Pulmonary valve replacement is performed with excellent resultant hemodynamics in patients that have underlying congenital or acquired heart valve defects. Despite recent advancements in right ventricular outflow tract reconstruction, an increased risk of developing infective endocarditis remains, which has a more common occurrence for conduits of bovine jugular vein (BJV) origin compared with cryopreserved homografts. The reason for this is unclear although it is hypothesized to be associated with an aberrant phenotypic state of cells that reendothelialize the graft tissue postimplantation. The aim of this study was to develop an in vitro model that enables the analysis of endothelial cell (EC) attachment to cardiac graft tissues under flow. In the experiments, EC attachment was optimized on bovine pericardium (BP) patch using human umbilical vein ECs. Different biological coatings, namely gelatin, fibronectin, plasma, or a combination of fibronectin and plasma were tested. After cell adaptation, graft tissues were exposed to laminar flow in a parallel-plate flow chamber. Cell retention to the tissue was analyzed after nuclear staining with YO-PRO-1 and a membranous localization of VE-cadherin. Experiments showed that combined coating with fibronectin and blood plasma together with a two-phased shear pattern resulted in a relevant cell monolayer on BP patch and cryopreserved homograft. For BJV tissue, no adherent cells under both static and shear conditions were initially observed. In conclusion, having established the new flow chamber system we could obtain EC layers on the surface of BP patch and cryopreserved pulmonary homograft tissues. The presented in vitro system can serve as a competent model to study cell phenotypes on cardiac grafts in the close-to-physiologic environment. Moreover, this approach allows broad applications and enables further development by testing more complex conditions.

中文翻译：

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研究流动下心脏移植组织内皮化的体外模型

在具有潜在先天性或后天性心脏瓣膜缺陷的患者中，肺瓣膜置换术具有优异的血流动力学效果。尽管最近在右心室流出道重建方面取得了进展，但感染性心内膜炎的风险仍然增加，与冷冻保存的同种移植物相比，牛颈静脉 (BJV) 起源的导管更常见。其原因尚不清楚，尽管假设它与植入后移植组织再内皮化的细胞的异常表型状态有关。本研究的目的是开发一种体外模型，能够分析内皮细胞 (EC) 与流动下的心脏移植组织的附着。在实验中，使用人脐静脉 EC 在牛心包 (BP) 贴片上优化 EC 附着。测试了不同的生物涂层，即明胶、纤连蛋白、血浆或纤连蛋白和血浆的组合。细胞适应后，移植组织在平行板流动室中暴露于层流。在用 YO-PRO-1 核染色和 VE-钙粘蛋白的膜定位后分析细胞对组织的保留。实验表明，纤连蛋白和血浆的组合涂层以及两相剪切模式在 BP 贴片和冷冻保存的同种移植物上产生相关的细胞单层。对于 BJV 组织，最初在静态和剪切条件下均未观察到贴壁细胞。总之，建立新的流动室系统后，我们可以在 BP 贴片和冷冻保存的肺同种移植组织表面获得 EC 层。提出的体外系统可以作为一个有能力的模型来研究接近生理环境中心脏移植物的细胞表型。此外，这种方法允许广泛的应用，并通过测试更复杂的条件实现进一步的开发。