Department of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.
Biotechnol Bioeng. 2012 Jun;109(6):1583-94. doi: 10.1002/bit.24424. Epub 2012 Jan 17.
Mechanically stimulating cell-seeded scaffolds by flow-perfusion is one approach utilized for developing clinically applicable bone graft substitutes. A key challenge is determining the magnitude of stimuli to apply that enhances cell differentiation but minimizes cell detachment from the scaffold. In this study, we employed a combined computational modeling and experimental approach to examine how the scaffold mean pore size influences cell attachment morphology and subsequently impacts upon cell deformation and detachment when subjected to fluid-flow. Cell detachment from osteoblast-seeded collagen-GAG scaffolds was evaluated experimentally across a range of scaffold pore sizes subjected to different flow rates and exposure times in a perfusion bioreactor. Cell detachment was found to be proportional to flow rate and inversely proportional to pore size. Using this data, a theoretical model was derived that accurately predicted cell detachment as a function of mean shear stress, mean pore size, and time. Computational modeling of cell deformation in response to fluid flow showed the percentage of cells exceeding a critical threshold of deformation correlated with cell detachment experimentally and the majority of these cells were of a bridging morphology (cells stretched across pores). These findings will help researchers optimize the mean pore size of scaffolds and perfusion bioreactor operating conditions to manage cell detachment when mechanically simulating cells via flow perfusion.
通过流动灌注机械刺激细胞接种支架是开发临床应用骨移植物替代物的一种方法。一个关键的挑战是确定施加刺激的幅度，以增强细胞分化，但最大限度地减少细胞从支架上脱落。在这项研究中，我们采用了组合计算建模和实验方法来研究支架的平均孔径如何影响细胞附着形态，进而在受到流体流动时对细胞变形和脱落产生影响。在灌注生物反应器中，通过不同的流速和暴露时间，在一系列支架孔径下，从成骨细胞接种的胶原-GAG 支架上评估细胞脱落。发现细胞脱落与流速成正比，与孔径成反比。利用这些数据，推导出一个理论模型，该模型可以准确地预测细胞脱落与平均剪切应力、平均孔径和时间的关系。对细胞对流体流动响应的变形进行计算建模表明，超过变形临界阈值的细胞百分比与实验中细胞脱落相关，并且这些细胞大多数是桥接形态（细胞伸展穿过孔）。这些发现将有助于研究人员优化支架的平均孔径和灌注生物反应器的操作条件，以在通过流动灌注机械模拟细胞时管理细胞脱落。
