Development of a biologically inspired in-vitro platform for long-term assessment of commercial and innovative ureteral stents

Ureteral stents are small flexible tubes which are clinically used to restore the urine drainage in presence of obstructions of the ureteral lumen such as tumours, kidney/ureteral stones. The lifetime risk of developing urinary stones is about 20% in men and 10% in women. Despite the wide clinical usage of ureteral stents, several side effects and complications are associated to their use; encrustation and biofilm formation can compromise the urine drainage through the stent even within few weeks after implantation and are widely recognised as the main cause of stent’s failure. Although fluid dynamics of urine in stented ureter is known to affect the initiation and the subsequent growth of encrusting deposits and biofilm, experimental and computational fluid dynamic investigations are still scarce. From previous experiments using a transparent ureter model (with a stent inside), we could identify typical local fluid dynamic patterns (i.e. presence of laminar vortices) which can trigger particle adhesion on the stent surface. We are currently expanding this model to include bladder and urethra, aiming at replicating the physiological properties of the whole urinary system in terms of relevant architecture, flow, volume, pressure and other typical features such as bladder contraction and corresponding filling-emptying cycle. This model will represent an in-vitro biologically inspired platform which will help: i) improve insights of encrustation and biofilm formation processes in available stents, ii) correlate these processes with the local fluid dynamics, and iii) test new stents and other relevant urological devices (e.g. device for incontinence and urinary retention).