Gorman S P, Tunney M M, Keane P F, Van Bladel K, Bley B
School of Pharmacy, Medical Biology Centre, The Queen's University of Belfast, UK.
J Biomed Mater Res. 1998 Mar 15;39(4):642-9. doi: 10.1002/(sici)1097-4636(19980315)39:4<642::aid-jbm20>3.0.co;2-7.
The effective long-term use of indwelling ureteral stents is often hindered by the formation of encrusting deposits which may cause obstruction and blockage of the stent. Development of improved ureteral stent biomaterials capable of preventing or reducing encrustation is therefore particularly desirable. In this study, the suitability as a ureteral stent biomaterial of Aquavene, a novel poly(ethylene oxide)/polyurethane composite hydrogel was compared with that of silicone and polyurethane, two materials widely employed in ureteral stent manufacture. Examination of Aquavene in dry and hydrated states by confocal laser scanning microscopy, scanning electron microscopy, and atomic force microscopy showed the presence of numerous channels within a cellular matrix structure. The channel size increased considerably to as much as 10 microm in diameter in the hydrated state. Aquavene provided superior resistance to encrustation and intraluminal blockage over a 24-week period in a simulated urine flow model. Unobstructed urine flow continued with Aquavene at 24 weeks, whereas silicone and polyurethane stents became blocked with encrustation at 8 and 10 weeks, respectively. Weight loss within Aquavene on the order of 9% (w/w) over the 24-week flow period indicates that extraction of the noncrosslinked poly(ethylene oxide) hydrogel may be responsible for the prevention of encrustation blockage of this biomaterial. In the dry state, Aquavene was significantly harder than either silicone or polyurethane, as shown by Young's modulus, and rapidly became soft on hydration. These additional properties of Aquavene would facilitate ease of stent insertion in the dry state past obstructions in the ureter and provide improved patient comfort on subsequent biomaterial hydration in situ. Aquavene is a promising candidate for use in the urinary tract, as it is probable that effective long-term urine drainage would be maintained in vivo. Further evaluation of this novel biomaterial is therefore warranted.
留置输尿管支架的长期有效使用常常受到结痂沉积物形成的阻碍，这些沉积物可能导致支架阻塞。因此，开发能够预防或减少结痂的改良输尿管支架生物材料尤为必要。在本研究中，将新型聚环氧乙烷/聚氨酯复合水凝胶Aquavene作为输尿管支架生物材料的适用性与硅酮和聚氨酯这两种输尿管支架制造中广泛使用的材料进行了比较。通过共聚焦激光扫描显微镜、扫描电子显微镜和原子力显微镜对干燥和水合状态的Aquavene进行检查，结果显示在细胞基质结构内存在大量通道。在水合状态下，通道尺寸显著增加，直径可达10微米。在模拟尿液流动模型中，Aquavene在24周内对结痂和管腔内阻塞具有优异的抗性。24周时，Aquavene的尿液流动仍未受阻，而硅酮和聚氨酯支架分别在8周和10周时被结痂阻塞。在24周的流动期内，Aquavene的重量损失约为9%（w/w），这表明非交联聚环氧乙烷水凝胶的析出可能是该生物材料预防结痂阻塞的原因。在干燥状态下，如杨氏模量所示，Aquavene比硅酮或聚氨酯都要硬得多，并且在水合后迅速变软。Aquavene的这些额外特性将便于在干燥状态下将支架轻松插入输尿管的梗阻部位，并在随后生物材料原位水合时提高患者的舒适度。Aquavene有望用于泌尿道，因为在体内可能维持有效的长期尿液引流。因此，有必要对这种新型生物材料进行进一步评估。
