• 한국발생생물학회지:발생과생식
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• 제9권2호
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• pp.105-114
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• 2005

배아 줄기세포는 세포 치료 목적을 위한 재료로써 매우 큰 잠재력을 가지고 있으며, 이러한 잠재력의 실현을 위해서 세포의 운명에 결정적인 역할을 하는 요소들을 확인하고 특정 세포의 대량 생산을 위한 방법을 개발하여야 한다. 조혈과정은 폭넓게 연구되어 왔으며, 배아 줄기세포로부터 조혈세포의 분화는 lineage commitment에 관한 연구에 좋은 모델이 된다. 본 연구에서는, 두 종류의 마우스 배아 줄기세포주 TC-1과 B6-1를 이용하여 그 특성과 조혈세포 분화능을 비교하여 보았다. 두 세포주는 작은 차이는 있으나 줄기세포로서의 특성을 공통적으로 가지고 있었다. 그러나 methylcellulose 배양 system을 사용하여 embryonic body 형성능을 확인한 결과 TC-1이 B6-1에 비해 월등함을 확인하였다. 조혈세포 분화의 추적을 위해 blast colony의 형성, progenitor assay, RT-PCR을 통한 조혈세포 분화 관련 marker의 발현 분석을 수행한 결과, TC-1은 정상적으로 조혈세포를 생성해 내지만, B6-1은 제대로 분화되지 못함을 확인할 수 있었다. 이러한 결과들은 in vitro에서 배아 줄기세포로부터 조혈세포로 분화를 유도할 때, 보다 적합한 세포주의 탐색이 요구됨을 제시하며 이는 향후 인간 배아 줄기세포주에서도 마찬가지로 적용될 수 있음을 암시한다고 사료된다.

• Clinical and Experimental Reproductive Medicine
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• 제31권4호
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• pp.209-215
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• 2004

Objective: Embryonic stem (ES) cells could be differentiated into the specific cell types by alternation of culture condition and modification of gene expression. This study was performed to evaluate the differentiation protocol for mouse and human ES cells to insulin secreting cells. Methods: Undifferentiated mouse (JH-I) and human (Miz-hESI) ES cells were cultured on STO feeder layer, and embryoid bodies (EBs) were formed by suspension culture. For the differentiation, EBs were cultured by sequential system with three stage protocol. The differentiating ES cells were collected and marker gene expressions were analyzed by seIni-quantitative RT-PCR in each stage. Amount of secreted insulin levels in culture media of human ES cells were measured by human insulin specific RIA kit. Results: During the differentiation process of human ES cells, GATA-4, a-fetoprotein, glucose transporter-2 and Ngn-3 expression were increased whereas OctA was decreased progressively. Insulin and albuInin mRNAs were expressed from stage IT in mouse ES cells and from stage III in human ES cells. We detected 3.0~7.9 IlU/rnl secretion of insulin from differentiated human ES cells by in vitro culture for 36 days. Conclusion: The sequential culture system could induce the differentiation of mouse and human ES cells into insulin secreting cells. This is the fIrst report of differentiation of human ES cells into insulin secreting cells by in vitro culture with serum and insulin free medium.

• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.97-97
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• 2003

Embryonic stem (ES) cells, derived from preimplantation embryos, are able to differentiate into various types of cells consisting the whole body, or pluripotency. In addition to the plasticity, ES cells are expected to be different from terminally differentiated cells in very many ways, such as patterns of gene expressions, ability and response of the cells in confronting environmental stimulations, metabolism, and growth rate. As a model system to differentiate these two types of cells, human ES (hES, MB03) cells and terminally differentiated cells (HeLa), we examined the ability of these two types of cells in confronting a severe oxidative insult, that is $H_2 O_2$. Ratio of dying cells as determined by the relative amount of dye neutral red entrapped within the cells after the exposures. Cell death rates were not significantly different when either MB03 or HeLa were exposed up to 0.4 mM $H_2 O_2$. However, relative amount of dye entrapped within the cells sharply decreased down to 0.12% in HeLa cells when the cells were exposed to 0.8 mM $H_2 O_2$, while it was approximately 54% in MB03. Pretreatment of cells with BSO (GSH chelator) and measurement of GSH content results suggest that cellular GSH is the major defensive mechanism of hES cells. Induction of apoptosis in hES cell was confirmed by DNA laddering, induction of Bax, and chromatin condensation. In summary, hES cells 1) are extremely resistant to oxidative stress, 2) utilize GSH as a major defensive mechanism. and 3) experience apoptosis upon exposure to oxidative stress.

• Clinical and Experimental Reproductive Medicine
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• 제29권2호
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• pp.129-138
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• 2002

Objective: This study was to compare the characteristics between parthenogenetic mES (P-mES) cells and in vitro fertilization mES cells. Materials and Methods: Mouse oocytes were recovered from superovulated 4 wks hybrid F1 (C57BL/6xCBA/N) female mice. For parthenogenetic activation, oocytes were treated with 7% ethanol for 5 min and $5{\mu}g$/ml cytochalasin-B for 4 h. For IVF, oocytes were inseminated with epididymal sperm of hybrid F1 male mice ($1{times}10^6/ml$). IVF and parthenogenetic embryos were cultured in M16 medium for 4 days. Cell number count of blastocysts in those two groups was taken by differential labelling using propidium iodide (red) and bisbenzimide (blue). To establish ES cells, b1astocysts in IVF and parthenogenetic groups were treated by immunosurgery and recovered inner cell mass (ICM) cells were cultured in LIF added ES culture medium. To identify ES cells, the surface markers alkaline phosphatase, SSEA-1, 3,4 and Oct4 staining were examined in rep1ated ICM colonies. Chromosome numbers in P-mES and mES were checked. Also, in vitro differentiation potential of P-mES and mES was examined. Results: Although the cleavage rate (${\geq}$2-cell) was not different between IVF (76.3%) and parthenogenetic group (67.0%), in vitro development rate was significantly low in parthenogenetic group (24.0%) than IVF group (68.4%) (p<0.05). Cell number count of ICM and total cell in parthenogenetic b1astocysts ($9.6{\pm}3.1,\;35.1{\pm}5.2$) were signficantly lower than those of IVF blastocysts ($19.5{\pm}4.7,\;63.2{\pm}13.0$) (p<0.05). Through the serial treatment procedure such as immunosurgery, plating of ICM and colony formation, two ICM colonies in IVF group (mES, 10.0%) and three ICM colonies (P-mES, 42.9%) in parthenogenetic group were able to culture for extended duration (25 and 20 passages, respectively). Using surface markers, alkaline phosphatase, SSEA-l and Oct4 in P-mES and mES colony were positively stained. The number of chromosome was normal in ES colony from two groups. Also, in vitro neural and cardiac cell differentiation derived from mES or P-mES cells was confirmed. Conclusion: This study suggested that P-mES cells can be successfully established and that those cell lines have similar characteristics to mES cells.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.75-75
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• 2003

Since the establishment of embryonic stem cell, pluripotency of the cells was known to allow differentiation of the cells into various cell types consisting whole body. Several protocols have been developed to induce expression of specific genes.. However, no precise protocol that will generate a single type of the cells from stem cells has been reported. In order to produce cells suitable for transplantion into brain of PD animal model, which arouse due to a progressive degeneration of dopaminergic neurons in midbrain, human embryonic stem cell (hESC, MB03) was transfected with cDNAs cording for tyrosine hydroxylase (TH). Successful transfection was confirmed by western immunoblotting. Newly transfected cell line (TH#2/MB03) was induced to differentiate by the two neurogenic factors retinoic acid (RA) and b-FGF. Exp. I) Upon differentiation using RA/ascorbic acid (AA), embryoid bodies (EB, for 4days) derived from hES cells were exposed to RA (10$^{-6}$ M)/AA (50 mM) for 4 days, and were allowed to differentiate in N2 medium for 7, 14, 21, or 28 days. Exp. II) When bFGF was used, neuronal precursor cells were selected for 8 days in N2 medium after EB formation. After selection, cells were expanded at the presence of bFGF (20 ng/ml) for another 6 days followed by a final differentiation in N2 medium for 7, 14, 21 or 28 days. By indirect immunocytochemical studies, proportion of cells expressing NF200 increased rapidly from 20% at 7 days to 70 % at 28 days in RA/AA-treated group, while those cells expressing NF160 decreased from 80% at 7 days to 10% at 28 days upon differentiation in N2 medium. However, in differentiation by RA/AA treatment system, there was a significant increase in proportion of neuron maturity (73%) at day 14 after N2 medium. TH#2/MB03 cells expressing TH are >90% when matured at the absence of either bDNF or TGF-$\alpha$. These results suggested that TH#2/MB03 cells could be differentiated in vitro into mature neurons by RA/AA.

• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.7-8
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• 2003

Since it was first reported in 1997, somatic cell cloning has been demonstrated in several other mammalian species. On the mouse, it can be cloned from embryonic stem (ES) cells, fetus-derived cells, and adult-derived cells, both male and female. While cloning efficiencies range from 0 to 20%, rates of just 1-2% are typical (i.e. one or two live offspring per one hundred initial embryos). Recently, abnormalities in mice cloned from somatic cells have been reported, such as abnormal gene expression in embryo (Boiani et al., 2001, Bortvin et al., 2003), abnormal placenta (Wakayama and Yanagimachi 1999), obesity (Tamashiro et ai, 2000, 2002) or early death (Ogonuki et al., 2002). Such abnormalities notwithstanding, success in generating cloned offspring has opened new avenues of investigation and provides a valuable tool that basic research scientists have employed to study complex processes such as genomic reprogramming, imprinting and embryonic development. On the other hand, mouse ES cell lines can also be generated from adult somatic cells via nuclear transfer. These 'ntES cells' are capable of differentiation into an extensive variety of cell types in vitro, as well assperm and oocytes in vivo. Interestingly, the establish rate of ntES cell line from cloned blastocyst is much higher than the success rate of cloned mouse. It is also possible to make cloned mice from ntES cell nuclei as donor, but this serial nuclear transfer method could not improved the cloning efficiency. Might be ntES cell has both character between ES cell and somatic cell. A number of potential agricultural and clinical applications are also are being explored, including the reproductive cloning of farm animals and therapeutic cloning for human cell, tissue, and organ replacement. This talk seeks to describe both the relationship between nucleus donor cell type and cloning success rate, and methods for establishing ntES cell lines. (중략)

• Clinical and Experimental Reproductive Medicine
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• 제31권1호
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• pp.19-27
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• 2004

Objective: This study was to examine the in vitro neural cell differentiation patterns of human embryonic stem (hES) cells following treatment of various neurotrophic factors [basic fibroblast growth factor (bFGF), retinoic acid (RA), brain derived neurotrophic factor (BDNF) and transforming growth factor (TGF)-$\alpha$], particulary in dopaminergic neuron formation. Methods: The hES cells were induced to differentiate by bFGF and RA. Group I) In bFGF induction method, embryoid bodies (EBs, for 4 days) derived from hES were plated onto gelatin dish, selected for 8 days in ITSFn medium and expanded at the presence of bFGF (10 ng/ml) for another 6 days followed by a final differentiation in N2 medium for 7, 14 and 21 days. Group II) For RA induction, EBs were exposed of RA ($10^{-6}M$) for 4 days and allowed to differentiate in N2 medium for 7, 14 and 21 days. Group III) To examine the effects of additional neurotrophic factors, bFGF or RA induced cells were exposed to either BDNF (10 ng/ml) or TGF-$\alpha$ (10 ng/ml) during the 21 days of final differentiation. Neuron differentiation and dopamine secretion were examined by indirect immunocytochemistry and HPLC, respectively. Results: The bFGF or RA treated hES cells were resulted in similar neural cell differentiation patterns at the terminal differentiation stage, specifically, 75% neurons and 11% glial cells. Additionally, treatment of hES cells with BDNF or TGF-$\alpha$ during the terminal differentiation stage led to significantly increased tyrosine hydroxylase (TH) expression of a dopaminergic neuron marker, compared to control (p<0.05). In contrast, no effect was observed on the rate of mature neuron (NF-200) or glutamic acid decarboxylase-positive neurons. Immunocytochemistry and HPLC analyses revealed the higher levels of TH expression (20.3%) and dopamine secretion (265.5 $\pm$ 62.8 pmol/mg) in bFGF and TGF-sequentially treated hES cells than those in $\alpha$ RA or BDNF treated hES cells. Conclusion: These results indicate that the generation of dopamine secretory neurons from in vitro differentiated hES cells can be improved by TGF-$\alpha$ addition in the bFGF induction protocol.

• Clinical and Experimental Reproductive Medicine
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• 제29권2호
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• pp.117-127
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• 2002

Objective: This study was to investigate the generation of the functional neuron derived from human embryonic stem (hES, MB03) cells on in vitro neural cell differentiation system. Methods: For neural progenitor cell formation derived from hES cells, we produced embryoid bodies (EB: for 5 days, without mitogen) from hES cells and then neurospheres (for $7{\sim}10$ days, 20 ng/ml of bFGF added N2 medium) from EB. And then finally for the differentiation into mature neuron, neural progenitor cells were cultured in i) N2 medium only (without bFGF), ii) N2 supplemented with 20 ng/ml platelet derived growth factor-bb (PDGF-bb) or iii) N2 supplemented with 5 ng/ml brain derived neurotrophic factor (BDNF) for 2 weeks. Identification of neural cell differentiation was carried out by immunocytochemistry using $\beta_{III}$-tubulin (1:250), MAP-2 (1:100) and GFAP (1:500). Also, generation of functional neuron was identified using anti-glutamate (Sigma, 1:1000), anti-GABA (Sigma, 1:1000), anti-serotonin (Sigma, 1:1000) and anti-tyrosine hydroxylase (Sigma, 1:1000). Results: In vitro neural cell differentiation, neurotrophic factors (PDGF and BDNF) treated cell groups were high expressed MAP-2 and GFAP than non-treated cell group. The highest expression pattern of MAP-2 and $\beta_{III}$-tubulin was indicated in BDNF treated group. Also, in the presence of PDGF-bb or BDNF, most of the neural cells derived from hES cells were differentiated into glutamate and GABA neuron in vitro. Furthermore, we confirmed that there were a few serotonin and tyrosine hydroxylase positive neuron in the same culture environment. Conclusion: This results suggested that the generation of functional neuron derived from hES cells was increased by addition of neurotrophic factors such as PDGF-bb or BDNF in b-FGF induced neural cell differentiation system and especially glutamate and GABA neurons were mainly produced in the system.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1641-1646
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• 2004

The objective of this study was to generate transgenic mice expressing human resistin gene by using the tetraploidembryonic stem (ES) cell complementation method. Human resistin gene was amplified from human fetal liver cDNA library by PCR, cloned into $pCR^{(R)}$ 2.1 $TOPO^{(R)}$ vector and constructed in pCMV-Tag4C vector. Mammalian expression plasmid containing human resistin was transfected into D3-GL ES cells by Lipofectamine 2,000, and then after 10-12 days of transfection, the human resistin-expressing cells were selected with G418. In order to produce tetraploid embryos, blastomeres of diploid embryos at the two-cell stage were fused with two times of electric pulse using 60 V 30 $\mu$sec (fusion rate: 2,114/2,256, 93.5%) and cultured up to the blastocyst stage (development rate: 1,862/2,114, 94.6%). The selected 15-20 ES cells were injected into tetraploid blastocysts, and then transferred into the uteri of E 2.5 d pseudopregnant recipient mice. To investigate the gestation progress, two E 19.5 mused fetuses were recovered by Cesarean section of which one fetus was confirmed to contain human resistin gene by genomic DNA-PCR. Therefore, our findings demonstrate that tetraploid-ES mouse technology can be considered as a useful tool to produce transgenic mice for the rapid analysis of gene function in vivo.

• 한국약용작물학회지
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• 제10권4호
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• pp.237-242
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• 2002

It was found that the purified extract from A. gigas Nakai (polysaccharide, M.W., 25 kD) controled differentiating human ES cells. Its optimal supplementation concentration was decided as 0.8 $({\mu}g/ml)$ to efficiently control the differentiation. It also enhanced the cell growth, compared to the control. However, most widely used and commercially available differentiating agent, Leukemia Inhibitory Factor (LIF) negatively affected on the cell growth even though it controls the differentiation of ES cells, down to 40-50 % based on morphological observation and telomerase activity. It was presumed that the extract first affected on cell membrane and resulted in controlling signal system, then amplify gene expression of telomere, which enhanced the telomerase activity up to three times compared to the control. LIF only increased the enzyme activity up to two times. It was confirmed that the extract from A. gigas Nakai could be used for substituting currently used differentiation controlling agent, LIF from animal resources as a cheap plant resource and not affecting the cell growth. It can broaden the application of the plants not only to functional foods and their substitutes but also to fine chemicals and most cutting-edge biopharmaceutical medicine.