• Reproductive and Developmental Biology
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• v.32 no.4
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• pp.211-215
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• 2008

The HMG box containing protein (HBP) has a high mobility group domain and involved in the regulation of proliferation and differentiation of tissues. We screened HBP2 in glioblastoma using Suppression Subtractive Hybridization (SSH) and isolated human spermatogonial stem cell-like cells (hSSC-like cells) derived from patients of nonobstructive azoospermia (NOA). Expression of HBP2 was analyzed by RT-PCR in undifferentiated stem cells (human Embryonic Stem Cells, hSSC-like cells 2P) and spontaneous differentiated stem cells (hSSC-like cells 4P). It was overexpressed in hESC and hSSC-like cells 2P but not in hSSC-like cells 4P. Also, the expression level of HBP2 was downregulated in colon tumor tissues compared to normal tissues. Specifically in synchronized WI-38 cells, HBP2 was highly upregulated until the G1 phase of the cell cycle and gradually decreased during the S phase. Our results suggest that HBP2 was downregulated during the spontaneous differentiation of hSSC-like cells. HBP2 was differently expressed in colon tissues and was related to G1-progression in WI-38 cells. It may playa role in the maintenance of an undifferentiated hSSC-like cell state and transits from G1 to S in WI-38 cells. This research was important that it identified a biomarker for an undifferentiated state of hSSC-like cells and characterized its involvement to arrest during cell cycle in colon cancer.

• Microbiology and Biotechnology Letters
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• v.39 no.4
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• pp.364-373
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• 2011

Human embryonic stem cells have been highlighted as a valuable cellular source in the regenerative medicine field, due to their pluripotency. However, there is the challenge of the establishment of specific functional cell type forms of undifferentiated human embryonic stem cells (hESC). To establish and purify functional cell types from hESCs, we differentiated undifferentiated hESCs into vascular lineage cells and sorted the specific cell population from the whole cell population, depending on their cell volume, and compared them with the non-sorted cell population. We observed that about 10% of the PECAM positive population existed in the VEGF induced differentiating human embryoid body (hEB), and differentiated hEBs were made into single cells for cell transplantation. After making single cells, we performed cell sorting using a fluorescence-activated cell sorter (FACs), according to their cell volume on the basis of FSC region gating, and compared their therapeutic capacity with the non-sorted cell population through cell transplantation into hindlimb ischemic disease model mice. 4 Weeks after cell transplantation, the recovery rate of blood perfusion reached 54% and 17% in the FSC regions of sorted cells- and non-sorted cells, respectively. This result suggests that derivation of a functional cell population from hESCs can be performed through cell sorting on the basis of cell volume after preliminary differentiation induction. This approach may then greatly contribute to overcoming the limitations of marker sorting.

• Archives of Plastic Surgery
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• v.33 no.2
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• pp.205-212
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• 2006

Using adipose derived stem cells(ASCs), neurogenic differentiation was induced in a mono layered culture medium containing neuronal induction agents. Cells differentiated to the neuronal cells were observed with a inverted microscope and immunofluorecent study. We made a 15 mm long defect in the sciatic nerve of 14 rats and connected a silicone tube to the defect. Then, we mixed neuronal progenitor cells differentiated from ASCs with collagen gel and grafted them to a group of rats(experimental group) and grafted only collagen gel into another group(control group). In 4 and 8 weeks after the graft, histological observation was made. According to the result, the number and diameter of myelinated axons were significantly increased in the experimental group. In addition, the nerve conduction velocity was improved more in the experimental group and neovascularity also increased. Moreover, reaction with S100 and p75 was observed in regenerated nerves in the experimental group, suggesting that the grafted cells were differentiated into supportive cells such as Schwann's cells. In conclusion, this research proved that ASCs can multiply and differentiate into neuronal cells. If they are grafted into nerve defects, the grafted cells are differ entiated into supportive cells such as Schwann's cells and thus contribute to nerve regeneration. Accordingly, the use of adipose tissue obtained easily without the limitation of donor site can be greatly helpful in treating peripheral nerve defects.

• BMB Reports
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• v.41 no.10
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• pp.705-709
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• 2008

NF-${\kappa}B$ is a transcriptional regulator involved in many biological processes including proliferation, survival, and differentiation. Recently, we reported that expression and activity of NF-${\kappa}B$ is comparatively low in undifferentiated human embryonic stem (ES) cells, but increases during differentiation. Here, we found a lower expression of NF-${\kappa}B$ p65 protein in mouse ES cells when compared with mouse embryonic fibroblast cells. Protein levels of NF-${\kappa}B$ p65 and relB were clearly enhanced during retinoic acid-induced differentiation. Furthermore, increased DNA binding activity of NF-${\kappa}B$ in response to TNF-$\alpha$, an agonist of NF-${\kappa}B$ signaling, was seen in differentiated but not undifferentiated mouse ES cells. Taken together with our previous data in human ES cells, it is likely that NF-${\kappa}B$ expression and activity of the NF-${\kappa}B$ signaling pathway is comparatively low in undifferentiated ES cells, but increases during differentiation of ES cells in general.

• International Journal of Stem Cells
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• v.10 no.1
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• pp.1-11
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• 2017

Human cardiomyocytes (CMs) cease to proliferate and remain terminally differentiated thereafter, when humans reach the mid-20s. Thus, any damages sustained by myocardium tissue are irreversible, and they require medical interventions to regain functionality. To date, new surgical procedures and drugs have been developed, albeit with limited success, to treat various heart diseases including myocardial infarction. Hence, there is a pressing need to develop more effective treatment methods to address the increasing mortality rate of the heart diseases. Functional CMs are not only an important in vitro cellular tool to model various types of heart diseases for drug development, but they are also a promising therapeutic agent for cell therapy. However, the limited proliferative capacity entails difficulties in acquiring functional CMs in the scale that is required for pathological studies and cell therapy development. Stem cells, human pluripotent stem cells (hPSCs) in particular, have been considered as an unlimited cellular source for providing functional CMs for various applications. Notable progress has already been made: the first clinical trials of hPSCs derived CMs (hPSC-CMs) for treating myocardial infarction was approved in 2015, and their potential use in disease modeling and drug discovery is being fully explored. This concise review gives an account of current development of differentiation, purification and maturation techniques for hPSC-CMs, and their application in cell therapy development and pharmaceutical industries will be discussed with the latest experimental evidence.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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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.

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.21-26
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• 2012

Suspension culture is a useful tool for culturing embryonic stem (ES) cells in large-scale, but the stability of pluripotency and karyotype has to be maintained $in$ $vitro$ for clinical application. Therefore, we investigated whether the chromosomal abnormality of ES cells was induced in suspension culture or not. The ES cells were cultured in suspension as a form of aggregate with or without mouse embryonic fibroblasts (MEFs), and 0 or 1,000 U/ml leukemia inhibitory factor (LIF) was treated to suspended ES cells. After culturing ES cells in suspension, their karyotype, DNA content, and properties of pluripotency and differentiation were evaluated. As a result, the formation of tetraploid ES cell population was significantly increased in suspension culture in which ES cells were co-cultured with both MEFs and LIF. Tetraploid ES cell population was also generated when ES cells were cultured alone in suspension regardless of the existence of LIF. On the other hand, the formation of tetraploid ES cell population was not detected in LIF-free condition, in which MEFs were included. The origin of tetraploid ES cell population was turned out to be E14 ES cells and not MEFs by microsatellite analysis and the basic properties of them were still maintained despite ploidy-conversion to tetraploidy. Furthermore, we identified the ploidy shift from tetraploidy to near-triploidy as tetraploid ES cells were differentiated spontaneously. From these results, we demonstrated that suspension culture system could induce ploidy-conversion generating tetraploid ES cell population. Moreover, optimization of suspension culture system may make possible mass-production of ES cells.

• Applied Microscopy
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• v.20 no.2
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• pp.46-56
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• 1990

Ultrastructure of the hemopoietic organ in the grasshopper, Euprepocnemis shirakii, was studied using light and electron microscopes. The hemopoietic organs located on the upper surface of the dorsal diaphragm between 1st and 8th segments were consisted of 3 kinds of cells; the reticular cells, stem cells and two types of granulocytes. The reticular cells had numerous cytoplasmic processes and forming a complex network. Characteristically, pinocytotic vesicles and rough endoplasmic reticulum were well developed in this cell. The stem cells give rise to differentiating hemocytes of the different cell lineages. Granulocytes within the hemopoietic organs were originated from the stern cells and differentiated into two types of hemocytes ; granulocyte( I ), granulocyte( II ).

• Reproductive and Developmental Biology
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• v.30 no.4
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• pp.287-291
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• 2006

We have developed a new passaging technique for the expansion of human embryonic stem cells (hESCs) that involves simply pipetting portions of hESCs acquired from colonies, reducing the laborious and time-consuming steps in the expansion of hESCs. Compared to general mechanical methods of passaging, our pipetting method allowed hESCs colonies to be broken into small fragments, which showed significantly higher attachment rates onto feeder cell layers. This technique produced three times the number of hESCs colonies than conventional mechanical methods. In addition, this pipetting method allowed us to distinguish differentiated hESCs from undifferentiated hESCs during hESCs colony pipetting. The hESCs cultured by pipetting method displayed normal human chromosomes for over 60 passages. According to RT-PCR and immunohistochemical analysis, the hESCs successfully maintained their undifferentiated state and pluripotency which was also confirmed by teratoma formation in viva Therefore, the pipetting method described in this study is a useful tool to efficiently and quickly expand hESCs on a large scale without enzyme treatment.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.556-561
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• 2006

The HOX genes coding homeodomain proteins have been suggested as a candidate molecular switch that determines the fates of cells during embryonic development and patterning. It is believed that a set of differentiation-specific HOX genes enter into a turn-on state during tissue differentiation, in contrast to stem cell-specific HOX genes that enter into a turn-off state. However, comprehensive data of expression profiles of HOX genes in human embryonic stem cells (hESC) and differentiated embryonic tissues are not available. In this study, we investigated the expression patterns of all 39 HOX genes in hESC and human fetal tissues and analyzed the relationships between hESC and each tissue. Of the 39 genes, 18 HOX genes were expressed in stem cells, and diverse expression patterning was observed in human fetal tissues when compared with stem cells. These results indicate that HOX genes could be main targets for switching of stem cell differentiation into tissues.