EXPRESS: Evaluation of the Degradation Profile of Biodegradable Polymers in a Dynamic In Vitro Model with Artificial Feline Urine

Objective: To evaluate the degradation profiles and mechanical properties of three absorbable polymers—poly(glycolide-co-trimethylene carbonate-co-epsilon-caprolactone) (PGTC), poly-p-dioxanone (PDO), and poly(glycolide-co-epsilon-caprolactone) (PGC)—envisioning the development of biodegradable ureteral stents in feline medicine. Methods: PGC, PGTC, and PDO samples were exposed to artificial feline urine circulated through a dynamic system replicating ureteral flow at 38 °C for eight weeks. Degradation was evaluated through weekly measurements of mass loss and qualitative changes. Tensile strength, strain, and stiffness were assessed at defined intervals (day 0, weeks 4, 6, and 7). Results: PGC degraded completely by week 6, showing rapid loss of tensile strength but consistent stiffness. PGTC exhibited gradual degradation and loss of manageability by week 8, with surface flaking visible microscopically. PDO did not fragment during manipulation or circulation, maintaining tensile strength over eight weeks, although stiffness fluctuations and brittleness were observed. Conclusion: The polymers showed distinct degradation and mechanical behaviors, providing options for different clinical scenarios. PGC, with rapid degradation, may suit short-term applications. PGTC, with gradual degradation and consistent mechanical properties, could serve intermediate applications. PDO, with slower degradation and prolonged tensile strength, appears suitable for longer-term use. These findings represent a step toward developing biodegradable ureteral stents for feline use, potentially simplifying postoperative management and avoiding stent removal. Relevance: Biodegradable ureteral stents may improve the management of feline ureteral obstructions by eliminating secondary removal procedures. In this in vitro dynamic model, the polymers degraded in a controlled and predictable manner, without accumulation of debris or flow obstruction in the in vitro system. Future studies should assess whether similar behavior occurs in smaller tubular structures similar to the feline ureter.