Wu Jian-Ping, Swift Benjamin John, Becker Thomas, Squelch Andrew, Wang Allan, Zheng Yong-Chang, Zhao Xuelin, Xu Jiake, Xue Wei, Zheng Minghao, Lloyd David, Kirk Thomas Brett
3D Imaging and Bioengineering Laboratory, Department of Mechanical Engineering, Curtin University, Bentley, Perth, Australia.
The School of Pathology and Laboratory Medicine, the University of Western Australia, Western Australia, Australia.
J Microsc. 2017 Jun;266(3):273-287. doi: 10.1111/jmi.12537. Epub 2017 Mar 2.
Knowledge of the collagen structure of an Achilles tendon is critical to comprehend the physiology, biomechanics, homeostasis and remodelling of the tissue. Despite intensive studies, there are still uncertainties regarding the microstructure. The majority of studies have examined the longitudinally arranged collagen fibrils as they are primarily attributed to the principal tensile strength of the tendon. Few studies have considered the structural integrity of the entire three-dimensional (3D) collagen meshwork, and how the longitudinal collagen fibrils are integrated as a strong unit in a 3D domain to provide the tendons with the essential tensile properties. Using second harmonic generation imaging, a 3D imaging technique was developed and used to study the 3D collagen matrix in the midportion of Achilles tendons without tissue labelling and dehydration. Therefore, the 3D collagen structure is presented in a condition closely representative of the in vivo status. Atomic force microscopy studies have confirmed that second harmonic generation reveals the internal collagen matrix of tendons in 3D at a fibril level. Achilles tendons primarily contain longitudinal collagen fibrils that braid spatially into a dense rope-like collagen meshwork and are encapsulated or wound tightly by the oblique collagen fibrils emanating from the epitenon region. The arrangement of the collagen fibrils provides the longitudinal fibrils with essential structural integrity and endows the tendon with the unique mechanical function for withstanding tensile stresses. A novel 3D microscopic method has been developed to examine the 3D collagen microstructure of tendons without tissue dehydrating and labelling. The study also provides new knowledge about the collagen microstructure in an Achilles tendon, which enables understanding of the function of the tissue. The knowledge may be important for applying surgical and tissue engineering techniques to tendon reconstruction.
了解跟腱的胶原蛋白结构对于理解该组织的生理学、生物力学、内环境稳定和重塑至关重要。尽管进行了深入研究，但关于微观结构仍存在不确定性。大多数研究都考察了纵向排列的胶原纤维，因为它们主要赋予了肌腱主要的抗张强度。很少有研究考虑整个三维（3D）胶原网络的结构完整性，以及纵向胶原纤维如何在3D区域整合为一个强大的单元，从而赋予肌腱必要的拉伸特性。利用二次谐波产生成像技术，开发了一种3D成像技术，并用于研究跟腱中部的3D胶原基质，无需对组织进行标记和脱水处理。因此，所呈现的3D胶原结构与体内状态非常接近。原子力显微镜研究证实，二次谐波产生在原纤维水平上揭示了肌腱的内部胶原基质。跟腱主要包含纵向胶原纤维，这些纤维在空间上编织成致密的绳状胶原网络，并被来自腱外膜区域的斜向胶原纤维紧密包裹或缠绕。胶原纤维的排列为纵向纤维提供了必要的结构完整性，并赋予肌腱承受拉伸应力的独特机械功能。已经开发出一种新颖的3D显微镜方法来检查肌腱的3D胶原微观结构，而无需对组织进行脱水和标记。该研究还提供了有关跟腱中胶原微观结构的新知识，这有助于理解该组织的功能。这些知识对于将手术和组织工程技术应用于肌腱重建可能很重要。
