• KSBB Journal
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• v.20 no.1 s.90
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• pp.1-11
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• 2005

Recently, there has been extremely active in the research of stem cell biology. Stem cells have excellent potential for being the ultimate source of transplantable cells for many different tissues. Researchers hope to use stem cells to repair or replace diseased or damaged organs, leading to new treatments for human disorders that are currently incurable, including diabetes, spinal cord injury and brain diseases. There are primary sources of stem cells like embryonic stem cells and adult stem cells. Stem cells from embryos were known to give rise to every type of cell. However, embryonic stem cells still have a lot of disadvantages. First, transplanted cells sometimes grow into tumors. Second, the human embryonic stem cells that are available for research would be rejected by a patient's immune system. Tissue-matched transplants could be made by either creating a bank of stem cells from more human embryos, or by cloning a patient's DNA into existing stem cells to customize them. However, this is laborious and ethically contentious. These problems could be overcome by using adult stem cells, taken from a patient, that are treated to remove problems and then put back. Nevertheless, some researchers do not convince that adult stem cells could, like embryonic ones, make every tissue type. Human stem cell research holds enormous potential for contributing to our understanding of fundamental human biology. In this review, we discuss the recent progress in stem cell research and the future therapeutic applications.

• Health Policy and Management
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• v.14 no.3
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• pp.97-121
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• 2004

Recently, human embryonic stem cell research raises exciting public expectation on medical possibilities as well as ethical debate. Embryo management has become an integral part of the management of infertility treatment, researches on embryo and human embryonic stem cells and so on. Britain has permitted the research on stem cells derived from human embryo which made the first nation to allow the cloning of human embryo for the stem cell research. However, new technologies such as the assisted reproductive technologies and human embryonic stem cell research continue to pose an increasing source of ethical dilemmas for physician, scientists, legislators, religious authorities and the general publics to deal with. None the less, the United Kingdom has adopted the most liberal policies regarding human embryo and human embryonic stem cell research. The implication of the British embryo management system are as follows: 1) the development of reproductive technologies and new stem cell research technologies continue to pose legal and ethical debates, since those involve several parties; 2) the UK has taken the legal and institutional approaches to cope with those serious issues; 3) the UK adopted most liberal policies regarding embryonic and human embryonic stem cell researches; 4) the British HFE Act is consistent with the existing Acts related to human embryo management and researches; 5) through amending the HFE Act to accomodate the changes of technologies, the UK try to minimize the legal and ethical burden on undertaking research regarding embryo. The debates about the researches on human embryo and human embryonic stem cells is likely to continue in the Korean society. Because of the controversy and competing ethical values, as well as the evolving technologies, so far no consensus exists in our society. It suggest that it is premature to bring closure by ruling out any particular approaches. Thus our society needs to make an efforts to find a basis which could resolve the societal controversies through enriching the societal conversation about the profound ethical issues regarding embryo management.

• BMB Reports
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• v.48 no.12
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• pp.668-676
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• 2015

Pluripotent stem cells only exist in a narrow window during early embryonic development, whereas multipotent stem cells are abundant throughout embryonic development and are retainedin various adult tissues and organs. While pluripotent stem cell lines have been established from several species, including mouse, rat, and human, it is still challenging to establish stable multipotent stem cell lines from embryonic or adult tissues. Based on current knowledge, we anticipate that by manipulating extrinsic and intrinsic signaling pathways, most if not all types of stem cells can be maintained in a long-term culture. In this article, we summarize current culture conditions established for the long-term maintenance of authentic pluripotent and multipotent stem cells and the signaling pathways involved. We also discuss the general principles of stem cell maintenance and propose several strategies on the establishment of novel stem cell lines through manipulation of signaling pathways.

• BMB Reports
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• v.42 no.2
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• pp.72-80
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• 2009

In mammals, major progress has recently been made with the dissection of early embryonic cell specification, the isolation of stem cells from early embryos, and the production of embryonic-like stem cells from adult cells. These studies have overcome long-standing species barriers for stem cell isolation, have revealed a deeper than expected similarity of embryo cell types across species, and have led to a better understanding of the lineage identities of embryo-derived stem cells, most notably of mouse and human embryonic stem (ES) cells. Thus, it has now become possible to propose a species-overarching classification of embryo stem cells, which are defined here as pre- to early post-implantation conceptus-derived stem cell types that maintain embryonic lineage identities in vitro. The present article gives an overview of these cells and discusses their relationships with each other and the conceptus. Consequently, it is debated whether further embryo stem cell types await isolation, and the study of the earliest extraembryonically committed stem cells is identified as a promising new research field.

• Proceedings of the Zoological Society Korea Conference
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• 2005.08a
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• pp.18-18
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• 2005

• 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 Science and Technology Studies
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• v.8 no.1
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• pp.55-95
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• 2008

This research was performed with the aim of analyzing the 'expectation dynamics' of embryonic stem cell research which was revealed throughout the establishment process of Stem Cell Research Center from 2000 to 2002. Expectation dynamics is a chained process: expectation construction - raising fund - performing research. Normally, researchers are considerably circumspect and politically neutral in assessing the result of research. However, some researchers are very involved in building the expectation dynamics by developing an overestimated impact of the result, which can be understood as a kind of strategy for solving the financial problem and defending the criticism in terms of bioethics. Nowadays Biotechnology R&D costs a big budget and requires large site human resources, so building the expectation dynamics is a decisive element for a successful R&D performance, which makes the strategy-development in the political context much more important. By analyzing the actors-network of embryonic stem cell research in term of 'expectation dynamics', we can clarify the identify of embryonic stem cell researchers and draw a conclusion which is very helpful for decision makers and the public to make a decision related with embryonic stem cells.

• Molecules and Cells
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• v.37 no.6
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• pp.497-502
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• 2014

Microfluidics can provide unique experimental tools to visualize the development of neural structures within a microscale device, which is followed by guidance of neurite growth in the axonal isolation compartment. We utilized microfluidics technology to monitor the differentiation and migration of neural cells derived from human embryonic stem cells (hESCs). We co-cultured hESCs with PA6 stromal cells, and isolated neural rosette-like structures, which subsequently formed neurospheres in suspension culture. Tuj1-positive neural cells, but not nestin-positive neural precursor cells (NPCs), were able to enter the microfluidics grooves (microchannels), suggesting that neural cell-migratory capacity was dependent upon neuronal differentiation stage. We also showed that bundles of axons formed and extended into the microchannels. Taken together, these results demonstrated that microfluidics technology can provide useful tools to study neurite outgrowth and axon guidance of neural cells, which are derived from human embryonic stem cells.

• Development and Reproduction
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• v.19 no.3
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• pp.119-126
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• 2015

The suitable feeder cell layer is important for culture of embryonic stem (ES) cells. In this study, we investigated the effect of two kinds of the feeder cell, MEF cells and STO cells, layer to mouse ES (mES) cell culture for maintenance of stemness. We compare the colony formations, alkaline phosphatase (AP) activities, expression of pluripotency marker genes and proteins of D3 cell colonies cultured on MEF feeder cell layer (D3/MEF) or STO cell layers (D3/STO) compared to feeder free condition (D3/-) as a control group. Although there were no differences to colony formations and AP activities, interestingly, the transcripts level of pluripotency marker genes, Pou5f1 and Nanog were highly expressed in D3/MEF (79 and 93) than D3/STO (61and 77) or D3/- (65 and 81). Also, pluripotency marker proteins, NANOG and SOX-2, were more synthesized in D3/MEF ($72.8{\pm}7.69$ and $81.2{\pm}3.56$) than D3/STO ($32.0{\pm}4.30$ and $56.0{\pm}4.90$) or D3/- ($55.0{\pm}4.64$ and $62.0{\pm}6.20$). These results suggest that MEF feeder cell layer is more suitable to mES cell culture.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.343-349
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• 2009

This study was designed to simplify a cryopreservation program for embryonic stem cells (ESCs) by selection of cooling method and cryoprotectant. Commercially available mouse E14 embryonic stem cells (ESCs) were cryopreserved with various protocols, and morphology and viability of the frozen-thawed ESCs and their reactive oxygen species (ROS) production were subsequently monitored. Post-thaw colony-formation of ESCs was detected only after a slow freezing using dimethyl sulfoxide (DMSO) by stepwise placement of a freezing container into a $-80^{\circ}C$ deep freezer and subsequently into -$196^{\circ}C$ liquid nitrogen, while no proliferation was detected after vitrification. When the simplified protocol was employed, the replacement of DMSO with a mixture of DMSO and ethylene glycol (EG) further improved the post-thaw survival. ROS generation in ESCs frozen-thawed with the optimized protocol was not increased compared with non-frozen ESCs. The use of fresh mouse embryonic fibroblasts as feeder cells for post-thaw subculture did not further increase post-thaw cell viability. In conclusion, a simplified slow-freezing program without employing programmable freezer but using DMSO and EG was developed which maintains cell viability and colony-forming activity of ESCs during post-thaw subculture.