title: Temperature shift as a process optimization step for the production of pro-urokinase by a recombinant Chinese hamster ovary cell line in high-density perfusion culture.
abstract: Based on the effects of temperature shift on the cell cycle, apoptosis and metabolism of a recombinant Chinese hamster ovary (rCHO) cell line (CL-11G) producing pro-urokinase (pro-UK) in batch cultures, the potential of temperature shift as a tool in the optimization of the perfusion culture of CL-11G cells for the production of pro-UK was examined. The proportion of CL-11G cells in the G0/G1 phase in static cultures increased from 56.4% to 82.8% following a temperature shift from 37 degrees C to 31 degrees C. Conversely, the proportion of CL-11G cells in the S phase decreased from 34.8% to 11.6%. The specific growth rate of CL-11G cells reflected the effect of temperature on the cell cycle and decreased from 0.024 h(-1) at 37 degrees C to 0.006 h(-1) at 31 degrees C. Continuous exposure to the non-permissive temperature of 31 degrees C led to a marginal increase in apoptosis. The specific pro-UK productivity of CL-11G cells increased by 74% at 34 degrees C compared with controls at 37 degrees C in batch cultures. CL-11G cells immobilized with Cytopore 1 in a 5-l bioreactor initiated at 37 degrees C and temperature shifted to 34 degrees C exhibited an average 17% increase in viable cell density and an average 47% increase in pro-UK production. These results demonstrated that temperature shift offers the prospect of enhancing the productivity of pro-UK in high-density perfusion culture.
authors.affiliation: Department of Cell Engineering, Institute of Biotechnology, 20 Dongdajie Street, Fengtai, Beijing 100071, P.R. China. chenzl@nic.bmi.ac.cn
authors.forename: Zhao-Lie
authors.initials: ZL
authors.lastname: Chen
authors.forename: Ben-Chuan
authors.initials: BC
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Xing-Mao
authors.initials: XM
authors.lastname: Liu
authors.forename: Pei-Tang
authors.initials: PT
authors.lastname: Huang