Cox Martijn A J, Driessen Niels J B, Boerboom Ralf A, Bouten Carlijn V C, Baaijens Frank P T
Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven,The Netherlands.
J Biomech. 2008;41(2):422-9. doi: 10.1016/j.jbiomech.2007.08.006. Epub 2007 Sep 25.
Heart valve tissue engineering offers a promising alternative for current treatment and replacement strategies, e.g., synthetic or bioprosthetic heart valves. In vitro mechanical conditioning is an important tool for engineering strong, implantable heart valves. Detailed knowledge of the mechanical properties of the native tissue as well as the developing tissue construct is vital for a better understanding and control of the remodeling processes induced by mechanical conditioning. The nonlinear, anisotropic and inhomogeneous mechanical behavior of heart valve tissue necessitates a mechanical characterization method that is capable of dealing with these complexities. In a recent computational study we showed that one single indentation test, combining force and deformation gradient data, provides sufficient information for local characterization of nonlinear soft anisotropic tissue properties. In the current study this approach is validated in two steps. First, indentation tests with varying indenter sizes are performed on linear elastic PDMS rubbers and compared to tensile tests on the same specimen. For the second step, tissue constructs are engineered using uniaxial or equibiaxial static constrained culture conditions. Digital image correlation (DIC) is used to quantify the anisotropy in the tissue constructs. For both validation steps, material parameters are estimated by inverse fitting of a computational model to the experimental results.
心脏瓣膜组织工程为当前的治疗和置换策略提供了一种有前景的替代方案，例如合成心脏瓣膜或生物人工心脏瓣膜。体外机械调节是构建坚固、可植入心脏瓣膜的重要工具。深入了解天然组织以及正在发育的组织构建体的力学性能，对于更好地理解和控制机械调节所引发的重塑过程至关重要。心脏瓣膜组织的非线性、各向异性和非均匀力学行为需要一种能够处理这些复杂性的力学表征方法。在最近的一项计算研究中，我们表明，结合力和变形梯度数据的单次压痕试验为局部表征非线性软各向异性组织特性提供了足够的信息。在当前研究中，该方法分两步进行验证。首先，对线性弹性聚二甲基硅氧烷（PDMS）橡胶进行不同压头尺寸的压痕试验，并与同一试样的拉伸试验进行比较。第二步，使用单轴或等双轴静态约束培养条件构建组织构建体。利用数字图像相关技术（DIC）量化组织构建体中的各向异性。对于这两个验证步骤，通过将计算模型反向拟合实验结果来估计材料参数。
