Fox Stephen R, Patel Upasana A, Yap Miranda G S, Wang Daniel I C
Biotechnology Process Engineering Center (BPEC) and Department of Chemical Engineering, Massachusetts Institute of Technology, Room 16-429, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA.
Biotechnol Bioeng. 2004 Jan 20;85(2):177-84. doi: 10.1002/bit.10861.
The Chinese hamster ovary (CHO) cell line producing interferon-gamma (IFN-gamma) exhibits a 2-fold increase in specific productivity when grown at 32 degrees C compared to 37 degrees C. Low temperature also causes growth arrest, meaning that the cell density is significantly lower at 32 degrees C, nutrients are consumed at a slower rate and the batch culture can be run for a longer period of time prior to the onset of cell death. At the end of the batch, product concentration is doubled at the low temperature. However, the batch time is nearly doubled as well, and this causes volumetric productivity to only marginally improve by using low temperature. One approach to alleviate the problem of slow growth at low temperature is to utilize a biphasic process, wherein cells are cultured at 37 degrees C for a period of time in order to obtain reasonably high cell density and then the temperature is shifted to 32 degrees C to achieve high specific productivity. Using this approach, it is hypothesized that IFN-gamma volumetric productivity would be maximized. We developed and validated a model for predicting the optimal point in time at which to shift the culture temperature from 37 degrees C to 32 degrees C. It was found that by shifting the temperature after 3 days of growth, the IFN-gamma volumetric productivity is increased by 40% compared to growth and production at 32 degrees C and by 90% compared to 37 degrees C, without any decrease in total production relative to culturing at 32 degrees C alone. The modeling framework presented here is applicable for optimizing controlled proliferation processes in general.
与在37℃培养相比，生产γ干扰素（IFN-γ）的中国仓鼠卵巢（CHO）细胞系在32℃培养时比生产率提高了2倍。低温还会导致生长停滞，这意味着在32℃时细胞密度显著降低，营养物质消耗速率较慢，并且在细胞死亡开始之前，分批培养可以运行更长时间。在分批培养结束时，低温下的产物浓度会加倍。然而，分批培养时间也几乎加倍，这使得通过使用低温仅略微提高了体积生产率。缓解低温下生长缓慢问题的一种方法是采用双相培养工艺，即先在37℃培养细胞一段时间以获得合理的高细胞密度，然后将温度转变为32℃以实现高比生产率。使用这种方法，据推测IFN-γ的体积生产率将达到最大化。我们开发并验证了一个模型，用于预测将培养温度从37℃转变为32℃的最佳时间点。结果发现，在生长3天后转变温度，与在32℃生长和生产相比，IFN-γ的体积生产率提高了40%，与在37℃相比提高了90%，并且相对于仅在32℃培养，总产量没有任何下降。这里提出的建模框架一般适用于优化受控增殖过程。
