Basic research for long-term evaluation of a growable vascular prosthesis and safetyness for clinical use.

在实验动物的长期植入过程中，评估了随着移植物的生长而生长的血管移植物的安全性。在本实验中，我们利用胶原性生物材料研制了一种特殊的可移植血管，其方法如下：以人大隐静脉为基质材料。它被浸泡在蒸馏水中，超声处理，导致细胞破坏；然后与聚环氧化合物进行交联，以获得受控的生物降解性、亲水性和抗血栓形成性能。首先进行短期评估。用内径为10 mm的聚酯网状管包裹4 mm直径的移植物，植入11只幼犬，6个月后移植物直径由原来的4 mm增长到6.5 mm。然后进行长期评估。用直径为10 mm的聚酯网状管包裹4 mm直径的移植物，植入15只幼犬。移植物直径由原来的4 mm长至1年后的9.5 mm，术后观察2年零7个月。聚酯网增强的新生内膜由复盖内皮细胞的平滑肌细胞组成。原静脉完全吸收，未见钙化、动脉瘤样扩张等退行性改变。对于可生长的血管移植物，提供了以下要求：1)小口径移植物的抗血栓形成能力；2)生长和终止生长的能力。大于接枝物的聚酯网管在预期直径处导致生长停滞，而生长速度受接枝交联度的控制。用这种方法，可以通过改变原移植物及其周围的聚酯网管的大小来制作任何尺寸的移植物。

The safetyness of a vascular graft that can grow with the growth of its reciepient was evaluated during long-term implantation in experimental animals. For this experiment, we developed a special grwoable vascular graft from collagenous biological materials along the following procedure : Human saphenous vein was used as the substrate material. It was dipped into distilled water and sonicated, resulting in cell destruction ; and followed by cross-linking with a polyepoxy compound to give both controlled biodegradability, hydrophilicity, and antithrombogenic properties.At first short-term evaluation was performed. Four millimeter inner diameter (ID) grafts, enveloped with polyester mesh tubes of 10 nun ID, were implanted in 11 puppies, The diameter of the grafts grew to 6.5 mm from original 4 mm after 6 month. Then the long-term evaluation was performed. The grafts 4 mm ID, enveloped with a polyester mesh tube of 10 mm ID were implanted in 15 puppies. The diameter of the graft grew to 9.5 mm after 1 year from the original 4 mm, and remained stabel for 2 years and 7 months of observation. The newly formed neointima reinforced with polyester mesh was composed of smooth muscle cells covered with endothelial cells. The original vein graft was completely absorbed, and there were no degenerative changes such as calcification or aneurysmal dilatation. The graft maintained the expected side for long period of time.For the growable vascular graft, the following requirements were provided : 1) antithrombogenicity in a small caliber graft ; 2) ability to grow as well as to terminate growth. The polyester mesh tube, which was larger than the graft, caused arrest of growth at the expected diameter, whereas the growth rate was controlled by the degree of graft cross-linking. With this method, any size graft can be made by changing tlie size of the original graft and the polyester mesh tube around it.