Hendrikson Wim J, Deegan Anthony J, Yang Ying, van Blitterswijk Clemens A, Verdonschot Nico, Moroni Lorenzo, Rouwkema Jeroen
Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente , Enschede , Netherlands.
Institute for Science and Technology in Medicine, School of Medicine, Keele University , Stoke on Trent , UK.
Front Bioeng Biotechnol. 2017 Feb 10;5:6. doi: 10.3389/fbioe.2017.00006. eCollection 2017.
Scaffolds for regenerative medicine applications should instruct cells with the appropriate signals, including biophysical stimuli such as stress and strain, to form the desired tissue. Apart from that, scaffolds, especially for load-bearing applications, should be capable of providing mechanical stability. Since both scaffold strength and stress-strain distributions throughout the scaffold depend on the scaffold's internal architecture, it is important to understand how changes in architecture influence these parameters. In this study, four scaffold designs with different architectures were produced using additive manufacturing. The designs varied in fiber orientation, while fiber diameter, spacing, and layer height remained constant. Based on micro-CT (μCT) scans, finite element models (FEMs) were derived for finite element analysis (FEA) and computational fluid dynamics (CFD). FEA of scaffold compression was validated using μCT scan data of compressed scaffolds. Results of the FEA and CFD showed a significant impact of scaffold architecture on fluid shear stress and mechanical strain distribution. The average fluid shear stress ranged from 3.6 mPa for a 0/90 architecture to 6.8 mPa for a 0/90 offset architecture, and the surface shear strain from 0.0096 for a 0/90 offset architecture to 0.0214 for a 0/90 architecture. This subsequently resulted in variations of the predicted cell differentiation stimulus values on the scaffold surface. Fluid shear stress was mainly influenced by pore shape and size, while mechanical strain distribution depended mainly on the presence or absence of supportive columns in the scaffold architecture. Together, these results corroborate that scaffold architecture can be exploited to design scaffolds with regions that guide specific tissue development under compression and perfusion. In conjunction with optimization of stimulation regimes during bioreactor cultures, scaffold architecture optimization can be used to improve scaffold design for tissue engineering purposes.
用于再生医学应用的支架应通过适当的信号指导细胞，包括诸如应力和应变等生物物理刺激，以形成所需的组织。除此之外，支架，特别是用于承重应用的支架，应能够提供机械稳定性。由于支架强度和整个支架的应力 - 应变分布都取决于支架的内部结构，因此了解结构变化如何影响这些参数非常重要。在本研究中，使用增材制造生产了四种具有不同结构的支架设计。这些设计在纤维取向上有所不同，而纤维直径、间距和层高保持不变。基于微计算机断层扫描（μCT）扫描，推导了有限元模型（FEM）用于有限元分析（FEA）和计算流体动力学（CFD）。使用压缩支架的μCT扫描数据对支架压缩的有限元分析进行了验证。有限元分析和计算流体动力学的结果表明支架结构对流体剪切应力和机械应变分布有显著影响。平均流体剪切应力范围从0/90结构的3.6 mPa到0/90偏移结构的6.8 mPa，表面剪切应变从0/90偏移结构的0.0096到0/90结构的0.0214。这随后导致了支架表面预测的细胞分化刺激值的变化。流体剪切应力主要受孔隙形状和大小的影响，而机械应变分布主要取决于支架结构中是否存在支撑柱。总之，这些结果证实可以利用支架结构来设计具有在压缩和灌注下引导特定组织发育区域的支架。结合生物反应器培养过程中刺激方案的优化，支架结构优化可用于改进用于组织工程目的的支架设计。
