TISSUE ENGINEERING CARDIOVASCULAR STRUCTURES

各种血管移植是心血管组织重建的常用方法。然而，目前使用的假体或生物假体材料缺乏生长潜力，因此，在儿童患者中，随着它们的成熟，随后需要更换。组织工程（TE）是一门新的学科，它提供了从自体细胞和可生物降解的聚合物支架中创建替代结构的潜力。由于TE结构含有活细胞，它们可能具有生长、自我修复和自我重塑的潜力。将杂种犬股静脉中提取的4-6 × 10^6个混合细胞植入到由聚乙醇酸（PGA）无纺布片和l-丙交酯和-己内酯共聚物组成的管状可生物降解聚合物支架（N=4）上，制备组织工程血管自体移植物（TEVAs）。7天后。用teva代替下腔静脉（IVCs）。术后3、4、5、6个月行血管造影。而那些狗……更多的人牺牲了。对植入的teva进行粗观和免疫组织学检查。植入的teva没有出现狭窄或扩张的迹象。在未进行抗凝治疗的情况下，teva内未发现血栓。所有标本均未观察到聚合物支架的残余，总体大体外观与天然IVCs相似。免疫组织染色显示在teva管腔表面存在因子VIII阳性有核细胞。此外，在α-平滑肌肌动蛋白和desmin阳性细胞处观察病变。植入的TEVAs含有足量的细胞外基质，未出现闭塞或动脉瘤形成。此外，内皮细胞排列在每个TEVA的管腔表面。这些结果强烈提示可以产生具有抗血栓形成性的“理想”静脉移植物。使用TE技术。利用自体静脉细胞成功重建了一名4岁女孩的肺动脉外周动脉。用TE血管移植重建闭塞的肺动脉。无术后并发症发生。在后续的血管造影中，移植血管完全通畅。显然需要长期的随访来确认这种方法的可行性。然而。鉴于我们的成功，我们现在计划继续在低压血管（如静脉或肺循环）中使用自体细胞的TE技术。由于我们的实验室和临床经验都非常令人鼓舞，我们建议TE方法可能在儿科心血管外科领域作为移植和人工器官使用的替代方法发挥重要作用。少

Various vascular grafts are commonly used in the reconstruction of cardiovascular tissues. However, currently used prosthetic or bioprosthetic materials lack growth potential and, therefore, subsequently require replacement in pediatric patients as they mature. Tissue engineering (TE) is a new discipline that offers the potential to create replacement structures from autologous cells and biodegradable polymer scaffolds. Because TE constructs contain living cells, they may have the potential to grow, self-repair, and self-remodel. Tissue Engineered Vascular Autografts (TEVAs) were made by seeding 4-6 x 10^6 of mixed cells obtained from femoral veins of mongrel dogs onto tube-shaped biodegradable polymer scaffolds composed of a polyglycolic acid (PGA) non-woven fabric sheet and a co-polymer of l-lactide and- caprolactone (N=4). After 7 days. the inferior vena cavas (IVCs) of the same dogs were replaced with TEVAs. After 3, 4, 5 and 6 months, angiographies were performed. and the dogs wer … More e sacrificed. The implanted TEVAs were examined both grossly and immunohistologically. The implanted TEVAs showed no evidence of stenosis or dilatation. No thrombus was found inside the TEVAs, even without any anticoagulation therapy. Remnants of the polymer scaffolds were not observed in all specimens, and the overall gross appearance appeared similar to that of native IVCs. Immunohistological staining revealed the presence of Factor VIII positive nucleated cells at the luminal surface of the TEVAs. In addition, lesions were observed where α-smooth muscle actin and desmin positive cells existed. Implanted TEVAs contained a sufficient amount of extracellular matrix, and showed neither occlusion nor aneurysmal formation. In addition, endothelial cells were found to line the luminal surface of each TEVA.These results strongly suggest that 'ideal' venous grafts with anti-thrombogenicity can be produced. Using the TE technique. a peripheral pulmonary artery was successfully reconstructed in a 4-year-old girl using autologous venous cells. The occluded pulmonary artery was reconstructed with the TE vessel graft. No postoperative complications occurred. On follow-up angiography, the transplanted vessels was noted to be completely patent. Long-term follow up is obviously necessary to confirm the feasibility of this approach. However. given our success, we now plan to continue to use this TE technique with autologous cells in only low pressure vessels, such as the venous or pulmonary circulation. Because both our laboratory and clinical experiences are quite encouraging, we suggest that the TE approach may play an important role as an alternative method to transplantation and to the use of artificial organs in the field of pediatric cardiovascular surgery. Less