Biochemical characterization and quantitation of the collagenous components of urethral stricture tissue

Ultrasound imaging of male urethral stricture disease: a narrative review of the available evidence, focusing on selected prospective studies

PURPOSE

To synthetize the current scientific knowledge on the use of ultrasound of the male urethra for evaluation of urethral stricture disease. This review aims to provide a detailed description of the technical aspects of ultrasonography, and provides some indications on clinical applications of it, based on the evidence available from the selected prospective studies. Advantages and limitations of the technique are also provided.

METHODS

A comprehensive literature search was performed using the Medline and Cochrane databases on October 2022. The articles were searched using the keywords "sonourethrography", "urethral ultrasound", "urethral stricture" and "SUG". Only human studies and articles in English were included. Articles were screened by two reviewers (M.F. and K.M.).

RESULTS

Our literature search reporting on the role of sonourethrography in evaluating urethral strictures resulted in selection of 17 studies, all prospective, even if of limited quality due to the small patients' number (varied from 28 to 113). Nine studies included patients with urethral stricture located in anterior urethra and eight studies included patients regardless of the stricture location. Final analysis was based on selected prospective studies, whose power was limited by the small patients' groups.

CONCLUSION

Sonourethrography is a cost-effective and safe technique allowing for a dynamic and three-dimensional urethra assessment. Yet, because of its limited value in detecting posterior urethral strictures, the standard urethrography should remain the basic 'road-map' prior to surgery. It is an operator-dependent technique, which can provide detailed information on the length, location, and extent of spongiofibrosis without risks of exposure to ionizing radiation.

Extracellular matrix analysis of fibrosis: A step towards tissue engineering for urethral stricture disease

The urogenital tract is a target for many congenital and acquired diseases, both benign and oncogenic. In males, the urethra that transports urine and semen can be obstructed by a fibrotic disease called urethral stricture disease (USD). In severe USD, the whole organ including the vascular embedding, the corpus spongiosum (CS), is affected. Recurrent or severe USD is treated by reconstructive surgery. Tissue engineering may improve the outcome of urethral reconstruction in patients with complicated USD. Currently in urethral reconstruction only the epithelial layer is replaced, no substitution for the CS is provided, while the CS is important for mechanical support and vascularization. To develop a tissue engineering strategy for the CS, it is necessary to know the protein composition of the CS. As the extracellular matrix (ECM) plays an important role in the formation of fibrosis, we analyzed the distribution and localization of ECM components in human healthy and fibrotic CS tissue using immunohistology. The morphology of components of the elastic network were affected in USD. After decellularization a clear enrichment of proteins belonging to the ECM was found. In the proteomic analysis collagens COL15A1 and COL4A2 as well as inter-alpha-trypsin inhibitor ITIH4 were upregulated in fibrotic samples. The glycoproteins Periostin (POSTN), Microfibrillar-associated protein 5 (MFAP5) and EMILIN2 are downregulated in fibrotic tissue. To our knowledge this is the first proteomic study of ECM proteins of the CS in healthy and in USD. With these results a regenerating approach for tissue engineered CS can be developed, including relevant ECM proteins that reduce fibrosis and promote healthy healing in urethral reconstructive surgery.

Pharmacotherapy of urethral stricture

ABSTRACT

Urethral stricture is characterized by the chronic formation of fibrous tissue, leading to the narrowing of the urethral lumen. Despite the availability of various endoscopic treatments, the recurrence of urethral strictures remains a common challenge. Postsurgery pharmacotherapy targeting tissue fibrosis is a promising option for reducing recurrence rates. Although drugs cannot replace surgery, they can be used as adjuvant therapies to improve outcomes. In this regard, many drugs have been proposed based on the mechanisms underlying the pathophysiology of urethral stricture. Ongoing studies have obtained substantial progress in treating urethral strictures, highlighting the potential for improved drug effectiveness through appropriate clinical delivery methods. Therefore, this review summarizes the latest researches on the mechanisms related to the pathophysiology of urethral stricture and the drugs to provide a theoretical basis and new insights for the effective use and future advancements in drug therapy for urethral stricture.

Biological Macromolecule-Based Scaffolds for Urethra Reconstruction

Urethral reconstruction strategies are limited with many associated drawbacks. In this context, the main challenge is the unavailability of a suitable tissue that can endure urine exposure. However, most of the used tissues in clinical practices are non-specialized grafts that finally fail to prevent urine leakage. Tissue engineering has offered novel solutions to address this dilemma. In this technology, scaffolding biomaterials characteristics are of prime importance. Biological macromolecules are naturally derived polymers that have been extensively studied for various tissue engineering applications. This review discusses the recent advances, applications, and challenges of biological macromolecule-based scaffolds in urethral reconstruction.

Complications after Prostate Cancer Treatment: Pathophysiology and Repair of Post-Radiation Urethral Stricture Disease

Radiation therapy (RT) in the management of pelvic cancers remains a clinical challenge to urologists given the sequelae of urethral stricture disease secondary to fibrosis and vascular insults. The objective of this review is to understand the physiology of radiation-induced stricture disease and to educate urologists in clinical practice regarding future prospective options clinicians have to deal with this condition. The management of post-radiation urethral stricture consists of conservative, endoscopic, and primary reconstructive options. Endoscopic approaches remain an option, but with limited long-term success. Despite concerns with graft take, reconstructive options such as urethroplasties in this population with buccal grafts have shown long-term success rates ranging from 70 to 100%. Robotic reconstruction is augmenting previous options with faster recovery times. Radiation-induced stricture disease is challenging with multiple interventions available, but with successful outcomes demonstrated in various cohorts including urethroplasties with buccal grafts and robotic reconstruction.

Ascorbic Acid 2-Phosphate-Releasing Supercritical Carbon Dioxide-Foamed Poly(L-Lactide-Co-epsilon-Caprolactone) Scaffolds Support Urothelial Cell Growth and Enhance Human Adipose-Derived Stromal Cell Proliferation and Collagen Production

Tissue engineering can provide a novel approach for the reconstruction of large urethral defects, which currently lacks optimal repair methods. Cell-seeded scaffolds aim to prevent urethral stricture and scarring, as effective urothelium and stromal tissue regeneration is important in urethral repair. In this study, the aim was to evaluate the effect of the novel porous ascorbic acid 2-phosphate (A2P)-releasing supercritical carbon dioxide-foamed poly(L-lactide-co-ε-caprolactone) (PLCL) scaffolds (scPLCLA2P) on the viability, proliferation, phenotype maintenance, and collagen production of human urothelial cell (hUC) and human adipose-derived stromal cell (hASC) mono- and cocultures. The scPLCLA2P scaffold supported hUC growth and phenotype both in monoculture and in coculture. In monocultures, the proliferation and collagen production of hASCs were significantly increased on the scPLCLA2P compared to scPLCL scaffolds without A2P, on which the hASCs formed nonproliferating cell clusters. Our findings suggest the A2P-releasing scPLCLA2P to be a promising material for urethral tissue engineering.

Myofibroblast-dominant proliferation associated with severe fibrosis in bulbar urethral strictures

OBJECTIVES

Myofibroblast-dominant proliferation (relative to fibroblast proliferation) is the key process in urethral fibrosis, but its association with clinical features is not understood. We conducted a histological analysis of urethral strictures and examined the association between myofibroblast proliferation and stricture characteristics.

METHODS

Formalin-fixed, paraffin-embedded urethral sections sliced axially from 175 male patients with bulbar urethral strictures were retrospectively analyzed. All patients underwent excision and primary anastomosis between September 2008 and January 2021 by a surgeon (AH). Masson's trichrome stain was used to estimate the area of fibrosis. Corresponding unstained slides with the largest area of fibrosis were selected and double-immunostained with anti-smooth muscle actin (SMA) and anti-TE-7 mouse monoclonal antibodies for the assessment of myofibroblasts and fibroblasts, respectively. The ratio of the number of SMA-positive cells to the number of TE-7-positive cells (SMA/TE-7 ratio) was calculated.

RESULTS

The area of fibrosis in strictures due to perineal trauma (n = 85, median 108.9 mm² ) was significantly larger than that in non-traumatic strictures (n = 90, median 42.9 mm² , p < 0.0001). The area of fibrosis positively correlated with SMA expression (r = 0.35, p < 0.0001) and the SMA/TE-7 ratio (r = 0.36, p < 0.0001), but not with TE-7 expression (r = -0.01, p = 0.75). In a multivariate linear regression model, traumatic etiology (standard coefficient 0.37, t value 3.9, p < 0.0001) and increased SMA expression (standard coefficient 0.17, t value 2.1, p = 0.03) were the predictors of wide fibrosis area.

CONCLUSIONS

Myofibroblast-dominant proliferation may contribute to the pathogenesis of severe urethral fibrosis.

The application of 3D bioprinting in urological diseases

Urologic diseases are commonly diagnosed health problems affecting people around the world. More than 26 million people suffer from urologic diseases and the annual expenditure was more than 11 billion US dollars. The urologic cancers, like bladder cancer, prostate cancer and kidney cancer are always the leading causes of death worldwide, which account for approximately 22% and 10% of the new cancer cases and death, respectively. Organ transplantation is one of the major clinical treatments for urological diseases like end-stage renal disease and urethral stricture, albeit strongly limited by the availability of matching donor organs. Tissue engineering has been recognized as a highly promising strategy to solve the problems of organ donor shortage by the fabrication of artificial organs/tissue. This includes the prospective technology of three-dimensional (3D) bioprinting, which has been adapted to various cell types and biomaterials to replicate the heterogeneity of urological organs for the investigation of organ transplantation and disease progression. This review discusses various types of 3D bioprinting methodologies and commonly used biomaterials for urological diseases. The literature shows that advances in this field toward the development of functional urological organs or disease models have progressively increased. Although numerous challenges still need to be tackled, like the technical difficulties of replicating the heterogeneity of urologic organs and the limited biomaterial choices to recapitulate the complicated extracellular matrix components, it has been proved by numerous studies that 3D bioprinting has the potential to fabricate functional urological organs for clinical transplantation and in vitro disease models.

•

Outline the advantages and characteristics of 3D printing compared with traditional methods for urological diseases.

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Guide the selection of 3D bioprinting technology and material in urological tissue engineering.

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Discuss the challenges and future perspectives of 3D bioprinting in urological diseases and clinical translation.

Mesh Graft Urethroplasty—Still a Safe and Promising Technique in Mostly Unpromising Complex Urethral Strictures

Long urethral strictures or even recurrent urethral strictures, mostly with scar tissue showing insufficient healing tendencies, are defined as complex and represent a big challenge in modern reconstructive urology. Initially, the treatment of complicated urethral strictures was associated with a high failure rate (20–40%) due to the growth of hair in the neourethra and a lack of sufficient suitable epithelium when scrotal skin was used. Although much effort was put into tissue engineering recently, harvesting and transplanting autologous tissue represent the standard of care for urethral substitution or augmentation. Since 1977, two-staged urethroplasty with the usage of free foreskin or 0.1 mm thick meshed skin from the upper leg was performed in complicated cases and was initially described in 1984 and 1989 by Schreiter and Schreiter and Noll, respectively. In stage 1, the graft is harvested by cutting the skin thinly above the hair follicles and transplanted as a plate around the opened urethra. In stage 2, after 8–12 weeks, the neourethra is formed. Success rates of up to 84% are described. Considering the complexity of the strictures in which mesh graft urethroplasty is usually performed, the reachable success rates are outstanding, especially considering that this surgery is most likely the last opportunity to prevent perineostomy or even urinary diversion. This article describes the surgical technique and embeds the mesh graft urethroplasty in today’s literature to underline its importance in the surgical management of complex urethral strictures.

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.

Urethral monopolar cauterization: alternative infravesical obstruction model in male rats

OBJECTIVE:

We aimed to determine which method gives the most consistent results between urethral monopolar cauterization and standard urethral partial ligation methods for the urethral obstruction model.

METHODS:

Thirty male rats were randomly divided into control, partial ligation, and monopolar cauterization groups. Six weeks after experimental procedures, the experimental groups were evaluated cystometrically, biochemically, and histologically.

RESULTS:

According to the cystometric results, bladder capacity, baseline bladder pressure, and compliance data of the monopolar cauterization group were higher than those of the partial ligation and monopolar cauterization groups (p<0.05 and p<0.01, respectively). As a biochemical evaluation, malondialdehyde levels in bladder tissues of group control were higher than partial ligation and monopolar cauterization groups (p<0.05 and p<0.01, respectively). The collagen type I level of the control group was higher than the partial ligation and monopolar cauterization groups (p<0.01 and p<0.05, respectively). Collagen type III levels of the monopolar cauterization group were higher than those of the control group (p<0.01), but the Collagen type I/Collagen type III and transforming growth factor-β levels of the monopolar cauterization group were significantly lower than those of the control group (p<0.001). As a histological evaluation (hematoxylin and eosin), fibrosis in the lamina propria was more prominent in the monopolar cauterization group than in the control group (p<0.05). In addition, the muscular thickness was higher in the monopolar cauterization group compared with control and partial ligation groups (p<0.001 and p<0.01, respectively).

CONCLUSION:

The needle-tipped monopolar cauterization of the posterior urethra may be the method of choice for creating a chronic infravesical obstruction model of infravesical obstruction in male rats.

Feline Gastrointestinal Eosinophilic Sclerosing Fibroplasia—Extracellular Matrix Proteins and TGF-β1 Immunoexpression

Feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF) has been described as an inflammatory disorder with an eosinophilic component with etiopathogenesis that is still unknown. Sixteen intestinal samples from two veterinary diagnostic services (2014–2017) were included in the study. A histopathological criterion classified the cases into three grades (mild, moderate, and severe) according to the distribution of the lesions and the course. An immunohistochemical study of collagen I, collagen III, fibronectin, and transforming growth factor β1 (TGF-β1) was performed in each case. An immunohistochemical study of mild grades shows greater collagen III immunoexpression, compared to collagen I and fibronectin, which suggests an “early” stage of fibrosis. In more intense grades, an increased immunoexpression of collagen I, compared to collagen III, suggests a “late” stage of fibrosis. Otherwise, the highest expression of TGF-β1 was observed in the moderate phase, due to the high proliferation of reactive fibroblast and intense inflammation. The results suggest that the inflammatory infiltrate is the trigger for the elevation in TGF-β1, altering the collagen type III:I ratio. In conclusion, immunohistochemical studies can be a very useful method in diagnosing cases of FGESF of mild grades and could help to apply a differential diagnosis regarding feline eosinophilic chronic enteritis (CEE) in the context of inflammatory bowel disease (IBD).

Exploring Relevant mRNAs and miRNAs in Injured Urethral Tissues of Rats with High-Throughput Sequencing

Acute urethral injuries caused by urethral endoscopy and other mechanical injuries are the main reasons for secondary infection and late urethral stricture. However, there are no studies to explore the transcriptomic changes in urethral injury and the molecular mechanism of urethral injury, which is important for the treatment and cure of urethral injury. Therefore, we used RNA-seq and sRNA-seq profiles from normal and injured urethral tissues to identify and characterize differentially expressed mRNAs and miRNAs. In total, we found 166 differentially expressed mRNAs, of which 69 were upregulated, and 97 were downregulated in injured urethral tissues. The differentially expressed mRNAs were mainly involved in the positive regulation of epithelial cell differentiation, focal adhesion, cell adhesion molecules, protein activation cascade, complement activation, complement and coagulation cascades, and chemokine-mediated signaling pathway. Additionally, we found six upregulated and four downregulated miRNAs, respectively, in the injured urethral tissues. Notably, their target genes were involved in the vascular endothelial growth factor receptor 2 binding, PI3k-Akt signaling pathway, and Notch signaling pathway. In summary, our results suggest that the cell damage response induced by mechanical injury activates the pathological immune response in a variety of ways in injured urethral tissues.

Long-term outcomes of paclitaxel-coated balloons for non-malignant ureteral strictures

PURPOSE

To evaluate the clinical efficacy and safety of drug-coated balloon (DCB) ureteroplasty for the management of non-malignant ureteral strictures.

MATERIAL AND METHODS

A prospective "off-label" monocentric single-arm pilot study investigating the safety and efficacy of drug-coated balloon (DCB) (Lutonix^®; BD, USA) was performed. Twenty-five patients with benign ureteral strictures related to uretero-enteric anastomosis (n = 13); lithiasis (n = 5), post-surgical complications (iatrogenic n = 5), transplanted kidney (n = 1) and post-radiotherapy (n = 1) were included. Following lesion crossing, predilatation was performed using 4-7 mm high-pressure balloon catheter (5-6Fr) with a balloon pressure of 6-7 atm based on the manufacturer's recommendation. In the absence of rupture of the ureteral wall, the DCB was dilated for 4 min. across the lesion. The process was repeated if deemed necessary to a maximum of three stricture dilatations. We analysed both clinical and radiological primary patency (no signs of ipsilateral hydronephrosis or improvement of the existing residual dilatation at the follow-up examinations) and secondarily safety endpoints.

RESULTS

Mean lesion length was 40 ± 28.5 mm. Mean time follow up was 36 months ± 10.46 months. Strictures were located at upper ureteric (12%), lower ureteric (32%), ureterovesical anastomosis (4%) and uretero-enteric anastomosis (52%) levels. The overall radiological success at 1-year follow-up was 88% (22/25 patients). In 56% patients (14/25 patients with primary patency) the nephrostomy catheter was removed 21 days following a single DCB procedure. In 32% (8/25 patients) an additional dilatation sessions were required for maintaining the ureteral patency. The overall failure rate at 1-year follow-up was 12% (3/25 patients). Only one case of febrile urinary tract infection in a female patient (acute pyelonephritis) was encountered after the first dilatation.

CONCLUSIONS

Paclitaxel-coated balloon ureteroplasty proved to be safe and effective for the treatment of non-malignant ureteral strictures. Larger studies are warranted to validate these promising initial results.

Tissue Engineering and Its Potential to Reduce Prostate Cancer Treatment Sequelae-Narrative Review

Tissue engineering offers the possibility to overcome limitations of current management for postprostatectomy incontinence and ED. Developed in recent years biotechnological feasibility of mesenchymal stem cell isolation, in vitro cultivation and implantation became the basis for new cell-based therapies oriented to induce regeneration of adult tissue. The perspective to offer patients suffering from post-prostatectomy incontinence or erectile dysfunction minimal invasive one-time procedure utilizing autologous stem cell transplantation is desired management.

Efficacy of Mitomycin C Combined with Direct Vision Internal Urethrotomy for Urethral Strictures: A Systematic Review and Meta-Analysis

BACKGROUND

The high recurrence of a urethral stricture after direct vision internal urethrotomy (DVIU) has been a problem for years. Mitomycin C (MMC) is an excellent antifibrosis antigen that has been used in many fields, but its effect on a urethral stricture remains controversial. The purpose of this review was to investigate the effectiveness of MMC in reducing the recurrence rate of a urethral stricture after the first urethrotomy.

METHODS

Common databases were searched for publications prior to November 30, 2020. Randomized controlled and cohort trials were all included. Recurrence and success rates after the first urethrotomy of the posterior urethra were the main outcomes. Revman 5.3 was used for statistical analysis. Two evaluation systems, the Cochrane risk of bias tool and the Newcastle Ottawa Scale, were used to examine the risk of bias for RCTs and all studies. The quality of evidence was assessed by the Grading of Recommendations, Assessment, Development, and Evaluation standard.

RESULTS

Sixteen trials were included, the reporting quality of which was generally poor, and the evidence level was very low to moderate. The addition of MMC could significantly reduce the recurrence rate of urethral strictures (risk ratio [RR] = 0.42; 95% confidence interval [CI]: 0.26, 0.67; p = 0.0002; 9 trials; 550 participants). The results of the subgroup analysis suggested that the effect of MMC combined with DVIU was significant in short (≤2 cm) anterior urethral strictures (RR = 0.39; 95% CI: 0.20, 0.78; p = 0.008), >12-month follow-up (RR = 0.45; 95% CI: 0.26, 0.76; p = 0.003). It also increased the success rate of the first urethrotomy procedure for posterior urethral contracture (RR = 0.74; 95% CI: 0.65, 0.84; p < 0.00001; 7 trials; 342 participants). Low-dose local injection of MMC was the most commonly used method.

CONCLUSION

MMC combined with DVIU is a promising way to reduce the long-term recurrence rate of a short-segment anterior urethral stricture. It also increases the success rate of the first urethrotomy of the posterior urethra. However, more high-quality randomized controlled trials are needed.

Retrograde urethrography, sonouretrography and magnetic resonance urethrography in evaluation of male urethral strictures. Should the novel methods become the new standard in radiological diagnosis of urethral stricture disease?

PURPOSE

To verify which of the diagnostic modalities: Voiding cystouretrography (VCUG), Sonouretrography (SUG) or Magnetic resonance uretrography (MRU) is the most accurate in the assessment of urethral strictures in males and in what cases the application of novel imaging techniques benefits most.

METHODS

55 male patients with a diagnosis of urethral stricture, were enrolled in this prospective study. Initial diagnosis of urethral stricture was based on anamnesis, uroflowmetry and VCUG. Additional imaging procedures-SUG and MRU were performed before the surgery. Virtual models and 3D printed models of the urethra with the stricture were created based on the MRU data. Exact stricture length and location were evaluated by each radiological method and accuracy was verified intraoperatively. Agreement between SUG and MRU assessments of spongiofibrosis was evaluated. MRU images were independently interpreted by two radiologists (MRU 1, MRU 2) and rater reliability was calculated.

RESULTS

MRU was the most accurate [(95% CI 0.786-0.882), p < 0.0005] with an average overestimation of 1.145 mm (MRU 1) and 0.727 mm (MRU 2) as compared with the operative measure. VCUG was less accurate [(95% CI 0.536-0.769), p < 0.0005] with an average underestimation of 1.509 mm as compared with operative measure. SUG was the least accurate method [(95% CI 0.510-0.776), p < 0.0005] with an average overestimation of 2.127 mm as compared with the operative measure. There was almost perfect agreement of MRU interpretations between the radiologists.

CONCLUSIONS

VCUG is still considered as a 'gold standard' in diagnosing urethral stricture disease despite its limitations. SUG and MRU provide extra guidance in preoperative planning and should be considered as supplemental for diagnosing urethral stricture. Combination of VCUG and SUG may be an optimal set of radiological tools for diagnosing patients with urethral strictures located in the penile urethra. MRU is the most accurate method and should particularly be considered in cases of post-traumatic or multiple strictures and strictures located in the posterior urethra.

The pre-operative and post-operative imaging appearances of urethral strictures and surgical techniques

Urethral strictures arise from a variety of etiologies, most commonly either iatrogenic or inflammatory in the anterior urethra and iatrogenic/surgical or traumatic etiologies in the posterior urethra. Diagnosis and treatment planning depend on urethrography, usually performed with a combination of retrograde urethrography (RUG) and voiding cystourethrography (VCUG) to evaluate the anterior and posterior urethra, respectively. While this is most commonly performed fluoroscopically, sonographic urethrography is an alternative, although at the expense of the posterior urethra, it is only visualized using a transrectal approach. In addition to understand urethral anatomy, familiarity with normal periurethral structures is necessary to avoid misdiagnosis, such as Cowper's ducts, the glands of Littré, and the prostatic and ejaculatory ducts. Surgical management depends on the stricture location, length, and number and options range from balloon dilatation to endoscopic urethrotomy to anastomotic and substitution urethrotomy. Postprocedural management includes urethrography to identify potential complications including urethral leak, graft failure, and stricture recurrence.

Fabrication of Adipose-Derived Stem Cell-Based Self-Assembled Scaffold under Hypoxia and Mechanical Stimulation for Urethral Tissue Engineering

Long urethral strictures are often treated with autologous genital skin and buccal mucosa grafts; however, risk of hair ingrowth and donor site morbidity, restrict their application. To overcome this, we introduced a tissue-engineered human urethra comprising adipose-derived stem cell (ASC)-based self-assembled scaffold, human urothelial cells (UCs) and smooth muscle cells (SMCs). ASCs were cultured with ascorbic acid to stimulate extracellular matrix (ECM) production. The scaffold (ECM) was stained with collagen type-I antibody and the thickness was measured under a confocal microscope. Results showed that the thickest scaffold (28.06 ± 0.59 μm) was achieved with 3 × 10⁴ cells/cm² seeding density, 100 μg/mL ascorbic acid concentration under hypoxic and dynamic culture condition. The biocompatibility assessment showed that UCs and SMCs seeded on the scaffold could proliferate and maintain the expression of their markers (CK7, CK20, UPIa, and UPII) and (α-SMA, MHC and Smootheline), respectively, after 14 days of in vitro culture. ECM gene expression analysis showed that the ASC and dermal fibroblast-based scaffolds (control) were comparable. The ASC-based scaffold can be handled and removed from the plate. This suggests that multiple layers of scaffold can be stacked to form the urothelium (seeded with UCs), submucosal layer (ASCs only), and smooth muscle layer (seeded with SMCs) and has the potential to be developed into a fully functional human urethra for urethral reconstructive surgeries.

Frontiers in urethra regeneration: current state and future perspective

Despite the positive achievements attained, the treatment of male urethral strictures and hypospadiases still remains a challenge, particularly in cases of severe urethral defects. Complications and the need for additional interventions in such cases are common. Also, shortage of autologous tissue for graft harvesting and significant morbidity in the location of harvesting present problems and often lead to staged treatment. Tissue engineering provides a promising alternative to the current sources of grafts for urethroplasty. Since the first experiments in urethral substitution with tissue engineered grafts, this topic in regenerative medicine has grown remarkably, as many different types of tissue-engineered grafts and approaches in graft design have been suggested and testedin vivo. However, there have been only a few clinical trials of tissue-engineered grafts in urethral substitution, involving hardly more than a hundred patients overall. This indicates that the topic is still in its inception, and the search for the best graft design is continuing. The current review focuses on the state of the art in urethral regeneration with tissue engineering technology. It gives a comprehensive overview of the components of the tissue-engineered graft and an overview of the steps in graft development. Different cell sources, types of scaffolds, assembling approaches, options for vascularization enhancement and preclinical models are considered.

Scar-modulating agents post urethroplasty: Could phosphodiesterase-5 inhibitors be the answer?

Background:

Phosphodiesterase enzyme inhibitors (PDEIs) are most commonly prescribed by urologists for the treatment of erectile dysfunction. They are also gaining popularity as a treatment for lower urinary tract symptoms, based on their effect on smooth muscles – either vascular smooth muscles or smooth muscles in the urinary tract. For vascular smooth muscles, they cause vasodilation, enhanced microcirculatory haemodynamics through inhibition of platelet aggregation and adhesion, induction of apoptosis of adhesion fibroblasts and a reduction in the scarring process.

Methodology:

We reviewed articles published in English and indexed in the PubMed, Embase and Google Scholar databases, and consulted textbooks. Key search terms used were: urethral stricture, anti-fibrotic, scar-modulating agent, PDEIs, urethral scarring and urethroplasty. We created a synopsis of relevant articles, including original research studies and reviews. Level of evidence: Not applicable.

Investigation of Triamcinolone Instillation in the Long-term Rate of Anterior Urethral Strictures' Recurrence

Background/Aims

Previous publications confirmed that after internal urethrotomy success rates in the short-term (less than 6 months) are varied (70-80%) and in the long-term results are generally low. In this study, the efficacy of triamcinolone instillation based on a newly introduced protocol on the rate of recurrence in patients with anterior urethral strictures was evaluated.

Methods

A total of 66 patients were divided into treatment group (n = 33), in which triamcinolone was instilled on urethra after removing of Foley catheter and control group (n = 33) that not received any intervention. Each 40 mg/1 ml of triamcinolone vial was dissolved in 9 ml of distilled water and then a 2 ml of diluted solution was used for each instillation and 8 ml was kept in 4°C. Triamcinolone was instilled based on daily in week 1, every other day for week 2 and then every Monday and Friday for 2 months. Penile clamp was used after instillation for 1 hour. Treatment failure was based on urine flow rate, rate of recurrence and time to appearance of recurrence.

Results

There were not any significant differences regrading to age (p = 0.09), length (p = 0.41) and diameter (p = 0.36) of stricture between 2 groups. Time to appearance of recurrence showed significantly in the treatment group when compared with that in the control group (1,350 ± 900 vs. 124.3 ±112 days; p < 0.01). In the treatment group, 88% had reasonable consequence, while in control 48%. There were 3 patients with a mean length-diameter of stricture around 0.3-5 cm who showed recurrence free with the mean of 720 days after intervention.

Conclusion

Administration of triamcinolone instillation in urethra is associated with a decreased risk of stricture recurrence. Superior outcomes were seen in patients with a stricture length of more than 2 cm and this may in part reflect the increasing efficacy of the instillation method in the management of urethral strictures. These findings help identify patients with aggressive features of strictures in urethra who may benefit from intensified treatment efficacy of triamcinolone instillation.

MRI in patients with urethral stricture: a systematic review

Magnetic resonance imaging (MRI) is gaining acceptance as a diagnostic tool in urethral stricture disease. Numerous publications emphasize on the advantages of MRI including its ability to determine periurethral spongiofibrosis, thus overcoming the main limitation of retrograde urethrography (RUG). It is also becoming an alternative for sonourethrography (SUG), which is a highly subjective examination. Magnetic resonance urethrography (MRU) has become an increasingly appreciated tool for diagnosing patients with urethral stricture disease. Obtained data provides radiologists and urethral reconstructive surgeons with additional information regarding anatomical relationships and periurethral tissue details, facilitating further treatment planning. Considering the great prevalence of urethral stricture disease and necessity of using accurate, and acceptable diagnostic method, this review was designed to provide radiologists and clinicians with a systematic review of the literature on the use of MRI in the urethral stricture disease.

Biodegradable drug-eluting urethral stent in limiting urethral stricture formation after urethral injury: An experimental study in rabbit

In this study, a reproducible urethral injury animal model was developed and the role of the biodegradable drug-eluting urethral stent in limiting urethral stricture formation after urethral injury was evaluated. A total of 22 rabbits were used, and 20 rabbits were randomly chosen to develop urethral injury animal model. Bulbar urethral injury was made by a self-designed explosion device in the 20 rabbits. The urethral injury animal model was then randomly assigned to 2 groups of 10 each, which received a treatment of biodegradable paclitaxel-eluting urethral stent or only end-to-end anastomosis. Other two rabbits served as normal control group. Stents were surgically implanted into the injured urethras of rabbits under direct vision. Reparative effects, including stent degradation, were evaluated by urethroscopy, retrograde urethrography, and histology at different intervals at weeks 4, 8, and 12. In stent-free group, 8 of 10 rabbits developed obvious urethral stricture which was demonstrated by urethroscopy and retrograde urethrography, while in biodegradable paclitaxel-eluting stent group, urethral stricture was absent in all animals (p < 0.05). Histological follow-up indicated that the drug-eluting stents can also minimize the inflammatory reactions and fibrosis formation compared with the stent-free groups. Scanning electron microscope demonstrated that the biodegradable drug-eluting stent can gradually degrade in 12 weeks. The biodegradable paclitaxel-eluting urethral stent is effective in limiting urethral stricture formation after urethral injury.

Longitudinal muscular column in the prostatic urethral wall: Its form, shape, and possible function based on mathematical simulation in ejaculation

BACKGROUND

The shape and function of the longitudinal muscular column (LMC) of the prostate have not been established in detail. The present study was undertaken to elucidate the roles of the LMC of the posterior wall of the prostatic urethra (PSU) in the emission phase of ejaculation by investigating the form and muscular arrangement of the LMC.

METHODS

Prostates and urinary bladders were obtained from 14 Korean adult cadavers. Nine specimens were histologically analyzed using hematoxylin and eosin, Masson's trichrome, and Verhoeff-van Gieson staining. Two specimens were scanned using microcomputed tomography (micro-CT), and all scanned images were reconstructed into a three-dimensional model.

RESULTS

At the proximal level of the prostate, the ejaculatory ducts (EDs) and prostatic utricle (PU) together were surrounded by circular smooth-muscle fibers. However, at the seminal colliculus (SC) where the EDs and PU opened, they were mainly surrounded by an abundance of longitudinal fibers. The longitudinal fibers posterior to the EDs and PU formed a distinctive LMC in the posterior urethral wall. In histologic sections and micro-CT images, the LMC extended distally from the level of the SC to the level of the membranous urethra (MBU). We simulated a potential mechanism of LMC using a mathematical model of its movements.

CONCLUSIONS

Comprehensive analyses based on in-depth assessment of histologic characteristics and micro-CT images demonstrated extension of the LMC from the level of the SC to the level of the MBU, enabling a better understanding of ejaculation physiology involving the LMC. These results suggest that the LMC in the posterior wall of the PSU is a critical component of ejaculation by facilitating the ejection of seminal vesicle fluid into the PSU via well-coordinated contractions.

Is neutrophil to lymphocyte ratio a predictive factor for recurrence of urethral stricture?

INTRODUCTION

Due to spongiofibrosis and inflammatory processes underlying the pathogenesis of urethral stricture, it is possible that the neutrophil-lymphocyte ratio (NLR) may give essential information about the course of the disease and recurrence possibilities. Our study aims to evaluate the correlation between NLR and recurrence rates.

METHODS

A total of 512 patients who underwent direct visual internal urethrotomy (DVIU) due to urethral stricture in our clinic between February 2010 and January 2018 were evaluated retrospectively.

RESULTS

The median follow up for non-recurrent and recurrent groups after DVIU was 30 and 36 months, respectively. During the follow-up, 280 (54.7%) of the patients had recurrences, and 232 (45,3%) had no recurrences. The mean time for recurrence after DVIU was 6,5±1,4 months, with a range of 1-36 months. The mean NLR in the non-recurrence group was 2,02±0,87, with a median of 1.9, and 3,66±2,30, with a median of 3 in the recurrence group. A highly significant statistical difference was observed between two groups in terms of neutrophil count and NLR (p: 0.000 - both). The area under curve value for NLR was 0.767, with a standard error of 0.021 (95% CI 0.727-0.808). The cut-off value of NLR was determined as 2.25, with a 70% sensitivity and 67,7% specificity.

CONCLUSION

By using NLR, the inflammatory features of the urethral tissue can be predicted, and possible recurrences after surgery can be estimated. Consequently, open urethroplasty techniques can be used in cases with a significant NLR value instead of the recurrent endoscopic procedure.

Can proliferative hypertrophic scars of the median sternotomy incision predict the occurrence and characteristics of urethral stricture?

Objectives:

To investigate the correlation between the characteristics of urethral stricture and incision scars in patients with urethral stricture and median sternotomy incision.

Methods:

We identified 368 patients who had undergone internal urethrotomy between January 2014 and December 2017. A total of 49 male patients with a median sternotomy scar and diagnosed with urethral stricture were retrospectively evaluated. The median sternotomy incision scars were assessed using the Vancouver Scar Scale (VSS) and the patients were divided into 2 groups. Group I consisted of patients with a VSS score of <4 points, and those with ≥4 points constituted group II. The groups were compared in terms of age, smoking habit, body mass index, diabetes mellitus, hypertension, urethral stricture etiology, length and localization, and stricture relapse after intervention.

Results:

The mean total VSS score was 2.0 points in group I and 7.46 points in group II. There was a significant correlation between the VSS total score and the urethral stricture length among the whole study population (correlation coefficient value=0.481; p<0.001). The urethral stricture was longer as the VSS score increased.

Conclusion:

A poorly healed median sternotomy incision scar can predict a poor wound healing in the urethra tissue. Further large scale, multi-center and prospective studies are needed to clarify this relationship.

Structural Analysis of the Bulbospongiosus Muscle in Patients With Bulbar Urethral Strictures

OBJECTIVE

To characterize the bulbospongiosus muscle (BSM) in patients with bulbar urethral strictures.

MATERIALS AND METHODS

We studied 21 patients divided into 2 groups: Stricture Group (n = 14; mean age = 62.00 years) with bulbar stricture submitted to open urethroplasty; and Control Group (n = 7; mean age = 60.14 years) with penile strictures (hypospadias cripples, penile cancer and/or penile infection) who were submitted to perineal urethrostomy. Samples of the BSM were dissected and histologic sections were stained by histochemical and immunohistochemical techniques. Histomorphometric analyzes were performed on photomicrographs. Means were statistically compared using the unpaired Student t test and the Mann-Whitney test (P <.05).

RESULTS

The etiology of bulbar urethral stricture was idiopathic in 2 cases (14.29%), post-TURP in 6 (42.86%), post open radical prostatectomy in 5 (35.71%) and post open prostatectomy in 1 case (7.14%). The average length of the stricture was 2.08 cm. The only parameter analyzed with significant difference between the groups was the vessels (significant difference between the control group: 5.11 ± 1.98% and stricture group: 3.57 ± 1.32%, P = .0460). The quantitative analysis of collagen (Control Group: 10.63 ± 5.37% and Stricture Group: 10.83 ± 4.55%, P = .9296); diameter of BSM muscle fibers (Control Group: 41.71 ± 14.63 µm and Stricture Group: 40.11 ± 8.59 µm, P = .76 and elastic system fibers (Control Group; 3.83 ± 1.54% and Stricture Group: 5.43 ± 2.90%, P = .2601) showed no significant difference.

CONCLUSIONS

Histologic analysis showed a significant decrease of the BSM vessels in urethral stricture, without changes in elastic fibers, collagen, nerves, and muscle fiber diameter. These findings show that the bulbar urethral stricture causes minimal alterations in the structure of the BSM.

Regenerative and engineered options for urethroplasty

Surgical correction of urethral strictures by substitution urethroplasty - the use of grafts or flaps to correct the urethral narrowing - remains one of the most challenging procedures in urology and is frequently associated with complications, restenosis and poor quality of life for the affected individual. Tissue engineering using different cell types and tissue scaffolds offers a promising alternative for tissue repair and replacement. The past 30 years of tissue engineering has resulted in the development of several therapies that are now in use in the clinic, especially in treating cutaneous, bone and cartilage defects. Advances in tissue engineering for urethral replacement have resulted in several clinical applications that have shown promise but have not yet become the standard of care.

Imbalance in extracellular matrix degradation in urethral stricture

BACKGROUND

Extracellular matrix degradation may play an important role in the etiology of urethral stricture. MMP1 and TIMP1 are involved in extracellular matrix degradation. The aim of this study was to investigate the roles of MMP1, TIMP1, and MMP1:TIMP1 ratio at the remodeling phase of urethral stricture in an animal model.

METHODS

This research was carried out in collaboration between the Bogor Institute of Agriculture, Universitas Indonesia, and the Eijkman Institute Indonesia. This was an experimental in vivo study in adult male New Zealand rabbits, divided into two groups: a urethral stricture group and a control group. Euthanasia was performed in four rabbits of each group on days 7, 14, 21, 28, and 56. Urethral stricture was confirmed with an 8 F urethral catheter. Several laboratory examinations were done, including H&E and Masson trichrome staining, immunohistochemistry, and ELISA, to determine levels of MMP1 and TIMP1. Percentages of total collagen and collagen type 1 were counted with ImageJ 1.46q software. A general linear model was used for statistic analysis.

RESULTS

We found that the level of MMP1 was lower, TIMP1 higher, and MMP1:TIMP1 ratio lower in the urethral stricture group than the control group. There was a correlation between MMP1 level with total collagen percentage (r=0.561, P=0.010) and no correlation between TIMP1 and total collagen (r=0.307, P=0.188).

CONCLUSION

Imbalance in extracellular matrix degradation was marked by decreased MMP1 level and MMP1:TIMP1 ratio and increased TIMP1 level. This results showed that urethral stricture is not only caused by collagen decomposition, but also by the imbalance of extracellular matrix degradation.

Sclerosis as a predictive factor for failure after bulbar urethroplasty: a prospective single-centre study

OBJECTIVE

The aim of this study was to assess whether sclerosis in histology following bulbar urethroplasty is a predictive factor for failure of surgery.

MATERIALS AND METHODS

Resected stricture specimens from 45 patients undergoing open urethroplasty with excision and anastomosis were collected prospectively during 2011-2014. Histopathological characteristics, including fibrosis (grade I-III), inflammation and sclerosis, were evaluated using different routine staining. These specimens were compared to normal urethral resection specimens from patients undergoing sex-correction surgery. The uropathologist who conducted the analyses was blinded to the study design.

RESULTS

The outcomes of the histological classifications were as follows: 19 patients had grade I fibrosis, of whom three had failures; 13 patients had grade II fibrosis, without any failures; and the most severe fibrosis, grade III, including sclerosis, was found in 13 patients (11 with sclerosis), with failure in eight. Sclerosis was a significant risk factor for restricture when comparing patients with sclerosis and those without sclerosis, and likewise when adjusting for age, inflammation and stricture length.

CONCLUSION

Histological findings of sclerosis in the resected urethral stricture specimen indicate a significantly higher risk for restricture after urethroplasty surgery.

Effect of angiotensin II receptor blocker on TGF-β1, MMP-1, and collagen type I and type III concentration in New Zealand rabbit urethral stricture model

Introduction

Urethral stricture is a disease with a high recurrence rate. Angiotensin II via AT1 receptor increases collagen formation through its effects on TGF-β1 and inhibition of collagenase activity. In this study, we evaluated the antifibrotic effect of angiotensin II receptor blocker on urethral stricture formation by creating a urethral stricture model in a male rabbit.

Material and methods

Thirty three male adult rabbits were separated into 3 groups (control, treatment, and sham). Group I consisted of 15 rabbits with urethral stricture that did not undergo any treatment, group II consisted of 15 rabbits with urethral stricture that were treated with a daily dose of 15 mg/kg losartan, given orally. Group III consisted of 3 rabbits with normal urethra and without any treatment. After 1, 2, and 4 weeks, the urethral tissues were collected, processed, and examined for TGF-β1, MMP-1, collagen type I, and collagen type III using enzyme-linked immunosorbent assay. Data were analyzed using 2-way analysis of variance using SPSS version 20.0.

Results

Urethral TGF-β1 concentration in the treatment group was significantly lower during the 2nd and 4th week of observation (p<0.0001), MMP-1 was significantly higher in the 1st, 2nd, and 4th week of observation (p<0.0001), collagen type I was significantly lower during the 2nd (p=0.001) and 4th week (p<0.0001), and collagen type III concentration was significantly lower in the 2nd and 4th week of observation (p<0.0001).

Conclusion

Angiotensin II receptor blocker could limit the progression of urethral stricture. The mechanism may be related to the AT1 blockage that leads to a decrease in TGF-β1 concentration, eventually resulting in lower collagen concentration due to increased MMP-1 activity.

Evaluation of the Distribution of Paclitaxel After Application of a Paclitaxel-Coated Balloon in the Rabbit Urethra

INTRODUCTION

Urethral strictures are a common urologic problem that could require complex reconstructive procedures. Urethral dilatation represents a frequent practiced intervention associated with high recurrence rates. Drug-coated percutaneous angioplasty balloons (DCBs) with cytostatic drugs have been effectively used for the prevention of vascular restenosis after balloon dilatation. To reduce restenosis rates of urethral dilatation, these balloons could be used in the urethra. Nevertheless, the urothelium is different than the endothelium and these drugs may not be distributed to the outer layers of the urethra. Thus, an experiment was performed to evaluate the distribution of paclitaxel (PTX) in the rabbit urethra after the inflation of a PTX-coated balloon (PCB).

MATERIALS AND METHODS

Eleven rabbits underwent dilatation of the posterior urethra with common endoscopic balloons after urethrography. Nine of these rabbits were additionally treated with PCB. The urethras of the two control animals were removed along with three more dilated with PCB urethras immediately after the dilatation. The remaining of the urethras were removed after 24 (n = 3) and 48 hours (n = 3). The posterior segments of the urethras were evaluated with hematoxylin and eosin staining as well as with immunohistochemistry with polyclonal anti-PTX antibody.

RESULTS

The two control specimens showed denudation of the urothelium after balloon dilatations and no PTX was observed. All specimens from dilated PCB urethras showed distribution of PTX to all layers of the urethra. The specimens that were immediately removed exhibited denudation of the urothelium without any inflammation. The specimens removed at 24 and 48 hours showed mild acute inflammation.

CONCLUSION

PTX was distributed to the urothelial, submucosal, and smooth muscle layers of the normal rabbit urethra immediately after dilatation with a DCB. PTX and mild inflammation were present at the site 24 and 48 hours after the dilatation.

Overcoming scarring in the urethra: Challenges for tissue engineering

Urethral stricture disease is increasingly common occurring in about 1% of males over the age of 55. The stricture tissue is rich in myofibroblasts and multi-nucleated giant cells which are thought to be related to stricture formation and collagen synthesis. An increase in collagen is associated with the loss of the normal vasculature of the normal urethra. The actual incidence differs based on worldwide populations, geography, and income. The stricture aetiology, location, length and patient's age and comorbidity are important in deciding the course of treatment. In this review we aim to summarise the existing knowledge of the aetiology of urethral strictures, review current treatment regimens, and present the challenges of using tissue-engineered buccal mucosa (TEBM) to repair scarring of the urethra. In asking this question we are also mindful that recurrent fibrosis occurs in other tissues-how can we learn from these other pathologies?

Urethral Rest with Suprapubic Cystostomy for Obliterative or Nearly Obliterative Urethral Strictures: Urethrographic Changes and Implications for Management

PURPOSE

Precise preoperative characterization of urethral stricture is important for surgical planning. A period of urethral rest by a suprapubic cystostomy tube may aid in stricture characterization and affect the surgical approach. In this study fellowship trained reconstructive urologists compared the radiographic characterization of anterior urethral strictures before and after a period of urethral rest. We then determined how this changed the planned operative approach.

MATERIALS AND METHODS

We queried our prospectively maintained urethroplasty database at our institution for men with an anterior urethral stricture who underwent retrograde urethrogram and voiding cystourethrogram before and after preoperative suprapubic cystostomy tube placement. A total of 29 men were identified for analysis. To minimize responder fatigue 20 pairs of radiographs were selected at random. All images before and after suprapubic tube placement were interpreted in random order by 11 fellowship trained reconstructive urologists. Interpretation included stricture length, diameter, location and surgeon operative plan. Preplacement and post-placement results were compared. Post-placement stricture length was also compared to intraoperative length. ICC was used to evaluate homogeneity among the urologists. Linear regression analysis was performed to determine the association of post-radiographic length after tube placement with intraoperative stricture length.

RESULTS

Imaging agreement among interpreting urologists was satisfactory (ICC 0.72). There was no statistically significant difference in stricture length before vs after suprapubic tube placement. Of the images 23% were considered obliterative before tube placement while 58% were obliterative after placement (p = 0.0005). Mean ± SD post-placement radiographic and intraoperative stricture length was 3.0 ± 2.6 and 3.8 ± 3.3 cm, respectively (p <0.0001). Deviation between the radiographic and intraoperative lengths increased with stricture length (slope 0.26, p = 0.0023). The surgeon operative plan changed 47% of the time, including to an excision approach in 37% of cases.

CONCLUSIONS

Despite optimal urethral imaging with a suprapubic tube in men with high grade stricture reconstructive urologists underestimated length by an average of almost 1 cm. This underestimation was less for shorter strictures and it increased with stricture length. In addition, a period of urethral rest resulted in more frequent stricture obliteration, which was associated with a change in the planned operative approach about half of the time. If urologists do not place a suprapubic cystostomy tube prior to urethroplasty for high grade stricture, the operative plan should account for the stricture being tighter than it may appear.

Effect of Mitomycin - C and Triamcinolone on Preventing Urethral Strictures

Urethral stricture is a common disease with high recurrence rate. Several manipulations were defined to prevent the recurrence but the results were disappointing. This study aimed to evaluate the efficacy of triamcinolone and mitomycin-C on urethral stricture formation and their effect on inhibition of urethral fibrosis. A total of 24 New Zealand rabbits were divided into 3 groups. Urethras of rabbits were traumatized with pediatric resectoscope. Resection area was irrigated with 10mL saline, swapped with a cotton wool soaked with 0.5mg/mL MMC and injected by 40mg triamcinolone in groups 1, 2 and 3 respectively. Retrograde urethrogram was performed at 28^th day of procedure and the urethra was removed for histopathologic evaluation. There were significant differences in urethral diameters and in lumen reduction rate between the control and study groups (p<0.001). Compared to control group, all treatment groups showed mild fibrosis, less collagen bundle irregularity, and lower numbers of fibroblasts (p=0.003). The Tunnel assay showed that the number of apoptotic cells in the submucosal connective tissue was quantitatively higher in control groups (p=0.034). In the view of efficacy and safety, MMC and triamcinolone have the potential to replace the use of stents, clean intermittent catheterization, or long term catheters following internal urethrotomy. There were no statistically significant differences between two agents in terms of preventing urethral stricture formation in the present study. Mitomycin C and triamcinolone decreased the recurrence rates of urethral stricture.

Anti-fibrotic function of Cu-bearing stainless steel for reducing recurrence of urethral stricture after stent implantation

Recurrent stenosis is the main reason inducing the failure of urethral stricture treatment. Our previous study has found that the 316L type Cu bearing stainless steel (316L-Cu SS) showed antimicrobial activity and anti-encrustation performance when it was used for relieving urethral obstructer. However, whether it can reduce the occurrence of fibrosis or not, we need further investigation to compare the cellular and molecular responses of human urethral scar fibroblast cells (USFCs) on 316L-Cu SS and medical grade 316L stainless (316L SS, as a control). [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)- 2H-tetrazolium (MTS) and Transwell were used to assess the cellular responses, which confirmed that 316L-Cu SS could inhibit proliferation and migration of USFCs. Molecular expressions of fibrosis were evaluated by western blot, real-time quantitative polymerase chain reaction (qPCR), and Cu/Zn superoxide dismutase (CuZnSOD) measurement. The results indicated that up-regulating of CuZnSOD attenuated the transforming growth factor-β1 expression and phosphorylation of Smad3 after exposure to 316L-Cu SS. Besides, the content of collagen type I (COL1) and collagen type III (COL3) secreting into the culture medium measured by enzyme-linked immunosorbent assay were in accord with the results of messenger ribonucleic acids. Both of them exhibited lower levels of COL1/COL3 exposure to 316L-Cu SS, demonstrating the inhibitory performance of 316L-Cu SS against fibrosis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2019-2028, 2018.

AT1 expression in human urethral stricture tissue

BACKGROUND

Urethral stricture has a high recurrence rate. There is a common doctrine stating that "once a stricture, always a stricture". This fibrotic disease pathophysiology, pathologically characterized by excessive production, deposition and contraction of extracellular matrix is unknown. Angiotensin II type 1 (AT₁) receptor primarily induces angiogenesis, cellular proliferation and inflammatory responses. AT₁ receptors are also expressed in the fibroblasts of hypertrophic scars, whereas angiotensin II (AngII) regulates DNA synthesis in hypertrophic scar fibroblasts through a negative cross talk between AT₁ and angiotensin II type 2 (AT₂) receptors, which might contribute to the formation and maturation of human hypertrophic scars.

OBJECTIVE

This study was conducted to determine the expression of AT₁ receptors in urethral stricture tissues.

METHODS

Urethral stricture tissues were collected from patients during anastomotic urethroplasty surgery. There were 24 tissue samples collected in this study with 2 samples of normal urethra for the control group. Immunohistochemistry study was performed to detect the presence of AT₁ receptor expression. Data were analyzed using Mann-Whitney U test, and statistical analysis was performed with SPSS version 20.

RESULTS

This study showed that positive staining of AT₁ receptor was found in all urethral stricture tissues (n=24). A total of 8.33% patients had low intensity, 41.67% had moderate intensity and 50% had high intensity of AT₁ receptors, while in the control group, 100% patients had no intensity of AT₁ receptors. Using the Mann-Whitney U test, it was found that urethral stricture tissue had a higher intensity of AT₁ receptors than normal urethral tissue with a p-value = 0.012.

CONCLUSION

The results showed that AT₁ receptor had a higher intensity in the urethral stricture tissue and that AT₁ receptor may play an important role in the development of urethral stricture.

Advances in urethral stricture management

Urethral stricture/stenosis is a narrowing of the urethral lumen. These conditions greatly impact the health and quality of life of patients. Management of urethral strictures/stenosis is complex and requires careful evaluation. The treatment options for urethral stricture vary in their success rates. Urethral dilation and internal urethrotomy are the most commonly performed procedures but carry the lowest chance for long-term success (0–9%). Urethroplasty has a much higher chance of success (85–90%) and is considered the gold-standard treatment. The most common urethroplasty techniques are excision and primary anastomosis and graft onlay urethroplasty. Anastomotic urethroplasty and graft urethroplasty have similar long-term success rates, although long-term data have yet to confirm equal efficacy. Anastomotic urethroplasty may have higher rates of sexual dysfunction. Posterior urethral stenosis is typically caused by previous urologic surgery. It is treated endoscopically with radial incisions. The use of mitomycin C may decrease recurrence. An exciting area of research is tissue engineering and scar modulation to augment stricture treatment. These include the use of acellular matrices or tissue-engineered buccal mucosa to produce grafting material for urethroplasty. Other experimental strategies aim to prevent scar formation altogether.

Experimental investigation of the biomechanics of urethral tissues and structures

NEW FINDINGS

What is the central question of this study? Prostheses for treatment of urinary incontinence elicit complications associated with an inadequate mechanical action. This investigation aimed to define a procedure addressed to urethral mechanical characterization. Experimental tests are the basis for constitutive formulation, with a view to numerical modelling for investigation of the interaction between the tissues and a prosthesis. What is the main finding and its importance? Horse urethra, selected for its histomorphometric similarity to human urethra, was characterized by integrated histological analysis and mechanical tests on the biological tissue and structure, leading to constitutive formulation. A non-linear, anisotropic and time-dependent response was found, representing a valid basis for development of a numerical model to interpret the functional behaviour of the urethra. Urinary dysfunction can lead to incontinence, with an impact on the quality of life. Severe dysfunction can be overcome surgically by the use of an artificial urinary sphincter. Nonetheless, several complications may result from inappropriate functioning of the prosthesis, in many instances resulting from an unsuitable mechanical action of the device on the urethral tissues. Computational models allow investigation of the mechanical interaction between biological tissues and biomedical devices, representing a potential support for surgical practice and prosthesis design. The development of such computational tools requires experimental data on the mechanics of biological tissues and structures, which are rarely reported in the literature. The aim of this study was to provide a procedure for the mechanical characterization of urethral tissues and structures. The experimental protocol included the morphometric and histological analysis of urethral tissues, the mechanical characterization of the response of tissues to tensile and stress-relaxation tests and evaluation of the behaviour of urethral structures by inflation tests. Results from the preliminary experiments were processed, adopting specific model formulations, and also providing the definition of parameters that characterize the elastic and viscous behaviour of the tissues. Different experimental protocols, leading to a comprehensive set of experimental data, allow for a reciprocal assessment of reliability of the investigation approach.

Management of Long-Segment and Panurethral Stricture Disease

Long-segment urethral stricture or panurethral stricture disease, involving the different anatomic segments of anterior urethra, is a relatively less common lesion of the anterior urethra compared to bulbar stricture. However, it is a particularly difficult surgical challenge for the reconstructive urologist. The etiology varies according to age and geographic location, lichen sclerosus being the most prevalent in some regions of the globe. Other common and significant causes are previous endoscopic urethral manipulations (urethral catheterization, cystourethroscopy, and transurethral resection), previous urethral surgery, trauma, inflammation, and idiopathic. The iatrogenic causes are the most predominant in the Western or industrialized countries, and lichen sclerosus is the most common in India. Several surgical procedures and their modifications, including those performed in one or more stages and with the use of adjunct tissue transfer maneuvers, have been developed and used worldwide, with varying long-term success. A one-stage, minimally invasive technique approached through a single perineal incision has gained widespread popularity for its effectiveness and reproducibility. Nonetheless, for a successful result, the reconstructive urologist should be experienced and familiar with the different treatment modalities currently available and select the best procedure for the individual patient.

Dorsal Onlay Urethroplasty for Membranous Urethral Strictures: Urinary and Erectile Functional Outcomes

PURPOSE

We evaluated urinary and erectile functional outcomes after dorsal onlay urethroplasty for bulbomembranous urethral strictures. Our aim was to understand the functional implications of dissection of the posterior urethra.

MATERIALS AND METHODS

We report on men who underwent membranous urethral stricture repair by buccal mucosal graft dorsal onlay substitution urethroplasty. Continence and erectile function were assessed preoperatively and postoperatively. Tissue routinely excised from the intercrural space during dissection of the dorsal aspect of the membranous urethra was evaluated for scar, striated muscle and nerves.

RESULTS

A total of 16 consecutive men with a mean age of 48.3 years (range 26 to 72) who had strictures with a mean length of 56 mm (range 15 to 170) involving the membranous urethra were included in analysis. Of the 16 men 15 were continent preoperatively and remained continent postoperatively. Three of 10 men (30%) with a preoperative SHIM (Sexual Health Inventory for Men) score of 17 to 25 had a decrease after urethroplasty. All 16 men had an improved maximum urinary flow rate with a mean improvement of 22 ml per second. I-PSS (International Prostate Symptom Score) improved from a median of 23 to 4 postoperatively with a median bother score improvement of 5 to 0. Histopathological assessment identified striated muscle and nerves in 6 (46%) and 9 (69%) of 13 specimens. Overall nerves and muscle comprised an average of less than 15% of the specimen.

CONCLUSIONS

The dorsal onlay technique with a buccal mucosal graft for membranous urethral stricture repair does not compromise continence or erectile function in most patients. Dissection at the level of the membranous urethra should be limited because striated muscle and cavernous nerves are present.

Male urethral strictures and their management

Male urethral stricture disease is prevalent and has a substantial impact on quality of life and health-care costs. Management of urethral strictures is complex and depends on the characteristics of the stricture. Data show that there is no difference between urethral dilation and internal urethrotomy in terms of long-term outcomes; success rates range widely from 8-80%, with long-term success rates of 20-30%. For both of these procedures, the risk of recurrence is greater for men with longer strictures, penile urethral strictures, multiple strictures, presence of infection, or history of prior procedures. Analysis has shown that repeated use of urethrotomy is not clinically effective or cost-effective in these patients. Long-term success rates are higher for surgical reconstruction with urethroplasty, with most studies showing success rates of 85-90%. Many techniques have been utilized for urethroplasty, depending on the location, length, and character of the stricture. Successful management of urethral strictures requires detailed knowledge of anatomy, pathophysiology, proper patient selection, and reconstructive techniques.

Reduced flow after tubularized incised plate urethroplasty--increased fibrogenesis, elastin fiber loss or neither?

PURPOSE

Low urinary flow rates are common after tubularized incised plate urethroplasty but the etiology remains unclear and may be related to low urethral compliance due to abnormal collagen concentrations and/or fewer elastic fibers in the healed urethral plate. We hypothesized that inserting a preputial mucosal graft over the dorsal raw area after the midline incision may avoid scarring and improve urethral compliance.

MATERIALS AND METHODS

Adult rabbits were submitted to tubularized incised plate urethroplasty with or without inlay preputial graft according to a previously described protocol. Tissular concentrations of collagens I, III, IV, VI, VIII and XIII were measured. Histomorphometric analysis was used to quantify elastic fibers in the urethra. Tubularized incised plate urethroplasty with and without inlay preputial graft was compared to normal rabbit urethras (controls).

RESULTS

mRNA concentrations for collagens I, II and XIII were similar between controls and operated rabbits. The proportions between collagens I and III were 1.05, 0.87 and 1.21, respectively, in controls and animals undergoing tubularized incised plate urethroplasty with and without inlay preputial graft. mRNA concentrations for collagen IV and collagens VI/VIII tended to be higher and lower, respectively, in the operated urethras, despite showing statistical significance only for collagen VIII in animals undergoing tubularized incised plate urethroplasty with inlay preputial graft vs controls (p=0.02). The operated animals did not demonstrate a reduced number of elastic fibers in the urethral tissues compared to controls.

CONCLUSIONS

Elastic fiber number and distribution were similar between tubularized incised plate urethroplasty cases and controls, suggesting that decreased concentrations of elastic fibers do not explain the reduced urethral compliance after tubularized incised plate urethroplasty. The raw area determined by the dorsal urethral incision regenerated after standard tubularized incised plate urethroplasty, while cicatrization with fibrosis occurred in correspondence to the grafted areas after tubularized incised plate urethroplasty with inlay preputial graft.