• Biomolecules & Therapeutics
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• v.6 no.2
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• pp.171-181
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• 1998

DA-3585, a biosynthetic recombinant human erythropoietin has been developed as a treatment for anemia associated with chronic renal failure in Dong-A pharmaceutical Co. Ltd. This study was carried out to assess its acute and subacute toxicities in rabbits. DA-3585 was intravenously administered to rabbits at dose levels of 6250, 12500 or 25000 lU/kg for single dose toxicity study and at dose levels of 100, 500 or 2500 lU/kg/day for 4-week repeated dose toxicity study. In the acute toxicity study, dose up to 25000 lU/kg had no adverse effect on the behavior or body weight gain. Pathological examinations revealed no abnormal gross lesions related to DA-3585. In the subacute toxicity study, all animals survived until termination of treatment. DA-3585 had no influence on clinical signs, food and water intake or on body weight changes. Hematological examination showed increases in the number of RBC, hemoglobin contents and hematocrit values with a dose dependent manner in the animals treated with DA-3585. Histopathological examination revealed erythroid hyperplasia in the bone marrow and extramedullary hematopoiesis in the liver. The changes detected in the hematological and histopathological examination presumably represent exaggerated pharmacological effects of erythropoietin. The NOAEL (no-observed-adverse-effect-level) of DA-3585 was estimated to be 100 lU/kg/ day under this study condition.

• KSBB Journal
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• v.18 no.4
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• pp.255-260
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• 2003

In vivo bioassays for biological medicines have been considered final resort to unequivocally assess the biological activities for them because there are some cases in which the biological activities obtained from in vivo bioassay and in vitro bioassay quite differ each other. The in vivo biological activity of EPO depends on its sialic acid contents which confer microheterogeneity-isoforms to this protein. We have devise a method which consists of a in vitro bioassay using BaF3 cell line and a capillary zone electrophoresis (CZE) for the measurement of the EPO isoform distribution. The biological activity of EPO obtained using in vitro bioassay with BaF3 cell line showed good correlation (C.V.(％) 7.34, 5.85, 8,16, 8.08, 8.8) to EPO content measured either spectrophotometric assay (A280 0.1 ％ ＝0.743) or radio immunoassay. The assay validation results of in vitro bioassay with 3 lot of in house EPO showed good results to EPO content measured either in vivo assay or radio immunoassay. and also showed good results the robustness of our method in terms of precision, accuracy, repeatability. The isoform distribution for EPO-BRP (1 : 1 mixture of epoetin-${\alpha}$ and epoetin-${\beta}$, European Pharmacopoeia) by CZE method resulted in isoform 2 through isoform 8. The major peaks in electrophoregram were composed of isoform 3 through 7. Our recombinant EPO (epoetin-${\alpha}$) having equivalent in vivo biological activity showed the isoform distribution of isoform 3 through 9. The major peaks consisted of isoform 4 through 8. The peak area of isoform 4 was always smaller than that of isoform 5. The preparations of recombinant epoetin-${\alpha}$ with lower in vivo biological activity than EPO-BRP showed the isoform 2 through 8 in their electrophoregrams whose major peaks consisted of the isoform 3 through 7. The peak area of isoform 4 was larger than that of isoform 5.

• YAKHAK HOEJI
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• v.51 no.3
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• pp.214-218
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• 2007

In the previous reports, we developed the CO5 by introducing genes for the first and second urea cycle enzymes, carbamoyl phosphate synthetase I (CPS I) and ornithine transcarbamoylase (OTC) into the IBE cell lines producing erythropoietin (EPO). The CO5 have been found out to have 15-20% higher cell growth rate and produce 2-times more EPO than the parental cell line, IBE. To investigate the role of CPS I in CO5 cell line for the cell growth and amount of EPO, we knock-downed CPS I gene expression via siRNA treatment. Expression level of EPO in cell lysate of CO5 was 3-5 fold higher than that of IBE. After siRNA treatment, the cell growth of CO5 was decreased 8-21% and the EPO productivity in the cell Iysate was significantly decreased. However, these changes of the cell growth and EPO productivity were not observed in IBE. These results indicate that CPS I gene expression is important for the increased cell growth and EPO productivity of CO5 cell line.

• 대한임상약리학회:학술대회논문집
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• 1992.11a
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• pp.44-44
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• 1992

• Biomolecules & Therapeutics
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• v.6 no.1
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• pp.56-62
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• 1998

Mutagenicity of recombinant human erythropoietin (rhEPO) was examined in the reverse mutation test on bacteria, in the chromosomal aberration test on cultured mammalian cells and in the micronucleus test on mice. The reverse mutation test was performed by a plate incorporation method with or wothout a metabolic activation system (59 Mix) using Salmonella typhimurium strain TA100, TA1535, TA98 and TA 1537. The rhEPO did not significantly increase revertant colonies in any of the test strains under any conditions at dose levels ranging from 1000 H/ml to 62.5 lu/plate, compared with the vehicle control. In the chromosomal aberration test using cultured Chinese Hamster Lung (CHL) cells, the number of aberrant cells was not increased in the presence or absence of 59 Mix at concentrations of 1000 lU/ml to 250 lU/ml, compared with the vehicle control. In the micronucleus test, male ICR mice were given rhEPO intraperitoneally at a dose level of 25000, 12500 and 6250 lU/kg. The incidence of bone marrow micronucleated polychromatic erythrocytes was not different from that of the vehicle control. From these results, rhEPO is considered to be non-mutagenic under the present test conditions.

• Reproductive and Developmental Biology
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• v.34 no.3
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• pp.193-199
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• 2010

We report here the production of transgenic chickens that can regulate human erythropoietin (hEPO) gene expression. The glycoprotein hormone hEPO is an essential for viability and growth of the erythrocytic progenitors. Retrovirus vector system used in this study has two features including tetracycline-controllable promoter and woodchuck hepatitis virus posttranscriptional regulator element (WPRE). The former is for to reduce the possibility of physiological disturbance due to constitutional and unregulated expression of hEPO gene in the transgenic chicken. The latter is for maximum expression of the foreign gene when we turn-on the gene expression. A replication-defective Moloney murine leukemia virus (MoMLV)-based vectors packaged with vesicular stomatitis virus G glycoprotein (VSV-G) was injected beneath the blastoderm of non-incubated chicken embryos (stage X). Out of 325 injected eggs, 28 chicks hatched after 21 days of incubation and 16 hatched chicks were found to express the hEPO gene delivered by the vector. The biological activity of the recombinant hEPO in transgenic chicken serum was comparable to its commercially available counterpart. The recombinant hEPO in transgenic chicken serum had N- and O-linked carbohydrate simillar to that produced from in vitro cultured cells transformed with hEPO gene.

• Biomolecules & Therapeutics
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• v.6 no.3
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• pp.312-316
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• 1998

Efficacy and in vivo bioassay of recombinant human erythropoietin (rho-EPO), was investigated. Efficacy studies were conducted in normal, and cisplatin-induced anemic rats. Normal and anemic animals were treated intravenously with rhu-EPO for 5 days, and the changes in the number of red blood cells (RBC), hemoglobin concentration (Hb), hematocrit value (Hct) and percentage reticulocyte value (Ret, reticulocyte/RBC) were examined. In normal rats, rho-EPO significantly increased RBC, Hb, Hct and Ret at the doses of 50∼ 1,250 lU/kg/day in a dose-dependent fashion. Cisplatin-induced anemic rats showed significant increase of RBC, Hb, Hct and Ret after administration of rho-EPO (50-200 lU/kg/day) in a dose-dependent manner. These changes of hematological parameters disappeared gradually after cessation of the treatment. The in vivo bioassay results in polycythemic mice showed that rho-EPO had 90% of bioactivity compared to NIBSC standard rhu-EPO. These results suggest that rho-EPO might be useful for the therapy of anemia originated from renal failure and chemotherapy-induced anemia.

• Molecules and Cells
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• v.37 no.11
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• pp.819-826
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• 2014

Protein modifications of recombinant pharmaceuticals have been observed both in vitro and in vivo. These modifications may result in lower efficacy, as well as bioavailability changes and antigenicity among the protein pharmaceuticals. Therefore, the contents of modification should be monitored for the quality and efficacy of protein pharmaceuticals. The interface of EPO and its receptor was visualized, and potential amino acids interacting on the interface were also listed. Two different types of modifications on the interface were identified in the preparation of rHu-EPO BRP. A UPLC/Q-TOF MS method was used to evaluate the modification at those variants. The modification of the oxidized variant was localized on the Met54 and the deamidated variants were localized on the Asn47 and Asn147. The extent of oxidation at Met54 was 3.0% and those of deamidation at Asn47 and Asn147 were 2.9% and 4.8%, respectively.

• Biomedical Science Letters
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• v.15 no.2
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• pp.161-166
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• 2009

Human erythropoietin(EPO) is a glycoprotein that enhances red blood cell production by stimulating proliferation and differentiation of erythroid progenitor cells in the bone marrow. Patients with chronic kidney disease(CKD) suffer from anemia caused by reduced production of EPO in the kidney. Recombinant human EPO protein has been used successfully for the treatment of anemia associated with CKD. Recently, attention has been paid to the development of side effect of EPO, pure red cell aplasia(PRCA), in some patients with CKD. PRCA is a rare disorder of erythropoiesis that leads to a severe anemia due to an almost complete cessation of red blood cell production. EPO-related PRCA is caused by the production of EPO-neutralizing antibodies(Abs) that eliminate the biological activity of EPO as well as endogenous EPO in patients undergoing therapy. Since 1988, almost 200 cases worldwide have been reported with Ab-positive PRCA after receiving EPO therapeutics. The underlying mechanisms of the breaking of immune tolerance to self-EPO have been investigated. Modification of formulation, organic compounds of container closures, and route of administration has been suggested for the possible mechanism of increased immunogenicity of EPO. A number of assays have been used to detect Abs specific to EPO. These assays are generally grouped into two major categories: binding Ab assays and neutralizing Ab assays(bioassays). There are several types of binding Ab assays, including radioimmunoprecipitation assay, enzyme-linked immunosorbent assay, and the BIAcore biosensor assay. In vitro cell-based bioassays have been utilized for the detection of neutralizing Abs. Finally, the recent experience with anti-EPO Abs may have considerable implications for the future development and approval of EPO preparations. Also, considering that millions of patients are being treated with EPO, clinicians need to be aware of signs and consequences of this rare but severe clinical case.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.383-391
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• 2008

The glycans linked to the insect cell-derived glycoproteins are known to differ from those expressed in mammalian cells, partly because of the low level or lack of glycosyltransferase activities. GnT II, GnT IV, GnT V, and ST3Gal IV, which play important roles in the synthesis of tetraantennarytype complex glycan structures in mammalian cells, were overexpressed in Trichoplusia ni cells by using a baculovirus expression vector. The glycosyltransferases, expressed as a fusion form with the IgG-binding domain, were secreted into the culture media and purified using IgG sepharose resin. The enzyme assay, performed using a pyridylaminated-sugar chain as an acceptor, indicated that the purified glycosyltransferases retained their enzyme activities. Human erythropoietin expressed in T. ni cells (rhEPO) was subjected to in vitro glycosylation by using recombinant glycosyltransferases and was converted into complex-type glycan with terminal sialic acid. The presence of Nacetylglucosamine, galactose, and sialic acid on the rhEPO moiety was detected by a lectin blot analysis, and the addition of galactose and sialic acid to rhEPO was confirmed by autoradiography using $UDP-^{14}C-Gal\;and\;CMP-^{14}C-Sia$ as donors. The in vitro glycosylated rhEPO was injected into mice, and the number of reticulocytes among the ed blood cells was counted using FACS. A significant increase in the number of reticulocytes was not observed in the mice injected with in vitro glycosylated rhEPO as compared with those injected with rhEPO.