Anterior urethral stricture review

Genitourinary Tissue Engineering: Reconstruction and Research Models

Tissue engineering is an emerging field of research that initially aimed to produce 3D tissues to bypass the lack of adequate tissues for the repair or replacement of deficient organs. The basis of tissue engineering protocols is to create scaffolds, which can have a synthetic or natural origin, seeded or not with cells. At the same time, more and more studies have indicated the low clinic translation rate of research realised using standard cell culture conditions, i.e., cells on plastic surfaces or using animal models that are too different from humans. New models are needed to mimic the 3D organisation of tissue and the cells themselves and the interaction between cells and the extracellular matrix. In this regard, urology and gynaecology fields are of particular interest. The urethra and vagina can be sites suffering from many pathologies without currently adequate treatment options. Due to the specific organisation of the human urethral/bladder and vaginal epithelium, current research models remain poorly representative. In this review, the anatomy, the current pathologies, and the treatments will be described before focusing on producing tissues and research models using tissue engineering. An emphasis is made on the self-assembly approach, which allows tissue production without the need for biomaterials.

AT1 expression in human urethral stricture tissue

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Buccal mucosal graft urethroplasty for proximal bulbar urethral stricture: A revisit of the surgical technique and analysis of eleven consecutive cases

BACKGROUND

Urethral stricture disease is prevalent, and many surgical techniques have been developed to treat it. Currently, urethroplasty for bulbar strictures implies ventral or dorsal stricturotomy and a buccal mucosa graft (BMG) patch.

OBJECTIVE

To describe the surgical approach of the ventral patch BMG urethroplasty for proximal bulbar urethral stricture and to analyze 11 consecutive cases for whom the technique was used.

PATIENTS AND METHODS

The diagnosis of urethral stricture was confirmed with a combined retrograde urethrography and micturating cystourethrography. A single team exposed the urethra, harvested, and planted the BMG in the lithotomy position under general anesthesia. The oral preoperative preparation was done with oraldene (hexetidine) mouth wash three times daily beginning from the 2nd preoperative day. The buccal mucosa was harvested from the left inner cheek in all the patients. The donor site was left unclosed but packed with wet gauze. Data related to age, preoperative adverse conditions, stricture length, urine culture result, perineal/oral wound complications, postoperative residual urine volume, and duration of hospital stay were recorded.

RESULTS

Eleven patients with proximal bulbar urethral stricture had BMG urethroplasty from August 2013 to October 2015. Stricture length ranged from 2 to 5 cm. In six (54%) of the men, the stricture resulted from urethritis thereby constituting the most common etiology of urethral stricture in this study. The preoperative adverse conditions were age above 70 in three, diabetes mellitus in two, severe dental caries in one, and recurrent stricture in two. All of them were able to resume reasonable oral intake 72 h postoperatively. One (9.2%) had perineal wound infection, while two (18.2%) still had mild pain at donor site 4 weeks postoperatively. Ten (90.9%) of the 11 patients had <30 ml residual urine volume at 2 months of follow-up.

CONCLUSION

Urethritis is still a common cause of urethral stricture in this rural community. Ventral onlay buccal mucosal graft urethroplasty for proximal bulbar urethral stricture is safe, even in certain adverse preoperative conditions. Buccal mucosa from the cheek is however now preferred.