Biocompatibility properties of a new braided biodegradable urethral stent: a comparison with a biodegradable spiral and a braided metallic stent in the rabbit urethra

OBJECTIVE: To compare the biocompatibility properties of a new braided biodegradable self-reinforced poly-L-lactic acid (SR-PLLA) urethral stent to the former spiral biodegradable SR-PLLA stent and the stainless steel stent in a rabbit model. MATERIALS AND METHODS: In all, 54 male New Zealand White rabbits were anaesthetized and stents inserted into the prostatic urethra, three of each kind for each sample time. The rabbits were killed after 1, 3, 6, 9, 12 or 15 months and light microscopy and scanning electron microscopy used to analyse the effects. RESULTS: The disintegration of the braided SR-PLLA stent was more closely controlled than that of the spiral SR-PLLA stent. The metallic stent induced epithelial hyperplasia and polyposis earlier than the biodegradable stents, and in these rabbits the polyposis disappeared after the disintegration process. There were no differences in the histological analyses between the biodegradable stents, whereas the metallic stents caused the strongest inflammatory reactions. CONCLUSIONS: The braided SR-PLLA urethral stent functioned well in the rabbit urethra and clinical studies are already planned.     

Biodegradable braided poly(lactic-co-glycolic acid) urethral stent combined with dutasteride in the treatment of acute urinary retention due to benign prostatic enlargement: a pilot study

OBJECTIVE

To evaluate, in a pilot study, the efficacy and safety of combining a braided poly(lactic‐co‐glycolic acid) (PLGA, a copolymer of l ‐lactide and glycolide) urethral stent and dutasteride in the treatment of acute urinary retention (AUR) due to benign prostatic enlargement (BPE).

PATIENTS AND METHODS

Ten men with AUR due to BPE were treated as outpatients. A biodegradable braided PLGA urethral stent was inserted into the prostatic urethra, using a specially designed insertion device under visual control. Dutasteride treatment was started and the patients were followed up for 3 months after insertion of the stents.

RESULTS

In all patients the stents were placed successfully with the new insertion device. All men were able to void after inserting the stent. At 1 month five patients voided freely with a low residual urine volume (<150 mL), two voided but had a high residual urine volume and a suprapubic catheter was placed, and three needed a suprapubic or an indwelling catheter before 1 month, due to AUR or comorbidities. At 3 months five patients were voiding with no problems.

CONCLUSIONS

We have developed a new and effective insertion device for biodegradable braided prostatic stents. The new braided‐pattern stent overcomes the earlier problems of migration and sudden breakage into large particles associated with biodegradable spiral stents. However, the mechanical properties of the new stent need to be improved and tested in a longer follow‐up. We consider that this new biodegradable braided‐pattern urethral stent could provide a new option in the future treatment of AUR.     

Biocompatibility and implantation properties of 2 differently braided, biodegradable, self-reinforced polylactic acid urethral stents: an experimental study in the rabbit

PURPOSE: Biodegradable urethral stents have been in clinical use for more than 10 years. To solve the problems connected with the helical spiral configuration of the stents used to date we developed a new tubular mesh configuration and evaluated the biocompatibility properties and degradation time of 2 differently braided stents in the rabbit urethra. MATERIALS AND METHODS: The biodegradable, self-expanding stents were made of self-reinforced polylactic acid polymer blended with BaSO4 (Alfa Chem, Kings Point, New York). Two braiding patterns, namely a diamond 1/1 and a regular 2/2 + 1 (Prodesco, Perkasie, Pennsylvania), were used to produce a tubular mesh configuration. Stainless steel stents with 1/1 braiding served as controls. The stents were inserted into the posterior urethra of 36 male rabbits. The animals were sacrificed after 1 week, 1 month, 6 months or 12 months. Light microscopy and scanning electron microscopy analyses were done. RESULTS: Tissue reactions to operative trauma were seen in all specimens at week 1. The changes gradually abated in the biodegradable stent groups, whereas chronic inflammatory changes and fibrosis were increasingly seen with metallic stents after 6 months. Epithelial hyperplasia increased with time for all stent types and materials. As expected, stent fragmentation started at 6 months. CONCLUSIONS: Biodegradable polymers are suitable materials for braided urethral stents. However, the braided configuration of the stent with a decreased mass of material does not prevent the development of epithelial hyperplasia. The biodegradable, self-expanding, braided stents functioned well in the rabbit urethra and are suitable for clinical studies.     

Urethral in situ biocompatibility of new drug‐eluting biodegradable stents: an experimental study in the rabbit

OBJECTIVE

To assess the effect of drug‐eluting properties on the degradation process and the biocompatibility of biodegradable drug‐eluting urethral stents.

MATERIALS AND METHODS

Braided biodegradable 80 L/20D‐PLGA (copolymer of polylactide and polyglycolide) stents with drug‐eluting properties were used as the test material. The drugs analysed were indomethacin, dexamethasone and ciprofloxacine. 80 L/20D‐PLGA stents without a drug coating served as controls. In all, 16 male rabbits were used and divided into four groups. The stents were inserted under general anaesthesia into the posterior urethra. After 1 month, the rabbits were killed and the urethra removed for histological and optic microscopy analyses.

RESULTS

Control stents and the dexamethasone‐eluting stents degraded totally during the follow‐up period. Conversely, in both indomethacin‐ and ciprofloxacine‐eluting stent groups, the degradation process was significantly delayed and they induced an increase in epithelial hyperplasia. Histological analysis showed that all the stents induced eosinophilia, but there were no significant differences in the intensity of acute or chronic inflammatory reactions and fibrosis.

CONCLUSIONS

A drug‐eluting capacity can be added to biodegradable stents. The addition of a drug influences the biodegradation time of PLGA urethral stents. Further studies are needed, to find the proper concentrations and releasing profiles of the drugs to achieve the desired bioactivity and biocompatibility properties.     

Expansion and fixation properties of a new braided biodegradable urethral stent: an experimental study in the rabbit

PURPOSE: Biodegradable spiral urethral stents have been used with favorable results combined with thermal treatments of the prostate and for recurrent urethral strictures but the configuration of the helical spiral is not ideal. We developed a new tubular mesh configuration for the biodegradable urethral stent and evaluated its expansion and locking properties in the rabbit urethra. MATERIALS AND METHODS: The stents were made of self-reinforced polylactic acid polymer (Bionx Implants, Ltd., Tampere, Finland) blended with BaSO (Alfa Chem, New York, New York) to achieve radiopacity. Two braiding patterns, that is 1 over 1 and 2 over 2 + 1, were used to produce a tubular mesh structure. Stainless steel stents (pattern 1 over 1) served as controls. The stents were inserted into the posterior urethra of 27 male rabbits. The animals were sacrificed after 1 week, 1 and 6 months, respectively. X-rays were done immediately after stent insertion and at sacrifice. Longitudinal movement and expansion were assessed on the x-rays.(4) RESULTS: All stents maintained position in the urethra without fixation. Macroscopic disorientation of the structure of the 2 over 2 + 1 braided self-reinforced polylactic acid polymer stents began before 1 month, while 1 over 1 braided stents retained their construction. At 6 months 3 of 6 biodegradable stents were degraded. Average longitudinal movement was 2 mm. (range 1 to 3) in the 1 over 1 self-reinforced polylactic acid polymer group, 2 mm. (range 0 to 7) in the 2 over 2 + 1 polylactic acid group and 3 mm. (range 3 to 3) in controls at 1 month. CONCLUSIONS: Biodegradable polymers are suitable materials for braided urethral stents. The expansion properties of the 2 braiding models tested in this study sufficed to fix the stents in situ in the prostatic urethra. However, the 1 over 1 braiding pattern was superior to the 2 over 2 + 1 pattern, in that it retained its macroscopic construction until the degradation of single self-reinforced polylactic acid polymer fibers.     

尿道移行上皮细胞与生物可降解尿道支架体外复合培养的研究

目的:研究体外培养的兔尿道上皮细胞在生物可降解性网状尿道支架上的贴附和生长增殖情况,观察其对尿道上皮细胞形态和功能的影响,利用组织工程技术培养种植细胞的尿道内支架.方法:应用机械分离与酶消化法分离培养兔尿道移行上皮细胞,并在体外行原代培养与扩增后制成细胞悬液,接种在网状尿道支架上,形成尿道移行上皮细胞-支架复合物.应用免疫组织化学、荧光染色法鉴定尿道上皮细胞及其活性,并用倒置显微镜、扫描电镜观察尿道上皮细胞在支架表面吸附与生长状态.结果:网状尿道支架具有良好的生物相容性,能使尿道移行上皮细胞增殖,不影响其活性.尿道移行上皮细胞在尿道支架上贴附生长良好,1～2天后完全贴壁,3～7天细胞生长增殖活跃,支架网眼内充满上皮细胞;长期培养仍保持尿道移行上皮细胞特性,扫描电镜可见上皮细胞与网状支架紧密贴附,适度伸展并有基质分泌.结论:网状尿道支架适合尿道移行上皮细胞黏附生长,可作为尿道组织工程的细胞载体,利用组织工程方法可获得适于移植尿道细胞的组织工程化尿道.     

Tissue-engineered buccal mucosa using silk fibroin matrices for urethral reconstruction in a canine model

Background

To investigate the feasibility of urethral reconstruction using tissue-engineered buccal mucosa (TEBM) with silk fibroin (SF) matrices in a canine model.

Materials and methods

Autologous oral keratinocytes and autologous fibroblasts were isolated, expanded, and seeded onto SF matrices to obtain TEBM. The TEBM was assessed using hematoxylin and eosin staining and scanning electron microscopy. A 5-cm urethral mucosal defect was created in 10 female canines. Urethroplasty was performed using TEBM in five canines in the experimental group and with SF matrices without cells in the five canines in the comparison group. Retrograde urethrography was performed after 6 mo of grafting. The urethral grafts were analyzed grossly and histologically.

Results

The oral keratinocytes and fibroblasts exhibited good biocompatibility with the SF matrices. TEBM could be constructed using SF matrices. The canines implanted with the tissue-engineered mucosa voided without difficulty. The retrograde urethrography revealed no sign of stricture. The histologic staining showed that epithelial cells developed gradually and exhibited stratified epithelial layers at 6 mo. In the comparison group, the canines had difficulty voiding, and the retrograde urethrography showed urethra stricture. The histologic staining showed that one to two layers of epithelial cells developed.

Conclusions

The TEBM using SF matrices could be a potential material for urethra reconstruction.     

Long-term results of permanent urethral stent Memotherm implantation in the management of recurrent bulbar urethral stenosis

Study Type – Therapy (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? Milroy reported 84% success at a mean of 4.5 years follow‐up by usage of a permanently implantable “urolume” spent in 1993. Memotherm was developed later, especially for urologic use. Our study is one of the largest in this urea, with a high number of patients and a long follow‐up period.

OBJECTIVE

? To evaluate the effectiveness and long‐term results of permanent urethral stent (Memotherm) implantation in the treatment of recurrent bulbar urethral stricture.

PATIENTS AND METHODS

? In all, 47 patients with a history of previous unsuccessful treatment for bulbar urethral stricture were treated using Memotherm bulbar urethral stents between 1998 and 2002. ? Long‐term follow‐up data was analysed and discussed.

RESULTS

? At the end of the 7‐year period 37 of 47 patients (78.7%) had been treated successfully. ? Post‐micturition dribbling incontinence lasting up to 3 months after stent placement occurred in 32 (68.1%) patients, but this was reduced to only seven patients (14.9%) by the 7‐year follow‐up. ? There was stress incontinence of various severities in nine (19.2%) patients at the 1‐year follow‐up. These patients were those who had stenosed urethral segments adjacent to the external sphincter. At the long‐term follow‐up <10% of the patients had stress incontinence complaints.

CONCLUSION

? Memotherm is a good treatment option in patients with recurrent bulbar urethral stricture of any cause.     

生物可降解性尿道内支架修复战伤性尿道狭窄的研究

目的建立战伤性尿道狭窄动物模型,探讨生物可降解性尿道内支架对其进行重建修复的可行性。方法将新西兰雄兔28只分为两组,实验组(n=20):以定位爆炸法建立尿道狭窄模型。一月后行逆行尿道造影、尿道镜检查,并切除狭窄段尿道,行病理组织学观察证实。后置入人工合成生物可降解尿道内支架,置入术后2、4、8、12周分别行逆行尿道造影、尿道镜检查以及尿流动力学检测。并在以上各时间点处死5只动物,取狭窄处尿道组织,观察组织学修复重建情况。对照组(n=8):于实验组爆炸处理后4周和支架置入12周,分别取对照组4只动物与实验组对比观察。结果实验组所有动物爆炸后4周在尿道球部狭窄形成稳定狭窄模型(狭窄段长5～10 mm,尿道腔缩窄50%以上)。尿道内支架置入后2周,组织学观察见黏膜上皮新生迹象,并有炎性细胞浸润;4周时上皮新生明显,炎性细胞消失;8周时出现尿道平滑肌细胞再生,12周时见损伤后尿道组织结构完全修复,与正常尿道组织比较差异无统计学意义(P>0.05)。。同时间点尿道镜检查证实尿道腔隙、黏膜形态结构无异于正常对照组。尿流动力学检测显示两组间差异无统计学意义(P>0.05)。。结论应用成功建立的战伤性尿道狭窄动物模型,证实生物可降解性尿道内支架能作为修复战伤性尿道狭窄的理想材料,具有损伤小,易操作,功能恢复快的特点。     

The effect of the somatostatin analogue lanreotide on the prevention of urethral strictures in a rabbit model

We evaluated the effect of the somatostatin analogue lanreotide on the development of surgically induced experimental strictures in the anterior urethra of the male rabbit. A total of 74 male rabbits were randomly allocated into four groups. Lanreotide was administered to the rabbits in groups 2 and 4 from day 0 to 14. To create a stricture, a resection was made in the urethra of the rabbits in groups 3 and 4 on day 2. On day 30, all rabbits were examined with urethrography, impedance planimetry and either histology or for collagen content. Urethrography and impedance planimetry demonstrated a urethral stricture in all operated animals. No difference was found between the two stricture groups, regardless of lanreotide administration, with respect to luminal cross-sectional area (CSA), circumferential tension-strain relation, histology or collagen content. The CSA of the urethra of the normal controls treated with lanreotide was smaller than the CSA of the normal controls not treated with lanreotide, however, no difference was found in histology or collagen content. Lanreotide had no measurable effect on the development of a surgically induced stricture in the male rabbit anterior urethra, however, lanreotide seems to exert an inhibitory effect on the normal growth of the urethra.     

Transperineal bulbo-prostatic anastomosis for posterior urethral stricture associated with false passage: a single-centre experience

Study Type – Therapy (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? The emergency treatment of patients with PFUDD in developing countries is not currently codified and the majority of these patients have been treated using incorrect procedures that add iatrogenic damage to the trauma. Sometimes urethral dilatation gruffly and repeatedly wound lead to formation of urethral false passage which results in infection and incontinence. The treatment of urethral false passage is still a major challenge for urologists. False passage can lead to prolonged unhealed infections, increase the scar around the urethra, increasing stricture significantly. If preoperative examination was careless, it leads to identify false passage difficultly intra‐operative, the variation of direction when the curved sound was used as internal guidance, anastomosis between distal urethra and bladder wall near the orificium urethrae internum, leading to surgical failure. Cystourethrogram, flexible cystocopy pre‐operatively and dissect urethral bulb carefully are key points of urethroplasty for posterior urethral stricture with false passage. Then to pass a curved sound via the suprapubic tract into the posterior urethra to act as a guide for subsequent excision of all scar tissue.

OBJECTIVE

? To evaluate the management of traumatic posterior urethral stricture associated with false passage, as this remains a challenge for urologists.

PATIENTS AND METHODS

? From January 2000 to February 2010, 19 patients (mean (range) age 34 [25–52] years) with traumatic posterior urethral obliteration associated with false passage were evaluated and treated at our centre. ? All patients underwent perineal excision and primary anastomotic urethroplasty using cystoscopy by the suprapubic route to insert a guidewire into the original bladder neck, allowing exposure of the normal posterior urethra. ? Patients underwent voiding cysto‐urethrography 1 month after the procedure. When symptoms of decreased force of stream were present and uroflowmetry was <15 mL/s, urethrography and urethroscopy were repeated. ? Clinical outcome was considered a failure when any postoperative instrumentation was needed, including dilatation.

RESULTS

? The mean (range) follow‐up was 12 (9–14) months. The overall success rate was 84%. ? Three patients (16%) with persistent voiding difficulty developed a short anastomotic stricture 1–3 months after surgery. ? The mean maximum urinary flow rate after surgery was 20.01 mL/s and no patient had urinary incontinence.

CONCLUSION

? The preoperative use of flexible cystoscopy via the suprapubic route represented a successful key point of urethroplasty for posterior urethral stricture associated with false passage.     

The management of urethral stricture after kidney transplantation

Objective

To investigate the incidence and causes of urethral stricture after kidney transplantation, as well as analyze its diagnosis, treatment and prevention.

Methods

Clinical data of patients who developed urethral stricture after living-donor kidney transplantation in our center between January 2007 and June 2012 were retrospectively analyzed.

Results

Urethral stricture occurred in 8 of the 677 eligible kidney recipients (1.18 %) during the study period; the complication occurred at a mean of 4.4 months (range 2–7 months) after transplantation. Cystoscope-related iatrogenic injury and urinary tract infection seemed to be the most likely causes. In addition to frequency and dysuria, three patients had hydronephrosis and four had elevated serum creatinine levels. Urethrography showed that the urethral stricture was anterior in two patients and posterior in the remaining six. Two patients were treated by urethral dilation, four by internal urethrotomy and two by urethra reconstruction surgery. All patients urinated readily after treatment and four patients with impaired renal function recovered.

Conclusion

Urethral strictures after kidney transplantation are rare, and they can be safely and effectively treated by urethral dilation, internal urethrotomy or urethra reconstruction. Avoiding iatrogenic injury and shortening catheterization time may help reduce the risk of this complication.     

Urethral Reconstruction Using Bone Marrow Mesenchymal Stem Cell– and Smooth Muscle Cell–Seeded Bladder Acellular Matrix

Background

Congenital or acquired abnormalities may lead to a urethral defect that often requires surgical reconstruction. The traditional methods often lead to complications, including urethrocutaneous fistulae and strictures. In this study, we proposed to construct a tissue-engineered sheet graft (TESG) using a bone marrow mesenchymal stem cell (BMSC)– and smooth muscle cell (SMC)–seeded bladder acellular matrix (BAM) for urethral reconstruction.

Methods

Rabbit BMSCs and SMCs were isolated, expanded, and identified in vitro before seeding into BAM as the experimental group, whereas BAM-only was the control group. The graft was used to construct TESG for implantation into the rabbit omentum for 2 weeks before urethral reconstruction. We divided 24 male rabbits into four experimental groups six each, and six other were the control group. Histological analysis was performed at 2 weeks, 4 weeks, 8 weeks, and 16 weeks postoperatively. Retrograde urethrography was performed at 16 weeks postoperatively.

Results

All experimental rabbits survived to they were humanly killed. At 8 weeks, there was no difference between the graft and the normal urethra with no severe shrinkage. At 8 and 16 weeks after TESG grafting in vivo, multilayer urothelium covered the graft, neovascularization was visible within the center of TESG, and organized smooth muscle bundles were present. Retrograde urethrography failed to demonstrate diverticula formation or urethral stricture. Three control rabbits died within 4 weeks postoperatively. Autopsy showed their urethras to be almost completely blocked whereas another three hosts displays urethral strictures.

Conclusion

A TESG was constructed using a BMSC- and SMC-seeded BAM for urethral reconstruction.     

离体尿道流率对兔尿道狭窄程度的评价意义

目的探讨离体尿道流率对兔尿道狭窄严重程度的评价意义。方法15只成年雄性新西兰大白兔，内镜直视下尿道粘膜电凝法制作尿道狭窄模型。30d后，逆行尿道造影、尿道镜检观察尿道狭窄形态。设计制作简易装置测定离体尿道流率。分析离体尿道流率与球部狭窄段尿道直径的相关性。结果15只动物死亡2只，余动物顺利完成实验。狭窄处直径（4．08±0．84）mm，狭窄段长（7．73±1．07）mm，尿道管腔缩窄（78．45±7．59）％；离体尿道流率（11．45±4．83）mL／s。离体尿道流率与狭窄段尿道直径具有显著相关性（Spearman相关分析，r=0．680，p=0．011）。结论本实验自行设计装置进行兔离体尿道流率测定，可从流体力学角度准确反映尿道狭窄所致的排尿阻力增加情况，结合尿道造影和尿道镜检，可全面、准确评价模型尿道狭窄的严重程度。     

An experimental model of bulbar urethral stricture in rabbits using endoscopic radiofrequency coagulation

OBJECTIVES: To develop an experimental model of endoscopic urethral stricture mimicking the human clinical situation. METHODS: Twenty-four New Zealand male rabbits were included. Eighteen animals (study group) underwent videourethroscopy with a pediatric resectoscope, and a 3 to 5-mm-long circumferential electrocoagulation of the bulbar urethra was performed, without postoperative urinary diversion. Six animals underwent the same procedure without application of electrocautery (control group). Each animal was assessed for urethral stricture on day 15 and day 30 by videourethroscopy and voiding cystogram. Among the study group, 8 animals were killed on day 15 and 10 on day 30 for histologic evaluation. All the control animals were killed on day 30 for histologic examination. RESULTS: Nine animals (50%) in the study group developed a significant bulbar stricture (reducing the lumen by more than 50%) at day 15. Histologic examination confirmed the presence of hyalin fibrosis mutilating the urethral wall. No spontaneous improvement of the stricture was observed on day 30. None of the controls developed urethral stricture, and histologic examination showed a normal urethra in each case. CONCLUSIONS: Endoscopic electrocoagulation of the urethral wall provides a reproducible model of stricture in the rabbit.     

尿道细胞外基质在兔尿道重建中的应用

目的 评价尿道细胞外基质作为一种生物材料重建尿道的效果. 方法 切取新西兰兔的尿道制备尿道细胞外基质.手术切除实验组1～1.5 cm的尿道片段后用细胞外基质修复缺损,采用ELISA法检测术前、术后12、24及48 h血清TNFα的水平,评估术后兔的免疫反应状态.术后10d和3、6、24周取修复段尿道,行组织学观察并做尿道造影、尿道镜及尿流动力学检查. 结果 术后实验组血清TNFα水平较对照组略有升高,但无统计学意义(P>0.05).术后10 d,上皮细胞开始从边缘向细胞外基质移行并出现新生小血管;3周上皮细胞覆盖细胞外基质的整个管腔;6周出现排列不规则的平滑肌纤维;24周平滑肌数量明显增多,成束状排列.尿道造影、尿道镜及尿流动力学检测检查显示,尿道基质管壁光滑,排尿通畅. 结论 尿道细胞外基质是一种安全有效的尿道重建材料.     

应用异体脱细胞尿道基质修复尿道缺损

目的探讨应用同种脱细胞尿道基质修复尿道缺损的可行性。方法将14只雄性新西兰兔分为两组，切除实验组长约1.0～1．5cm的尿道，用相应长度脱细胞尿道基质修复；对照组行假手术。术后行尿道造影并取尿道标本作病理检查。结果12只实验兔的脱细胞基质移植物没有移位。除2例狭窄、2例尿瘘外，其余满意效果。病理检测示，术后3周尿道管腔上皮化，6个月基质中平滑肌及血管再生明显。结论同种脱细胞尿道基质材料可以修复兔尿道部分缺损。     

放疗对前尿道狭窄模型兔iNOs和MMP-2的影响

目的建立前尿道狭窄模型兔动物模型,研究局部放疗对尿道移行上皮下的结缔组织中与瘢痕修复密切相关的组织型一氧化氮合酶（iNOs）基质金属蛋白酶2（MMP-2）表达的影响。方法建立电刀灼热伤所致的前尿道狭窄兔动物模型,随机分为放疗2周组,放疗4周组和未放疗组。当灼热伤后,在尿道内镜下可见到灼伤处黏膜苍白,周围血管扩张时,放疗组应用铱192γ射线对灼伤处上下0.5cm进行内照射,1.25Gy/次,隔日一次,共5Gy/次。当放疗结束后两周,同时处死放疗组,未放疗组兔。将前尿道狭窄段及上下0.5cm进行取材;当放疗结束后4周,同时处死放疗组,未放疗组兔。将前尿道狭窄段及上下0.5cm进行取材。免疫组化法检测尿道移行上皮下的组织中组织型一氧化氮合酶（iNOs）和基质金属蛋白酶2（MMP-2）表达。结果 2周和4周的取材标本中,放疗组的iNOs和较未放疗组表达降低（P〈0.05）;而基质金属蛋白酶（MMP-2）较未放疗组表达增强（P〈0.05）。结论放疗增强了前尿道狭窄兔动物模型尿道组织中基质金属蛋白酶（MMP-2）的表达;降低了组织型一氧化氮合酶（iNOs）的表达,为临床联合运用冷刀尿道瘢痕切开术后于早期安全剂量的放疗以及细胞因子靶向治疗,预防尿道狭窄复发提供了实验依据。     

Metalloproteinase-1 usefulness in urethral stricture treatment

Background  

Urethral stricture disease is an obstruction or thinning of the urethra that causes restriction of urinary flow from the bladder during micturition. The object of the present study was to evaluate the effectiveness of the proteolytic enzyme metalloproteinase-1 as treatment in urethral stricture disease.     

Dorsal onlay lingual mucosal graft urethroplasty for urethral strictures in women

Study Type – Therapy (case series)
Level of Evidence 4

OBJECTIVE

To describe the technique and results of dorsal onlay lingual mucosal graft (LMG) urethroplasty for the definitive management of urethral strictures in women.

PATIENTS AND METHODS

In all, 15 women (mean age 42 years) with a history suggestive of urethral stricture who had undergone multiple urethral dilatations and/or urethrotomy were selected for dorsal onlay LMG urethroplasty after thorough evaluation, from October 2006 to March 2008. After a suprameatal inverted‐U incision, the dorsal aspect of the urethra was dissected and urethrotomy was done at the 12 o’clock position across the strictured segment. Tailored LMG harvested from the ventrolateral aspect of the tongue was then sutured to the urethrotomy wound over an 18 F silicone catheter.

RESULTS

The preoperative mean maximum urinary flow rate of 7.2 mL/s increased to 29.87 mL/s, 26.95 mL/s and 26.86 mL/s with a ‘normal’ flow rate curve at 3, 6 and 12 months follow‐up, respectively. One patient at the 3‐month follow‐up had submeatal stenosis and required urethral dilatation thrice at monthly intervals. At the 1‐year follow‐up, none of the present patients had any neurosensory complications, urinary incontinence, or long‐term functional/aesthetic complication at the donor site.

CONCLUSION

LMG urethroplasty using the dorsal onlay technique should be offered for correction of persistent female urethral stricture as it provides a simple, safe and effective approach with durable results.