Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, WH4.107, The Netherlands.
Tissue Eng Part A. 2010 May;16(5):1527-37. doi: 10.1089/ten.TEA.2009.0263.
Creating autologous tissues with on-demand and native-like biomechanical properties is the ultimate challenge in functional heart valve tissue engineering. A promising approach toward this goal is to induce development of native-like tissue structure in vitro by mimicking the diastolic loading phase in a bioreactor. Heart valves cultured with this approach showed in vitro sufficient strength to withstand systemic pressures. This study aims to link global functioning of these valves to the development of a native-like fiber architecture induced by in vitro diastolic loading. It is hypothesized that increased loading magnitude during culture will lead to increased collagen fiber alignment. To test this hypothesis, 10 tissue-engineered heart valves were subjected to different loading protocols in vitro. Local fiber distribution and mechanics were determined in an inverse numerical-experimental approach, combining indentation tests with confocal imaging. Indentation tests on native ovine heart valves were used as a comparison. Although the effect of loading magnitude was small within the tested range, results indicated that the local fiber architecture indeed developed toward native structural properties for all loading protocols. However, apparent fiber mechanics were much stiffer compared with native. This confirms that in vitro mechanical conditioning induces development of a native-like tissue architecture, which underlines its importance for functional heart valve tissue engineering.
用按需和类似原生的生物力学特性来创建自体组织是功能心脏瓣膜组织工程的终极挑战。一种有前途的方法是通过在生物反应器中模拟舒张加载阶段，在体外诱导类似原生的组织结构的发育。用这种方法培养的心脏瓣膜在体外显示出足够的强度来承受全身压力。本研究旨在将这些瓣膜的整体功能与体外舒张加载诱导的类似原生纤维结构的发展联系起来。假设在培养过程中增加加载幅度将导致胶原纤维排列的增加。为了验证这一假设，10 个组织工程心脏瓣膜在体外接受了不同的加载方案。通过将压痕试验与共聚焦成像相结合的反演数值实验方法，确定了局部纤维分布和力学性能。将对天然绵羊心脏瓣膜的压痕试验用作比较。尽管在测试范围内加载幅度的影响很小，但结果表明，对于所有加载方案，局部纤维结构确实朝着类似原生的结构特性发展。然而，明显的纤维力学性质与天然的相比要硬得多。这证实了体外力学处理可诱导类似原生的组织结构的发育，这凸显了其在功能心脏瓣膜组织工程中的重要性。
