Biocompatibility properties of a new braided biodegradable urethral stent:: a comparison with a biodegradable spiral and a braided metallic stent in the rabbit urethra

To compare the biocompatibility properties of a new braided biodegradable self-reinforced poly-L-lactic acid (SR-PLLA) urethral stent to the former spiral biodegradable SR-PLLA stent and the stainless steel stent in a rabbit model. In all, 54 male New Zealand White rabbits were anaesthetized and stents inserted into the prostatic urethra, three of each kind for each sample time. The rabbits were killed after 1, 3, 6, 9, 12 or 15 months and light microscopy and scanning electron microscopy used to analyse the effects. The disintegration of the braided SR-PLLA stent was more closely controlled than that of the spiral SR-PLLA stent. The metallic stent induced epithelial hyperplasia and polyposis earlier than the biodegradable stents, and in these rabbits the polyposis disappeared after the disintegration process. There were no differences in the histological analyses between the biodegradable stents, whereas the metallic stents caused the strongest inflammatory reactions. The braided SR-PLLA urethral stent functioned well in the rabbit urethra and clinical studies are already planned.