• Reproductive and Developmental Biology
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• 제30권4호
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• pp.279-285
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• 2006

Vitrification has been suggested to be an effective method for the cryopreservation of human ES cells. However, the efficiency of vitrification with different vehicles remains a matter of ongoing controversy. The objective of this study was to assess the efficiency of cryopreservation in human ES cells by vitrification using different vehicles. A human ES cell line and a variety of vehicles, including micro-droplet (MD), open-pulled straw (OPS) and electron microscopic grid (EM-grid), were employed in an attempt to assess vitrification efficiency. In order to evaluate the survivability and the undifferentiated state of the post-vitrified human ES cells, we conducted alkaline phosphatase staining and characterization via both RT-PCR and immunofluorescence assays. The survival rates of the post-vitrified human ES cells using MD, OPS and EM-grid were determined to be 61.5%, 66.6% and 53.8%, respectively. There also exist significant differences between slow-freezing and vitrification (p<0.01). However, no significant differences were detected between the vehicle types. Finally, the pluripotency of human ES cells after thawing was verified by teratoma formation. Cryopreservation using vitrification is more effective than slow-freezing, and the efficiency of vehicles proved effective with regard to the preservation of human ES cells.

• KSBB Journal
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• 제20권1호
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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.

• Molecules and Cells
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• 제21권3호
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• pp.343-355
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• 2006

Stem cells are unique cell populations with the ability to undergo both self-renewal and differentiation, although a wide variety of adult stem cells as well as embryonic stem cells have been identified and stem cell plasticity has recently been reported. To identify genes implicated in the control of the stem cell state as well as the characteristics of each stem cell line, we analyzed the expression profiles of genes in human embryonic, hematopoietic ($CD34^+$ and $CD133^+$), and mesenchymal stem cells using cDNA microarrays, and identified genes that were differentially expressed in specific stem cell populations. In particular we were able to identify potential hESC signature-like genes that encode transcription factors (TFAP2C and MYCN), an RNA binding protein (IMP-3), and a functionally uncharacterized protein (MAGEA4). The overlapping sets of 22 up-regulated and 141 down-regulated genes identified in this study of three human stem cell types may also provide insight into the developmental mechanisms common to all human stem cells. Furthermore, our comprehensive analyses of gene expression profiles in various adult stem cells may help to identify the genetic pathways involved in self-renewal as well as in multi-lineage specific differentiation.

• 디지털융복합연구
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• 제15권7호
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• pp.415-424
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• 2017

본 연구는 공중의 체세포복제기술에 대한 위험특성, 위험심각성, 위험인식 및 위험수용의 관계를 살펴보기 위하여 서울에 거주하는 한국인 300명을 대상으로 IBM SPSS 21 프로그램과 IBM AMOS 21 프로그램을 활용하여 탐색적 요인분석과 확인적 요인분석, 상관관계 분석, 구조모형분석을 수행하였다. 주요결과를 요약 제시하면 다음과 같다. 첫째, 공중의 체세포복제기술에 대한 위험특성은 위험심각성에 통계적으로 유의한 정적 영향을 미치는 것으로 나타났다. 둘째, 공중의 체세포복제기술에 대한 위험특성은 위험인식에 통계적으로 유의한 정적 영향을 미치는 것으로 나타났다. 셋째, 공중의 체세포복제기술에 대한 위험심각성은 위험인식에 통계적으로 유의한 정적 영향을 미치는 것으로 나타났다. 넷째, 공중의 체세포복제기술에 대한 위험특성은 위험수용에 통계적으로 유의한 부적 영향을 미치는 것으로 나타났다. 다섯째, 공중의 체세포복제기술에 대한 위험심각성은 위험수용에 통계적으로 유의한 영향을 미치지 못하였다. 여섯째, 공중의 체세포복제기술에 대한 위험인식은 위험수용에 통계적으로 유의한 영향을 미치지 못하였다.

• 보건행정학회지
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• 제14권3호
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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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• 제49권4호
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• pp.197-198
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• 2016

Although three different research groups have reported successful derivations of human somatic cell nuclear transfer-derived embryonic stem cell (SCNT-ESC) lines using fetal, neonatal and adult fibroblasts, the extremely poor development of cloned embryos has hindered its potential applications in regenerative medicine. Recently, however, our group discovered that the severe methylation of lysine 9 in Histone H3 in a human somatic cell genome was a major SCNT reprogramming barrier, and the overexpression of KDM4A, a H3K9me3 demethylase, significantly improved the blastocyst formation of SCNT embryos. In particular, by applying this new approach, we were able to produce multiple SCNT-ES cell lines using oocytes obtained from donors whose eggs previously failed to develop to the blastocyst stage. Moreover, the success rate was closer to 25%, which is comparable to that of IVF embryos, so that our new human SCNT method seems to be a practical approach to establishing a pluripotent stem cell bank for the general public as well as for individual patients.

• International Journal of Stem Cells
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• 제17권2호
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• pp.204-211
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• 2024

With recent advances in adeno-associated virus (AAV)-based gene therapy, efficacy and toxicity screening have become essential for developing gene therapeutic drugs for retinal diseases. Retinal organoids from human pluripotent stem cells (hPSCs) offer a more accessible and reproducible human test platform for evaluating AAV-based gene therapy. In this study, hPSCs were differentiated into retinal organoids composed of various types of retinal cells. The transduction efficiencies of AAV2 and AAV8, which are widely used in clinical trials of inherited retinal diseases, were analyzed using retinal organoids. These results suggest that retinal organoids derived from hPSCs serve as suitable screening platforms owing to their diverse retinal cell types and similarity to the human retina. In summary, we propose an optimal stepwise protocol that includes the generation of retinal organoids and analysis of AAV transduction efficacy, providing a comprehensive approach for evaluating AAV-based gene therapy for retinal diseases.

• BMB Reports
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• 제53권8호
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• pp.400-412
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• 2020

The world has witnessed unimaginable damage from the coronavirus disease-19 (COVID-19) pandemic. Because the pandemic is growing rapidly, it is important to consider diverse treatment options to effectively treat people worldwide. Since the immune system is at the hub of the infection, it is essential to regulate the dynamic balance in order to prevent the overexaggerated immune responses that subsequently result in multiorgan damage. The use of stem cells as treatment options has gained tremendous momentum in the past decade. The revolutionary measures in science have brought to the world mesenchymal stem cells (MSCs) and MSC-derived exosomes (MSC-Exo) as therapeutic opportunities for various diseases. The MSCs and MSC-Exos have immunomodulatory functions; they can be used as therapy to strike a balance in the immune cells of patients with COVID-19. In this review, we discuss the basics of the cytokine storm in COVID-19, MSCs, and MSC-derived exosomes and the potential and stem-cell-based ongoing clinical trials for COVID-19.

• Reproductive and Developmental Biology
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• 제30권4호
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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.

• Molecules and Cells
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• 제19권1호
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• pp.46-53
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• 2005

Human embryonic stem (hES) cells, unlike most cells derived from adult or fetal human tissues, represent a potentially unlimited source of various cell types for basic clinical research. To meet the increased demand for characterized hES cell lines, we established and characterized nine new lines obtained from frozen-thawed pronucleus-stage embryos. In addition, we improved the derivation efficiency from inner cell masses (to 47.4%) and optimized culture conditions for undifferentiated hES cells. After these cell lines had been maintained for over a year in vitro, they were characterized comprehensively for expression of markers of undifferentiated hES cells, karyotype, and in vitro/in vivo differentiation capacity. All of the cell lines were pluripotent, and one cell line was trisomic for chromosome 3. Improved culture techniques for hES cells should make them a good source for diverse applications in regenerative medicine, but further investigation is needed of their basic biology.