Flow Dynamics in Bioreactors Containing Tissue Engineering Scaffolds
Flow Dynamics in Bioreactors Containing Tissue Engineering Scaffolds
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DOI：
10.1002/bit.22106
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发表时间：
2009-02-15
影响因子：
3.8
通讯作者：
Madihally, Sundararajan V.
中科院分区：
文献类型：
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作者：
Lawrence, Benjamin J.;Devarapalli, Mamatha;Madihally, Sundararajan V.
生物反应器作为一种在多孔材料中分配营养物质并提供多种组织所需的物理刺激的方法，在组织工程中得到了广泛的应用。然而，大孔隙结构内部的流体力学尚未得到很好的理解。在这项研究中，我们通过使用具有三种不同进出口模式的矩形和圆形反应器来探索反应器几何形状的影响。分别使用计算流体动力学软件Comsol Multiphysics 3.4和/或ANSYS CFX 11模拟有和没有多孔结构的几何形状。利用示踪剂在反应器内阶跃变化的停留时间分布分析揭示了反应器内非理想流体分布特征。采用Brinkman方程对壳聚糖多孔结构的渗透特性进行了建模。孔径为10 ~ 200 μ m，单位面积孔隙数为15 ~ 1500孔/mm(2)。在保持单位面积孔隙数不变的情况下，通过改变孔隙大小（85-10 μ m）来评估细胞生长和组织重塑对流量分布的影响。这些结果表明，随着孔隙尺寸的减小，压力显著增加，这可能会限制流体的流动和营养物质的运输。然而，实测压降略高于模拟结果。两个反应器的最大剪切应力相似，范围为0.2-0.3达因/厘米(2)。模拟实验使用内部构建的矩形和圆形生物反应器进行验证。实验用0.5%壳聚糖溶液在-80℃下冷冻干燥形成多孔结构，并监测反应器的压降。
Bioreactors are widely used in tissue engineering as a way to distribute nutrients within porous materials and provide physical stimulus required by many tissues. However, the fluid dynamics within the large porous structure are not well understood. In this study, we explored the effect of reactor geometry by using rectangular and circular reactors with three different inlet and outlet patterns. Geometries were simulated with and without the porous structure using the computational fluid dynamics software Comsol Multiphysics 3.4 and/or ANSYS CFX 11 respectively. Residence time distribution analysis using a step change of a tracer within the reactor revealed non-ideal fluid distribution characteristics within the reactors. The Brinkman equation Was used to model the permeability characteristics with in the chitosan porous structure. Pore size was varied from 10 to 200 mu m and the number of pores per unit area was varied from 15 to 1,500 pores/mm(2). Effect of cellular growth and tissue remodeling on flow distribution was also assessed by changing the pore size (85-10 mu m) while keeping the number of pores per unit area constant. These results showed significant increase in pressure with reduction in pore size, which could limit the fluid flow and nutrient transport. However, measured pressure drop was marginally higher than the simulation results. Maximum shear stress was similar in both reactors and ranged similar to 0.2-0.3 dynes/cm(2). The simulations were validated experimentally using both a rectangular and circular bioreactor, constructed in-house. Porous structures for the experiments were formed using 0.5% chitosan solution freeze-dried at -80 degrees C, and the pressure drop across the reactor was monitored.