A Chinese Hamster Ovary cell line, CHO1-15 500 , producing recombinant human tissue type plasminogen activator (tPA) via the dihydrofolate reductase (DHFR) amplification system, was studied in batch culture. In this system both DHFR and tPA are under the control of the strong constitutive viral SV40 early promoter. Employing the cumulative viable cell-hour approach, the specific productivity of tPA had maxima in the lag (0.065 pg cell -1 h -1 ) and early decline (0.040 pg cell -1 h -1 ) population growth phases. The viable population was assigned into four subpopulations (G1, S, G2/M phase, and Apoptotic cells) using flow cytometric analysis. As expected, intracellular DHFR was maximally expressed during the S cell cycle phase. The production of tPA, however, was found to be a direct linear function of the G1 phase, with a subpopulation specific productivity of 0.080 pg c-h -1. Productivity maxima in the lag and early decline corroborate the flow cytometric data, indicative that this recombinant tPA production occurs primarily in the G1 cell cycle phase, not the S phase. This suggests that endogenous regulatory mechanisms are important controlling influences on the production of recombinant tPA in this ovarian cell line. Productivity from recombinant cell lines cannot be inferred from either the plasmid construct or the host cell alone. Elucidation of the relationship between expression of recombinant protein and the cell cycle phases of the host cell is a major component of the characterization of the animal cell production system. This information facilitates rational process design, including operating mode, modelling and control, and medium formulation.Keywords Cell cycle associated protein productivity Á Chinese hamster ovary (CHO) Á DHFR Á Regulation of expression Á Specific productivity Á Tissue plasminogen activator (tPA) Abbreviation CH vol volumetric cell-hours
Apart from gas concentrations, temperature, and pH, generally only the initial conditions can be manipulated in batch culture. Inoculum size and initial conditioned medium concentration represent two important considerations for optimal batch production. Two hybridoma cell lines were used to assess the impact of these initial conditions on population growth and monoclonal antibody productivity in suspension batch culture. Varying initial cell concentration over the range of 1.0 x 105 cells mL-1 to 3.0 x 105 cells mL-1 did not affect maximum product titre or maximum volumetric cell-hours attained. Initial percent of conditioned medium up to 40 percent strongly impacted on population growth and productivity, with initial levels of 30 to 40% conditioned medium reducing or eliminating lag phase and increasing average viable cell density. However, specific productivity and product titre declined with increasing initial percent conditioned medium, even on a per volume of fresh medium basis. Glutamine and glucose depletion or ammonia toxicity could cause depressed product titres when conditioned medium is used. Glutamine and glucose levels can easily be replenished in conditioned medium at minimal cost, and ammonia can be removed. Specific productivity was higher during cyclic batch operating mode than during batch operating mode. This may be because cyclic batch operating mode results in an incidental volume of conditioned medium at the beginning of each cycle. A two stage, cyclic-batch/batch operating mode can be employed to fully utilize medium and maximize product titre.
The second edition of Comprehensive Biotechnology provides a comprehensive coverage of the broad multidisciplinary field of biotechnology with important updates of its principles and practices in industry, medicine, agriculture, and the environment. It organizes and expands on material that is dispersed among different specialized publications. It is a response to many enquiries from many quarters. From the publisher records, the first edition was accepted worldwide with much appreciation. For example, a review of the publication in the prestigious periodical Nature observed that it "will be an essential purchase for all departments and institutions, academic or industrial that claim an interest in…biotechnology". As before, this publication would be valuable to researchers, instructors, students, policy makers, and others in biotechnology-related activities.In addition to traditional hard-copy print, this edition is also published as an online digitized document, which allows the use of modern electronic tools for seamless connections to the first edition and other relevant information with hyperlinks. For convenience, each article carries a glossary and a professional summary of the authors indicating their appropriate credentials. In a few instances, recent reprints are provided to acquire expertise in a timely manner. An extensive index for the entire publication gives a complete list of the many topics treated in the increasingly expanding field.To facilitate 'one-stop shopping' for rapid service, the work is designed as an integrated compendium of six volumes covering all the essential elements of the field. The first two volumes provide the basics of the underlying scientific and engineering principles of biotechnology; the following four volumes treat the major application branches that have an impact on industry, agriculture, medicine, and environment. Each volume has several sections to address various aspects of the given constituent areas. The volume editors provide a specific introduction to the nature and scope of the contents of a given volume. The volume titles, section titles, and respective editors of the six volumes are as follows.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.