Clark Jeffrey N, Tavana Saman, Heyraud Agathe, Tallia Francesca, Jones Julian R, Hansen Ulrich, Jeffers Jonathan R T
Department of Mechanical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Materials (Basel). 2020 Sep 3;13(17):3890. doi: 10.3390/ma13173890.
Regenerative medicine solutions require thoughtful design to elicit the intended biological response. This includes the biomechanical stimulus to generate an appropriate strain in the scaffold and surrounding tissue to drive cell lineage to the desired tissue. To provide appropriate strain on a local level, new generations of scaffolds often involve anisotropic spatially graded mechanical properties that cannot be characterised with traditional materials testing equipment. Volumetric examination is possible with three-dimensional (3D) imaging, in situ loading and digital volume correlation (DVC). Micro-CT and DVC were utilised in this study on two sizes of 3D-printed inorganic/organic hybrid scaffolds ( = 2 and = 4) with a repeating homogenous structure intended for cartilage regeneration. Deformation was observed with a spatial resolution of under 200 µm whilst maintaining displacement random errors of 0.97 µm, strain systematic errors of 0.17% and strain random errors of 0.031%. Digital image correlation (DIC) provided an analysis of the external surfaces whilst DVC enabled localised strain concentrations to be examined throughout the full 3D volume. Strain values derived using DVC correlated well against manually calculated ground-truth measurements (R = 0.98, = 8). The technique ensures the full 3D micro-mechanical environment experienced by cells is intimately considered, enabling future studies to further examine scaffold designs for regenerative medicine.
再生医学解决方案需要经过深思熟虑的设计，以引发预期的生物学反应。这包括生物力学刺激，以在支架和周围组织中产生适当的应变，从而将细胞谱系引导至所需组织。为了在局部水平上提供适当的应变，新一代支架通常具有各向异性的空间梯度力学性能，而传统材料测试设备无法对其进行表征。通过三维（3D）成像、原位加载和数字体积相关（DVC）可以进行体积检查。在本研究中，对两种尺寸（ = 2和 = 4）的3D打印无机/有机混合支架进行了微计算机断层扫描（Micro-CT）和DVC，这些支架具有用于软骨再生的重复均匀结构。观察到变形的空间分辨率低于200 µm，同时保持位移随机误差为0.97 µm、应变系统误差为0.17%和应变随机误差为0.031%。数字图像相关（DIC）提供了对外表面的分析，而DVC则能够在整个3D体积中检查局部应变浓度。使用DVC得出的应变值与手动计算的真实测量值相关性良好（R = 0.98， = 8）。该技术确保了对细胞所经历的完整3D微机械环境进行深入考虑，使未来的研究能够进一步研究再生医学的支架设计。
