• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.2
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• pp.51-54
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• 1998

It has been proved that co-cultivation of human neroblastoma cells and human fibroblast cells can enhance nerve cell growth and the production of BDNF in perfusion cultivation. In batch co-cultivation, maximum cell density was increased up to 1.76${\times}$106 viable cells/mL from 9${\times}$105 viable cells/mL of only neuroblastoma cell culture. The growth of neuroblastoma cells was greatly improved by culturing both nerve and fibroblast cells in a perfusion process, maintaining 1.5${\times}$106 viable cells/mL, which was much higher than that form fed-batch cultivation. The nerve cell growth was greatly enhance in both fed-batch and perfusion cultivations while the growth of fibroblast cells was not. It strongly implies that the factors secreted from human fibrobast cells and/or the environments of co-culture system can enhance both cell growth and BDNF secretion. Specific BDNF production rate was not enhanced in co-cultures; however, the production period was increased as the cell growth was lengthened in the co-culture case. Competitive growth between nerve cells and fibroblast cells was not observed in all cases, showing no changes of fibroblast cell growth and only enhancement of the neuroblastoma cell growth and overall BDNF production. It was also found that the perfusion cultivation was the most appropriate process for cultivating two cell lines simultaneously in a bioreactor.

• Advances in biomechanics and applications
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• v.1 no.4
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• pp.227-237
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• 2014

The in vitro construction of osteo-articular large implants combining biomaterials and cells is of great interest since these tissues have limited regeneration capability. But the development of such organoids is particularly challenging, especially in the later time of the culture, when the extracellular matrix has almost filled the initial porous network. The fluid flow needed to efficiently perfuse the sample can then not be achieved using only the hydraulic driving force. In this paper, we investigate the interest of using an electric field to promote mass transport through the scaffold at the late stage of the culture. Based on the resolution of the electrokinetics equations, this study provides an estimation of the necessary electric driving force to reach a sufficient oxygen perfusion through the sample, thus analyzing the feasibility of this concept. The possible consequences of such electric fields on cellular activities are then discussed.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.457-462
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• 2002

Low Electromagnetic Field (EMF) intensity in the range of $1{\mu}T\;to\;10{\mu}T$(Tesla) was found to enhance the growth of CHO cells and the production of tPA in batch and perfusion cultivations. At $1{\mu}T\;intensity,\;1.3{\times}10^7$ viable cells/ml of maximum cell density and 80 mg/l of maximum tPA production were obtained in batch cultivation, compared to $2.8{\times}10^6$ viable cells/ml and 59 mg tPA/1 in unexposed case (control). A similar trend was observed in the perfusion process, where it was possible to obtain $1.2{\times}10^7$ viable cells/ml of maximum cell density and 81 mg tPA/l of maximum tPA production by more than 80 days of cultivation. However, there was not much difference between $1{\mu}T\;and\;10{\mu}T$ in perfusion cultivation, possibly due to better environmental growth conditions being maintained by continuous feeding of fresh medium into the reactor. On the contrary, both cell growth and tPA production were severely inhibited at higher than 1 mT intensity, showing no growth at 10 mT exposure. Specific growth rate was linearly correlated to specific tPA production rate at $1{\mu}T$EMF intensity, which represents a partially growth-related relationship. It was also found that a large amount of $Ca^2+$ was released at low EMF intensity, even though the cell growth was not much affected. Low EMF intensity significantly improved both cell growth and tPA production, and tPA production seemed to be more affected than the cell growth, possibly due to the changes of cell membrane characteristics. It can be concluded that the elaboration of EMF intensity less than $10{\mu}T$ could improve cell growth and tPA production, but mainly tPA secretion through batch or perfusion process in a bioreactor.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.37-37
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• 2005

Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone consisting of non-covalently linked two subunits, the ${\alpha}$ and ${\beta}$ subunit. It has been used as a infertility drug for ovulation to mimic luteinizing hormone $(LH).^{1)}$ A stable cell line was established by transfection of Rc/CMV-i-dhfr-hCG, expression vector containing hCG ${\alpha}-$ and ${\beta}-genes$, into dihydrofolate reductase-deficient CHO cells and subesquent methotrexate-mediated gene amplification. Anchorage-dependent CHO cells were adapted into a serum-free and/or animal component-free suspension medium through gradual serum weaning for the hCG production. The established cell line showed typical morphological characteristics and growth profile of CHO cells, and could produce FSH with passage-to-passage consistency. The high density perfusion culture of the CHO cells was carried out in Celligen Plus bioreactor equipped with a spin-filter as a internal cell retention device. The cell density reached up to $>1x10^{7}$ cells/ml in less than 7 days and a perfusion-control strategy based on cellular consumption rates of glucose was $established.^{2)}$ Biologically active recombinant hCG was purified by a series of chromatographic steps including anion exchange chromatography and hydrophobic interaction chromatography to homogeneity. The highly purified recombinant hCG was characterized for physicochemical, immunological and biological properties.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.159-162
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• 2000

It has been commonly known that cell growth is inhibited by the lack of dissolved oxygen and mass transfer inhibition of nutrients at stationary phase in fed-batch culture. In this study, Pluronic F-68 and oxygen vectors were added in Angelica gigas Nakai suspension culture in order to enhance cell growth in fed-batch culture. It was observed that the addition of 6%(w/v) Pluronic F-68 promoted cell growth up to 6.1% compared to control and that the use of 4%(v/v) n-hexadecane markedly enhanced cell growth up to 11.4%.

• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.47-51
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• 2006

Sodium butyrate (NaBu) is used as an enhancer for the production of recombinant proteins in Chinese hamster ovary (CHO) cells. However, NaBu is well-known for its cytotoxic effect, thereby inducing apoptosis. CHO cells which had been engineered to express a humanised anti-HBV antibody were cultured using serum-free medium, Ex-cell 301. From a seeding density of $2{\times}10^5$ cells/ml, CHO cells grown with serum-free medium reached a maximum cell density of $1.3{\times}10^6$ cells/ml after 9 days in culture and produced a maximal antibody concentration of 130 mg/l after 13 days in culture. In the perfusion culture system, CHO cells producing anti-HBV antibody grown in an 7.5 1 bioreactor seeded with $2{\times}10^5$ cells/ml reached a maximal antibody concentration of 85 mg/1 after 720 h in culture. The addition of 0.3 mM NaBu and lowering culture temperature to $33^{\circ}C$ elongated the culture period to 60 days and increased the production yield by 2-fold, compared to control culture.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.425-428
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• 2000

To enhance the productivity of recombinant protein, ${\beta} -glucuronidase(GUS)$, by transgenic Nicotiana suspensions, perfusion culture was carried out in a 5-L stirred tank bioreactor. Maximum cell density of 20.0 gDCW/L was obtained and GUS activity was noticeably affected by medium composition, such as salt concentration. Effect of headspace purging by $CO_2-enriched$ air was also investigated. Aeration of $CO_2(5%)-enriched$ air with 0.2 vvm significantly promoted the cell growth in lag pahse and increased volumetric GUS activity from 0.69 U/mL to 5.76 U/mL. In contrast, aeration of $CO_2(5%)-enriched$ air with 0.1 vvm did not affect the cell growth but enhanced the GUS acitivity from 3.24 to 5.25 U/mL at the 4th day.