• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.747-749
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• 2001

의약용 인간 단백질은 현재 여러 제약으로 인해 동물 세포에서 만들어지고 있다. 그렇지만 곤충세포 시스템의 문제점인 수율과 배양의 까다로움과 같은 단점들을 보완할 수 있는 곤충세포 시스템 개발의 필요성이 대두되고 있고 본 연구에서는 의약용으로 많이 생산되고 있는 erythropoietin (EPO)을 Drosophila S2 cell에서 발현하여 CHO cell 유래의 EPO와 비교하였다. 그 결과 CHO cell에서보다 더 작은 분자량을 갖는 EPO를 확인하였다.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.153-158
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• 2003

The genome-wide program of gene expression during the cell division cycle response to serum free media in chinese hamster ovary(CHO) cells was characterized using cDNA microarrays. Many transcripts of genes showed variation during the cell cycle. Characterization is critical step toward understanding the basic cell cycle processes and serum-free media role in CHO cells

• KSBB Journal
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• v.21 no.4
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• pp.306-311
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• 2006

Cell preservation is indispensable in animal cell culture process and should be established according to the cell characteristics. In this study, we experimented hypothermic preservation of CHO cells that is widely used in pharmaceutical industry to produce therapeutic proteins and established a stable method of preservation. The highest viability of CHO cells was obtained when the cells were preserved using rolling tube, which means the cells should be suspended to avoid the cell lumping during the preservation. Also, we obtained superior preservation result under the anaerobic condition. To evaluate the serum-free media as a preservation solution, we investigated cell growth after hypothermic preservation using serum-free media. High cell viability and normal cell growth was observed during 10 days using serum-free media. Moreover, we found that more effective preservation when ${\alpha}$-tocopherol and retinoic acid is added to media as an additive. In the case of 1 liter large scale hypothermic preservation using established protocol, cell viability and growth rate was obtained as good as small scale one. This study is considered to be helpful for hypothermic preservation of CHO cells and large scale hypothermic preservation may be available through the further studies.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.293-296
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• 2002

Hyperosmotic pressure increased specific antibody productivity ($q_{Ab}$) of recombinant CHO cells (SH2-0.32) while it depressed cell growth. Thus, the use of hyperosmolar medium did not increase the maximum antibody concentration substantially. To overcome this drawback, the feasibility of biphasic culture strategy was investigated. In the biphasic culture, cells were first cultivated in the standard medium with physiological osmolality(294 mOsm/kg) for cell growth. When cells reached the late exponential phase of growth, the spent standard medium was replaced with the fresh hyperosmolar medium (522 mOsm/kg) for antibody production. The ($q_{Ab}$) in growth phase with the standard medium was 2.1 ${\mu}g/10^6cell/day$ while the ($q_{Ab}$) in antibody production phase with the hyperosmolar medium (522 mOsm/kg) was 11.1 ${\mu}g/10^6cell/day$. Northern blot analysis showed a positive relationship between the relative contenet of Ig mRNA and ($q_{Ab}$), indicating that transcriptional regulation was involved in the response of rCHO cells to hyperosmotic pressure. Due to the enhanced ($q_{Ab}$) and increased cell concentration in biphasic culture, the maximum antibody concentration obtained in biphasic culture with 522 mOsm/kg medium exchange was 161% higher than that obtained in batch culture with the standard medium. Taken together, simple biphasic culture strategy based on hyperosmotic culture for improved foreign protein production from rCHO cells is effective in improving antibody production of rCHO cells.

• KSBB Journal
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• v.32 no.3
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• pp.193-198
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• 2017

Sialylation is important in producing therapeutic proteins such as antibody, cytokine and fusion protein. Thus, enhancement of sialylation is usually performed in CHO cell cultures. ${\alpha}2,6$-Sialyltransferase (ST), which plays a key role in the attachment of ${\alpha}2,6-sialic$ acid, is present in human cells but not in Chinese hamster ovary (CHO) cells. Overexpression of ${\alpha}2,6-ST$ can be used for enhancing the degree of sialylation and achieving human-like glycosylation. In this study, we constructed CHO cells producing human cytotoxic T-lymphocyte antigen4-immunoglobulin (hCTLA4-Ig) as well as ${\alpha}2,6-ST$. Transfected CHO cells were selected using G418 and stable cell line was established. Profiles of viable cell density and hCTLA4-Ig titer in an overexpressed cell line were similar to those of a wild-type cell line. It was confirmed that the total amount of sialic acid was increased and ${\alpha}2,6-sialic$ acid was attached to the terminal residues of N-glycan of hCTLA4-Ig by ESI-LC-MS. Compared to 100% of ${\alpha}2,3-sialic$ acid in wild type cells, 70.9% of total sialylated N-glycans were composed of ${\alpha}2,6-sialic$ acid in transfected cells. In conclusion, overexpression of ${\alpha}2,6-ST$ in CHO cells led to the increase of both the amount of total sialylated N-glycan and the content of ${\alpha}2,6-sialic$ acid, which is more resemble to human-like structure of glycosylation.

• Journal of Microbiology and Biotechnology
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• v.23 no.8
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• pp.1176-1184
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• 2013

Anti-hepatocyte growth factor (anti-HGF) monoclonal antibodies (mAbs) are potential therapeutics against various cancers. Screening for high-producer clones is a time-consuming and complex process and is a major hurdle in the development of therapeutic mAbs. Here, we describe an efficient approach that allows the selection of high-producer Chinese hamster ovary (CHO) cell lines producing the novel anti-HGF mAb SFN68, which was generated previously by immunizing HGF bound to its receptor c-Met. We selected an SFN68-producing parental cell line via transfection of the dihydrofolate reductase-deficient CHO cell line DG44, which was preadapted to serum-free suspension culture, with an SFN68-expression vector. Subsequent gene amplification via multiple passages of the parental cell line in a methotrexate-containing medium over 4 weeks, followed by clonal isolation, enabled us to isolate two cell lines, 2F7 and 2H4, with 3-fold higher specific productivity. We also screened 72 different media formulated with diverse feed and basal media to develop a suboptimized medium. In the established suboptimized medium, the highest anti-HGF mAb yields of the 2F7 and 2H4 clones were 842 and 861 mg/l, respectively, which were about 10.5-fold higher than that of the parental cell line in a non-optimized basal medium. The selected CHO cell lines secreting high titers of SFN68 would be useful for the production of sufficient amounts of antibodies for efficacy evaluation in preclinical and early clinical studies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.549-550
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• 2006

Mobile fuel cell is highlighted in these days because mobile fuel cell can contain more energy than existing batteries. Nowadays mobile devices like cellular phone, PMP(portable multi-media player), notebook, and etc. need more energy, But existing batteries like Li-ion or Ni-MH batteries are not going to satisfy such demands. In this paper, mobile fuel cell is developed. Its size is 50*70*8mm and it is made of aluminium plates. The fuel cell type is PEM and the fuel is pure hydrogen and oxygen.

• Korean Journal of Veterinary Pathology
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• v.5 no.2
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• pp.79-80
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• 2001

A gingival mass was detected from a 1-year-old female Great Dane dog. After surgical removal, the lesions recurred in 2 weeks and died of septicemia. Characteristic histologic features were large numbers of multinucleated giant cells which were connected with capillary vessels. Neovascularization was prominent with mononuclear and polynuclear cell infiltration. Overall features of these lesions except for giant cell infiltration were similar to granuloma. From these results, a gingival mass excised from a dog was diagnosed to be a peripheral giant cell granuloma (PGCG). This is the first report of canine subcutaneous PGCG in Korea.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.1036-1040
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• 2007

Sodium butyrate (NaBu) has been used to enhance protein expression levels in mammalian cell culture. To determine the clonal variability of recombinant Chinese hamster ovary (rCHO) cells in response to NaBu addition regarding specific antibody productivity $(q_{Ab})$, three rCHO clones were subjected to different concentrations of NaBu. For all three clones, NaBu addition inhibited cell growth and decreased cell viability in a dose-dependent manner. On the other hand, the enhancing effect of NaBu on $q_{Ab}$ varied significantly among the clones. NaBu addition enhanced the antibody production of only one clone. RT-PCR analysis revealed that the changes in $q_{Ab}$ correlated linearly with those of the mRNA transcription level. Thus, it was concluded that the different enhancing effects of NaBu on protein expression in rCHO cell clones resulted from their different mRNA transcription levels.

• Parasites, Hosts and Diseases
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• v.46 no.1
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• pp.37-40
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• 2008

Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 ${\mu}M$ did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron ($24.6{\pm}2.1%$) compared with $62.7{\pm}2.8\;and\;63.1{\pm}1.4%$ of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed $69.1{\pm}4.3%\;and\;72.6{\pm}5.7%$ of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells ($2.8{\pm}0.2%$). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.