Teng ZHANG, Wei ZHAO, Tengzhou REN, Zhiwei CHEN, Xiaoju CHENG, Jie WU, Chaoyong YUAN, Tao HE, Yan WANG

The Effects and Mechanisms of the Rapamycin-eluting Stent in Urethral Stricture Prevention in Rabbits

Background: Rapamycin was shown to reduce transforming growth factor β1 (TGF-β1) expression, inhibit the Mammalian target of rapamycin function, and prevent TGF-β1-induced pulmonary fibrosis. Rapamycin-eluting stents (RES) were successfully used to prevent coronary artery restenosis. Urethral stricture is one of the most challenging problems in urology. Thus, combining the pharmacological effects of rapamycin and the mechanical support of the stent on the urethra may prevent urethral stricture formation. However, the use of RES for urethral stricture treatment has not been studied. Aims: To observe the effects of RES in urethral stricture in a rabbit model. Study Design: Animal experimentation. Methods: Twenty adult male New Zealand rabbits were randomly divided into control, urethral stricture model, bare-metal stent, and RES groups. The rabbits in the control group underwent urethroscopy alone without electrocoagulation. The rabbit model of urethral stricture was established by electrocoagulation using a self-made electrocoagulation device under direct vision using ureteroscopy. After model establishment, the rabbits in the bare-metal stent and RES groups received stent placement by ureteroscopy. On day 30, retrograde urethrography was performed to assess urethral stricture formation, ureteroscopy to remove the stents, and histological examinations to assess the degree of fibrosis. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used to evaluate the expression levels of TGF-β1, Smad3, and matrix metalloproteinase 1 (MMP1). Results: Urethral stricture formation was seen in the model group, whereas not in the bare-metal stent group. The bare-metal stents did not displace but were difficult to remove. In the RES group, RES was dislodged in itself at postoperative day 27 in one rabbit, whereas successfully removed by ureteroscopy in the remaining four rabbits, and urethral stricture formation was not seen on retrograde urethrography after stent removal. Histological examination revealed a large number of dense fibroblasts and blue-stained collagen fibers in the bare-metal stent group, whereas the number of fibroblasts and collagen fibers under the mucosa was reduced in the RES group. RT-qPCR and Western blot analyses showed that the messenger ribonucleic acid (mRNA) and protein expression of TGF-β1and Smad3 was significantly decreased, and mRNA and protein expression of MMP1 was significantly increased in the RES group than that in the model (P < 0.001) and bare-metal stent groups (P < 0.001). Conclusion: RES can effectively prevent electrocoagulation-induced urethral stricture in rabbits. The mechanism may be related to the effect of rapamycin on inhibiting TGF-β1 and Smad3 expression and promoting MMP1 expression in urethral tissues.

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1. King C, Rourke KF. Urethral Stricture is Frequently a Morbid Condition: Incidence and Factors Associated With Complications Related to Urethral Stricture. Urology. 2019;132:189-194. [CrossRef]
2. Gottipamula S, Sundarrajan S, Chokalingam K, Sridhar KN. The effect of human amniotic epithelial cells on urethral stricture fibroblasts. J Clin Transl Res. 2019;5:44- 49. [CrossRef]
3. Verla W, Oosterlinck W, Spinoit AF, Waterloos M. A Comprehensive Review Emphasizing Anatomy, Etiology, Diagnosis, and Treatment of Male Urethral Stricture Disease. Biomed Res Int. 2019;2019:9046430. [CrossRef]
4. Heyns CF, van der Merwe J, Basson J, van der Merwe A. Treatment of male urethral strictures - possible reasons for the use of repeated dilatation or internal urethrotomy rather than urethroplasty. S Afr J Surg. 2012;50:82-87. [CrossRef]
5. Prihadi JC, Sugandi S, Siregar NC, Soejono G, Harahap A. Imbalance in extracellular matrix degradation in urethral stricture. Res Rep Urol. 2018;10:227-232. [CrossRef]
6. Lodyga M, Hinz B. TGF-β1 - A truly transforming growth factor in fibrosis and immunity. Semin Cell Dev Biol. 2020;101:123-139. [CrossRef]
7. Fang X, Hu X, Zheng Z, et al. Smad interacting protein 1 influences transforming growth factor-β1/Smad signaling in extracellular matrix protein production and hypertrophic scar formation. J Mol Histol. 2019;50:503-514. [CrossRef]
8. Chuang HM, Chen YS, Harn HJ. The Versatile Role of Matrix Metalloproteinase for the Diverse Results of Fibrosis Treatment. Molecules. 2019;24:4188. [CrossRef]
9. Siregar S, Farenia R, Sugandi S, Roesli RM. Effect of angiotensin II receptor blocker on TGF-β1, MMP-1, and collagen type I and type III concentration in New Zealand rabbit urethral stricture model. Res Rep Urol. 2018;10:127-133. [CrossRef]
10. Zhu P, Zhou X, Zhang C, Li H, Zhang Z, Song Z. Safety and efficacy of ultrathin strut biodegradable polymer sirolimus-eluting stent versus durable polymer drug-eluting stents: a meta-analysis of randomized trials. BMC Cardiovasc Disord. 2018;18:170. [CrossRef]
11. Yanaba K. Strategy for treatment of fibrosis in systemic sclerosis: Present and future. J Dermatol. 2016;43:46-55. [CrossRef]
12. Meria P, Anidjar M, Brouland JP, et al. An experimental model of bulbar urethral stricture in rabbits using endoscopic radiofrequency coagulation. Urology. 1999;53:1054-1057. [CrossRef]
13. Zaid UB, Lavien G, Peterson AC. Management of the Recurrent Male Urethral Stricture. Curr Urol Rep. 2016;17:33. [CrossRef]
14. Horiguchi A, Shinchi M, Masunaga A, Ito K, Asano T, Azuma R. Do Transurethral Treatments Increase the Complexity of Urethral Strictures? J Urol. 2018;199:508- 514. [CrossRef]
15. Han JS, Liu J, Hofer MD, et al. Risk of urethral stricture recurrence increases over time after urethroplasty. Int J Urol. 2015;22:695-699. [CrossRef]
16. Arriola Apelo SI, Lamming DW. Rapamycin: An InhibiTOR of Aging Emerges from the Soil of Easter Island. J Gerontol A Biol Sci Med Sci. 2016;71:841-849. [CrossRef]
17. Liu CF, Liu H, Fang Y, Jiang SH, Zhu JM, Ding XQ. Rapamycin reduces renal hypoxia, interstitial inflammation and fibrosis in a rat model of unilateral ureteral obstruction. Clin Invest Med. 2014;37:E142. [CrossRef]
18. Saxton RA, Sabatini DM. mTOR Signaling in Growth, Metabolism, and Disease. Cell. 2017;168:960-976. [CrossRef]
19. Gao Y, Xu X, Ding K, Liang Y, Jiang D, Dai H. Rapamycin inhibits transforming growth factor β1-induced fibrogenesis in primary human lung fibroblasts. Yonsei Med J. 2013;54:437-444. [CrossRef]
20. Rozen-Zvi B, Hayashida T, Hubchak SC, Hanna C, Platanias LC, Schnaper HW. TGF-β/Smad3 activates mammalian target of rapamycin complex-1 to promote collagen production by increasing HIF-1α expression. Am J Physiol Renal Physiol. 2013;305:F485-E494. [CrossRef]
21. Das F, Bera A, Ghosh-Choudhury N, Abboud HE, Kasinath BS, Choudhury GG. TGFβ-induced deptor suppression recruits mTORC1 and not mTORC2 to enhance collagen I (α2) gene expression. PLoS One. 2014;9:e109608. [CrossRef]
22. Chong T, Fu DL, Li HC, et al. Rapamycin inhibits formation of urethral stricture in rabbits. J Pharmacol Exp Ther. 2011;338:47-52. [CrossRef]
23. Huang SL, Fu DL, Li HC, Zhang P, Chong T. The effect of rapamycin on TGFβ1 and MMP1 expression in a rabbit model of urethral stricture. Int Urol Nephrol. 2016;48:717-723. [CrossRef]
24. Fu D, Yin J, Huang S, Li H, Li Z, Chong T. Rapamycin Inhibits the Growth and Collagen Production of Fibroblasts Derived from Human Urethral Scar Tissue. Biomed Res Int. 2018;2018:7851327. [CrossRef]
25. De Vocht TF, van Venrooij GE, Boon TA. Self-expanding stent insertion for urethral strictures: a 10-year follow-up. BJU Int. 2003;91:627-630. [CrossRef]
26. Cui N, Hu M, Khalil RA. Biochemical and Biological Attributes of Matrix Metalloproteinases. Prog Mol Biol Transl Sci. 2017;147:1-73. [CrossRef]
27. Tamaki Z, Asano Y, Kubo M, et al. Effects of the immunosuppressant rapamycin on the expression of human α2(I) collagen and matrix metalloproteinase 1 genes in scleroderma dermal fibroblasts. J Dermatol Sci. 2014;74:251-259. [CrossRef]