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  • 1
    Electronic Resource
    Electronic Resource
    Regulation of Interleukin-6-dependent B-Cell Hybridoma Growth (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 557 (1989), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1989.tb24069.x
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  • 2
    Electronic Resource
    Electronic Resource
    Hybridoma perfusion systems: A comparison study (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 25-32 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma culture ; monoclonal antibody production ; perfusion culture ; tangential filtration ; cell separation ; Nucleopore membranes ; alginate beads ; hollowfiber bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The efficiency of lgM production by hybridoma cells (1) cultured in suspension; (2) entrapped in alginate beads; or (3) packed in hollowfiber cartridge bioreactors, were compared in long-term perfusion cultures. The results showed that steady-state cell concentration and antibody production, per liter of perfused medium per day, were similar when cells were either entrapped in alginate beads of maintained in suspension. These values were also similar whether cells were maintained at high density in a hollowfiber cartridge bioreactro, or at low density in suspension. This work points out that cell behavior and antibody yield are comparable overall in the various perfusion systems currently used. However, a significant reduction of antibody production appeared whenever a part of the viable cells was lost in the filtrate. The reduction was due both to a decrease of viable cell yield and a decline of lgM productivity on a percell basis. This result is well in agreement with the previously presented model of “grow or die” cell cycle system of hybridoma, which proposes that the ratio of arrested to proliferating cells in perfusion cultures, should be increased in proportion to cell retention in the bioreactor, with a concomitant increase of lgM productivity.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400105
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  • 3
    Electronic Resource
    Electronic Resource
    Filtration-based perfusion of hybridoma cultures in protein-free medium: Reduction of membrane fouling by medium supplementation with DNase I (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 833-846 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, a filtration-based perfusion process was developed for the production of monoclonal antibodies (IgM) by suspended hybridoma cells grown in protein-free medium. It was found that the use of protein-free medium for perfusion culture generated the formation of numerous visible suspended particles consisting of dead cells and cellular debris aggregated into fibrous material. Surprisingly high apparent viabilities were observed in such protein-free cultures. In addition, membrane fouling occurred more rapidly in protein-free medium than in conventional serum-supplemented medium. By the addition of deoxyribonuclease I (DNase I) to the protein-free medium, it was possible to prevent the formation of aggregates and to follow the evolution of the total cell population more accurately. Moreover, DNase I significantly reduced the fouling of filtration membranes, and that, for two different types of separation systems (cross-flow and vortex-flow filtration) and two different types of membranes (polycarbonate and hydrophilized polysultone). From these results, it is clear that the presence of DNA fragments liberated following cellular death is playing an important role in membrane fouling. Longevity of filtration membranes was found to be considerably greater using a vortex-flow filtration module than with a static plate-and-frame cross-flow filtration module. The use of vortex-flow filtration of conjuction with DNase I allowed maintenance of perfusion cultures for more than 1 month without membrane fouling or antibody retention and with a constant permeate IgM concentration of 250 mg/L. Hybridomacells appeared to gradually adapt to increasing rotational speed in the vortex-flow filtration module.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430902
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  • 4
    Electronic Resource
    Electronic Resource
    Long-term perfusion culture of hybridoma: A “grow or die” cell cycle system (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 781-787 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma culture ; monoclonal antibody production ; perfusion culture ; continuous culture ; cell cycle ; tangential filtration ; cell separation ; nuclepore membranes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to elucidate the hybridoma life cycle and the limiting factors in perfusion systems, we performed cultures in a stirred tank bioreactor, coupled to an external tangential flow filtration unit. Cell density and antibody production in perfusion were consistent with previous studies. The average life span of the cells (2.1-2.2 days), antibody, productivity per cell produced (30-38 mg/109 cells) and cell size diameter evolution appeared similar to values observed in batch cultures. These observations highly suggest a similar “grow or die” life cycle. Cell and antibody production, strictly related to the medium perfusion rate, seem to be under the control of the nutrient availability. A hypothesis to explain such a life cycle of hybridoma cells in perfusion systems and a model for viable and dead cell density is proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380712
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  • 5
    Electronic Resource
    Electronic Resource
    Essential role of optimal protein synthesis in preventing the apoptotic death of cultured B cell hybridomas (1993)
    Springer
    Cytotechnology 13 (1993), S. 99-105 
    Details
    ISSN: 1573-0778
    Keywords: amino acids ; apoptosis ; cell viability ; hybridoma ; protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The monoclonal antibody productivity of cell culture systems is strongly dependent on the maintenance of hybridoma cell viability. We report that partial (〈50%) and transient (3 h) inhibition of protein synthesis by cycloheximide or deprivation of an essential amino acid induces apoptosis (programmed cell death) in B cell hybridomas. This unusual mechanism of apoptosis induction is likely to play a significant role in limiting cell viability in batch and perfusion cultures of hybridomas and emphasizes the importance of constantly maintaining a near optimal rate of macromolecular synthesis by optimization of all culture parameters. Inhibition of apoptosis in hybridomas by cell engineering and other technologies should permit, in the near future, a significant increase in the antibody productivity of existing cell culture systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00749936
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  • 6
    Electronic Resource
    Electronic Resource
    Rapid apoptotic cell death of B-cell hybridomas in absence of gene expression (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 286-293 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Apoptosis is an active form of cell death which plays an important role in different biological processes. The induction of apoptosis usually requires de novo gene expression but has also been observed in certain types of cells in absence of gene expression or following a block of gene expression. We show here that inhibition of macromolecular synthesis induced the rapid apoptotic death of most antibody-secreting B-cell hybridomas. The effect was observed in presence of both protein synthesis (cycloheximide [CHX]) and transcription (actinomycin D [Act D]) inhibitors and was characterized by extensive degradation of nucleic acids (DNA and RNA) within 2-3 h of treatment. The CHX treatment not only severely impaired the proliferation of the cells but also resulted in the loss of cell viability (MTT assay) without the need of de novo gene expression. The susceptibility to apoptosis varied among different B-cell hybridomas and was inherited from the SP2/0 myeloma cell fusion partner. These results indicate the constitutive activation of a death program in B-cell hybridomas and its inhibition at a late stage by the continuous expression of gene(s) coding for short-lived protein(s). The occurrence of this phenomenon may well be related to the abundant and deregulated (trans-location) expression, in this type of cells, of the c-myc gene which has recently been shown to be a potent inducer of apoptosis in growth-arrested fibroblasts. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560210
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