Center for Free-Electron Laser Science (CFEL), University of Hamburg, Hamburg, 22607, Germany.
Beiersdorf AG, Hamburg, 20245, Germany.
Sci Rep. 2021 Apr 7;11(1):7565. doi: 10.1038/s41598-021-86907-7.
Collagen fibers and their orientation play a major role in the mechanical behavior of soft biological tissue such as skin. Here, we present a proof-of-principle study correlating mechanical properties with collagen fiber network morphologies. A dedicated multiphoton stretching device allows for mechanical deformations in combination with a simultaneous analysis of its collagen fiber network by second harmonic generation imaging (SHG). The recently introduced Fiber Image Network Evaluation (FINE) algorithm is used to obtain detailed information about the morphology with regard to fiber families in collagen network images. To demonstrate the potential of our method, we investigate an isotropic and an anisotropic ex-vivo dorsal pig skin sample under quasi-static cyclic stretching and relaxation sequences. Families of collagen fibers are found to form a partially aligned collagen network under strain. We find that the relative force uptake is accomplished in two steps. Firstly, fibers align within their fiber families and, secondly, fiber families orient in the direction of force. The maximum alignment of the collagen fiber network is found to be determined by the largest strain. Isotropic and anisotropic samples reveal a different micro structural behavior under repeated deformation leading to a similar force uptake after two stretching cycles. Our method correlates mechanical properties with morphologies in collagen fiber networks.
胶原纤维及其取向在皮肤等软生物组织的力学行为中起着重要作用。在这里，我们提出了一项原理验证研究，将力学性能与胶原纤维网络形态相关联。专门的多光子拉伸装置允许进行机械变形，同时通过二次谐波产生成像 (SHG) 对其胶原纤维网络进行同步分析。最近引入的纤维图像网络评估 (FINE) 算法用于从胶原网络图像中获得有关纤维家族形态的详细信息。为了展示我们方法的潜力，我们在准静态循环拉伸和松弛序列下研究了各向同性和各向异性的离体猪背部皮肤样本。发现纤维家族在应变下形成部分排列的胶原网络。我们发现相对力的吸收分两步完成。首先，纤维在其纤维家族内对齐，其次，纤维家族沿力的方向取向。发现胶原纤维网络的最大对齐度由最大应变决定。各向同性和各向异性样本在重复变形下表现出不同的微观结构行为，导致在两个拉伸循环后具有相似的力吸收。我们的方法将力学性能与胶原纤维网络中的形态相关联。
