Duncan Neil A, Bruehlmann Sabina B, Hunter Christopher J, Shao Xinxin, Kelly Elizabeth J
a McCaig Institute for Bone and Joint Health, University of Calgary , 2500 University Drive, NW, Calgary AB Canada T2N 1N4 .
Comput Methods Biomech Biomed Engin. 2014;17(1):39-47. doi: 10.1080/10255842.2012.742075. Epub 2012 Dec 13.
Designing biomaterials to mimic and function within the complex mechanobiological conditions of connective tissues requires a detailed understanding of the micromechanical environment of the cell. The objective of our study was to measure the in situ cell-matrix strains from applied tension in both tendon fascicles and cell-seeded type I collagen scaffolds using laser scanning confocal microscopy techniques. Tendon fascicles and collagen gels were fluorescently labelled to simultaneously visualise the extracellular matrix and cell nuclei under applied tensile strains of 5%. There were significant differences observed in the micromechanics at the cell-matrix scale suggesting that the type I collagen scaffold did not replicate the pattern of native tendon strains. In particular, although the overall in situ tensile strains in the matrix were quite similar (∼2.5%) between the tendon fascicles and the collagen scaffolds, there were significant differences at the cell-matrix boundary with visible shear across cell nuclei of >1 μm measured in native tendon which was not observed at all in the collagen scaffolds. Similarly, there was significant non-uniformity of intercellular strains with relative sliding observed between cell rows in tendon which again was not observed in the collagen scaffolds where the strain environment was much more uniform. If the native micromechanical environment is not replicated in biomaterial scaffolds, then the cells may receive incorrect or mixed mechanical signals which could affect their biosynthetic response to mechanical load in tissue engineering applications. This study highlights the importance of considering the microscale mechanics in the design of biomaterial scaffolds and the need to incorporate such features in computational models of connective tissues.
设计能够在结缔组织复杂的机械生物学条件下模拟并发挥功能的生物材料，需要深入了解细胞的微观力学环境。我们研究的目的是使用激光扫描共聚焦显微镜技术，测量在施加张力时肌腱束和接种细胞的I型胶原支架中的原位细胞-基质应变。对肌腱束和胶原凝胶进行荧光标记，以便在施加5%拉伸应变的情况下同时观察细胞外基质和细胞核。在细胞-基质尺度上观察到微观力学存在显著差异，这表明I型胶原支架无法复制天然肌腱应变的模式。特别是，尽管肌腱束和胶原支架中基质的整体原位拉伸应变相当相似（约2.5%），但在细胞-基质边界存在显著差异，在天然肌腱中测量到细胞核上可见的剪切力超过1μm，而在胶原支架中完全没有观察到。同样，肌腱中细胞间应变存在显著的不均匀性，细胞行之间观察到相对滑动，而在应变环境更为均匀的胶原支架中再次未观察到这种情况。如果生物材料支架不能复制天然的微观力学环境，那么细胞可能会接收到错误或混合的机械信号，这可能会影响它们在组织工程应用中对机械负荷的生物合成反应。这项研究强调了在生物材料支架设计中考虑微观尺度力学的重要性，以及在结缔组织计算模型中纳入这些特征的必要性。
