Objective: To evaluate the safety, feasibility, and tissue response of a novel device for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia, using the first-generation Urocross Expander System (Mercury Expander System). Methods: The implant was deployed and retrieved using flexible cystoscope in 8 adult male canines, separated into three study arms by retrieval date (1-, 6-, and 12- months post-deployment). Cystoscopy and urethrograms verified implant position/diameter; bladder neck and external sphincter function/changes; prostatic tissue response; and implant condition. One-month post-retrieval, the prostate and surrounding tissue was sectioned and evaluated by a veterinary pathologist. Results: All implants were successfully deployed in the prostatic urethra. Urethral width was increased (6.9 ± 1.8 mm to 10.2 ± 0.6 mm, P = .012) and preserved through the dwell period. Urethral length and sphincter diameters didn't significantly change. All subjects (n = 8) remained continent without obstruction or retention. Adverse events included incisional site bleeding (n = 2) and transient hematuria (n = 3). One implant migrated into the bladder and spontaneously repositioned into the prostatic urethra. Post-retrieval, explant surfaces demonstrated no tissue growth, encrustation or stone formation. Imaging revealed contact site erythema and indentation, but no stones, strictures, perforations, erosions, nor ulcerations. Histopathology revealed glandular acinar changes, inflammation, and fibrosis. Conclusion: The first generation of the Urocross Expander System demonstrated a favorable safety profile in the canine model. Changes in the prostatic urethra shape were noted with an increase in urethral width during the dwell period with minimal tissue changes. Further, the implant didn't demonstrate any encrustation, tissue growth or stone formation.
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