The prostatic urethral lift (PUL) using UroLift® implants employs a mechanical method of widening the prostatic urethra and has been shown to provide safe and effective relief from LUTS in BPH patients. In the current study, we elucidate the long-term biological mechanism of action of the UroLift implant and expand on safety outcomes utilizing histological data from pre-clinical canine tissue and resected tissue from human subjects treated with the UroLift System, as well as post-market surveillance data.

The pre-clinical canine study for PUL included 24 dogs. Histopathology was conducted on canine prostatic tissue surrounding implants at 1, 3, 6 and 12 months after the PUL procedure. Histopathology data was available from 4 human PUL patients who underwent prostatic tissue resection for symptom return between 13-43 months post-PUL; cystoscopies of these patients were also available and reviewed at 6-27 months post-PUL. Worldwide post-market data were reviewed for cases of implant migration, encrustation, and breakage from April 2018 through September 2020.

Clinical cystoscopy of human PUL subjects provides evidence for an acute mechanical mechanism of action. The delivery device compresses the prostate lobe and delivers the implant to the prostatic capsule; compression is maintained as the stainless steel endpiece is deployed at the urethral surface while affixed to the tensioned suture. This acute mechanical process results in the immediate widening of the urethra and retraction of prostatic lobes. Canine histopathology confirms that tissue compression occurs immediately post-implantation, and provides evidence for benign lobular atrophy by 1 and 6 months (Figure 1) likely due to decreased blood flow locally. A similar process is evidenced by human histopathology data. Evidence of a stable and normal healing response were observed with minimal-mild chronic inflammation at the implant-tissue interface at 1-month post-implantation, and minimal chronic inflammation and minimal-mild fibrosis occurring at 6 and 12 months post-implantation. Lobular atrophy increased through 12 months post-implantation, accompanied by progression to scarring. Histopathology data suggests that the implant may become fully encapsulated within the prostatic tissue as early as 6 months. Post-market data from over 775,000 implants demonstrate no evidence of migration after a successful deployment, and reveal a 0.006% rate of stone formation from encrustation and a 0.004% breakage rate.

The acute mechanism of action of the UroLift System results in the immediate deobstruction of the prostate and widening of the urethra. The long-term mechanism of action involves a biological tissue remodeling response to the compression that occurs upon implantation, that includes lobular atrophy and scarring. Cellular changes that occur over 12 months in response to the implant are indicative of a typical healing response, and post-market data reveal further evidence that the implants are benign and safe.

The UroLift implants immediately incur localized compression that induces chronic tissue remodeling observed through 12 months. When placed properly, the implants safely affect these changes with minimal risk of migration, encrustation, or breakage, affirming the benign nature of this non-thermal approach.