• Clinical and Experimental Reproductive Medicine
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• v.32 no.2
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• pp.133-147
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• 2005

Objectives: This study was carried out to establish human embryonic stem cells derived from frozen-thawed embryos using mouse embryonic fibroblasts (mEFs), human fetal skin and muscle fibroblasts as feeder cells, and to identify the characteristic of embryonic stem cells. Methods: When primary mEFs, human fetal skin and muscle fibroblasts were prepared, passaging on 4 days from replating could have effective trypsinization and clear feeder layers. Eight of 23 frozenthawed 4~8 cell stage embryos donated from consenting couples developed to blastocysts. Inner cell mass (ICM) was isolated by immunosurgery. ICM was co-cultured on mEFs, human fetal skin or muscle fibroblasts. The ICM colonies grown on mEFs, human fetal skin or muscle fibroblasts were tested the expression of stage specific embryonic antigen-3, -4 (SSEA-3, -4), octamer binding transcription factor-4 mRNA (Oct-4) and alkaline phosphatase surface marker. Results: We obtained 1 ICM colony from 2 ICM co-cultured on mEFs as feeder cells and did not obtain any ICM colony from 6 ICM clumps co-cultured on human fetal skin or muscle fibroblasts. The colony formed on mEFs could be passaged 30 times every 5 days with sustaining undifferentiated colony appearance. When the colonies cultured on mEFs were grown on human fetal skin or muscle fibroblasts, the colonies could be passaged 15 times every 9 days with sustaining undifferentiated colony appearance. The colonies grown on mEFs and human fetal fibroblasts expressed SSEA-4 and alkaline phosphatase surface markers and positive for the expression of Oct-4 by reverse transcription-polymerase chain reaction (RT-PCR). The produced embryoid body differentiated spontaneously to neural progenitorlike cells, neuron-like cells and beating cardiomyocyte-like cells, and frozen-thawed embryonic stem cells displayed normal 46,XX karyotype. Conclusions: The human embryonic stem cells can be established by using mEFs and human fetal fibroblasts produced in laboratory as feeder cells.

• International Journal of Stem Cells
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• v.17 no.2
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• pp.194-203
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• 2024

Evaluating cell metabolism is crucial during pluripotent stem cell (PSC) differentiation and somatic cell reprogramming as it affects cell fate. As cultured stem cells are heterogeneous, a comparative analysis of relative metabolism using existing metabolic analysis methods is difficult, resulting in inaccuracies. In this study, we measured human PSC basal metabolic levels using a Seahorse analyzer. We used fibroblasts, human induced PSCs, and human embryonic stem cells to monitor changes in basal metabolic levels according to cell number and determine the number of cells suitable for analysis. We evaluated normalization methods using glucose and selected the most suitable for the metabolic analysis of heterogeneous PSCs during the reprogramming stage. The response of fibroblasts to glucose increased with starvation time, with oxygen consumption rate and extracellular acidification rate responding most effectively to glucose 4 hours after starvation and declining after 5 hours of starvation. Fibroblasts and PSCs achieved appropriate responses to glucose without damaging their metabolism 2~4 and 2~3 hours after starvation, respectively. We developed a novel method for comparing basal metabolic rates of fibroblasts and PSCs, focusing on quantitative analysis of glycolysis and oxidative phosphorylation using glucose without enzyme inhibitors. This protocol enables efficient comparison of energy metabolism among cell types, including undifferentiated PSCs, differentiated cells, and cells undergoing cellular reprogramming, and addresses critical issues, such as differences in basal metabolic levels and sensitivity to normalization, providing valuable insights into cellular energetics.

• Development and Reproduction
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• v.21 no.4
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• pp.425-434
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• 2017

Polyploidy is occurred by the process of endomitosis or cell fusion and usually represent terminally differentiated stage. Their effects on the developmental process were mainly investigated in the amphibian and fishes, and only observed in some rodents as mammalian model. Recently, we have established tetraploidy somatic cell nuclear transfer-derived human embryonic stem cells (SCNT-hESCs) and examined whether it could be available as a research model for the polyploidy cells existed in the human tissues. Two tetraploid hESC lines were artificially acquired by reintroduction of remained 1st polar body during the establishment of SCNT-hESC using MII oocytes obtained from female donors and dermal fibroblasts (DFB) from a 35-year-old adult male. These tetraploid SCNT-hESC lines (CHA-NT1 and CHA-NT3) were identified by the cytogenetic genotyping (91, XXXY,-6, t[2:6] / 92,XXXY,-12,+20) and have shown of indefinite proliferation, but slow speed when compared to euploid SCNT-hESCs. Using the eight Short Tendem Repeat (STR) markers, it was confirmed that both CHA-NT1 and CHA-NT3 lines contain both nuclear and oocyte donor genotypes. These hESCs expressed pluripotency markers and their embryoid bodies (EB) also expressed markers of the three embryonic germ layers and formed teratoma after transplantation into immune deficient mice. This study showed that tetraploidy does not affect the activities of proliferation and differentiation in SCNT-hESC. Therefore, tetraploid hESC lines established after SCNT procedure could be differentiated into various types of cells and could be an useful model for the study of the polyploidy cells in the tissues.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.75-75
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• 2002

The present study was conducted for the production of transgenic cloned cows by somatic cell nuclear transfer (SCNT) that secrete human prourokinase into milk. To establish an efficient production system for bovine transgenic SCNT embryos, the offset was examined of various conditions of donor cells including cell type, size, and passage number on the developmental competence of transgenic SCNT embryos. An expression plasmid far human prourokinase (pbeta-ProU) was constructed by inserting a bovine beta-casein promoter, a green fluorescent protein (GFP) marker gene, and a human prourokinase target gene into a pcDNA3 plasmid. Three types of bovine somatic cells including two adult cells (cumulus cells and ear fibroblasts) and fetal fibroblasts were prepared and transfected using a lipid-meidated method. In Experiment 1, developmental competence and rates of GFP expression in bovine transgenic SCNT embryos reconstructed with cumulus cells were significantly higher than those from fetal and ear fibroblasts. In Experiment 2, the effect of cellular senescence in early (2 to 4) and late (8 to 12) passages was investigated. No significant differences in the development of transgenic SCNT embryos were observed. In Experient 3, different sizes of GFP-expressing transfected cumulus cells [large (>30 ${\mu}{\textrm}{m}$) or small cell (<30 ${\mu}{\textrm}{m}$)] were used for SCNT. A significant improvement in embryo development and GFP expression was observed when small cumulus cells were used for SCNT. Taken together, these results demonstrate that (1) adult somatic cells could serve as donor cells in transgenic SCNT embryo production and cumulus cells with small size at early passage were the optimal cell type, and (2) transgenic SCNT embryos derived from adult somatic cells have embryonic development potential.

• YAKHAK HOEJI
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• v.52 no.1
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• pp.67-72
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• 2008

The use of doxorubicin, which is one of the most effective anticancer agents, is often limited by occurrence of acquired resistance in tumor cells. GSH has been shown to be involved in the development of this drug resistance. Transcription factor Nrf2 governs the expression of GSH synthesizing glutamylcysteine ligase (GCL), as well as multiple phase 2 detoxifying enzymes. Here we show that Nrf2 is one of factors determining doxorubicin sensitivity. Nrf2-deficient fibroblasts (murine embryonic fibroblasts, MEF) were more susceptible to doxorubicin mediated cell death than wild-type cells. Doxorubicin treatment elevated levels of Nrf2-regulated genes including NAD(P)H: quinone oxidoreductase (Nqo1) and GCL in wild-type fibroblasts, while no induction was observed in Nrf2-deficient cells. Doxorubicin resistance in human ovarian SK-OV cells was reversed by treatment with L-buthionine-sulfoxamine (BSO), which is depleting intracellular GSH. Finally, transfection of SK-OV cells with Nrf2 siRNA resulted in exacerbated cytotoxicity following doxorubicin treatment compared to scrambled RNA control. These results indicate that the Nrf2 pathway, which plays a protective role in normal cells, can be a potential target to control cancer cell resistance to anticancer agents.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.133-137
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• 2009

Pluripotent embryonic stem (ES) cells isolated from inner cell mass (ICM) of blastocyst-stage embryos are capable of differentiating into various cell lineages and demonstrate germ-line transmission in experimentally produced chimeras. These cells have a great potential as tools for transgenic animal production, screening of newly-developed drugs, and cell therapy. Miniature pigs, selectively bred pigs for small size, offer several advantages over large breed pigs in biomedical research including human disease model and xenotransplantation. In the present study, factors affecting primary culture of somatic cell nuclear transfer blastocysts from miniature pigs for isolation of ES cells were investigated. Formation of primary colonies occurred only on STO cells in human ES medium. In contrast, no ICM outgrowth was observed on mouse embryonic fibroblasts (MEF) in porcine ES medium. Plating intact blastocysts and isolated ICM resulted in comparable attachment on feeder layer and primary colony formation. After subculture of ES-like colonies, two putative ES cell lines were isolated. Colonies of putative ES cells morphologically resembled murine ES cells. These cells were maintained in culture up to three passages, but lost by spontaneous differentiation. The present study demonstrates factors involved in the early stage of nuclear transfer ES cell isolation in miniature pigs. However, long-term maintenance and characterization of nuclear transfer ES cells in miniature pigs are remained to be done in further studies.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2001.11a
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• pp.40-46
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• 2001

The use of pluripotent stem cells has tremendous advantages for various purposes but these cell lines with proven germ-line transmission have been completely established only in the mouse. Embryonic germ (EG) cell lines are also pluripotent and undifferentiated stem cells established from primordial germ cells (PGCs). This study was conducted to establish and characterize the chicken EG cells derived from gonadal primordial germ cells. We isolated gonadal PGCs from 5.5-day-old (stage 28) White leghorn (WL) embryos and established chicken EG cells lines with EG culture medium supplemented with human stem cell factor (hSCF), murine leukemia inhibitory factor (mLIF), bovine basic fibroblast growth factor (bFGF), human interleukin-11 (hIL-11), and human insulin-like growth factor-I (hIGF-I). These cells grew continuously for 4 months (10 passages) on a feeder layer of mitotically active chicken embryonic fibroblasts. These cells were characterized by screening with the Periodic acid-Shiff＇s reaction, anti-SSEA-1 antibody, and a proliferation assay after several passages. As the results, the chicken EG cells maintained characteristics of undifferentiated stem cells as well as that of gonadal PGCs. When cultured in suspension, the chicken EG cells successfully formed an embryoid body and differentiated into a variety of cell types when re-seeded onto culture dish. The chicken EG cells were injected into blastodermal layer at stage X and dorsal aorta of recipient embryo at stage 14 (incubation of 53hrs) and produced chimeric chickens with various differentiated tissues derived from the EG cells. The germline chimeras were also successfully induced by using EG cells. Thus, Chicken EG cells will be useful for the production of transgenic chickena and for studies of germ cell differentiation and genomic imprinting.

• Reproductive and Developmental Biology
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• v.32 no.2
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• pp.135-140
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• 2008

Recent studies on nuclear transfer and induced pluripotent stem cells have demonstrated that differentiated somatic cells can be returned to the undifferentiated state by reversing their developmental process. These epigenetically reprogrammed somatic cells may again be differentiated into various cell types, and used for cell replacement therapies through autologous transplantation to treat many degenerative diseases. To date, however, reprogramming of somatic cells into undifferentiated cells has been extremely inefficient. Hence, reliable markers to identify the event of reprogramming would assist effective selection of reprogrammed cells. In this study, a transgene construct encoding enhanced green fluorescent protein (EGFP) under the regulation of human Oct4 promoter was developed as a reporter for the reprogramming of somatic cells. Microinjection of the transgene construct into pronuclei of fertilized mouse eggs resulted in the emission of green fluorescence, suggesting that the undifferentiated cytoplasmic environment provided by fertilized eggs induces the expression of EGFP. Next, the transgene construct was introduced into human embryonic fibroblasts, and the nuclei from these cells were transferred into enucleated porcine oocytes. Along with their in vitro development, nuclear transfer embryos emitted green fluorescence, suggesting the reprogramming of donor nuclei in nuclear transfer embryos. The results of the present study demonstrate that expression of the transgene under the regulation of human Oct4 promoter coincides with epigenetic reprogramming, and may be used as a convenient marker that non-invasively reflects reprogramming of somatic cells.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.1-12
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• 2002

The periodontal ligament(PDL) is a unique tissue that is crucial for tooth function. However, little is known of the molecular mechanisms controlling PDL function. PDL-specific protein;PDLs22 had been previously identified as a novel protein isolated from cultured human PDL fibroblasts using subtraction hybridization between human gingival fibroblasts and PDL fibroblasts. The aim of this study was to examine the expression pattern and tissue localization of PDLs22 protein in embryonic and various postnatal stages of developing mouse using immunohistochemical staining. Embryos (E18) and postnatal (P1, P4, P5, P15, P18) were decapitated and the heads were fixed overnight in a freshly prepared solution of 4% paraformaldehyde. Some specimens were decalcified for $2{\sim}4$ weeks in a solution containing 10% of the disodium salt of ethylenediamine-tetraacetic acid (EDTA). Next, tissues were dehydrated, embedded in paraffin and sectioned serially at $6{\mu}m$ in thickness. Polyclonal antiserum raised against PDLs22 peptides, ISNKYLVKRQSRD, were made. The localization of PDLs22 in tissues was detected by polyclonal antibody against PDLs22 by means of immunohistochemical staining. The results were as follows; 1. Expression of PDLs22 protein was not detected in the tooth germ of bud and cap stage. 2. At the late bell stage and root formation stage, strong expression of PDLs22 protein was observed in developing tooth follicle, osteoblast-like cells, and subodontoblastic cells in the tooth pulp, but not in gingival fibroblasts, ameloblasts and odontoblasts of tooth germ 3. In erupted tooth, PDLs22 protein was intensely expressed in PDL and osteoblast-like cells of alveolar bone, but not in gingival fibroblasts, mature osteocytes and adjacent salivary glands. 4. In the developing alveolar bone and mid-palatal suture, expression of PDLs22 protein was seen in undifferentiated mesenchymal cells and osteoblast-like cells of developing mid-palatal suture, but not in mature osteocytes and chondrocytes. These results suggest that PDLs22 protein may play an important role in the differentiation of undifferentiated mesenchymal cells in the bone marrow and PDL cells, which can differentiate into multiple cell types including osteoblasts, cementoblasts, and PDL fibroblasts. However, more researches should be performed to gain a better understanding of the exact function of PDLs22 protein which related to the PDL cell differentiation.

• Development and Reproduction
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• v.21 no.3
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• pp.335-342
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• 2017

While adipose-derived stem cell-conditioned medium (ADSC-CM) has been demonstrated to promote skin wound healing, the mechanism regulating this effect remains unelucidated. In this study, we aimed to investigate the role of Ell3 in the wound healing activity of ADSC-CM. In vitro analysis revealed that Ell3 suppression in ADSCs impairs the promotive activity of ADSC-CM on the proliferation and migration of mouse embryonic fibroblasts (MEF) and normal human dermal fibroblasts (NHDF). Consistently, the expression of MMP family genes, which regulate cell proliferation and migration, was significantly suppressed in MEF and NHDF treated with siEll3-transfected ADSC-CM. Proinflammatory cytokines, such as interleukin-1 and interleukin-6, were highly expressed in MEF treated with siEll3-transfected ADSC-CM. The wound healing activity of siEll3-transfected ADSC-CM was significantly lower than that of the control in vivo. Our results suggest that Ell3 may contribute to the inhibition of inflammatory response during skin wound healing.