clinical study design is required to improve clinical translation of tissue engineering technologies.

Urethral Reconstruction Using Mesothelial Cell-Seeded Autogenous Granulation Tissue Tube: An Experimental Study in Male Rabbits.

Objective. This study was to evaluate the utility of the compound graft for tubularized urethroplasty by seeding mesothelial cells onto autogenous granulation tissue. Methods. Silastic tubes were implanted subcutaneously in 18 male rabbits, of which nine underwent omentum biopsies simultaneously for in vitro expansion of mesothelial cells. The granulation tissue covering the tubes was harvested 2 weeks after operation. Mesothelial cells were seeded onto and cocultured with the tissue for 7 days. A pendulous urethral segment of 1.5 cm was totally excised. Urethroplasty was performed with mesothelial cell-seeded tissue tubes in an end-to-end fashion in nine rabbits and with unseeded grafts in others as controls. Serial urethrograms were performed at 1, 2, and 6 months postoperatively. Meanwhile, the neourethra was harvested and analyzed grossly and histologically. Results. Urethrograms showed cell-seeded grafts maintained wide at each time point, while strictures formation was found in unseeded grafts. Histologically, layers of urothelium surrounded by increasingly organized smooth muscles were observed in seeded grafts. In contrast, myofibroblasts accumulation and extensive scarring occurred in unseeded grafts. Conclusions. Mesothelial cell-seeded granulation tissue tube can be successfully used for tubularized urethroplasty in male rabbits.

Glans reconstruction with the use of an inverted urethral flap after distal penile amputation for carcinoma.

Restoration of adequate cosmesis and preservation of sexual and urinary function are the main goals of penile reconstructive surgery following amputation for carcinoma. Split thickness skin grafts and oral mucosa grafts have been widely used for the creation of a pseudoglans with excellent cosmetic and functional results. The main drawbacks associated with the use of grafts are donor site morbidity, the lack of engorgement of the pseudoglans and the risk of poor graft take, which may lead to contracture and poor cosmetic results. In the present series the long term cosmetic and functional outcomes of glans reconstruction with an inverted distal urethral flap are described.

Update on tissue engineering in pediatric urology.

Pediatric urology patients often present with congenital or acquired tissue and organ dysfunction that requires surgical reconstruction to recreate the normal genitourinary systems functions. The traditional methods have varying degrees of donor site morbidity or inherent side effects. Tissue engineering is a developing field that aims to replace or regenerate these dysfunctional tissues and organs with cells, biomaterials, or a combination thereof. A tremendous amount of work has been done to these ends in terms of preclinical work, and some clinical trials have resulted. This review highlights the status of these studies in pediatric urology for the use of tissue engineering and reconstruction of the corporal bodies, urethra, and bladder.

Two-layer tissue engineered urethra using oral epithelial and muscle derived cells.

PURPOSE: We fabricated novel tissue engineered urethral grafts using autologously harvested oral cells. We report their viability in a canine model. MATERIALS AND METHODS: Oral tissues were harvested by punch biopsy and divided into mucosal and muscle sections. Epithelial cells from mucosal sections were cultured as epithelial cell sheets. Simultaneously muscle derived cells were seeded on collagen mesh matrices to form muscle cell sheets. At 2 weeks the sheets were joined and tubularized to form 2-layer tissue engineered urethras, which were autologously grafted to surgically induced urethral defects in 10 dogs in the experimental group. Tissue engineered grafts were not applied to the induced urethral defect in control dogs. The dogs were followed 12 weeks postoperatively. Urethrogram and histological examination were done to evaluate the grafting outcome. RESULTS: We successfully fabricated 2-layer tissue engineered urethras in vitro and transplanted them in dogs in the experimental group. The 12-week complication-free rate was significantly higher in the experimental group than in controls. Urethrogram confirmed urethral patency without stricture in the complication-free group at 12 weeks. Histologically urethras in the transplant group showed a stratified epithelial layer overlying well differentiated submucosa. In contrast, urethras in controls showed severe fibrosis without epithelial layer formation. CONCLUSIONS: Two-layer tissue engineered urethras were engineered using cells harvested by minimally invasive oral punch biopsy. Results suggest that this technique can encourage regeneration of a functional urethra.

Staged male urethroplasty transferring megalourethra tissue as free graft dorsal inlay to proximal urethral atresia in VACTERL association.

Megalourethra is a rare spectrum of urologic malformations of penile corporal structures frequently associated with multiple congenital anomalies, such as prune belly syndrome or vertebral, anorectal, cardiac, trachea-esophageal, renal, and limb (VACTERL association) defects. A 6-year-old boy with VACTERL association and proximal urethral atresia with distal fusiform megalourethra underwent staged reconstruction, including appendicovesicostomy, perineal urethrostomy, and first-stage urethroplasty with a dorsal inlay free graft of megalourethra tissue to the proximal urethral atretic region, followed by second-stage urethroplasty. At 2.6 years of follow-up, he was continent, voids per urethra without postvoid residual urine volume, and no longer performs clean intermittent catheterization by way of the appendicovesicostomy.

Peritoneal cavity as bioreactor to grow autologous tubular urethral grafts in a rabbit model.

PURPOSE: To investigate whether peritoneal cavity could function as bioreactor to produce autologous tubular grafts for urethral reconstruction in male rabbits. METHODS: 8Fr silastic tubes were implanted into peritoneal cavities of nine male rabbits. By 2 weeks, tubes were harvested and the tubular tissue covering the tubes was everted. A pendulous urethral segment of 1.5 cm long was totally excised and urethroplasty was performed with the everted tubular tissue in an end-to-end fashion. Another nine male rabbits underwent the same urethral resection and re-anastomosis as controls. Urethrography was performed at 1, 2 and 6 months postoperatively. Meanwhile, the neo-urethra were harvested and analyzed grossly and histologically. RESULTS: Histological analysis of the tubular tissue demonstrated transversely arranged myofibroblasts embedded in homogeneous collagen bundles and an outer layer of mesothelium. The tissue was easily everted and successfully transplanted as a urethral graft. Serial urethrography indicated no stricture or diverticula formation. While all animals of the control group developed stricture. Histological analysis of the neo-urethra demonstrated normal urethral architecture by 1 month, composed of multi-layers of urothelium surrounded by smooth muscle bundles, which became increasingly organized with time. By 6 months, the neo-urethra could be hardly distinguished from native urethra both grossly and histologically. CONCLUSIONS: These results show that the autologous tissue grown within the recipients' peritoneal cavity can be used successfully for tubularized urethral reconstruction in male rabbits.

Current status of tissue engineering in urology.

PURPOSE OF REVIEW: Tissue engineering is a rapidly advancing technology that is shifting from the laboratory to urological practice. The review explores recent developments and considers the relationship to existing treatments. RECENT FINDINGS: Different strategies to generate transplantable tissue grafts in vitro and harness host regenerative processes for integration of grafts and biomaterials in vivo are common themes in the recent literature. Highlights include dynamic cell culture to precondition grafts and the use of omental wrapping to promote vascularization. Emphasis on specific cell culture conditions is set to shift towards the monitoring of differentiation and functional outcome. The future might encompass the use of stem cells to overcome the issues of harvesting cells from diseased tissues. Improved understandings of scaffold and cell interactions are particularly important to advance graft development and outcome. Recent trials give some indication of clinical outcome for tissue-engineered treatments, but patient benefit could be difficult to interpret in salvage cases. SUMMARY: Tissue engineering applications can be broken down into tissue- or organ-based approaches, only through examining these in clinical settings can potential success can be judged. Treatments must be appropriately evaluated for risk/benefit in comparison to existing treatments. This approach requires open and robust debate amongst clinicians and scientists.

Cirugía de la estenosis de uretra. Actualización / Surgical treatment of urethral stenosis: update

Objetivo: Llevar a cabo una recopilación de los principales métodos de tratamiento quirúrgico de la estenosis de uretra peneana y bulbar. Métodos: Revisamos la bibliografía más actualizada, centrándonos en autores con gran experiencia en el tratamiento de la estenosis uretral, y utilizamos nuestra experiencia para contrastar o reafirmar alguna de las técnicas. Resultados/Conclusiones: La base del tratamiento de la estenosis uretral radica en la propia estenosis, es decir, localización, etiología y longitud, así como en las características del paciente (edad, historia clínica). Entre las uretroplastias disponemos de técnicas en un tiempo, como la excisión y anastomosis, y el uso de injertos libres o colgajos pediculados. Las técnicas en dos tiempos como la de Johanson o la perineostomía son de gran utilidad en determinados casos de estenosis complejas. Debemos permanecer atentos al desarrollo de nuevas técnicas y al empleo de nuevos materiales que ayudaran, una vez consolidados a obtener mejores resultados (AU

Objectives: To compile the main methods of surgical treatment of penile and bulbar urethral stenosis. Methods: We review the most updated bibliography, focusing on authors with large experience in the treatment of urethral stenosis, and we use our own experience to contrast or reaffirm some of the techniques. Results/Conclusions: The base of the treatment of urethral stenosis remains in the stenosis itself (localization, etiology and length) and also in patient’s characteristics (age, past medical history). Among the techniques of urethroplasty we have techniques in one step, as the technique of excision and anastomosis, and the use of free grafts or vascularized flaps. The techniques in two steps like Johannson's or perineostomy are very useful in certain cases of complex stenosis. We should keep an eye on the development of new techniques and the use of new materials that will help, once consolidated, to improve results (AU)

Resultado a largo plazo de la uretroplastia término-terminal / Long-term results of end-to-end urethroplasty

Objetivo: Evaluamos los resultados a largo plazo de la uretroplastia término-terminal. Material y Métodos: Revisamos 40 pacientes afectos de estenosis de uretra bulbar de etiología diversa: yatrógena40%, traumática 15%, infecciosa 2% y desconocida 40%. En 17 casos se realizó previamente uretrotomíainterna. El estudio mediante CUMS reveló una localización bulbar en todos los casos y una longitud inferior a 1cm en 13 casos, entre 1-2 cm en 26 casos y entre 2-3 cm en 1 caso. El flujo máximo varió de 3-13 ml/s. Se valoró mediante cultivo preoperatorio la ausencia de bacteriuria. El tiempo medio de seguimiento fue de 45 meses (12-142 meses). Se consideró resuelta la estenosis cuando no aparecieron datos radiológicos ni flujométricos compatibles con reestenosis. Resultados: En 37 casos (92%) los resultados fueron satisfactorios, no precisando los pacientes ningún otro procedimiento quirúrgico secundario. Tras la cirugía el flujo máximo varió entre 18-45 ml/s. En dos de los tres pacientes con reestenosis la uretrotomía interna endoscópica fue resolutiva. Se trató de dos pacientes con estenosisde origen traumático y longitud mayor a 1,5 cm. En el tercer paciente con recidiva se optó finalmente por realizar una nueva uretroplastia termino-terminal, con buen resultado posterior. Conclusiones: La uretroplastia término-terminal es una técnica altamente resolutiva en la estenosis de uretrabulbar. El diagnóstico preoperatorio se basa en el estudio radiológico (CUMS). El control postoperatorio debe fundamentarse en la clínica y estudio flujométrico. El origen traumático de la estenosis empeora los resultados de la cirugía. En casos de reestenosis la uretrotomía interna endoscópica permite complementar de forma exitosa los resultados de la uretroplastia (AU)

Objective: We evaluated long term results of end-to-end urethroplasty. Material and methods: We reviewed 40 patients with bulbar urethral stricture of diverse origin: iatrogenic 40%, traumatic 15%, infectious 2% and unknown 40%. In 17 cases internal urethrotomy was made previously. The radiological study with retrograde and voiding cystogram revealed a bulbar location in all cases and a length inferior to 1 cm in 13 cases, between 1-2 cm in 26 cases and 2-3 cm in 1 case. The maximum flow rate varied between 3-13 ml/s. The absence of bacteriuria was valued by means of preoperating culture. The average time of pursuit was 45 months (12-142 months). The stricture was considered resolute when not appear compatible radiological or functional finds of failure. Results: In 37 cases (92%) the results were satisfactory, without secondary surgical procedure. After surgery maximum flow-rate varied between 18-45 ml/s. In two patients with failure, internal urethrotomy was decisive. In this case the stricture origin was traumatic. The third patient with failure was finally chosen to make new endto- end urethroplasty, with good later result. Conclusions: End-to-end urethroplasty is a highly decisive technique for bulbar urethral stricture. The preoperating diagnosis is based on the radiological study (retrograde and voiding cystogram). The postoperating control must be based on clinic and uroflow study. Traumatic stricture repair showed worse results. In cases of failure, internal urethrotomy allows to complement successful results of end-to-end urethroplasty (AU)

Uretroplastía de aumento con injerto de mucosa bucal / Augmenting urethroplasty with graft buccal mucosa

La patología de la estenosis uretral tiene diversa etiología, el tratamiento varía según su ubicación anatómica, extensión y espongiofibrosis. Los tratamientos previos como la uretrotomía interna (UI) pueden determinar que una estenosis breve se transforme en compleja, con un detrimento en el éxito de curación. Frente a estenosis complejas que requieren algún tipo de aumento del lumen uretral, ha surgido una tendencia por el uso de mucosa bucal, ya que presenta características favorables (fácil obtención, buen prendimiento y ser cosméticamente aceptable).Se revisa la experiencia de uretroplastía con mucosa oral en 11 pacientes: diez portadores de estenosisbulbar y uno de estenosis anterior secundaria a Balanitis Xerótica Obliterans (BXO).La tasa de éxito fue del 91 porciento (10 de 11 pacientes), con un seguimiento promedio de 10,4 meses. No se registraron complicaciones mayores. La curva de aprendizaje para la obtención de la mucosa bucal es breve y simple. Los injertos libres de mucosa oral son, al menos, igual de buenos que otros materiales para uretroplastía de aumento, con mínimas complicaciones y sin alteración cosmética del pene.

Further experience with the tubularized-incised urethral plate technique for hypospadias repair.

OBJECTIVES: To report further experience of hypospadias repair using the tubularized-incised urethral plate (TIP) technique and to evaluate the role of postoperative neourethral dilatation as a method of preventing complications. PATIENTS AND METHODS: The study included 64 patients (aged 2-18 years) who underwent TIP repair of hypospadias; 47 required a primary and 17 a secondary repair. After removing the stent they were randomized into two groups; group 1 (38 patients) underwent regular neourethral dilatation for 12 weeks and group 2 (26 patients) did not. Patients were followed for a mean (range) of 28 (6-52) months. RESULTS: The functional and cosmetic results were excellent in all patients in group 1, except for slight meatal regression in one patient (3%). In group 2, 17 patients had excellent results; eight (31%) were re-operated upon to correct complications, six developed a fistula (four of which were associated with meatal stenosis) and two developed a neourethral stricture. CONCLUSIONS: TIP urethroplasty is a versatile technique that provides an excellent functional and cosmetic outcome. Regular urethral calibration after repair should be considered as an integral part of the technique, to prevent neourethral and/or meatal stenosis with subsequent fistula formation.