Bioprocess Engineering, Wageningen University, PO Box 16, 6700, AA, Wageningen, the Netherlands.
Synthon Biopharmaceuticals BV, Upstream Process Development, PO Box 7071, 6503, GN, Nijmegen, the Netherlands.
Appl Microbiol Biotechnol. 2017 Nov;101(22):8101-8113. doi: 10.1007/s00253-017-8531-y. Epub 2017 Sep 26.
Normally, the growth profile of a CHO cell fed-batch process can be divided into two main phases based on changes in cell concentration, being an exponential growth phase and a stationary (non-growth) phase. In this study, an additional phase is observed during which the cell division comes to a halt but the cell growth continues in the form of an increase in cell size. The cell size increase (SI) phase occurs between the exponential proliferation phase (also called the number increase or NI phase) and the stationary phase. During the SI phase, the average volume and dry weight per cell increase threefold linearly with time. The average mAb specific productivity per cell increases linearly with the cell volume and therefore is on average two times higher in the SI phase than in the NI phase. The specific essential amino acids consumption rates per cell remain fairly constant between the NI and the SI phase, which agrees with the similar biomass production rate per cell between these two phases. Accumulation of fatty acids and formation of lipid droplets in the cells are observed during the SI phase, indicating that the fatty acids synthesis rate exceeds the demand for the synthesis of membrane lipids. A metabolic comparison between NI and SI phase shows that the cells with a larger size produce more mAb per unit of O and nutrient consumed, which can be used for further process optimization.
通常情况下，根据细胞浓度的变化，CHO 细胞分批培养的生长曲线可以分为两个主要阶段，即指数生长期和（不生长）稳定期。在本研究中，观察到在细胞分裂停止但细胞生长以细胞大小增加的形式继续的附加阶段。细胞大小增加（SI）阶段发生在指数增殖阶段（也称为数量增加或 NI 阶段）和稳定阶段之间。在 SI 阶段，每个细胞的平均体积和干重随时间呈三倍线性增加。每个细胞的 mAb 比产率与细胞体积呈线性关系，因此平均而言，SI 阶段比 NI 阶段高两倍。在 NI 和 SI 阶段之间，每个细胞的必需氨基酸消耗率保持相当稳定，这与这两个阶段之间每个细胞的生物量生产速率相似。在 SI 阶段观察到细胞内脂肪酸的积累和脂滴的形成，表明脂肪酸的合成速率超过了合成膜脂的需求。NI 和 SI 阶段之间的代谢比较表明，较大细胞的每个单位 O 和消耗的营养物质产生更多的 mAb，这可用于进一步的工艺优化。
