Effectiveness factor and diffusion limitations in collagen gel modules containing HepG2 cells
Effectiveness factor and diffusion limitations in collagen gel modules containing HepG2 cells
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DOI：
10.1002/term.296
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发表时间：
2011-02-01
影响因子：
3.3
通讯作者：
Sefton, Michael V.
中科院分区：
文献类型：
--
作者：
Corstorphine, Lindsay;Sefton, Michael V.
组织工程中的一个主要障碍是克服厚的三维（3D）工程组织中的缺氧，这是由氧气的扩散限制和缺乏内部脉管系统以促进质量传递引起的。模块化组织工程是一种仿生策略，通过组装小的（亚毫米）含细胞模块形成可扩展的、血管化的和均匀的3D构建体。先前假设由于其小尺寸，各个模块内的传质阻力可以忽略不计。在本研究中，这一假设进行了测试，使用理论分析的模块内的氧气传输（有效性因子）和实验研究。制备小（收缩后直径400 μ m）和大（收缩后直径700 μ m）HepG 2-胶原模块，接种密度范围为（2 × 10（6）-1 × 10（7）细胞/ml胶原）。模块内的细胞密度、分布和形态表明，小模块能够维持高细胞密度（8.0 x 10（7）+/- 4.4 x 10（7）个细胞/cm（3）），传质抑制可忽略不计。相反，大模块形成坏死核心，细胞密度显著降低（p < 0.05）（1.5 x 10（7）+/- 9.2 x 10（6）个细胞/cm（3））。还观察到，嵌入的细胞通过增殖或死亡对氧气可用性快速响应，以达到约8000个细胞/模块的可持续密度。此外，一个简单的有效性因子计算是成功的，在估计每个模块的最大细胞密度。本研究中收集的结果证实了先前的假设，即小直径模块避免了在较大结构中经常观察到的内部传质限制。版权所有（C）2010约翰威利父子有限公司
A major obstacle in tissue engineering is overcoming hypoxia in thick, three-dimensional (3D) engineered tissues, which is caused by the diffusional limitations of oxygen and lack of internal vasculature to facilitate mass transfer. Modular tissue engineering is a bio-mimetic strategy that forms scalable, vascularized and uniform 3D constructs by assembling small (sub-mm), cell-containing modules. It was previously assumed that mass transfer resistance within the individual modules was negligible, due to their small size. In the present study, this assumption was tested using theoretical analysis of oxygen transport within the module (effectiveness factor) and experimental studies. Small (400 mu m diameter post-contraction) and large (700 mu m diameter post-contraction) HepG2-collagen modules were made for a range of seeding densities (2 x 10(6)-1 x 10(7) cells/ml collagen). Cell density, distribution and morphology within the modules showed that the small modules were capable of sustaining high cell densities (8.0 x 10(7) +/- 4.4 x 10(7) cells/cm(3)) with negligible mass transfer inhibition. Conversely, large modules developed a necrotic core and had significantly (p < 0.05) reduced cell densities (1.5 x 10(7) +/- 9.2 x 10(6) cells/cm(3)). It was also observed that the embedded cells responded quickly to the oxygen availability, by proliferating or dying, to reach a sustainable density of approximately 8000 cells/module. Furthermore, a simple effectiveness factor calculation was successful in estimating the maximum cell density per module. The results gathered in this study confirm the previous assumption that the small-diameter modules avoid the internal mass transfer limitations that are often observed in larger constructs. Copyright (C) 2010 John Wiley & Sons, Ltd.