MacDonald J M, Wolfe S P, Roy-Chowdhury I, Kubota H, Reid L M
Department of Biomedical Engineering, University of North Carolina School of Medicine, Chapel Hill 27599-7038, USA.
Ann N Y Acad Sci. 2001 Nov;944:334-43. doi: 10.1111/j.1749-6632.2001.tb03845.x.
A novel "multicoaxial hollow fiber bioreactor" has been developed consisting of four concentric tubes, the two innermost tubes are called hollow fibers. Bioartificial livers are created by culturing liver progenitors in the space between the two innermost hollow fibers and with culture media contained in the two compartments (intracapillary and extracapillary) sandwiching the cell compartment. The outermost compartment is used for gas exchange. A hydrodynamic model has recently been established to predict the optimum hydraulic permeability and bioreactor operational parameters to create the physicochemical environment found in the liver acinus. However, perfusion with serum-free hormonally-defined media and inoculation of cells introduces membrane fouling into the equation, and this parameter must be incorporated into the model. Using commercially available semipermeable hollow fibers (1 mm [0.65 microm pores] and 3 mm [0.1 microm pores] outer diameters [o.d]), the primary cause of resistance is the middle hollow fiber. Preliminary studies using bioreactors inoculated with isolated rat hepatocytes and perfused with serum-containing culture media demonstrated that the middle hollow fiber is the primary site of fouling, and this fouling ultimately causes cell mortality by blocking the transfer of nutrients. Experiments were performed to determine the best commercially available middle hollow fiber for construction of bioreactors and two 3-mm outer-diameter middle hollow fibers were compared: polypropylene and polysulfone, with 0.2 microm and 0.1 microm pore sizes, respectively. Dead-ended and cross flow configurations were compared for their effectiveness at reducing membrane fouling in the middle hollow fiber by determining the change in resistance with time. The results demonstrate that the 0.2-microm pore size polypropylene hollow fiber is the best choice for construction of the multicoaxial hollow-fiber bioreactor, and that cross flow results in two orders of magnitude lower resistance than dead-ended flow after 36 h.
一种新型的“多轴中空纤维生物反应器”已被开发出来，它由四根同心管组成，最里面的两根管子被称为中空纤维。通过在最里面的两根中空纤维之间的空间培养肝祖细胞，并在夹着细胞区室的两个隔室（毛细管内和毛细管外）中加入培养基来制造生物人工肝。最外面的隔室用于气体交换。最近建立了一个流体动力学模型，以预测最佳水力渗透率和生物反应器操作参数，从而创造出肝腺泡中的物理化学环境。然而，用无血清激素限定培养基灌注和细胞接种会在这个等式中引入膜污染，这个参数必须纳入模型。使用市售的半透性中空纤维（外径分别为1毫米[0.65微米孔径]和3毫米[0.1微米孔径]），阻力的主要原因是中间的中空纤维。使用接种了分离大鼠肝细胞并灌注含血清培养基的生物反应器进行的初步研究表明，中间的中空纤维是污染的主要部位，这种污染最终通过阻断营养物质的转移导致细胞死亡。进行实验以确定用于构建生物反应器的最佳市售中间中空纤维，并比较了两种外径为3毫米的中间中空纤维：聚丙烯和聚砜，孔径分别为0.2微米和0.1微米。通过确定阻力随时间的变化，比较了死端配置和错流配置在减少中间中空纤维膜污染方面的有效性。结果表明，0.2微米孔径的聚丙烯中空纤维是构建多轴中空纤维生物反应器的最佳选择，并且在36小时后，错流导致的阻力比死端流低两个数量级。
