RADIAL PERFUSION, DIFFUSION, OXYGEN IN COAXIAL BIOREACTOR: HUMAN HEPATOCYTE LINE

同轴生物反应器中的径向灌注、扩散、氧气：人肝细胞线

• 批准号: 6282356
• 负责人: Jeffrey M. Macdonald
• 金额: $ 1.33万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-30 至 1999-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6282356
• 关键词: biomaterials; biomedical resource; biotechnology; magnetic resonance imaging; model design /development; technology /technique

We have developed a coaxial bioreactor that mimics the architecture of the liver asinus. It is composed of a polypropylene fiber (0.8 mm o.d.) centered inside an outer polypropylene fiber (1.8 mm i.d., 2.4 mm o.d) all contained inside a 5 mm NMR tube. Hepatocytes will be cultured in the space between the 2 fibers - the annular space. We want to mimic the physico-chemical gradients in the asinus and want to use MRM to measure radially across the annular space (1) perfusion and diffusion with and without hepatocytes, and (2) oxygen concentration using 19F MRM of perflourodecanoic acid. 1) The flow rates in the lumen of the inner tube (intracapillary space; ICS) and around the outer fiber (extracapillary space; ECS) will be varied with respect to each other, such that media will flow from the ECS through the annular space to the ICS. Then flow rates will be switch between ECS and ICS to visualize perfusion in the opposite direction. The difference in bulk flow between the ECS and ICS will be correlated with radial perfusion. Three images obtained using three ECS/ICS flow differentials will be obtained for each flow direction (i.e., ECS to ICS; ICS to ECS) - a total of 6 images. With hepatocytes in the annular space we believe coherent flow will be disrupted due to the resistance imposed by the tissue mass and diffusion will dominate. At a given ECS/ICS flow differential corresponding to a calibrated radial perfusion rate obtained from the experiment described above, we will measure the 'apparent' diffusion coefficient of water across the hepatocyte mass and/or measure radial perfusion at perhaps the fringe of the cell mass. 2) Oxygen concentration will be varied in the same manor that radial flow is varied by perfusing medium in the ECS and ICS that has been aerated with 40% and 20% oxygen plus air, respectively. T1-weighted 19F images will be obtained and will be calibrated to the intensity of the ECS where the oxygen concentration will be measured with an in-line electrode. The ECS intensity will need to be corrected for axial bulk flow effects. I will construct a 5 turn solenoid NMR probe that can be tuned to 1H and 19F. It will be wrapped around the outside of the 5mm NMR tube, so the FOV = 5 mm. The region of interest is only 0.5 mm (the annular space) and a voxel of 50 fm x 50 fm x 200 fm (will an anisotropic voxel effect relative quantitation?) will generate 10 voxels across the annular space. The absolute intensity of these 10 voxels will be plotted to generate 3 graphs: (1) ECS/ICS flow differential versus radial perfusion; (2) diffusion coefficient across the cell mass at one flow rate; (3) oxygen concentration across the cell mass at one flow rate. These data will be fit to determine function relationships.

我们已经开发了一种同轴生物反应器，它可以模拟 肝窦的结构。它是由一种聚丙烯 光纤(0.8 mm o.d.)位于外部丙纶纤维(1.8)内部 直径2.4 mm)都包含在5 mm的核磁共振管内。 肝细胞将在两根纤维之间的空隙中培养 环形空间。我们想要模拟物理-化学梯度 并希望使用MRM在环上径向测量 间隔(1)有或无肝细胞的灌流和扩散，以及 (2)用全氟癸酸的~(19)F磁共振波谱测定氧浓度。1) 内管腔的流速(毛细血管内间隙； ICS)和周围的外层纤维(毛细血管外间隙；ECS)将 彼此不同，因此媒体将从 ECS通过环形空间到达ICS。那么流速将会是 在ECS和ICS之间切换以显示相反的血流灌注 方向。ECS和ICS之间的散装流量差异将 与放射状血流灌注相关。使用以下工具获取的三幅图像 将为每个流获取三个ECS/ICS流差异 方向(即，ECS到ICS；ICS到ECS)-总共6幅图像。使用 环状空间的肝细胞我们相信相干流动将是 由于组织块施加的阻力而被破坏 扩散将占主导地位。在给定的ECS/ICS流量差下 对应于从 上面描述的实验，我们将测量‘表观’扩散 穿过肝细胞团和/或测量径向的水系数 可能是细胞团边缘的灌注区。2)氧气 浓度将在径向流动的同一庄园中变化 根据ECS和ICS中已充气的灌流介质而变化 氧气加空气的比例分别为40%和20%。T1加权19F 将获得图像，并将其校准为 氧浓度将通过在线测量的ECS 电极。ECS强度将需要针对轴向体积进行校正 流动效果。我将建造一个5圈螺线管核磁共振探头 调到1H和19F。它将被包裹在 5 mm核磁共振管，因此视野=5 mm。感兴趣的区域仅为0.5 Mm(环形空间)和50 fm x 50 fm x 200 fm的体素(将 各向异性体素效应相对定量？)将生成10 环形空间中的体素。这10个词的绝对强度 将绘制体素以生成3个图形：(1)ECS/ICS流 (2)弥散系数 一个流速下的细胞质量；(3)细胞内的氧气浓度 同一流速下的细胞团。这些数据将适合于确定 函数关系。