One-stage Penile Urethroplasty Using Oral Mucosal Graft and Glue

Tailor-made natural and synthetic grafts for precise urethral reconstruction

Injuries to the urethra can be caused by malformations, trauma, inflammation, or carcinoma, and reconstruction of the injured urethra is still a significant challenge in clinical urology. Implanting grafts for urethroplasty and end-to-end anastomosis are typical clinical interventions for urethral injury. However, complications and high recurrence rates remain unsatisfactory. To address this, urethral tissue engineering provides a promising modality for urethral repair. Additionally, developing tailor-made biomimetic natural and synthetic grafts is of great significance for urethral reconstruction. In this work, tailor-made biomimetic natural and synthetic grafts are divided into scaffold-free and scaffolded grafts according to their structures, and the influence of different graft structures on urethral reconstruction is discussed. In addition, future development and potential clinical application strategies of future urethral reconstruction grafts are predicted.

Anterior substitutional urethroplasty using a biomimetic poly‐ l ‐lactide nanofiber membrane: Preclinical and clinical outcomes

The aim of this study is to investigate the feasibility and efficacy of a novel biomimetic poly‐l‐lactide (PLLA) nanofiber membrane in repairing anterior urethral strictures from both preclinic and clinic. Biomimetic PLLA membrane was fabricated layer by layer according to the structure of human extracellular matrix. Microstructure, tensile strength, and suture retention strength were fully assessed. Before the clinical application, the safety and toxicology test of the biomimetic PLLA membrane was performed in vitro and in experimental animals. The patients underwent urethroplasty used dorsal onlay or lateral onlay technique. Then, they were followed up for 1 month, 3 months, 6 months, and then annually after the surgery. The mechanical experiments showed well property for application. Biomimetic PLLA membrane was safe according to the in vitro and animal studies. Then, a total of 25 patients (mean age 48.96 years) were included in the study from September 2016 to December 2018. After a mean follow‐up of 33.56 months, 20 patients successfully treated with biomimetic PLLA membrane. Five patients (2 bulbar and 3 penile) suffered postoperational urethral stricture recurrence. None of infection or urinary fistula or any other adverse events related to the use of biomimetic PLLA membrane were observed during the follow‐up period for all patients. The preliminary result confirmed the feasibility and efficacy of the biomimetic PLLA membrane as a novel material for anterior urethral repair. The long‐term effects with more patients should be investigated in further studies.

Update on the management of penile and meatal strictures

PURPOSE OF REVIEW

Treatment of penile and distal urethral strictures including the fossa navicularis and the meatus remains challenging due to their adverse etiology and lack of ventral tissue support. In this contemporary review, we summarize the available evidence and recent advancements in reconstructive techniques.

RECENT FINDINGS

Over the last years, several refinements of already established techniques have been added to the reconstructive armamentarium in the management of penile urethral strictures. These include the single-stage combination of flap and graft, the additional use of tissue glue, or an optimized single-stage tubularization using a free graft.

SUMMARY

There is a shift toward an increased use of single-stage procedures even in complex strictures of the penile and distal urethra. This is reflected by advancements and refinements in operative techniques. Nonetheless, staged urethroplasty remains a cornerstone of curative management in such patients with durable success rates. Future research should focus on identifying distinct patient and stricture characteristics to determine the individual therapeutic approach with optimal functional outcomes.

Cell-Seeded Acellular Artery for Reconstruction of Long Urethral Defects in a Canine Model

The management of urethral stricture remains a major therapeutic challenge in clinics. Herein, we explored the feasibility of reconstructing a relatively long segment of the urethra by the cell-seeded acellular artery in a canine model. The acellular arterial matrix was obtained from the excised carotid artery of donor dogs. Autologous adipose-derived stem cells (ADSCs) from 6 male dogs were grown and seeded onto the premade acellular arterial matrix. A 3 cm long segment of the urethra was resected in 12 male dogs. Urethroplasty was performed with the acellular arterial matrix seeded with ADSCs in 6 animals and without cells in 6. Serial urethrography was performed at 1 and 3 months postoperatively. Wide urethral calibers without any signs of strictures were confirmed in all 6 animals in the experimental group. In contrast, urethral stricture was demonstrated in 3 animals in the control group. The graft was highly epithelialized and smooth in the experimental group, while graft contracture and scar formation were showed in the control group. Histologic analysis of the cell-seeded arterial matrix at 1 month confirmed the presence of multilayered urothelium and muscle. The levels of tissue formation developed over time with a progressive increase in muscle content. In contrast, extensive fibrosis and sparse smooth muscle were seen in animals treated with matrix without ADSCs. This study provides preclinical evidence that the ADSC-seeded arterial matrix can be used as a tubularized scaffold in the reconstruction of 3 cm long urethral defect in a male canine model. The ADSC-seeded arterial matrix remodels and regenerates normal-appearing urethral tissue layers over time.

Patient-reported outcomes for typical single cheek harvesting vs atypical lingual, labial or bilateral cheeks harvesting: a single-center analysis of more than 800 patients

PURPOSE

The optimal harvesting site for oral grafting in patients with urethral strictures remain controversial, with no study investigating morbidity on large scale. We aimed to compare typical single cheek harvesting vs atypical lingual, labial or bilateral cheeks harvesting in terms of complications and patient-reported outcomes.

METHODS

Within 827 patients treated at our referral center with oral graft urethroplasty, we compared typical vs atypical harvesting techniques. A self-administered, semiquantitative, non-validated questionnaire assessed early (10 days) and late (4 months) postoperative complications and patient-reported outcomes. A semiquantitative score was calculated according to patient responses, and it was used to assess early (6 questions) and late (13 questions) patient dissatisfaction status. Patients were defined early and/or late dissatisfied when they scored ≥ 7 and ≥ 10 at the early or late questionnaires, respectively.

RESULTS

Between 1998 and 2019, our patients predominantly received typical single cheek harvesting (89% vs 11%), with + 1.5% increase rate per year (p < 0.001). Early and late dissatisfied patients were, respectively, 170 (23%) vs 39 (44%) and 59 (8%) vs 16 (18%) in the typical vs atypical groups. Atypical harvesting was associated with higher rates of early (Odds ratio [OR]: 2.34; 95% Confidence interval [CI] 1.44-3.75; p = 0.001) and late (OR: 2.37; 95%CI 1.22-4.42; p = 0.008) postoperative dissatisfaction.

CONCLUSIONS

Typical single cheek harvesting was the preferred surgical option at our center and it was associated with negligible early and late rates of complications and patient's dissatisfaction. Conversely, atypical lingual, labial or bilateral cheeks harvesting was associated with higher complications and frequent patient dissatisfaction.

Sustained release of stromal cell-derived factor-1 alpha from silk fibroin microfiber promotes urethral reconstruction in rabbits

We developed a stromal cell-derived factor-1 alpha (SDF-1α)-aligned silk fibroin (SF)/three-dimensional porous bladder acellular matrix graft (3D-BAMG) composite scaffold for long-section ventral urethral regeneration and repair in vivo. SDF-1α-aligned SF microfiber/3D-BAMG, aligned SF microfiber/3D-BAMG, and nonaligned SF microfiber/3D-BAMG scaffolds were prepared using electrostatic spinning and wet processing. Adipose-derived stem cell (ADSC) and bone marrow stromal cell (BMSC) migration was assessed in the SDF-1α-loaded scaffolds. Sustained SDF-1α release in vitro and vivo was analyzed using enzyme-linked immunosorbent assay (ELISA) and western blotting, respectively. The scaffolds were used to repair a 1.5 × 1 cm² ventral urethral defect in male rabbits in vivo. General observation and retrograde urinary tract contrast assessment were used to examine urethral lumen patency and continuity at 1 and 3 months post-surgery. Postoperative rehabilitation was evaluated using histological detection. The composite scaffolds sustained SDF-1α release for over 16 days in vitro. SDF-1α-aligned SF nanofiber promoted regeneration of urethral mucosa, submucosal smooth muscles, and microvasculature, increased cellular proliferation, and reduced collagen deposition. SDF-1α expression was increased in reconstructed urethra at 3 months post-surgery in SDF-1α-aligned SF group. SDF-1α-aligned SF microfiber/3D-BAMG scaffolds may be used to repair and reconstruct long urethral defects because they accelerate urethral regeneration.

Risk calculator for prediction of treatment-related urethroplasty failure in patients with penile urethral strictures

PURPOSE

To design a dedicated risk calculator for patients with penile urethra stricture who are scheduled to urethroplasty that might be used to counsel patients according to their pre-operative risk of failure.

METHODS

Patients treated with penile urethroplasty at our center (1994-2018) were included in the study. Patients received 1-stage or staged penile urethroplasty. Patients with failed hypospadias repair, lichen sclerosus or incomplete clinical records were excluded. Treatment failure was defined as any required postoperative instrumentation, including dilation. Univariable Cox regression identified predictors of post-operative treatment failure and Kaplan-Meier analysis plotted the failure-free survival rates according to such predictors. Multivariable Cox regression-based risk calculator was generated to predict the risk of treatment failure at 10 years after surgery.

RESULTS

261 patients met the inclusion criteria. Median follow-up was 113 months. Out of 216 patients, 201 (77%) were classified as success and 60 (23%) failures. Former smoker (hazard ratio [HR] 2.12, p = 0.025), instrumentation-derived stricture (HR 2.55, p = 0.006), and use of grafts (HR 1.83, p = 0.037) were predictors of treatment failure. Model-derived probabilities showed that the 10-year risk of treatment failure varied from 5.8 to 41.1% according to patient's characteristics.

CONCLUSIONS

Long-term prognosis in patients who underwent penile urethroplasty is uncertain. To date, our risk-calculator represents the first tool that might help physicians to predict the risk of treatment failure at 10 years. According to our model, such risk is largely influenced by the etiology of the stricture, the use of graft, and patient's smoking habits.

Treatments of 1242 bulbar urethral strictures: multivariable statistical analysis of results

PURPOSE

We investigated the success rate of different surgical techniques for bulbar stricture repair.

METHODS

Retrospective study of patients with bulbar urethral strictures treated using different techniques. The primary outcome of the study was to evaluate the overall results of treatment (success vs. failure); the secondary outcome was to evaluate the outcome according to any surgical technique. Cysto-urethrography was performed 1 month following surgery. Patients underwent clinical evaluation, uroflowmetry and residual urine measurement every 6 months for 2 years after surgery and later once on year. When patient showed obstructive symptoms, Q_max < 12 ml/s, the urethrography was repeated. Patients who underwent further treatment for recurrent stricture were classified as failures. A bivariable and multivariable statistical analysis was performed.

RESULTS

Overall, 1242 patients were included in the study with mean age 40 years (range 12-84). Median stricture length was 4 cm (range 1-8). The median follow-up was 103 months (range 12-362). Over 1242 patients, 916 (73.8%) were success and 326 (26.2%) failures. Fourteen different surgical techniques showed a success rate ranging from 87.5 to 14.3%. The multivariable analysis showed that stricture length was an independent predictor factors for failure: p < 0.0001 CI 1146-1509. End-end anastomosis and oral mucosa graft urethroplasty are independent predictor factor of success after internal urethrotomy failure.

CONCLUSIONS

Our results showed that treatment of bulbar urethral stricture is satisfactory on 73.8% of patients, but with a wide range of success rate (from 14.3 to 87.5%) using different techniques. Oral mucosa is greatly superior to the skin as substitute material.

Anterior Urethroplasty Using a New Tissue Engineered Oral Mucosa Graft: Surgical Techniques and Outcomes

PURPOSE

We investigated whether tissue engineered material may be adopted using standard techniques for anterior urethroplasty.

MATERIALS AND METHODS

We performed a retrospective multicenter study in patients with recurrent strictures, excluding those with failed hypospadias, lichen sclerosus, traumatic and posterior strictures. A 0.5 cm² oral mucosa biopsy was taken from the patient cheek and sent to the laboratory to manufacture the graft. After 3 weeks the tissue engineered oral mucosal MukoCell® graft was sent to the hospital for urethroplasty. Four techniques were used, including ventral onlay, dorsal onlay, dorsal inlay and a combined technique. Cystourethrography was performed 1 month postoperatively. Patients underwent clinical evaluation, uroflowmetry and post-void residual urine measurement every 6 months. When the patient showed obstructive symptoms, defined as maximum urine flow less than 12 ml per second, the urethrography was repeated. Patients who underwent further treatment for recurrent stricture were classified as having treatment failure.

RESULTS

Of the 38 patients with a median age of 57 years who were included in study the strictures were penile in 3 (7.9%), bulbar in 29 (76.3%) and penobulbar in 6 (15.8%). Median stricture length was 5 cm and median followup was 55 months. Treatment succeeded in 32 of the 38 patients (84.2%) and failed in 15.8%. Success was achieved in 85.7% of ventral onlay, 83.3% of dorsal onlay, 80% of dorsal inlay and 100% of combined technique cases. No local or systemic adverse reactions due to the engineered material were noted.

CONCLUSIONS

Our findings show that a tissue engineered oral mucosa graft can be implanted using the same techniques suggested for anterior urethroplasty and native oral mucosa, and guaranteeing a similar success rate.