Mechanical and Aerospace Engineering, One Shields Avenue, University of California-Davis, Davis, CA 95616, United States of America.
J Breath Res. 2019 Oct 21;14(1):016002. doi: 10.1088/1752-7163/ab3d23.
Volatile organic compound (VOC) emissions were measured from Chinese Hamster Ovary (CHO) cell and T cell bioreactor gas exhaust lines with the goal of non-invasively metabolically profiling the expansion process. Measurements of cellular 'breath' were made directly from the gas exhaust lines using polydimethylsiloxane (PDMS)-coated magnetic stir bars, which underwent subsequent thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) analysis. Baseline VOC profiles were observed from bioreactors filled with only liquid media. After inoculation, unique VOC profiles correlated to cell expansion over the course of 8 d. Partial least squares (PLS) regression models were built to predict cell culture density based on VOC profiles of CHO and T cells (R = 0.671 and R = 0.769, respectively, based on a validation data set). T cell runs resulted in 47 compounds relevant to expansion while CHO cell runs resulted in 45 compounds; the 20 most relevant compounds of each cell type were putatively identified. On the final experimental days, sorbent-covered stir bars were placed directly into cell-inoculated media and into media controls. Liquid-based measurements from spent media containing cells could be distinguished from media-only controls, indicating soluble VOCs excreted by the cells during expansion. A PLS-discriminate analysis (PLS-DA) was performed, and 96 compounds differed between T cell-inoculated media and media controls with 72 compounds for CHO cells; the 20 most relevant compounds of each cell line were putatively identified. This work demonstrates that the volatilome of cell cultures can be exploited by chemical detectors in bioreactor gas and liquid waste lines to non-invasively monitor cellular health and could possibly be used to optimize cell expansion conditions 'on-the-fly' with appropriate control loop systems. Although the basis for statistical models included compounds without certain identification, this work provides a foundation for future research of bioreactor emissions. Future studies must move towards identifying relevant compounds for understanding of underlying biochemistry.
挥发性有机化合物（VOC）排放来自中国仓鼠卵巢（CHO）细胞和 T 细胞生物反应器的废气线，旨在非侵入性地代谢分析扩展过程。使用聚二甲基硅氧烷（PDMS）涂层的磁性搅拌棒直接从废气线测量细胞“呼吸”，然后进行热解吸-气相色谱-质谱（TD-GC-MS）分析。仅用液体培养基填充生物反应器时观察到基线 VOC 谱。接种后，独特的 VOC 谱与 8 天内细胞的扩展相关。基于 CHO 和 T 细胞的 VOC 谱，建立偏最小二乘（PLS）回归模型来预测细胞培养密度（基于验证数据集，分别为 R = 0.671 和 R = 0.769）。T 细胞运行导致 47 种与扩展相关的化合物，而 CHO 细胞运行导致 45 种化合物；每种细胞类型的 20 种最相关化合物被推测鉴定。在最后一个实验日，将涂覆有吸附剂的搅拌棒直接放入接种细胞的培养基和对照培养基中。含有细胞的废培养基中的液体测量值可以与仅培养基对照区分开来，表明细胞在扩展过程中排出的可溶性 VOC。进行了偏最小二乘法判别分析（PLS-DA），T 细胞接种培养基与对照培养基之间有 96 种化合物不同，CHO 细胞有 72 种化合物；两种细胞系的 20 种最相关化合物被推测鉴定。这项工作表明，可以通过生物反应器气体和废液线中的化学探测器利用细胞培养物的挥发组来非侵入性地监测细胞健康状况，并可能用于通过适当的控制回路系统“实时”优化细胞扩展条件。尽管统计模型的基础包括某些未鉴定的化合物，但这项工作为生物反应器排放的未来研究提供了基础。未来的研究必须致力于确定相关化合物，以了解潜在的生物化学。
