Developing Repair Materials for Stress Urinary Incontinence to Withstand Dynamic Distension

BackgroundPolypropylene mesh used as a mid-urethral sling is associated with severe clinical complications in a significant minority of patients. Current in vitro mechanical testing shows that polypropylene responds inadequately to mechanical distension and is also poor at supporting cell proliferation.Aims and ObjectivesOur objective therefore is to produce materials with more appropriate mechanical properties for use as a sling material but which can also support cell integration.MethodsScaffolds of two polyurethanes (PU), poly-L-lactic acid (PLA) and co-polymers of the two were produced by electrospinning. Mechanical properties of materials were assessed and compared to polypropylene. The interaction of adipose derived stem cells (ADSC) with the scaffolds was also assessed. Uniaxial tensiometry of scaffolds was performed before and after seven days of cyclical distension. Cell penetration (using DAPI and a fluorescent red cell tracker dye), viability (AlamarBlue assay) and total collagen production (Sirius red assay) were measured for ADSC cultured on scaffolds.ResultsPolypropylene was stronger than polyurethanes and PLA. However, polypropylene mesh deformed plastically after 7 days of sustained cyclical distention, while polyurethanes maintained their elasticity. Scaffolds of PU containing PLA were weaker and stiffer than PU or polypropylene but were significantly better than PU scaffolds alone at supporting ADSC.ConclusionsTherefore, prolonged mechanical distension in vitro causes polypropylene to fail. Materials with more appropriate mechanical properties for use as sling materials can be produced using PU. Combining PLA with PU greatly improves interaction of cells with this material.

背景：用于尿道中段悬吊术的聚丙烯补片会在相当比例的患者中引发严重临床并发症。现有体外力学测试表明，聚丙烯对机械牵张的响应不足，且在支持细胞增殖方面表现不佳。
研究目的：本研究旨在制备兼具更适配力学性能（可作为悬吊术补片材料）且支持细胞整合的新型材料。
研究方法：采用静电纺丝法制备两种聚氨酯（PU）、聚左旋乳酸（PLA）以及二者共聚物的支架材料。对材料的力学性能进行评估，并与聚丙烯补片对比；同时评估脂肪来源干细胞（ADSC）与该支架的相互作用。分别在周期性牵张7天前后，对支架开展单轴张力测试。针对在支架上培养的ADSC，检测其细胞穿透能力（采用DAPI染色与红色荧光细胞追踪染料）、细胞活性（AlamarBlue检测法）以及总胶原生成量（天狼星红检测法）。
研究结果：聚丙烯的强度高于PU与PLA。但在持续7天的周期性牵张后，聚丙烯补片发生塑性变形，而PU仍可保持弹性。含PLA的PU支架强度低于纯PU或聚丙烯，但在支持ADSC方面，其表现显著优于纯PU支架。
研究结论：体外长期机械牵张会导致聚丙烯补片失效。采用PU可制备具备更适配力学性能的悬吊术补片材料；将PLA与PU复合，可显著改善细胞与该材料的相互作用。