Donor site morbidity in oral mucosa graft urethroplasty: implications of tobacco consumption

Decellularization of the human urethra for tissue engineering applications

Recently, several scaffolds have been introduced for urethral tissue engineering. However, acellular human urethral scaffold harvested from deceased donors may provide significant advantages compared to synthetic, composite, or other biological scaffolds. This study aims to develop the protocol for decellularization of the human urethra that preserves substantial extracellular matrix (ECM) components, which are essential for subsequent recellularization mimicking the natural environment of the native ECM. A total of 12 human urethras were harvested from deceased donors. An equal part of every harvested urethra was used as a control sample for analyses. The protocol design was based on the enzyme-detergent-enzyme method. Trypsin and Triton X-100 were used to remove cells, followed by DNase treatment to remove DNA residues. Subsequently, the specimens were continually rinsed in deionized water for seven days. The efficiency of decellularization was determined by histochemistry, immunohistochemical staining, scanning electron microscopy (SEM), and DNA quantification. Histological analysis confirmed cell removal and preservation of urethral structure after decellularization. The preservation of collagen IV and fibronectin was confirmed by histologic examination and immunohistochemical staining. SEM confirmed the maintenance of the ultrastructural architecture of ECM and fibers. DNA content in decellularized urethra was significantly lower compared to the native sample (P < 0.001), and so the criteria for decellularized tissue were met. Cytotoxicity analysis data showed that the matrix-conditioned medium did not contain soluble toxins and had no significant inhibitory effect on cell proliferation, providing evidence that the decellularized samples are not toxic. This study demonstrates the feasibility of the enzyme-detergent-enzyme-based decellularization protocol for removing cellular components and maintaining urethral ECM and its ultrastructure. Moreover, obtained results provide solid ground for recellularization and urethral tissue engineering, which will follow.

Tunica albuginea versus buccal mucosa graft urethroplasty for anterior urethral stricture: A prospective randomised pilot study

Objective

The objective of the study was to compare the outcome of tunica albuginea urethroplasty (TAU) and buccal mucosa graft (BMG) urethroplasty for anterior urethral stricture.

Methods

Thirty patients who met the inclusion criteria were randomised into two groups: TAU (Group A) and BMG urethroplasty (Group B). Surgical outcome was evaluated with pre- and post-operative work-up involving retrograde urethrogram, voiding cystourethrogram, uroflowmetry, and urethroscopy. Patients were followed up till 1 year.

Results

Mean duration of surgery was statistically significant between two groups (p=0.0005). Maximum urine flow rate was comparable when compared between two groups (p=0.22) but statistically significant when compared pre- and post-operatively (p<0.001). At follow-up of 1 year, the successful outcomes were 80% in Group A and 87% in Group B. A total of five patients who had unsuccessful results required redo urethroplasty. Complications were minimal in both the groups.

Conclusion

TAU provides outcomes equivalent to those of BMG urethroplasty. TAU has less operative time, easy to perform, and beneficial in patients with poor oral hygiene.

Tissue Engineering of the Urethra: From Bench to Bedside

Tissue engineering (TE) is a promising approach for repair/substitution of damaged tissues and organs. Urethral strictures are common and serious health conditions that impair quality of life and may lead to serious organ damage. The search for ideal materials for urethral repair has led to interest of scientists and surgeons in urethral TE. Over the last decades, a significant amount of preclinical studies and considerable progress have been observed. In contrast, urethral TE has made slow progress in clinical practice so far. To address this, we conducted a systematic review of the literature on clinical applications of TE constructs for urethral repair in the last three decades. In summary, the TE approach is promising and effective, but many issues remain that need to be addressed for broader adoption of TE in urethral repair. Better design of trials, better cooperation of research groups and centralization could lead to reduction of costs and slowly proceed to commercialization and routine use of TE products for urethral reconstruction.

The Expanding Use of Buccal Mucosal Grafts in Urologic Surgery

The advent and success of buccal mucosal grafts as a substitution material in the urinary tract has changed the landscape of reconstructive urology. Due to its ease to harvest, low morbidity, and advantageous properties, there has been a growing number of applications for buccal mucosal grafts in upper and lower urinary tract reconstruction as well as genital reconstruction. In this article, we review the historical application and the evolution of buccal mucosal grafts and provide an up-to-date review on its utilization in urologic procedures.

Tubularized urethral reconstruction using everted saphenous vein graft in a beagle model

Background

A long segment stricture in the anterior urethra is a challenge in urology. We conducted a study to investigate the efficacy of anterior urethral reconstruction using an everted saphenous vein graft (SVG) in a tubular fashion.

Methods

Twelve male beagles were randomly divided into three groups: experimental group (n = 5), control group (n = 5) and normal group (n = 2). A 3 cm defect in the anterior urethra was created. Autologous SVG was harvested. In the experimental group, urethral defect was replaced by an everted SVG in a tubular fashion. In the control group, urethral reconstruction was performed using an uneverted SVG. Beagles in all groups received retrograde urethrography to evaluate urethral patency and were killed for histological examination 6 months after operation.

Results

Four beagles in the experimental group had no voiding difficulty and the other one could not void spontaneously. Retrograde urethrography showed the four beagles in experimental group had wide urethral lumens. Ether urethral stricture or fistula were detected in all animals in the control group. Histological analysis of the four beagles in the experimental group indicated the everted SVG completely integrated into the urethra. The reconstructed urethra contained a wide lumen and was completely covered by urothelium. The periurethral collagen and muscle fibers formed and were highly organized. Everted SVG showed a high ability of neovascularization. In the control group, the reconstructed segment showed a fibrotic urethral lumen where the urothelium was not intact. Only few new capillaries were formed.

Conclusions

Everted SVG demonstrates for a promising strategy for potential urethral stricture repair.

Onlay Repair Technique for the Management of Ureteral Strictures: A Comprehensive Review

Ureteroplasty using onlay grafts or flaps emerged as an innovative procedure for the management of proximal and midureteral strictures. Autologous grafts or flaps used commonly in ureteroplasty include the oral mucosae, bladder mucosae, ileal mucosae, and appendiceal mucosae. Oral mucosa grafts, especially buccal mucosa grafts (BMGs), have gained wide acceptance as a graft choice for ureteroplasty. The reported length of BMG ureteroplasty ranged from 1.5 to 11 cm with success rates of 71.4%-100%. However, several studies have demonstrated that ureteroplasty using lingual mucosa grafts yields better recipient site outcomes and fewer donor site complications than that using BMGs. In addition, there is no essential difference in the efficacy and complication rates of BMG ureteroplasty using an anterior approach or a posterior approach. Intestinal graft or flap ureteroplasty was also reported. And the reported length of ileal or appendiceal flap ureteroplasty ranged from 1 to 8 cm with success rates of 75%-100%. Moreover, the bladder mucosa, renal pelvis wall, and penile/preputial skin have also been reported to be used for ureteroplasty and have achieved satisfactory outcomes, but each graft or flap has unique advantages and potential problems. Tissue engineering-based ureteroplasty through the implantation of patched scaffolds, such as the small intestine submucosa, with or without cell seeding, has induced successful ureteral regeneration structurally close to that of the native ureter and has resulted in good functional outcomes in animal models.

Is circumferential urethral mobilisation an overdo? A prospective outcome analysis of dorsal onlay and dorso - lateral onlay BMGU for anterior urethral strictures

Introduction

For dorsal onlay graft placement, unilateral urethral mobilization is less invasive than standard circumferential urethral mobilization. Apart from success in terms of patency of urethra, other issues like sexual function, overall quality of life and patient satisfaction remain important issues while comparing outcomes of urethroplasty.

Aim

To prospectively compare the objective as well as subjective outcomes of two approaches.

Materials and Methods

Between July 2011 and January 2015, 136 adult males having anterior urethral stricture with urethral lumen ≥ 6 Fr. were prospectively assigned between two groups by alternate randomization. Operative time, complications, success rate (no obstructive symptoms, no need of any postoperative intervention, Q max > 15mL/sec), sexual functions (using Brief Male Sexual Function Inventory) were compared.

Results

Baseline parameters were similar in both groups (68 in each group). Overall success rate was similar in both groups (89 % and 91 % respectively). Improvement in total LUTS scores was similar in groups. Changes in overall health status (VAS and EQ 5D) was equal in both groups. Erectile function score was significantly decreased in DO than DL group while ejaculatory function and sexual desire remained stable after urethroplasty in both groups.

Conclusions

In anterior urethral stricture buccal mucosa graft provides satisfactory results as onlay technique. No technique whether dorsolateral and dorsal techniques is superior to other. Dorsolateral technique needs minimal urethral mobilization and should be preferred whenever feasible.

Looking beyond oral mucosa: Initial results of everted saphenous vein graft urethroplasty (eSVGU) in long anterior urethral strictures

Objective

To prospectively evaluate the feasibility and initial results of an everted saphenous vein graft (eSVG) as a dorsolateral onlay, in patients with long anterior urethral strictures and/or chronic tobacco users.

Patients and methods

In all, 20 patients with long anterior urethral strictures (>7 cm) and/or chronic tobacco exposed oral mucosa were included in the study. The harvested SVG was hydro-distended, detubularised, and everted. Substitution urethroplasty using an eSVG was performed using a dorsolateral onlay technique. Symptoms were assessed using the International Prostate Symptom Score (IPSS) and uroflowmetry at 1, 3 and 6 months; and voiding and retrograde urethrograms, and urethroscopy were done at 3 months. Failure was defined as failure to void, need for interventions in form of direct-vision internal urethrotomy or endodilatation.

Results

Three patients were excluded because they underwent a staged urethroplasty. In all, 17 patients underwent eSVG substitution urethroplasty. The mean (SD, range) follow-up of our patients was 17.64 (5.23, 10–26) months. The mean (SD, range) length of the strictured segment was 14 (2.5, 10–18) cm and the length of the harvested SVG was 16.3 (2.7, 12–20) cm. The mean (SD) IPSS at 1, 3 and 6 months after catheter removal was 10 (2.8), 10 (3.4) and 10 (1.4) and the quality-of-life score was 1.76 (0.5), 2.05 (1.0) and 2.05 (1.0), respectively. Postoperatively, endodilatation was required in two patients. Complete failure occurred in one patient.

Conclusions

An eSVG, as a dorsolateral onlay graft, is a promising and prudent option for long anterior urethral strictures, especially in patients with poor oral hygiene and chronic tobacco use.

Tissue engineering of urethra: Systematic review of recent literature

The purpose of this article was to perform a systematic review of the recent literature on urethral tissue engineering. A total of 31 articles describing the use of tissue engineering for urethra reconstruction were included. The obtained results were discussed in three groups: cells, scaffolds, and clinical results of urethral reconstructions using these components. Stem cells of different origin were used in many experimental studies, but only autologous urothelial cells, fibroblasts, and keratinocytes were applied in clinical trials. Natural and synthetic scaffolds were studied in the context of urethral tissue engineering. The main advantage of synthetic ones is the fact that they can be obtained in unlimited amount and modified by different techniques, but scaffolds of natural origin normally contain chemical groups and bioactive proteins which increase the cell attachment and may promote the cell proliferation and differentiation. The most promising are smart scaffolds delivering different bioactive molecules or those that can be tubularized. In two clinical trials, only onlay-fashioned transplants were used for urethral reconstruction. However, the very promising results were obtained from animal studies where tubularized scaffolds, both non-seeded and cell-seeded, were applied. Impact statement The main goal of this article was to perform a systematic review of the recent literature on urethral tissue engineering. It summarizes the most recent information about cells, seeded or non-seeded scaffolds and clinical application with respect to regeneration of urethra.

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.

Collagen cell carriers seeded with human urothelial cells for urethral reconstructive surgery: first results in a xenograft minipig model

PURPOSE

Urethral strictures are a common disease of the lower urinary tract in men. At present, the use of buccal mucosa is the method of choice for long or recurrent strictures. However, autologous tissue-engineered grafts are still under investigation for reconstructive urological surgery. The aim of this pilot study was to evaluate the use of human urothelial cells (HUC) seeded on bovine collagen type I-based cell carriers (CCC) in an animal model and to evaluate short-term outcome of the surgical procedure.

METHODS

Four male Göttingen minipigs were used with immunosuppression (cyclosporine A) for this pilot xenograft study. HUC obtained from human benign ureteral tissue were stained by PKH26 and seeded on a collagen cell carrier (CCC). Seven weeks after urethral stricture induction and protective vesicostomy, cell-seeded CCC was implanted in the urethra with HUC luminal and antiluminal, respectively. After two weeks animals were euthanized, urethrography and histological assessment were performed.

RESULTS

Surgery was technically feasible in all minipigs. Stricture was radiologically established 7 weeks after induction. CCC was visible after two weeks and showed good integration without signs of inflammation or rejection. In the final urethrography, no remaining stricture could be detected. Near porcine urothelium, PKH26-positive areas were found even if partially detached from CCC. Although diminished, immunofluorescence with pankeratin, CK20, E-cadherin and ZO-1 showed intact urothelium in several areas on and nearby CCC.

CONCLUSION

Finally, this study demonstrates that the HUC-seeded CCC used as a xenograft in minipigs is technically feasible and shows promising results for further studies.

Silk Fibroin Scaffolds for Urologic Tissue Engineering

Urologic tissue engineering efforts have been largely focused on bladder and urethral defect repair. The current surgical gold standard for treatment of poorly compliant pathological bladders and severe urethral stricture disease is enterocystoplasty and onlay urethroplasty with autologous tissue, respectively. The complications associated with autologous tissue use and harvesting have led to efforts to develop tissue-engineered alternatives. Natural and synthetic materials have been used with varying degrees of success, but none has proved consistently reliable for urologic tissue defect repair in humans. Silk fibroin (SF) scaffolds have been tested in bladder and urethral repair because of their favorable biomechanical properties including structural strength, elasticity, biodegradability, and biocompatibility. SF scaffolds have been used in multiple animal models and have demonstrated robust regeneration of smooth muscle and urothelium. The pre-clinical data involving SF scaffolds in urologic defect repair are encouraging and suggest that they hold potential for future clinical use.

Outcome of buccal mucosa and lingual mucosa graft urethroplasty in the management of urethral strictures: A comparative study

Objective:

The objective of the study was to compare the outcome of buccal and lingual mucosa graft (LMG) augmentation urethroplasty along with donor sites morbidities in anterior urethra stricture.

Subjects and Methods:

From September 2010 to January 2014, 125 patients underwent single stage augmentation urethroplasty. They were randomly divided into two groups to receive either buccal mucosa graft (BMG) or LMG. The patients were prospectively followed for complications and outcome.

Results:

Baseline characteristics such as mean age, etiology, stricture length, and location were comparable in both groups. Overall success rate for Group 1 and Group 2 were 69.2% and 80%, respectively. Mean follow-up periods were 28.2 and 25 months in Group 1 and Group 2, respectively.

Conclusions:

LMG provides the better outcome with fewer immediate and delayed complications as compared to BMG. The length of stricture and width of graft were main factors affecting the outcome.

Acellular matrix in urethral reconstruction

The treatment of severe urethral stenosis has always been a challenge even for skilled urologists. Classic urethroplasty, skin flaps and buccal mucosa grafting may not be used for long and complex strictures. In the quest for an ideal urethral substitute, acellular scaffolds have demonstrated the ability to induce tissue regeneration layer by layer. After several experimental studies, the use of acellular matrices for urethral reconstruction has become a clinical reality over the last decade. In this review we analyze advantages and limitations of both biological and polymeric scaffolds that have been reported in experimental and human studies. Important aspects such as graft extension, surgical technique and cell-seeding versus cell-free grafts will be discussed.

Outcomes of dorsal and ventral buccal graft urethroplasty at a tertiary hospital in Uganda

Purpose. Although the use of buccal mucosa in substitution urethroplasty has been practiced for some years, it has not been free of controversy over which surgical technique is the most appropriate to use. There is paucity of data in Sub-Saharan Africa about its success; this study presents the outcomes of dorsal and ventral buccal graft urethroplasty at a sub-Saharan tertiary hospital. Methods. This is a prospective study in which buccal mucosa was used for ventral and dorsal grafts; followup was up to two years. All patients provided informed written consent for the procedures. Results. Seventy-two patients with bulbar urethral strictures underwent buccal graft one-stage urethroplasty. Mean age was 55 years; etiology of the strictures was postinflammatory due to urethritis from sexually transmitted infections 97% (70/72) and trauma 3% (2/72). Buccal mucosa grafts were harvested from the cheek using a two-team approach. Grafts were placed on the ventral and dorsal urethral surfaces in 32 and 40 cases, respectively; the success rate was 84 and 80%, respectively. Repeated urethroplasty was successfully done among 10% (7/72) and patients reported resolution of symptoms in the follow-up period. Conclusion. There was no difference between dorsal and ventral onlay buccal graft outcomes for bulbar urethral strictures. The success rate was 80 to 84%.

Tissue engineering in urethral reconstruction--an update

The field of tissue engineering is rapidly progressing. Much work has gone into developing a tissue engineered urethral graft. Current grafts, when long, can create initial donor site morbidity. In this article, we evaluate the progress made in finding a tissue engineered substitute for the human urethra. Researchers have investigated cell-free and cell-seeded grafts. We discuss different approaches to developing these grafts and review their reported successes in human studies. With further work, tissue engineered grafts may facilitate the management of lengthy urethral strictures requiring oral mucosa substitution urethroplasty.

Management of anterior urethral stricture: an evidence-based approach

PURPOSE OF REVIEW

To provide a review of the latest evidence on the management of anterior urethral strictures.

RECENT FINDINGS

A continuing role exists for urethrotomy or dilatation in the management of urethral strictures as first-line therapy in selected patients. In those patients with bulbar strictures who fail or are not suitable for these procedures, an anastomotic urethroplasty, and if not feasible a substitution urethroplasty using either a flap or oral mucosal graft either by a dorsal, lateral or ventral onlay approach should be considered. For penile strictures, a ventral onlay procedure using skin can be considered except in cases of lichen sclerosis when an onlay procedure utilizing oral mucosa provides the best results using either a one-stage or two-stage approach.

SUMMARY

Various options exist for the management of anterior urethral stricture disease. The 'reconstructive ladder' has served to guide urologists over the years. The selection of the correct procedure should be patient-centred and based on the latest evidence.

Anterior urethral reconstruction using the circular fasciocutaneous flap technique: long-term follow-up

PURPOSE

The circular fasciocutaneous skin flap technique (FCF) yields excellent short-term results for complex anterior urethral reconstruction. We performed an observational retrospective and descriptive study to report our long-term experience.

METHODS

A total of 36 adults with anterior urethral strictures (AUS) exceeding 3 cm underwent single-stage urethroplasty using the FCF. Exclusion criteria were: lichen sclerosus, absence of the urethral plate and hypospadias. All had a minimum follow-up of 7 years. Mean age was 49.7 years. Radiological work-up was supplemented by urethral ultrasound showing a mean stricture length of 5.9 cm. A circumferential island of distal penile skin was mobilized on a vascularized pedicle and used for urethral reconstruction. Tube repairs were not included. Outcome was considered a failure when post-operative instrumentation was needed. The Mann-Whitney U test was used for statistical analysis.

RESULTS

Mean follow-up was 96.7 months (86-117). All received a ventral onlay repair secondary to stricturotomy. Complication rate was 8.3% (3/36): A flimsy stricture at the proximal anastomotic site occurred in 1 requiring optical urethrotomy. In 2 patients, glans dehiscence was noted. No penile skin necrosis was observed proximal to the flap-harvesting site. We did not observe neurovascular lower extremity complications. Long-term success rates exceeded 90%.

CONCLUSIONS

FCF-urethroplasty yields excellent long-term results with no late stricture recurrence. All complications occurred early after surgery underlining the durability of pedicled genital skin flaps. Despite extensive stricture, disease complication rates and morbidity were low. In case of paucity of local skin or lichen scleroses, oral grafts are required for optimal treatment.