Department of Cardiac Surgery, Carl Gustav Carus Faculty of Medicine, Technische Universität Dresden, Heart Centre Dresden, Dresden, Germany.
Clinical Sensoring and Monitoring, Department of Anesthesiology and Intensive Care Medicine, Carl Gustav Carus Faculty of Medicine, Technische Universität Dresden, Dresden, Germany.
Clin Hemorheol Microcirc. 2021;79(1):179-192. doi: 10.3233/CH-219119.
Heart valves are exposed to a highly dynamic environment and underlie high tensile and shear forces during opening and closing. Therefore, analysis of mechanical performance of novel heart valve bioprostheses materials, like SULEEI-treated bovine pericardium, is essential and usually carried out by uniaxial tensile tests. Nevertheless, major drawbacks are the unidirectional strain, which does not reflect the in vivo condition and the deformation of the sample material. An alternative approach for measurement of biomechanical properties is offered by Brillouin confocal microscopy (BCM), a novel, non-invasive and three-dimensional method based on the interaction of light with acoustic waves.
BCM is a powerful tool to determine viscoelastic tissue properties and is, for the first time, applied to characterize novel biological graft materials, such as SULEEI-treated bovine pericardium. Therefore, the method has to be validated as a non-invasive alternative to conventional uniaxial tensile tests.
Vibratome sections of SULEEI-treated bovine pericardium (decellularized, riboflavin/UV-cross-linked and low-energy electron irradiated) as well as native and GA-fixed controls (n = 3) were analyzed by BCM. In addition, uniaxial tensile tests were performed on equivalent tissue samples and Young's modulus as well as length of toe region were analyzed from stress-strain diagrams. The structure of the extracellular matrix (ECM), especially collagen and elastin, was investigated by multiphoton microscopy (MPM).
SULEEI-treated pericardium exhibited a significantly higher Brillouin shift and hence higher tissue stiffness in comparison to native and GA-fixed controls (native: 5.6±0.2 GHz; GA: 5.5±0.1 GHz; SULEEI: 6.3±0.1 GHz; n = 3, p < 0.0001). Similarly, a significantly higher Young's modulus was detected in SULEEI-treated pericardia in comparison to native tissue (native: 30.0±10.4 MPa; GA: 31.8±10.7 MPa; SULEEI: 42.1±7.0 MPa; n = 3, p = 0.027). Native pericardia showed wavy and non-directional collagen fibers as well as thin, linear elastin fibers generating a loose matrix. The fibers of GA-fixed and SULEEI-treated pericardium were aligned in one direction, whereat the SULEEI-sample exhibited a much denser matrix.
BCM is an innovative and non-invasive method to analyze elastic properties of novel pericardial graft materials with special mechanical requirements, like heart valve bioprostheses.
心脏瓣膜暴露在高度动态的环境中，在瓣膜开启和关闭过程中承受高拉伸和剪切力。因此，分析新型心脏瓣膜生物假体材料的力学性能至关重要，通常采用单轴拉伸试验进行。然而，主要缺点是单向应变，这不能反映体内情况和样品材料的变形。一种替代测量生物力学特性的方法是布里渊共焦显微镜（BCM），这是一种基于光与声波相互作用的新型、非侵入性和三维方法。
BCM 是一种确定粘弹性组织特性的有力工具，并且首次应用于表征新型生物移植物材料，如 SULEEI 处理的牛心包。因此，该方法必须作为传统单轴拉伸试验的非侵入性替代方法进行验证。
采用 BCM 分析 SULEEI 处理的牛心包（脱细胞、核黄素/UV 交联和低能电子辐照）的振动切片以及天然和 GA 固定对照物（n=3）。此外，还在等效组织样本上进行了单轴拉伸试验，并从应力-应变图中分析了杨氏模量和趾区长度。通过多光子显微镜（MPM）研究细胞外基质（ECM）的结构，特别是胶原蛋白和弹性蛋白。
与天然和 GA 固定对照物相比，SULEEI 处理的心包膜表现出明显更高的布里渊位移，因此具有更高的组织刚度（天然：5.6±0.2 GHz；GA：5.5±0.1 GHz；SULEEI：6.3±0.1 GHz；n=3，p<0.0001）。同样，在 SULEEI 处理的心包膜中检测到的杨氏模量也明显高于天然组织（天然：30.0±10.4 MPa；GA：31.8±10.7 MPa；SULEEI：42.1±7.0 MPa；n=3，p=0.027）。天然心包表现出波浪状和非定向的胶原蛋白纤维以及薄而线性的弹性蛋白纤维，形成松散的基质。GA 固定和 SULEEI 处理的心包膜纤维沿一个方向排列，而 SULEEI 样品表现出更密集的基质。
BCM 是一种创新的非侵入性方法，可用于分析具有特殊机械要求的新型心包移植物材料的弹性特性，如心脏瓣膜生物假体。
