Wood M A, Yang Y, Baas E, Meredith D O, Richards R G, Kuiper J H, El Haj A J
Institute of Science and Technology in Medicine, Keele University, Thornburrow Drive, Hartshill, Staffordshire ST4 7QB, UK.
J R Soc Interface. 2008 Aug 6;5(25):899-907. doi: 10.1098/rsif.2007.1265.
A number of bone tissue engineering strategies use porous three-dimensional scaffolds in combination with bioreactor regimes. The ability to understand cell behaviour relative to strain profile will allow for the effects of mechanical conditioning in bone tissue engineering to be realized and optimized. We have designed a model system to investigate the effects of strain profile on bone cell behaviour. This simplified model has been designed with a view to providing insight into the types of strain distribution occurring across a single pore of a scaffold subjected to perfusion-compression conditioning. Local strains were calculated at the surface of the pore model using finite-element analysis. Scanning electron microscopy was used in secondary electron mode to identify cell morphology within the pore relative to local strains, while backscattered electron detection in combination with X-ray microanalysis was used to identify calcium deposition. Morphology was altered according to the level of strain experienced by bone cells, where cells subjected to compressive strains (up to 0.61%) appeared extremely rounded while those experiencing zero and tensile strain (up to 0.81%) were well spread. Osteoid mineralization was similarly shown to be dose dependent with respect to substrate strain within the pore model, with the highest level of calcium deposition identified in the intermediate zones of tension/compression.
许多骨组织工程策略都采用多孔三维支架并结合生物反应器模式。了解细胞行为与应变分布的关系，将有助于实现并优化骨组织工程中机械调节的效果。我们设计了一个模型系统来研究应变分布对骨细胞行为的影响。这个简化模型的设计目的是深入了解在灌注压缩条件下，支架单个孔隙中出现的应变分布类型。使用有限元分析计算孔隙模型表面的局部应变。在二次电子模式下使用扫描电子显微镜来识别孔隙内相对于局部应变的细胞形态，同时结合背散射电子检测和X射线微分析来识别钙沉积。细胞形态根据骨细胞所经历的应变水平而改变，承受压缩应变（高达0.61%）的细胞显得极其圆润，而经历零应变和拉伸应变（高达0.81%）的细胞则铺展良好。同样，类骨质矿化在孔隙模型中显示出与底物应变呈剂量依赖性，在拉伸/压缩的中间区域发现了最高水平的钙沉积。
