Overview of Urethral Reconstruction by Tissue Engineering: Current Strategies, Clinical Status and Future Direction

BACKGROUND: Urinary tract is subjected to a variety of disorders such as urethral stricture, which often develops as a result of scarring process. Urethral stricture can be treated by urethral dilation and urethrotomy; but in cases of long urethral strictures, substitution urethroplasty with genital skin and buccal mucosa grafts is the only option. However a number of complications such as infection as a result of hair growth in neo-urethra, and stone formation restrict the application of those grafts. Therefore, tissue engineering techniques recently emerged as an alternative approach, aiming to overcome those restrictions. The aim of this review is to provide a comprehensive coverage on the strategies employed and the translational status of urethral tissue engineering over the past years and to propose a combinatory strategy for the future of urethral tissue engineering. METHODS: Data collection was based on the key articles published in English language in years between 2006 and 2018 using the searching terms of urethral stricture and tissue engineering on PubMed database. RESULTS: Differentiation of mesenchymal stem cells into urothelial and smooth muscle cells to be used for urologic application does not offer any advantage over autologous urothelial and smooth muscle cells. Among studied scaffolds, synthetic scaffolds with proper porosity and mechanical strength is the best option to be used for urethral tissue engineering. CONCLUSION: Hypoxia-preconditioned mesenchymal stem cells in combination with autologous cells seeded on a prevascularized synthetic and biodegradable scaffold can be said to be the best combinatory strategy in engineering of human urethra.

Ureteral stricture formation after ureteroscope treatment of impacted calculi: A prospective study

PURPOSE: Urinary calculi is a familiar disease. A well-known complication of endourological treatment for impacted ureteral stones is the formation of ureteral strictures, which has been reported to occur in 14.2% to 24% of cases. MATERIALS AND METHODS: This was a prospective study. Ureterotripsy treatment was used on patients with impacted ureteral stones. Then, after 3 months and 6 months, the condition of these patients was assessed by means of a kidney-ureter-bladder (KUB) ultrasound. If the KUB ultrasound indicated moderate to serious hydronephrosis, the patient was further assessed by means of a computed tomography intravenous urogram or retrograde pyelogram to confirm the occurrence of ureteral strictures. RESULTS: Of the 77 patients who participated in the study, 5 developed ureteral strictures. Thus, the stricture rate was 7.8%. An analysis of the intraoperative risk factors including perforation of the ureter, damage to the mucous membrane, and residual stone impacted within the ureter mucosa revealed that none of these factors contributed significantly to the formation of the ureteric strictures. The stone-related risk factors that were taken into consideration were stone size, stone impaction site, and duration of impaction. These stone factors also did not contribute significantly to the formation of the ureteral strictures. CONCLUSIONS: This prospective study failed to identify any predictable factors for ureteral stricture formation. It is proposed that all patients undergo a simple postoperative KUB ultrasound screening 3 months after undergoing endoscopic treatment for impacted ureteral stones.