Department of Biomedical Engineering, Lund University, Box 118, 221 00, Lund, Sweden.
Department of Biomedical and Clinical Sciences, Linköping University, 581 83, Linköping, Sweden.
Sci Rep. 2021 Aug 27;11(1):17313. doi: 10.1038/s41598-021-96589-w.
Achilles tendons are mechanosensitive, and their complex hierarchical structure is in part the result of the mechanical stimulation conveyed by the muscles. To fully understand how their microstructure responds to mechanical loading a non-invasive approach for 3D high resolution imaging suitable for soft tissue is required. Here we propose a protocol that can capture the complex 3D organization of the Achilles tendon microstructure, using phase-contrast enhanced synchrotron micro-tomography (SR-PhC-μCT). We investigate the effects that sample preparation and imaging conditions have on the resulting image quality, by considering four types of sample preparations and two imaging setups (sub-micrometric and micrometric final pixel sizes). The image quality is assessed using four quantitative parameters. The results show that for studying tendon collagen fibers, conventional invasive sample preparations such as fixation and embedding are not necessary or advantageous. Instead, fresh frozen samples result in high-quality images that capture the complex 3D organization of tendon fibers in conditions as close as possible to natural. The comprehensive nature of this innovative study by SR-PhC-μCT breaks ground for future studies of soft complex biological tissue in 3D with high resolution in close to natural conditions, which could be further used for in situ characterization of how soft tissue responds to mechanical stimuli on a microscopic level.
跟腱是力学敏感的，其复杂的层次结构部分是肌肉传递的机械刺激的结果。为了充分了解其微观结构如何对机械加载做出响应，需要一种适用于软组织的非侵入性、用于 3D 高分辨率成像的方法。在这里，我们提出了一种使用基于同步辐射的相衬增强显微断层扫描（SR-PhC-μCT）来获取跟腱微观结构的复杂 3D 组织的方案。我们通过考虑四种类型的样品制备和两种成像设置（亚微米和微米最终像素尺寸），研究了样品制备和成像条件对图像质量的影响。使用四个定量参数评估图像质量。结果表明，对于研究跟腱胶原纤维，传统的侵入性样品制备（如固定和包埋）不是必需的或有利的。相反，新鲜冷冻的样品可获得高质量的图像，以尽可能接近自然的条件来捕获跟腱纤维的复杂 3D 组织。这项由基于同步辐射的相衬增强显微断层扫描所进行的创新性研究全面性为未来在尽可能接近自然的条件下对 3D 复杂生物组织进行高分辨率研究奠定了基础，这可以进一步用于在微观水平上原位表征软组织对机械刺激的响应方式。
