Michaels J D, Papoutsakis E T
Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208-3120.
J Biotechnol. 1991 Jul;19(2-3):241-57. doi: 10.1016/0168-1656(91)90062-z.
Two identical bioreactors run in parallel were used to examine the phenomenological characteristics of two additives, polyethylene glycol (PEG) and polyvinyl alcohol (PVA), used as protectants against fluid-mechanical cell damage. Cell-protecting ability was evaluated by comparing apparent cell growth rates of freely suspended CRL-8018 hybridoma cells cultured in serum-free medium under surface aerated conditions whereby cell damage is due to bubble entrainment and breakup. PEG of various molecular weights was used to determine whether the size of the polymer has significant effects on PEG's cell-protecting capabilities. All the PEG's with molecular weights larger than 1400 showed similar protective effects. The effect of PEG concentration was then evaluated and results showed that concentrations greater than 0.05% w/v did not significantly improve the cell-protecting properties. Direct comparisons made between the PVA, PEG, and pluronic F68 as cell protectants showed that PEG protected cells better than F68 and that PVA provided even better protection than PEG. The mechanism of protection, fluid-mechanical or biological in nature, was examined by growing the cells in additive from the beginning of the experiment (long-term exposure), or adding the additive after the cells had been agitated at rates detrimental to the cells (short-term exposure). In agreement with results reported previously on PEG and F68, fast-acting protection was seen. This implies a fluid-mechanical rather than a biological protection mechanism. In an attempt to correlate interfacial properties of the resulting media with shear protection, interfacial tension and viscosity measurements of all the media were made. On the basis of these measurements, we find no definitive correlations for evaluating these additives' cell-protecting capabilities.
使用两个并行运行的相同生物反应器来研究两种添加剂（聚乙二醇（PEG）和聚乙烯醇（PVA））作为防止流体机械细胞损伤的保护剂的现象学特征。通过比较在表面曝气条件下无血清培养基中自由悬浮的CRL - 8018杂交瘤细胞的表观细胞生长速率来评估细胞保护能力，在这种条件下细胞损伤是由于气泡夹带和破裂造成的。使用各种分子量的PEG来确定聚合物的大小是否对PEG的细胞保护能力有显著影响。所有分子量大于1400的PEG都显示出相似的保护作用。然后评估了PEG浓度的影响，结果表明浓度大于0.05% w/v并没有显著提高细胞保护性能。对作为细胞保护剂的PVA、PEG和普朗尼克F68进行直接比较，结果表明PEG对细胞的保护作用优于F68，并且PVA提供的保护甚至比PEG更好。通过在实验开始时就在添加剂中培养细胞（长期暴露），或者在细胞以对其有害的速率搅拌后添加添加剂（短期暴露），来研究保护机制是流体机械性质还是生物学性质。与先前关于PEG和F68的报道结果一致，观察到了快速起效的保护作用。这意味着是流体机械保护机制而非生物学保护机制。为了将所得培养基的界面性质与剪切保护相关联，对所有培养基进行了界面张力和粘度测量。基于这些测量结果，我们没有发现用于评估这些添加剂细胞保护能力的明确相关性。
