A morphometric analysis of bulbar urethral strictures

High frequency of concomitant squamous metaplasia in bulbar urethral stricture and its association with reconstructive delay and urethral rest

PURPOSE

To determine the prevalence of concomitant squamous metaplasia (SM), the initial histological change from normal urethra to urethral stricture, in bulbar urethral strictures and to investigate the associated clinical factors.

METHODS

A retrospective review was conducted on 165 male patients with bulbar urethral strictures who underwent excision and primary anastomosis (EPA) between 2010 and 2020, for whom complete clinical data and excised urethral specimens were available. An experienced pathologist histologically evaluated concomitant SM in paraffin sections of the proximal end of the excised urethra blinded to the clinical data. Disease duration was calculated as the period from the initial diagnosis of urethral stricture to the date of EPA. The association between concomitant SM and clinical background was investigated.

RESULTS

SM was identified in 86 (52.1%) patients. The median disease duration in patients with SM (38 months) was significantly longer than that in patients without SM (9 months, p < 0.0001). In multivariate analysis, the longer disease duration, non-traumatic stricture etiology, and failure to maintain urethral rest with urinary diversion via a suprapubic tube for more than 90 days were independent factors predicting concomitant SM. No significant difference was observed in success rates of EPA between patients with SM (93.2%) and those without SM (97.5%, p = 0.18).

CONCLUSIONS

Reconstructive urologists need to be aware that concomitant SM is frequent in patients with bulbar urethral stricture, especially in those with long disease duration and those who were voiding volitionally during the period of urethral rest.

Prevention of Postoperative Urethral Strictures by Irrigation with 5-Fluorouracil via a Modified Urinary Catheter

Background and Objectives: Urethral strictures are the most common complications after surgical treatments of benign prostatic hyperplasia (BPH). Despite various preventive measures, the search for medications with antiproliferative activity and the development of surgical procedures to prevent the development of urethral strictures are still relevant. We evaluated the preventive efficacy of 5-fluorouracil against urethral strictures in patients undergoing surgery for BPH. Materials and Methods: A non-randomized clinical trial including 246 male patients with an average age of 70.0 ± 8.0 years was conducted. The main study group included 124 patients who, in addition to the standard treatment, received lavage with a 5-fluorouracil solution (1000 mg/20 mL per 500 mL of 0.9% isotonic saline) using a modified three-way urethral catheter. The monitoring of clinical, laboratory, and instrumental parameters was carried out 10 days, 3 months, and 6 months after surgery. Results: The evaluation of severity for dysuria symptoms in patients using the IPSS scale throughout the entire follow-up period showed a statistically significant decrease in ischuria and stranguria, prolongation of the interval between urinations, a decrease in intermittent urination, urinary incontinence, and straining before urination in the main group in comparison with the control patients. The patients of both study groups noted an improvement in the quality of life. It was found statistically significant decrease in the maximum urinary flow rate in the main group (p < 0.001). In the control group, after three months, four cases of urethral strictures and stenosis were recorded; after six months, this rate reached nine cases (7.3%), while in the main group, only one patient with infravesical obstruction was found (0.8%) (χ2 = 3.855, p < 0.05). Conclusions: The results of our study could indicate the effectiveness of the antiproliferative drug 5-fluorouracil in combination with use of a modified catheter in relation to the development of postoperative urethral strictures.

Safety of Xiaflex® (Collagenase Clostridium histolyticum) Treatment for Adult Anterior Urethral Stricture Disease

Male urethral stricture disease is highly prevalent and difficult to treat due to potential complications. Minimally invasive treatments tend to have high recurrence rates, keeping urethroplasty as the gold standard. Collagenase Clostridium histolyticum (CCH) has been used in humans to treat fibrosis in a minimally invasive manner. Herein, we present the preliminary results from treatments of three males with urethral stricture as a feasibility and safety evaluation of the first-in-human CCH treatment for male urethral stricture disease.

Wound healing responses of urinary extravasation after urethral injury

The post-surgical fluid leakage from the tubular tissues is a critical symptom after gastrointestinal or urinary tract surgeries. Elucidating the mechanism for such abnormalities is vital in surgical and medical science. The exposure of the fluid such as peritonitis due to urinary or gastrointestinal perforation has been reported to induce severe inflammation to the surrounding tissue. However, there have been no reports for the tissue responses by fluid extravasation and assessment of post-surgical and injury complication processes is therefore vital. The current model mouse study aims to investigate the effect of the urinary extravasation of the urethral injuries. Analyses on the urinary extravasation affecting both urethral mesenchyme and epithelium and the resultant spongio-fibrosis/urethral stricture were performed. The urine was injected from the lumen of urethra exposing the surrounding mesenchyme after the injury. The wound healing responses with urinary extravasation were shown as severe edematous mesenchymal lesions with the narrow urethral lumen. The epithelial cell proliferation was significantly increased in the wide layers. The mesenchymal spongio-fibrosis was induced by urethral injury with subsequent extravasation. The current report thus offers a novel research tool for surgical sciences on the urinary tract.

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.

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.

Circ_0047339 promotes the activation of fibroblasts and affects the development of urethral stricture by targeting the miR-4691-5p/TSP-1 axis

Urethral stricture is related to scar tissue fibrosis, but its pathogenesis is still unclear. This study aims to explore the regulatory mechanism of circular RNA (circRNA) in the occurrence and development of urethral stricture. CircRNA microarray was employed to analyze circRNA expression profiles between human urethral scar tissue and normal urethral tissue. The results of circRNA microarray showed that there were 296 differentially expressed genes between urethral scar tissue and normal urethral tissue. The enrichment analysis of Kyoto encyclopedia of genes and genomes showed that these circRNAs were significantly correlated with ECM–receptor interaction. The first nine differentially expressed circRNA were selected to predict the circRNA–miRNA network. RT-qPCR results showed that circ_0047339 was upregulated considerably in urethral scar tissue. Urethral scar fibroblasts were isolated from human urethral scar tissue and cultured in vitro. After silencing circ_0047339, the proliferation of urethral scar cells decreased significantly, and the expressions of Collagen I (COL-1) and α-smooth muscle actin (α-SMA) also reduced. As a competing endogenous RNA, circ_0047339 could increase the expression of TSP-1 by competitively binding miR-4691-5p. In addition, miR-4691-5p mimic transfection could inhibit the proliferation of urethral scar fibroblasts and the presentation of thrombospondin-1 (TSP-1), α-SMA and COL-1, while circ_0047339 overexpression eliminated this inhibition. Our results showed that circ_0047339 might promote the growth and fibrosis of urethral scar fibroblasts through miR-4691-5p/TSP-1 axis, thus promoting the development of urethral stricture.

Verapamil inhibited the development of ureteral stricture by blocking CaMK II-mediated STAT3 and Smad3/JunD pathways

BACKGROUND

Ureteral stricture (US) is a fibrotic process that leads to urinary tract obstruction and even kidney damage, with the characteristic of reduced extracellular matrix (ECM) degradation and increased collagen synthesis. Verapamil, as a calcium channel blocker, was reported to prevent scar formation. Our work aimed to investigate the biological effects and mechanism of verapamil in US.

METHODS

Fibroblasts were subjected to transforming growth factor-beta 1 (TGF-β1) to stimulate collagen synthesis, and the messenger ribonucleic acid (mRNA) and protein expressions in fibroblasts were assessed using quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. The location of phosphorylation-signal transducer and activator of transcription 3 (p-STAT3) and Jund proto-oncogene subunit (JunD) in fibroblasts were determined by immunofluorescence (IF). The binding relationship between signal transducer and activator of transcription 3 (STAT3) and collagen type I alpha1 (COL1A1)/collagen type III alpha 1 chain (COL3A1) and the binding relationship between JunD and tissue inhibitor of metalloproteinases-1 (TIMP-1) were verified by dual luciferase reporter gene and chromatin Immunoprecipitation (ChIP) assays.

RESULTS

Herein, we found that verapamil could inhibit TGF-β1/Ca2 + ⁄calmodulin-dependent protein kinase II (CaMK II)-mediated STAT3 activation in fibroblasts, and STAT3 inhibition repressed collagen production. In addition, verapamil could inhibit TGF-β1/CaMK II-mediated Mothers against DPP homolog 3 (Smad3)/JunD pathway activation in fibroblasts, and JunD silencing inhibited TIMP1 (a matrix metalloproteinase inhibitor) expression. Our subsequent experiments revealed that STAT3 bound with COL1A1 promoter and COL3A1 promoter and activated their transcription, and JunD bound with TIMP1 promoter and activated its transcription. Moreover, as expected, STAT3 activation could eliminate the inhibitory effect of verapamil treatment on TGF-β1-induced collagen production in fibroblasts, and JunD overexpression reversed the inhibitory effect of verapamil treatment on TGF-β1-induced TIMP1 expression in fibroblasts.

CONCLUSION

Verapamil inhibited collagen production and TIMP-1 expression in US by blocking CaMK II-mediated STAT3 and Smad3/JunD pathways.

Prevention of urethral fibrosis induced by transforming growth factor beta 1 using selective Wnt/β-catenin signaling inhibitors in a rat model

OBJECTIVES

To determine the anti-fibrotic effects of Wnt/β-catenin signaling inhibitors on urethral stricture.

METHODS

Human fibroblasts were exposed to transforming growth factor beta 1 combined with various concentrations of Wnt/β-catenin inhibitors (ICG-001, IWR-1, and PRI-724), and cell proliferation and migration were evaluated. Urethral fibrosis was induced in male Sprague-Dawley rats by urethral injection of transforming growth factor beta 1 and co-treatement with inhibitors. Urethral tissues were harvested 2 weeks after the injection. The messenger ribonucleic acid and protein expression was examined for fibrosis markers Axin-1, collagen type 1, alpha smooth muscle actin, and β-catenin. Histological analysis of fibrosis and collagen deposition was also performed.

RESULTS

Cell migration was ameliorated by ICG-001 and PRI-724. Protein and messenger ribonucleic acid expression of collagen type 1 and alpha smooth muscle actin in transforming growth factor beta 1-treated fibroblasts decreased in a concentration-dependent manner with the ICG-001 and PRI-724 treatments (P < 0.05). However, there were no significant changes with the IWR-1 treatment. Collagen type I and alpha smooth muscle actin messenger ribonucleic acid and protein expression were both significantly increased in the urethral tissues of rats with transforming growth factor beta 1-induced urethral fibrosis. Rats co-treated with ICG-001 or PRI-724 showed relatively mild fibrosis and significantly reduced collagen type I and alpha smooth muscle actin messenger ribonucleic acid and protein expression (P < 0.05).

CONCLUSIONS

ICG-001 and PRI-724 significantly ameliorated urethral fibrosis induced by transforming growth factor beta 1 in rats. These results suggest that ICG-001 and PRI-724 can be developed as therapeutics for treating urethral stricture.

Effect of uncultured adipose-derived stromal vascular fraction on preventing urethral stricture formation in rats

Urethral stricture (US) remains a challenging disease without effective treatment options due to the high recurrence rate. This study aims to evaluate the preventive effect of uncultured adipose derived stromal vascular fraction (SVF) on urethral fibrosis in a rat model of US. Results demonstrated that US rats displayed hyperechogenic urethral wall with a narrowed lumen compared with sham rats, while SVF rats exhibited less extensive urethral changes. By histology, US rats showed obvious submucosal fibrosis in the urethral specimens, while SVF rats exhibited mild submucosal fibrosis with less extensive tissue changes. Furthermore, US rats showed increased gene and protein expression of collagen I (2.0 ± 0.2, 2.2 ± 0.2, all were normalized against GAPDH, including the following), collagen III (2.5 ± 0.3, 1.2 ± 0.1), and TGFβ1R (2.8 ± 0.3, 1.9 ± 0.2), while SVF cells administration contributed to decreased gene and protein expression of collagen I (1.6 ± 0.2, 1.6 ± 0.2), collagen III (1.8 ± 0.4, 0.9 ± 0.1), and TGFβ1R (1.8 ± 0.3, 1.3 ± 0.2), in parallel with the improvement of vascularization and increased expression of VEGF (1.7 ± 0.1) and bFGF (3.1 ± 0.3). Additionally, SVF served anti-inflammatory effect through regulation of inflammatory cytokines and cells, accompanied with conversion of the macrophage phenotype. Our findings suggested that uncultured SVF presented an inhibitory effect on stricture formation at an early stage of urethral fibrosis.

The Role of LIM Kinase in the Male Urogenital System

The LIM kinases (LIMK1 and LIMK2), known as downstream effectors, and the Rho-associated protein kinase (ROCK), a regulator of actin dynamics, have effects on a diverse set of cellular functions. The LIM kinases are involved in the function of the male urogenital system by smooth muscle contraction via phosphorylation of cofilin and subsequent actin cytoskeleton reorganization. Although LIMK1 and LIMK2 share sequence similarities as serine protein kinases, different tissue distribution patterns and distinct localization during cell cycle progression suggest other biological functions for each kinase. During meiosis and mitosis, the LIMK1/2–cofilin signaling facilitates the orchestrated chromatin remodeling between gametogenesis and the actin cytoskeleton. A splicing variant of the LIMK2 transcript was expressed only in the testis. Moreover, positive signals with LIMK2-specific antibodies were detected mainly in the nucleus of the differentiated stages of germ cells, such as spermatocytes and early round spermatids. LIMK2 plays a vital role in proper spermatogenesis, such as meiotic processes of spermatogenesis after puberty. On the other hand, the literature evidence revealed that a reduction in LIMK1 expression enhanced the inhibitory effects of a ROCK inhibitor on the smooth muscle contraction of the human prostate. LIMK1 may have a role in urethral obstruction and bladder outlet obstruction in men with benign prostatic hyperplasia. Moreover, LIMK1 expression was reduced in urethral stricture. The reduced LIMK1 expression caused the impaired proliferation and migration of urethral fibroblasts. In addition, the activated LIMK2–cofilin pathway contributes to cavernosal fibrosis after cavernosal nerve injury. Recent evidence demonstrated that short-term inhibition of LIMK2 from the immediate post-injury period prevented cavernosal fibrosis and improved erectile function in a rat model of cavernosal nerve injury. Furthermore, chronic inhibition of the LIMK2–cofilin pathway significantly restrained the cavernosal veno-occlusive dysfunction, the primary pathophysiologic mechanism of post-prostatectomy erectile dysfunction through suppressing fibrosis in the corpus cavernosum. In conclusion, the LIM kinases–cofilin pathway appears to play a role in the function of the male urogenital system through actin cytoskeleton reorganization and contributes to the pathogenesis of several urogenital diseases. Therefore, LIM kinases may be a potential treatment target in urogenital disorder.

Histopathologic and clinical comparison of recurrent and non-recurrent urethral stricture disease treated by reconstructive surgery

Background

Urethral stricture is a relatively frequent problem often requiring multiple surgical interventions. The objective of this study was to compare the clinicopathologic features of urethral resections from patients who underwent open end-to-end anastomotic urethroplasty and later recurred compared to those who did not.

Methods

A retrospective review of the pathology files identified 36 consecutive patients who underwent urethroplasty. The histopathological analysis included evaluation of the inflammatory infiltrate based on the predominant (>50%) cell type: lymphocyte-rich, neutrophil-rich, plasma cell-rich, and mixed; length and thickness of the fibrous plaque; and the cellularity of the fibrous plaque: cellular (>40 stroma nuclei/HPF) or paucicellular (<40 stroma nuclei/high power field).

Results

Ten (28%) patients recurred, and 26 (72%) did not. There was no significant difference between recurrent and non-recurrent cases in age, race, comorbidities, location of the stricture, and etiology. All patients with recurrent strictures showed dense paucicellular fibrotic plaques (10/10; 100%), while this was seen in 14/26 (53.8%) non-recurrent cases (P=0.01). Only one patient with cellular fibrosis showed recurrence during follow-up. The log-rank test shows that time to recurrence is significantly shorter in patients with paucicellular fibrosis compared to those with cellular fibrosis (P=0.036). The inflammation consisted of a mixed population of CD3(+) T-lymphocytes, CD20(+) B-lymphocytes, and CD68(+) histiocytes, and there was no difference in the composition of the inflammation between groups. All cases with plasma cell-rich infiltrate showed normal IgG4:IgG.

Conclusions

Our study supports reporting cellularity of the fibrous plaque as a potential predictor of outcome in patients undergoing reconstructive urethroplasty. Patients with paucicellular fibrosis are at increased risk of recurrence.

Effects of a gamma-secretase inhibitor of notch signalling on transforming growth factor β1-induced urethral fibrosis

Urethral stricture (US) is a common disorder of the lower urinary tract in men caused by fibrosis. The recurrence rate of US is high; however, there are no effective therapies to prevent or treat urethral fibrosis. The pathogenesis of urethral fibrosis involves myofibroblast activation and excessive extracellular matrix (ECM) deposition. The molecular mechanisms underlying this pathological activation are not completely understood. It has been demonstrated that Notch signalling contributes to the development of fibrosis and inflammation. However, whether this contributes to urethral fibrosis remains unclear. In this study, activation of Notch signalling was observed in patients with US. Additionally, it was noted that activation of Notch signalling promoted ECM production and myofibroblast activation in human urethral scar fibroblasts (HUSFs) treated with transforming growth factor (TGF) β1. However, the Notch inhibitor N‐[N‐(3,5‐difluorophenacetyl)‐L‐alanyl]‐S‐phenylglycine t‐butyl ester (DAPT) suppressed activation of Notch signalling as well as proliferation and migration of the TGFβ1‐treated HUSFs. Additionally, DAPT ameliorated TGFβ1‐induced urethral fibrosis in Sprague Dawley rats by suppressing ECM production, myofibroblast activation and the TGFβ signalling pathway. These findings demonstrate that Notch signalling may be a promising and potential target in the prevention or treatment of urethral fibrosis.

Verapamil inhibits ureteral scar formation by regulating CaMK II-mediated Smad pathway

Verapamil is reported to prevent scar formation. However, whether verapamil is involved in the ureteral stricture scar and the underlying mechanism need further investigation. Fibroblasts were isolated from ureteral scar tissues. TGF-β1 stimulation was used to induce fibrosis of fibroblasts. Inhibition of CaMK II was achieved by shRNA transfection. CCK-8 was performed to evaluate cell viability. qRT-PCR was applied to determine the level of mRNA while western blotting was used to determine the level of proteins. Immunofluorescence was used to detect the level of vimentin, collagen I and collagen III. Primary fibroblasts was successfully isolated from ureteral scar tissues. TGF-β1 stimulation was capable to induce collagen production and fibrosis in primary fibroblasts while inhibition of CaMK II attenuate collagen production. Overexpression of wild type CaMK II lead to further increase of collagen production upon TGF-β1 stimulation while the mutated CaMK II did not exert this promotion. Treatment of verapamil inhibits TGF-β1 induced collagen production via inhibiting CaMK II. In present study, we revealed a vital role of Verapamil and CaMK II in the formation of ureteral scar. Verapamil inhibited TGF-β1 induced collagen fiber formation by regulating CaMK II. Our finding might provide new insight into mechanism of prevention and treatment of ureteral scar.

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.

Ectopic Germinal Centres with B and T Cells and Follicular Dendritic Cell Networks in Urethral Stricture Tissue: Possible Avenue for Immunological Treatments

Background

The underlying cause of a urethral stricture can sometimes be obscure. It is possible that an injury to the urethra induces an immunological cascade that generates scar tissue and fibrosis, eventually resulting in a stricture. If such immunological reactions could be better elucidated, immunological therapies could possibly emerge.

Objective

To evaluate if ectopic germinal centres exist in urethral stricture disease.

Design, setting, and participants

Resected stricture specimens from 45 patients undergoing open bulbar urethroplasty with excision and anastomosis were assessed. Histopathological characteristics, such as fibrosis (grade I–III), inflammation, and sclerosis, were evaluated using immunostaining for CD3 (T cells), CD20 (B cells), and CD21 (follicular dendritic cells).

Outcome measurements and statistical analysis

The primary outcome measure was the presence or absence of a germinal centre. The secondary outcome was evaluation of any correlation between the degree of fibrosis and germinal centres. Fisher’s exact test was used for univariate analysis.

Results and limitations

In six patients, ectopic germinal centres were found. In ten patients, there was no inflammation at all. There was no correlation found between the degree of fibrosis and the abundance of immunohistochemically detected immune cells.

Conclusions

Ectopic germinal centres, with B and T cells as well as follicular dendritic cell networks, do exist in urethral stricture disease. This finding may open up for novel research avenues on the possibility of adopting immunological treatments for urethral stricture disease.

Patient summary

In patients with a narrowing of the urethra due to any kind of trauma, we looked for the presence of centres of immunological reaction in urethral tissue. We identified these immunological centres (also called germinal centres) in some patients. This intriguing finding suggests that immunological treatments may have potential for men with scar tissue in a narrowed urethra.

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.

Determination of Stent Load Conditions in New Zealand White Rabbit Urethra

Background: Frequency of urethral stenosis makes it necessary to develop new innovative methods of treating this disease. This pathology most often occurs in men and manifests itself in painful urination, reduced urine flow, or total urinary retention. This is a condition that requires immediate medical intervention. Methods: Experimental tests were carried out on a rabbit in order to determine the changes of pressure in the urethra system and to estimate the velocity of urine flow. For this purpose, a measuring system was proposed to measure the pressure of a fluid-filled urethra. A fluoroscope was used to observe the deformability of the bladder and urethra canal. Results: Based on these tests, the range of changes in the urethra tube diameter, the pressures inside the system, and the flow velocity during micturition were determined. Conclusions: The presented studies allowed determining the behavior of the urethra under the conditions of urinary filling. The fluid-filled bladder and urethra increased their dimensions significantly. Such large changes require that the stents used for the treatment of urethral stenosis should not have a fixed diameter but should adapt to changing urethral dimensions.

Impact of Cardiovascular and Metabolic Risk Factors on Stricture Recurrence After Anterior One-stage Buccal Mucosal Graft Urethroplasty

OBJECTIVES

To evaluate the impact of cardiovascular, metabolic and smoking related risk factors on recurrence in patients with buccal mucosal graft urethroplasty for anterior urethral strictures.

PATIENTS AND METHODS

Retrospective single-center analysis between 2009 and 2016. Covariates included American Society of Anesthesiology (ASA) score, body mass index, and smoking status (never vs ever), coronary artery disease, arterial hypertension, diabetes mellitus, change in hemoglobin, creatinine, c-reactive protein, and leucocyte count. Descriptive and survival analyses evaluated the association with stricture recurrence.

RESULTS

Overall, 1039 patients had buccal mucosal graft urethroplasty of which 517 remained for final analysis. Patients with stricture recurrence (n = 76) were significantly older (P < .001), had a higher American Society of Anesthesiology score (P = .006), higher proportion coronary artery disease (P = .011), and hypertension (P = .003) compared to those patients without stricture recurrence. Patients without stricture recurrence had a significantly larger drop in hemoglobin (1.5 [0.9, 2.1] vs 1.2 [0.7, 1.8]) mg/dl ( = .005).Overall stricture-free recurrence rate was 86%, with a median follow-up of 32 (95% confidence interval: 26-30) months. In multivariable analysis, a larger drop of hemoglobin remained the only independent, statistically significant negative predictor of stricture recurrence (Hazard ratio, 95% confidence interval: 0.74, 0.57-0.97, P = .03).

CONCLUSION

A larger drop of hemoglobin is independently associated with recurrence free survival. This may be considered as a surrogate marker for good microvascular circulation of the corpus spongiosum and therefore neovascularization of the graft. Contrary to the existing and mostly heterogenous previous studies, our findings suggest that stricture recurrence is largely independent of cardiovascular and metabolic risk factors.

The standard for the management of male urethral strictures in the UK: a consensus document

Objective:

The aim of this study was to establish an evidence-based best clinical practice consensus for the management of urethral stricture disease in the UK.

Methods:

A systematic review of optimal management of urethral stricture generated a base document which was endorsed by the British Association of Urological Surgeons (BAUS) section of Andrology and Genito-Urinary Reconstructive Surgeons (AGUS). A two-round electronic mail modified Delphi survey of 43 consultant reconstructive urologists, members of the British Association of Genito-Urinary Reconstructive Surgeons (BAGURS), was then performed. The panel’s views about the base document was sought in seven domains: definition, diagnosis, investigation, conservative, endoscopic and reconstructive treatments, and follow up. Responses were collated and used to modify the base to achieve a consensus statement.

Results:

In round one of the Delphi process four panel members commented on the base document and seven in round two. Consensus was thereby reached on 38 statements regarding definition (one), diagnosis (three), investigation (two), conservative/endoscopic (five) and reconstructive (24) treatments and follow up (three) for the management of urethral stricture disease.

Conclusion:

This consensus statement will help standardise care, provide guidance on the management of urethral stricture disease, and assist in clinical decision-making for healthcare professionals of all grades.

Effects of pelvic bone fracture on recurrence-free rate after bulbomembranous anastomotic urethroplasty in men with posterior urethral injuries

Purpose

To determine the impact of pelvic bone fracture on the recurrence of urethral stenosis after bulbomembranous anastomotic urethroplasty.

Materials and Methods

A total of 197 patients with complete posterior urethral injuries underwent bulbomembranous anastomotic urethroplasty. These patients were divided into two groups according to the presence of pelvic bone fracture. Recurrence of urethral stenosis was defined as the need for any postoperative surgical intervention. The surgical outcomes and postoperative recurrence rate of urethral stenosis were compared between the two groups, and significant predictors for posterior urethral restenosis, including pelvic bone fracture, were analyzed via multivariate analysis.

Results

Of the patients, 92 had pelvic bone fractures and the other 105 patients did not. The patients with pelvic bone fracture had increased involvement of the prostatic urethra compared to the group without pelvic bone fracture (3.8% vs. 17.4%, p=0.002). Recurrence of urethral stenosis was more common in the pelvic bone fracture group (42/92, 45.7%) than the group without pelvic fracture (27/105, 25.7%). In a Kaplan—Meier analysis, the recurrence rate at 5 years was significantly lower in the pelvic bone fracture group (59.1% vs. 72.6%, p=0.003). A Cox proportional hazard analysis showed that the presence of pelvic bone injury was a significant predictor of posterior urethral re-stenosis.

Conclusions

Patients with posterior urethral injuries associated with pelvic bone fracture had a higher recurrence rate of urethral stenosis after bulbomembranous anastomotic urethroplasty than those without pelvic bone fracture.

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.

TNF-α-induced exosomal miR-146a mediates mesenchymal stem cell-dependent suppression of urethral stricture

The effective treatment of urethral stricture remains a medical problem. The use of proinflammatory cytokines as stimuli to improve the reparative efficacy of mesenchymal stem cells (MSCs) towards damaged tissues represents an evolving field of investigation. However, the therapeutic benefits of this strategy in the treatment of urethral stricture remain unknown. Here, we enriched exosomes derived from human umbilical cord-derived MSCs pretreated with or without tumor necrosis factor alpha (TNF-α) to evaluate their therapeutic effects in an in vivo model of TGFβ1-induced urethral stricture. Male Sprague-Dawley rats received sham (saline) or TGFβ1 injections to urethral tissues followed by incisions in the urethra. Animals in the TGFβ1 injection (urethral fibrosis) cohort were subsequently injected with vehicle control, or with exosomes derived from MSCs cultured with or without TNF-α. After 4 weeks, rats underwent ultrasound evaluation and, following euthanasia, urethral tissues were harvested for histological and molecular analysis. In vitro, the effects of MSC-derived exosomes on fibroblast secretion of collagen and cytokines were studied by enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and western blot analysis. Exosomes derived from MSCs pretreated with TNF-α were more effective in suppressing urethral fibrosis and stricture than exosomes from untreated MSCs. We found that miR-146a, an anti-inflammatory miRNA, was strongly upregulated in TNF-α-stimulated MSCs and was selectively packaged into exosomes. Moreover, miR-146a-containing exosomes were taken up by fibroblasts and inhibited fibroblast activation and associated inflammatory responses, a finding that may underlie the therapeutic mechanism for suppression of urethral stricture. Inhibition of miR-146a in TNF-α-treated MSCs partially reduced antifibrotic effects and increased the release of proinflammatory factors of exosomes derived from these cells. Together these findings demonstrate that exosomes derived from TNF-α-treated MSCs are of therapeutic benefit in urethral fibrosis, suggesting that this strategy may have utility as an adjuvant therapy in the treatment of urethral stricture diseases.

Insulin-like growth factor 1 sustained-release collagen on urethral catheter prevents stricture after urethral injury in a rabbit model

OBJECTIVES

To evaluate the preventive effect of an insulin-like growth factor 1 sustained-release collagen urethral catheter on urethral stricture after urethral injury in a rabbit model.

METHODS

We made urethral catheters coated either with insulin-like growth factor 1 impregnated collagen or with only collagen, and we divided 19 male Japanese white rabbits into three groups according to the kind of catheter inserted immediately after the rabbit's urethra was injured by electrocoagulation. Group 1 (n = 7) had a catheter coated with insulin-like growth factor 1 impregnated collagen inserted; group 2 (n = 7) had a catheter coated with only collagen inserted; and group 3 (n = 5) had an uncoated catheter inserted. A total of 14 days later, the injured urethras were evaluated by urethrography and urethroscopy, and were also histologically examined.

RESULTS

Urethrography showed that the ratio of the urethral lumen diameter in injured urethra to that in normal urethra was the largest in group 1 (P < 0.0001). In addition, five of the seven rabbits in group 1 (71.4%) had a urethral lumen large enough for passage of a urethroscope, a fraction larger than the corresponding fractions in groups 2 (57.1%) and 3 (20%). On histological analysis, the injured area not covered with regenerated urethral epithelium tended to be smaller in group 1 than the other two groups, but the mean difference was not significant (P = 0.19).

CONCLUSIONS

An insulin-like growth factor 1 sustained-release collagen urethral catheter significantly improves wound healing and prevents urethral stricture after urethral injury.

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.

Fasudil inhibits actin polymerization and collagen synthesis and induces apoptosis in human urethral scar fibroblasts via the Rho/ROCK pathway

Purpose

To examine the effects and mechanism of action of fasudil on cytoskeletal polymerization, collagen synthesis, and apoptosis in fibroblasts derived from human urethral scar tissue.

Materials and methods

Fibroblasts treated with or without transforming growth factor β1 (TGF-β1, 10 ng/mL) were incubated with fasudil (12.5, 25, 50 μmol/L) for 24 hours. Quantitative real-time polymerase chain reaction and Western blotting were used to determine the expression of Arp2, Arp3, WASP, and WAVE2. Collagen I and III protein levels were also evaluated by Western blotting. The filamentous actin cytoskeleton was examined by immunofluorescence and epifluorescence microscopy. An Annexin V-FITC/PI staining assay was used to investigate apoptosis.

Results

TGF-β1-dependent induction of actin polymerization and collagen synthesis and promotion of apoptosis were dose dependent. When compared with untreated controls, fasudil significantly decreased the expression of Arp2, Arp3, WASP, WAVE2, Collagen I, and Collagen III in cells treated with or without TGF-β1. Fasudil also promoted apoptosis in cells, irrespective of TGF-β1 treatment.

Conclusion

Irrespective of TGF-β1 activation status, fasudil suppressed actin polymerization and collagen synthesis and induced apoptosis in human urethral scar fibroblasts via the Rho/ROCK signaling pathway.

Structural study of the cremaster muscle in patients with retractile testis

OBJECTIVE

To analyze the structure of the cremaster in patients with retractile testis (RT), comparing the distribution of nerves, elastic system and muscles with patients having cryptorchidism and inguinal hernia (IH).

PATIENTS AND METHODS

We studied 31 patients, 17 with RT (mean age=5.17years); 9 with IH (mean age=2.6) and 5 with cryptorchidism (mean age=3). A cremaster biopsy was performed and submitted to routine histological processing and studied using histochemistry and immunohistochemistry. The samples were photographed under an Olympus BX51 microscope. The images were processed with the Image J software and the cremaster muscle structures were quantified. Means were compared statistically using ANOVA and the unpaired t-test (p<0.05).

RESULTS

There were no differences (p=0.08) in diameter of muscle fiber between the groups. The muscle fiber density differed between patients with RT and IH (p=0.02): RT (mean=17.71%, SD=16.67), IH (mean=38.06%, SD=14) and cryptorchidism (mean=21.47%, SD=16.18). There was no difference (p=0.07) in the density of elastic fibers in the three groups. We observed a lower concentration of cremaster nerves of patients with RT compared with IH (p=0.0362): RT (mean=1.72%, SD=0.58), IH (mean=3.28% SD=0.94) and cryptorchidism (mean=2.52%, SD=0.53).

CONCLUSIONS

Retractile testis is not a normal variant, and presented a similar cremaster muscle structure as in patients with cryptorchidism.

LEVEL OF EVIDENCE

II; prospective comparative study.

An Experimental Model of Anterior Urethral Stricture in Rabbits With Local Injections of Bleomycin

OBJECTIVE

To develop an experimental model of anterior urethral stricture in rabbits using a bleomycin (BLM) injection technique.

MATERIALS AND METHODS

Thirty adult male New Zealand rabbits were randomly divided into 4 groups. In group 1 (BLM group), BLM was injected into the urethral submucosal tissue every other day through a catheter for 6 weeks at the 3-, 6-, 9-, and 12-o'clock positions of the urethra in 12 rabbits. In group 2 (phosphate-buffered saline [PBS] group), PBS was injected instead of BLM in 6 rabbits. In group 3 (stricture control group), an 8 × 20 mm urethral defect was created in 6 rabbits. In group 4 (normal group), 6 normal rabbits were included. All rabbits in the PBS group and stricture control group, as well as 6 rabbits in the BLM group, were sacrificed at 6 weeks. The remaining 6 rabbits in the BLM group were sacrificed at 10 weeks. Urethrography was performed in all rabbits before sacrifice, and the urethra was harvested for histologic analysis.

RESULTS

All rabbits in the BLM group showed mild urethral stricture at 4 weeks and significant urethral stricture at 6 weeks, without spontaneous resolution of the stricture at 10 weeks. No urethral stricture was observed in the PBS group at 4 and 6 weeks. Histologic examination confirmed the presence of fibrosis in the BLM group without spontaneous improvement.

CONCLUSION

BLM injection can induce an experimental model of anterior urethral stricture in rabbits. This simple, highly efficient, reproducible method can be carried out in any laboratory.

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?

Characteristics of Idiopathic Urethral Strictures: A Link to Remote Perineal Trauma?

OBJECTIVE

To characterize the physical features and reconstructive outcomes of a series of idiopathic urethral strictures (IUS) in an effort to elucidate the nature of this common yet poorly understood entity.

PATIENTS AND METHODS

We retrospectively reviewed our urethroplasty database to identify men undergoing initial urethral reconstruction from 2007 to 2014 at 1 of 3 hospitals (N = 514). Patients were stratified by stricture etiology, including IUS, acute trauma, iatrogenic, hypospadias, balanitis xerotica obliterans, and radiation. IUS that had a known history of subacute or repetitive blunt force to the perineum (horseback riding, avid cycling, motocross, etc.) were subclassified as subacute or repetitive perineal trauma (SRPT).

RESULTS

Among 466 men undergoing initial reconstruction with available data, 215 (46%) were IUS cases. The median delay between IUS diagnosis and urethroplasty was 5.2 years, during which time men underwent a median of 2 endoscopic treatments. A total of 51 (24%) IUS cases recalled a distinct history of SRPT. Men with SRPT were slightly younger (median 43 vs 48 years, P = .01) but were remarkably similar in terms of urethral stricture length (2 vs 2 cm, P = .15), location (bulbar 96% vs 89%, P = .41), and treatment success (92% vs 88%; P = .61). Bulbar (-)SRPT and (+)SRPT IUS had similar clinical and morphometric features as those with known acute bulbar trauma with excellent 24-month stricture recurrence-free survival rates (93% vs 92% vs 97%, P = .19).

CONCLUSION

IUS have clinical features suggesting that many may be related to unrecognized or repetitive perineal trauma. Although treatment tends to be delayed, IUS have excellent urethroplasty success because most are short bulbar strictures amenable to anastomotic urethroplasty.

Experimental investigation of the structural behavior of equine urethra

BACKGROUND AND OBJECTIVE

An integrated experimental and computational investigation was developed aiming to provide a methodology for characterizing the structural response of the urethral duct. The investigation provides information that are suitable for the actual comprehension of lower urinary tract mechanical functionality and the optimal design of prosthetic devices.

METHODS

Experimental activity entailed the execution of inflation tests performed on segments of horse penile urethras from both proximal and distal regions. Inflation tests were developed imposing different volumes. Each test was performed according to a two-step procedure. The tubular segment was inflated almost instantaneously during the first step, while volume was held constant for about 300s to allow the development of relaxation processes during the second step. Tests performed on the same specimen were interspersed by 600s of rest to allow the recovery of the specimen mechanical condition. Results from experimental activities were statistically analyzed and processed by means of a specific mechanical model. Such computational model was developed with the purpose of interpreting the general pressure-volume-time response of biologic tubular structures. The model includes parameters that interpret the elastic and viscous behavior of hollow structures, directly correlated with the results from the experimental activities.

RESULTS

Post-processing of experimental data provided information about the non-linear elastic and time-dependent behavior of the urethral duct. In detail, statistically representative pressure-volume and pressure relaxation curves were identified, and summarized by structural parameters. Considering elastic properties, initial stiffness ranged between 0.677 ± 0.026kPa and 0.262 ± 0.006kPa moving from proximal to distal region of penile urethra. Viscous parameters showed typical values of soft biological tissues, as τ₁=0.153±0.018s, τ₂=17.458 ± 1.644s and τ₁=0.201 ± 0.085, τ₂= 8.514 ± 1.379s for proximal and distal regions respectively.

DISCUSSION

A general procedure for the mechanical characterization of the urethral duct has been provided. The proposed methodology allows identifying mechanical parameters that properly express the mechanical behavior of the biological tube. The approach is especially suitable for evaluating the influence of degenerative phenomena on the lower urinary tract mechanical functionality. The information are mandatory for the optimal design of potential surgical procedures and devices.

Urethral lumen occlusion by artificial sphincteric devices: a computational biomechanics approach

The action induced by artificial sphincteric devices to provide urinary continence is related to the problem of evaluating the interaction between the occlusive cuff and the urethral duct. The intensity and distribution of the force induced within the region of application determine a different occlusion process and potential degradation of the urethral tissue, mostly at the borders of the cuff. This problem is generally considered in the light of clinical and surgical operational experience, while a valid cooperation is established with biomechanical competences by means of experimental and numerical investigation. A three-dimensional model of the urethra is proposed aiming at a representation of the phases of the urethral occlusion through artificial sphincters. Different conformations of the cuff are considered, mimicking different loading conditions in terms of force intensity and distribution and consequent deformation caused in soft tissues. The action induced in the healthy urethra is investigated, as basis for an evaluation of the efficacy and reliability of the sphincteric devices. The problem is characterized by coupled nonlinear geometric and material problem and entails a complex constitutive formulation. A heavy computational procedure is developed by means of analyses that operate within an explicit finite element formulation. Results reported outline the overall response of the urethral duct during lumen occlusion, leading to an accurate description of the phenomenon in the different phases.

The Nontransecting Approach to Bulbar Urethroplasty

The standard treatment of bulbar urethral strictures of appropriate length is excision and primary anastomosis (EPA), irrespective of the cause of the stricture. This involves transection of the corpus spongiosum (CS) and disruption of the blood flow within the CS as a consequence. The success rate of EPA in curing these strictures is very high, but there is a considerable body of evidence and of opinion to suggest that there is a significant risk of sexual dysfunction and, potentially, of other adverse consequences that occur because of transection of the CS.

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.

A Nationwide Assessment of the Emergency Department Management of Acute Urinary Retention Due to Urethral Stricture

OBJECTIVE

To evaluate the nationwide practice patterns of the management of acute urinary retention (AUR) secondary to urethral stricture (US) in an emergency department (ED) setting.

MATERIALS AND METHODS

We used the 2006-2010 Nationwide Emergency Department Sample to identify men with US who received treatment for AUR. We excluded patients with benign prostatic hyperplasia, vesicourethral anastomotic stenosis, neurogenic bladder, and bladder cancer. Primary outcome was urethral dilation or suprapubic tube (SPT) placement as initial AUR management. Patient demographics and hospital factors were also examined. Multivariate logistic regression was performed to examine factors associated with initial AUR management.

RESULTS

We identified 4794 weighted ED encounters of men with US who underwent urethral dilation or SPT placement for AUR. Mean age was 58.6 ± 0.8 years. A total of 4084 (85%) men received urethral dilation, whereas 710 had SPT (15%) placement. In bivariate analysis, patients who received SPT were likely to be younger (P <.001), treated in recent years (P = .002), and in hospitals in the West region (P = .003). In multivariate analysis, SPT placement was significantly associated with younger age (P = .004), public insurance (P = .03), recent treatment years (P = .02), and hospitals in the West region (P = .02). Income and hospital teaching status did not have significant association with initial treatment choice.

CONCLUSION

Urethral dilation remains the most common urologic intervention in the ED for AUR due to US; however, there is an increasing trend toward SPT placement. Patients who are younger, publicly insured, or who receive care in the West region are more likely to receive a SPT for initial treatment of AUR due to US.

Effect of adipose tissue-derived stem cell injection in a rat model of urethral fibrosis

INTRODUCTION

We sought to evaluate the therapeutic effect of adi-pose tissue-derived stem cells (ADSCs) in a rat model of urethral fibrosis.

METHODS

Eighteen (18) male Sprague-Dawley rats (300‒350 g) were divided into three groups: (1) sham (saline injection); (2) urethral fibrosis group (10 μg transforming growth factor beta 1 (TGF-β1) injection); and (3) ADSCs group (10 μg TGF-β1 injection plus 2 × 10⁵ ADSCs). Rat ADSCs were harvested from rat inguinal fat pads. All study animals were euthanized at two weeks after urethral injection. Following euthanasia, rat urethral tissue was harvested for histologic evaluation. Type I and III collagen levels were quantitated by Western blot analysis.

RESULTS

TGF-β1 injection induced significant urethral fibrosis and increased collagen type I and III expression (p<0.05). Significant decrease in submucosal fibrosis and collagen type I and III expression were noted in the ADSCs group compared with the urethral fibrosis group (p<0.05). TGF-β1 induced fibrotic changes were ameliorated by injection of ADSCs.

CONCLUSIONS

Local injection of ADSCs in a rat model of urethral fibrosis significantly decreased collagen type I and III. These findings suggest that ADSC injection may prevent scar formation and potentially serve as an adjunct treatment to increase the success rate of primary treatment for urethral stricture disease. Further animal and clinical studies are needed to confirm these results.

Adipose-derived Stem Cells Counteract Urethral Stricture Formation in Rats

BACKGROUND

A medical treatment for urethral stricture (US) is not yet available.

OBJECTIVE

To evaluate if local injection of human adipose tissue-derived stem cells (hADSC) prevents urethral fibrosis in a rat model of US.

DESIGN, SETTING, AND PARTICIPANTS

Male rats were divided into three groups: sham, US, and hADSC (n=12 each). Sham rats received a vehicle injection in the urethral wall. US and hADSCs were incised and injected with the fibrosis-inducer transforming growth factor-β1 in the urethral wall.

INTERVENTION

One day later, hADSCs were injected in the urethral wall of hADSC rats whereas sham and US rats were injected with the vehicle. After 4 wk, the rats underwent cystometries and tissues were then harvested for functional and molecular analyses.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cystometry, microultrasound, histochemistry, organ bath studies, reverse transcription polymerase chain reaction, and western blot.

RESULTS AND LIMITATIONS

US rats exhibited 49-51% shorter micturition intervals, 35-51% smaller micturition volumes and bladder capacity, 33-62% higher threshold pressures and flow pressures, and 35-37% lower bladder filling compliance compared with hADSC-treated rats and sham rats (p<0.05). By ultrasound, US rats had hyperechogenic and thick urethral walls with narrowed lumen compared with sham rats, whereas hADSC rats displayed less extensive urethral changes. Isolated detrusor from US rats exhibited 34-55% smaller contractions than detrusor from sham rats (p<0.05). Corresponding values were 11-35% for isolated detrusors from hADSC rats. Collagen and elastin protein expression were increased in the penile urethras of US rats compared with sham and hADSC groups (p<0.05). Endothelial and inducible nitric oxide synthase expressions were higher (p<0.05) in the hADSC group. Compared with US rats, hADSC rats demonstrated decreased expression of several fibrosis-related genes. Administration of hADSCs was performed at an early stage of US development, which we consider a limitation of the study.

CONCLUSIONS

Local injection of hADSCs prevents stricture formation and urodynamic complications in a new rat model for US.

PATIENT SUMMARY

Stem cell therapy is effective for preventing urethral stricture in an experimental setting.

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.

Current management of urethral stricture disease

Introduction:

Broadly defined, urethral strictures are narrowing of the urethral lumen that is surrounded by corpus spongiosum, i.e., urethral meatus through the bulbar urethra. Urethral stenosis is narrowing of the posterior urethra, i.e., membranous urethra through bladder neck/prostate junction, which is not enveloped by corpus spongiosum. The disease has significant quality of life ramifications because many times younger patients are affected by this compared to many other urological diseases.

Methods:

A review of the scientific literature concerning urethral stricture, stenosis, treatment, and outcomes was performed using Medline and PubMed (U.S. National Library of Medicine and the National Institutes of Health). Abstracts from scientific meetings were included in this review.

Results:

There is level 3 evidence regarding the etiology and epidemiology of urethral strictures, stenoses, and pelvic fracture urethral injuries. Outcomes data from literature regarding intervention for urethral stricture are largely limited to level 3 evidence and expert opinion. There is a single level 1 study comparing urethral dilation and direct vision internal urethrotomy. Urethroplasty outcomes data are limited to level 3 case series.

Conclusions:

Progress is being made toward consistent terminology, and nomenclature which will, in turn, help to standardize treatment within the field of urology. Treatment for urethral stricture and stenosis remains inconsistent between reconstructive and nonreconstructive urologists due to varying treatment algorithms and approaches to disease management. Tissue engineering appears to be future for reconstructive urethral surgery with reports demonstrating feasibility in the use of different tissue substitutes and grafts.

The effect of rapamycin on TGFβ1 and MMP1 expression in a rabbit model of urethral stricture

PURPOSE

To investigate the effect of rapamycin on TGFβ1 and MMP1 expression in a rabbit model of urethral stricture.

METHODS

Twenty-four adult New Zealand male rabbits underwent an electrocoagulation of the bulbar urethra with a 13Fr pediatric resectoscope. Then rabbits were randomly divided into three groups: (1) normal control group: normal saline (NS), (2) the vehicle control group: dimethyl sulfoxide (DMSO), and (3) the treatment group: effective-dose rapamycin in DMSO (Ra), with 12, 6, and 6 rabbits in each group, respectively. Drugs were given by urethral irrigation daily for 4 weeks. Urethral tissue was harvested for histological and molecular analyses. TGFβ1 and MMP1 expression levels were evaluated by real-time quantitative PCR and immunohistochemistry.

RESULTS

Ten, six, and six rabbits were evaluated finally in Ra, DMSO, and NS group, respectively. Histological examination revealed the distribution of fibrosis and the degree of collagen deposition in the Ra group were smaller and slighter than the two control groups. Collagen content was significantly less in the Ra group than in the DMSO group (P < 0.001) and the NS group (P < 0.001). qRT-PCR analysis showed a higher expression of MMP1 mRNA in the Ra group than in the DMSO group (P < 0.001) and the NS group (P < 0.001). Immunohistochemistry showed the protein levels of MMP1 in the Ra group were significantly increased when compared with the DMSO group (P < 0.01) and the NS group (P < 0.01). On the other hand, no statistical difference could be found between every two groups in both mRNA and protein levels of TGFβ1.

CONCLUSIONS

Rapamycin enhances the expression of MMP1 in a rabbit model of urethral stricture, but has no direct effect on the expression of TGFβ1.

Non-transecting bulbar urethroplasty

Excision and end-to-end anastomosis (EPA) has been the preferred urethroplasty technique for short bulbar strictures and is associated with an excellent functional outcome. Driven by concerns over the potential morbidity associated with dividing the urethra, therefore compromising spongiosal blood flow, as well as spongiofibrosis being superficial in the majority of non-traumatic bulbar strictures, the non-transecting technique for bulbar urethroplasty has been developed with the aim of achieving the same success as EPA without the morbidity associated with transection. This manuscript highlights the fundamental principles underlying the ongoing debate-transection or non-transection of the strictured bulbar urethra? The potential advantages of avoiding dividing the corpus spongiosum of the urethra are discussed. The non-transecting anastomotic procedure together with its various modifications are decribed in detail. Our experience with this technique is presented. Non-transecting excision of spongiofibrosis with preservation of well vascularised underlying spongiosum provides an excellent alternative to dividing the urethra during urethroplasty for short non-traumatic proximal bulbar strictures.

Structural study of endopelvic fascia in prostates of different weights. Anatomic study applied to radical prostatectomy

PURPOSE

To evaluate the structure of the endopelvic fascia in prostates of different weights.

METHODS

We studied 10 patients with BPH (prostates> 90 g); 10 patients with prostate adenocarcinoma (PAC) (prostates< 60 g) and five young male cadavers (control group). During the surgery a small sample of endopelvic fascia was obtained. We analyzed elastic fibers, collagen and smooth muscle. The stereological analysis was done with the Image Pro and Image J programs. Means were statistically compared using the one-way ANOVA with the Bonferroni test and a p<0.05 was considered statistically significant.

RESULTS

The mean of the prostate weight was 122 g in BPH patients, 53.1g in PAC patients and 18.6g in control group. Quantitative analysis documented that there are no differences (p=0.19) in Vv of elastic fibers and in Vv of type III collagen (p=0.88) between the three groups. There was a significant difference (p=0<0.0001) in the quantification of SMC in patients with prostates > 90 g (mean=9.61%) when compared to patients with prostates < 60 g (mean=17.92%) and with the control group (mean=33.35%).

CONCLUSION

There are differences in endopelvic fascia structure in prostates> 90 g, which can be an additional factor for pre-operatory evaluation of radical prostatectomy.