Ureteral stents are routinely used in daily urological practice for a variety of indications. Nevertheless, it is widely recognized that these medical devices can produce significant symptoms, like infection, encrustation, patient discomfort. Moreover, a cystoscopy procedure is usually required for stent removal. Eventually, the so-called “forgotten stent syndrome” can lead to kidney loss or even death. Because of these issues, much research over the past two decades has been focused on “biodegradable” materials as a way to minimize stent-related morbidity, and to avoid a second procedure for stent removal. Several biodegradable ureteral stents have been reported, but all of them have failed because of poor biocompatibility or incomplete degradation. The main challenge remains to have a uniform and homogenous degradation, preventing the formation of fragments that can cause obstruction. We recently described a biodegradable ureteral stent (BUS) produced with natural based polymers. In the present study, we assessed in vivo (in a porcine model) this newly developed BUS, by comparing its degradation, mechanical properties, drainage, physiological and histological features with those of a commercially available ureteral stent. To perform an in vivo assessment of a newly developed biodegradable ureteral stent (BUS) produced with natural based polymers.

A total of 10 female Yorkshire pigs were used in this study. In seven of them (study group) a BUS 6-Fr stent was inserted by cystoscopy, and a commercially available 6-Fr stent (Biosoft® duo, Porges, Coloplast) was inserted in the remaining three (control group). Intravenous pyelography (IVP), blood and urine tests were carried out. During the in vivo degradation, the mechanical characteristics of stents were tested in tensile mode and compared with the in vitro degradation performed in artificial urine solution (AUS). After degradation, pigs were euthanized, and histopathological analysis was performed.

All BUS stents had completely degraded by day 10, without the presence of any fragments in the ureter and bladder. From day 1 to day 10, hydronephrosis was significantly less with the BUS group compared to control group. BUS stents collected at day 5 and day 7showed to have mechanical properties similar to the commercial stents. Also, it was confirmed that BUS stents degraded by surface erosion. Histopathological analysis of the ureters showed that the stent-related tissue reaction of the two type of stents was different, and fewer histopathology changes were observed in BUS group.

A newly developed BUS shows to be biocompatible, featuring homogenous degradation, and capacity to provide urine drainage similar to non-degradable commercially available ureteral stents.