Lin Chih-Hsun, Kao Yun-Chu, Lin Yu-Heng, Ma Hsu, Tsay Ruey-Yug
Institute of Biomedical Engineering, National Yang-Ming University, No. 155, Sec. 2, Linong St., Beitou Dist., Taipei City 112, Taiwan, ROC; Division of Plastic Surgery, Department of Surgery, Taipei Veterans General Hospital, No. 201, Sec. 2, Shipai Rd., Beitou Dist., Taipei City 112, Taiwan, ROC; Department of Surgery, School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Linong St., Beitou Dist., Taipei City 112, Taiwan, ROC.
Institute of Biomedical Engineering, National Yang-Ming University, No. 155, Sec. 2, Linong St., Beitou Dist., Taipei City 112, Taiwan, ROC.
Acta Biomater. 2016 Dec;46:101-111. doi: 10.1016/j.actbio.2016.09.025. Epub 2016 Sep 22.
The theoretical fiber-progressive-engagement model was proposed to describe the pseudoelastic behavior of an artery pre- and post-decellularization treatments. Native porcine arteries were harvested and decellularized with 0.05% trypsin for 12 h. The uniaxial tensile test data were fitted to the fiber-progressive-engagement model proposed herein. The effects of decellularization on the morphology, structural characteristics, and composition of vessel walls were studied. The experimental stress-strain curve was fitted to the model in the longitudinal and circumferential direction, which demonstrated the adequacy of the proposed model (R>0.99). The initial and turning strains were similar in the longitudinal and circumferential directions in the aorta, suggesting the occurrence of collagen conjugation in both directions. Discrepancies in the initial and turning strain and initial and stiff modulus in both directions in the coronary artery revealed the anisotropic features of this vessel. Decellularization induced a decrease in the initial and turning strains, a slight change in the initial modulus, and a substantial decrease in the stiffness modulus. The decrease in the initial and turning strain can be attributed to the loss of waviness of collagen bundles because of the considerable decrease in elastin and glycosaminoglycan contents. This simple non-linear model can be used to determine the fiber modulus and waviness degree of vascular tissue. Based on these results, this mechanical test can be used as a screening tool for the selection of an optimized decellularization protocol for arterial tissues.
Decellularized vascular graft has potential in clinical application, such as coronary artery bypass surgery, peripheral artery bypass surgery or microsurgery. An ideal decellularization protocol requires balance in cell removal efficiency and extracellular matrix preserving. Both biochemical and biomechanical properties are crucial to the success of scaffold in cell seeding and animal study. A comprehensive understanding of the composition, microstructure, and mechanical behavior of the arterial wall is the key to the development of decellularized vascular grafts. For this purpose, we proposed this "Fiber-Progressive-Engagement" model to evaluate the microstructure, composition and mechanical properties of porcine coronary artery. The model provides a new perspective regarding the non-linear behavior of arterial tissue and its decellularized derivatives. It can be widely applied to different types of tissues, as demonstrated in the aorta and coronary artery. This model has several advantages; it provides an improved fit of non-linear curves (R>0.99), can be used to elucidate the pseudoelastic properties of porcine vascular tissues using the concept of fiber engagement, and can estimate an elastic modulus with greater accuracy (compared to the graphical estimation or calculation by simple linear fittings), as well as to plot typical stress-strain curves.
提出了理论纤维渐进式啮合模型来描述动脉在去细胞处理前后的伪弹性行为。采集天然猪动脉，并用0.05%胰蛋白酶去细胞处理12小时。将单轴拉伸试验数据拟合到本文提出的纤维渐进式啮合模型。研究了去细胞处理对血管壁形态、结构特征和组成的影响。将实验应力-应变曲线在纵向和周向方向上拟合到该模型，这证明了所提出模型的适用性（R>0.99）。主动脉在纵向和周向方向上的初始应变和转折应变相似，表明在两个方向上都发生了胶原蛋白结合。冠状动脉在两个方向上的初始应变和转折应变以及初始模量和刚性模量的差异揭示了该血管的各向异性特征。去细胞处理导致初始应变和转折应变降低，初始模量略有变化，刚性模量大幅降低。初始应变和转折应变的降低可归因于弹性蛋白和糖胺聚糖含量的显著降低导致胶原束波纹度的丧失。这个简单的非线性模型可用于确定血管组织的纤维模量和波纹度。基于这些结果，这种力学测试可作为一种筛选工具，用于选择优化的动脉组织去细胞处理方案。
去细胞血管移植物在临床应用中具有潜力，如冠状动脉搭桥手术、外周动脉搭桥手术或显微手术。理想的去细胞处理方案需要在细胞去除效率和细胞外基质保留之间取得平衡。生化和生物力学特性对于支架在细胞接种和动物研究中的成功都至关重要。全面了解动脉壁的组成、微观结构和力学行为是去细胞血管移植物开发的关键。为此，我们提出了这个“纤维渐进式啮合”模型来评估猪冠状动脉的微观结构、组成和力学性能。该模型为动脉组织及其去细胞衍生物的非线性行为提供了一个新的视角。它可以广泛应用于不同类型的组织，如在主动脉和冠状动脉中所示。该模型有几个优点；它能更好地拟合非线性曲线（R>0.99），可以用纤维啮合的概念来阐明猪血管组织的伪弹性特性，并且可以更准确地估计弹性模量（与图形估计或简单线性拟合计算相比），以及绘制典型的应力-应变曲线。
