Purpose

The lack of long-term patency of synthetic vascular grafts currently available on the market has directed research towards improving the performance of small diameter grafts. Improved radial compliance matching and tissue ingrowth into the graft scaffold are amongst the main goals for an ideal vascular graft.

Methods

Biostable polyurethane scaffolds were manufactured by electrospinning and implanted in subcutaneous and circulatory positions in the rat for 7, 14 and 28 days. Scaffold morphology, tissue ingrowth, and mechanical properties of the scaffolds were assessed before implantation and after retrieval.

Results

Tissue ingrowth after 24 days was 96.5 ± 2.3% in the subcutaneous implants and 77.8 ± 5.4% in the circulatory implants. Over the 24 days implantation, the elastic modulus at 12% strain decreased by 59% in direction of the fibre alignment whereas it increased by 1379% transverse to the fibre alignment of the highly aligned scaffold of the subcutaneous implants. The lesser aligned scaffold of the circulatory graft implants exhibited an increase of the elastic modulus at 12% strain by 77% in circumferential direction.

Conclusion

Based on the observations, it is proposed that the mechanism underlying the softening of the highly aligned scaffold in the predominant fibre direction is associated with scaffold compaction and local displacement of fibres by the newly formed tissue. The stiffening of the scaffold, observed transverse to highly aligned fibres and for more a random fibre distribution, represents the actual mechanical contribution of the tissue that developed in the scaffold.

中文翻译：

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组织向内生长显着降低了高度对齐的静电纺聚氨酯支架在纤维方向上的机械各向异性和刚度。

目的

目前市场上缺乏合成血管移植物的长期开放性，这已将研究方向转向改善小直径移植物的性能。理想的血管移植物的主要目标之一是改善径向顺应性匹配和组织向内生长到移植物支架中。

方法

通过静电纺丝生产生物稳定的聚氨酯支架，并将其植入大鼠的皮下和循环位置7、14和28天。在植入前和取出后评估支架的形态，组织向内生长和力学性能。

结果

24天后，皮下植入物的组织向内生长为96.5±2.3％，而循环植入物的组织向内生长为77.8±5.4％。在植入的24天中，在12％应变下的弹性模量在纤维排列方向上下降了59％，而在高度对齐的皮下植入物支架的纤维排列方向上，弹性模量增加了1379％。循环移植物植入物的排列较少的支架在12％应变下的弹性模量沿周向增加了77％。

结论

基于这些观察，提出了高度对准的支架在主要纤维方向上软化的基础机理与支架压紧和新形成的组织对纤维的局部移位有关。横向于高度对准的纤维观察到的支架的硬化以及对于更多的随机纤维分布而言，代表了在支架中发展的组织的实际机械贡献。