Patient Compliant Biodegradable Urinary Stents

A urinary stent is a thin tube, which is inserted in the ureter to prevent or treat the obstruction of urine flow from the kidney. Silicone, latex, PVC and polyurethanes are the most widely used materials for the preparation of stents. Nonetheless, severe clinical complications may result from the use of these materials such as, fracture, encrustation and infection. In some of the cases, the ureteral stents are temporary and it is often required a second surgery to remove the stent.

In this work, the possibility to prepare hollow tubes from natural origin polysaccharides, was evaluated. Polymeric solutions were injected in templates of appropriate geometry and cross-linked at room temperature with CaCl₂ or KCl. Hollow tubes, with a diameter of 2 mm, were prepared and characterized in terms of surface morphology by SEM. Water uptake and polymer degradation studies were executed using an artificial urine immersion solution. The developed stents presented high water uptake ability but are able to maintain their shape and integrity. The degradation timeframe can be tuned to occur between 14 and 60 days. In vitro assessment of possible encrustation, i.e. the deposition of Mg and/or Ca salts, was also carried out using SEM-EDS and no encrustation was observed for the tested time periods (up to 28 days). The ability to avoid bacterial adhesion and the creation of a biofilm was evaluated with gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa and we obtained results comparable with commercially available stents. Cytotoxicity and cell adhesion studies were also executed to compare the developed materials with a commercial stent. The results obtained reveal that the proposed materials are major breakthroughs in the development of biodegradable urinary stents.