• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2003.10a
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• pp.102-102
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• 2003

• 대한생식의학회:학술대회논문집
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• 2006.06a
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• pp.166.1-166.1
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• 2006

• Korean Journal of Animal Reproduction
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• v.21 no.2
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• pp.157-165
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• 1997

포유류 배반포배의 epiblast는 내세포괴에 포함되어 있으며, 이 epiblast cells이 배 및 태아의 생식세포와 일반 체세포로 분화된다 (Beddington, 1986; Lawson 등, 1991). 그런데 조기에 발달된 부화배반포기 배가 지연발생된 부화배반포기 배보다도 많은 epiblast cells을 가지고 있다고 한다(Talbot 등, 1995). 그래서 본 연구에서는 체외수정 유래의 배반포배의 발육속도에 따른 내세포괴/영양배엽세포의 비율 및 배아간세포 확립 효율을 비교하여 발달일령 간에 차이가 있는지를 규명하고자 하였다. 공시한 소의 난포란을 TCM-199에 0.5$\mu\textrm{g}$/ml FSH, 5$\mu\textrm{g}$/ml LH, 10% FBS, 100 units/ml penicilin, 및 100$\mu\textrm{g}$/ml streptomycin을 첨가하여 39$^{\circ}C$, 5% CO2 조건하에서 24시간 동안 체외성숙한 후, 5$\mu\textrm{g}$/ml heparin으로 수정능이 획득된 1$\times$106 sperm/ml의 정자로 체외수정을 유도하였다. 체외수정 후 18~20시간에 과립막세포를 vortexing으로 제거하여 얻은 모든 체외수정란을 3mg/ml BSA, 20${\mu}\ell$/ml NEM amino acids, 40${\mu}\ell$/ml BME amino acids, 10mM glycine 및 1mM alanine이 함유된 CR1aa 배양액에서 BRL 단층세포와 공배양을 실시하였다. 수정후 7, 8 및 9일재 (체외수정일 : 0일)에 확장배반포기까지 발달한 수정란을 이중염색 및 배아간세포의 확립 실험에 공시하였다. 체외수정후 24시간에 분할된 총 1,145개의 수정란이 7, 8 및 9일째에 후기 배반포기까지 각각 222(15.6%), 103(7.2%) 및 52(3.6%)로 발달하여 총 377개 (26.4%)가 발달하였다. 내세포괴/영양배엽세포의 비율은 7일 및 8일째 배반포배에서 각각 47.2$\pm$11.9/95.1$\pm$24.4개 (33/67%) 및 40.3$\pm$12.4/83.3$\pm$26.9개 (33/67%)로서 9일째 배반포배의 19.3$\pm$8.1/62.3$\pm$23.1개 (24/76%) 보다 유의적(P<0.05)으로 높았다. ES-like cells을 확립하기 위하여 후기배반포기 배를 mouse embryonic fibroblast 단층 공배양기에 옮긴 후 5일에 내세포괴의 부착 여부를 판정하고, 10일에 배아간세포의 확립 여부를 판정하였다. 그 결과 7, 8 및 9일째의 배반포기배의 각각 47.7% (82/172), 30.9%(22/71) 및 15.6%(5/32)에서 배아간세포가 확립되었다. 이상의 결과에서 배반포기까지의 발육이 빠른 수정란에서 영양배엽에 대한 내세포괴세포의 비율이 높았고 배아간세포의 확립율도 높다는 사실을 입증할 수 있었으며, 이와 같은 결과에서 체외수정란 유래 배반포배의 질을 결정할 수 있을 것으로 생각된다.

• Clinical and Experimental Reproductive Medicine
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• v.29 no.1
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• pp.13-20
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• 2002

Objective: This study was carried out to establish the effectiveness of the vitrification method and the optimal cryoprotectants in the cryopreservation of human embryonic stem cells (ESC). Materials and Methods: Human ESC clumps established at Seoul National University Hospital (SNUhES 1) were cryopreserved with the vitrification method using the EM grid. EDS and EFS40 were used as vitrification solutions. Results: Between the EDS and EFS40 groups, there was no significant difference in the recovery rate after cryopreservation of human ESC. The formation rates of ESC colonies in the vitrified groups were significantly lower than those in the control ESC group (p<0.05, p<0.05). In addition, the formation rate of ESC colonies in the EDS group was significantly higher than that in the EFS40 group (p<0.05). The ESC colonies in the vitrified groups were significantly smaller after culture duration of 2 and 4 days, respectively, compared with the control ESC group (p<0.1, p<0.05). However, these effects could be reduced to nonsignificant level by the additional culture of ESC colonies. The vitrified human ESC retained the properties of pluripotent cells, including the expression of cell surface. markers for the undifferentiated cells such as alkaline phosphatase and SSEA-4 (stage-specific embryonic antigen-4), and the expression of transcription factor Oct-4 (octamer-binding transcription factor-4), and the normal karyotype. Conclusion: The vitrification method using the EM grid and EDS solution was confirmed to be very effective for the cryopreservation of human ESC.

• Journal of Embryo Transfer
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• v.23 no.3
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• pp.133-139
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• 2008

DNA methylation is one of the reasons for poor survival of clone animals. The OCT-4 gene is essential for maintaining pluripotency of embryonic stem (ES) cells and early embryos. We previously reported that the 5'-promoter region of Oct-4 gene was a target of DNA methylation and the methylation status was changed variously during embryonic development in bovine. The study conducted to examine the expression and methylation pattern of tissue-dependent differentially methylated region (T-DMR) of Oct-4 gene in bovine somatic cell nuclear transfer (SCNT) and in vitro fertilization (IVF) blastocysts. The Oct-4 gene expression was evaluated by RT-PCR and fluorescence immunocytochemistry. The methylation pattern of T-DMR was analyzed using restriction mapping and bisulfite sequencing methods. The Oct-4 transcripts were highly expressed in IVF, while they were not expressed in SCNT. The Oct-4 protein was not detected or expressed at very low level in SCNT, the intensity of Oct-4 protein, however, was strong in IVF. On the other hand, the T-DMR of Oct-4 gene was hypermethylated in SCNT compared to that of IVF. These results suggested that expression and the failure of demethylation of Oct-4 gene was closely associated with incomplete development of SCNT embryos.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.19-24
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• 2005

The low density lipoprotein receptor-related protein 5 (LRP5) highly expressed in many tissues, including hepatocytes and pancreatic beta cells, can bind to apolipoprotein E. To evaluate in vivo roles of LRP5, we generated LRP5-deficient mice. LRP5 genomic DNA was isolated from TT2 embryonic stem (ES) cells. Targeting vector was constructed to disrupt an exon 18 of the mouse LRP5 gene and transfected into ES cells. Three homologous recombinants at LRP5 locus were identified from 178 G418-resistant clones. Chimeric males generated by morula aggregation technique were mated to C57BL/6 female mice. After achieving germ-line transmission, LRP5+/- females were crossed with LRP5+/- males to obtain LRP5-deficient mice. One line of mice lacking LRP5 gene was confirmed by Southern blotting. Such knock-out mice may serve as an effective animal model to study in vivo function of LRP5 gene.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.4
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• pp.311-319
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• 2009

Objective: Human embryonic stem cells (hESCs) have the capacity to differentiate into all of the cell types and therefore hold promise for cell therapeutic applications. In order to utilize this important potential of hESCs, enhancement of currently used technologies for handling and manipulating the cells is required. The cryopreservation of hESC colonies was successfully performed using the vitrification and slow freezing-rapid thawing method. However, most of the hESC colonies were showed extremely spontaneous differentiation after freezing and thawing. In this study, we were performed to rapidly collect of early passage hESCs, which was thawed and had high rate of spontaneously differentiation of SNUhES11 cell line. Methods: Four days after plating, partially spontaneously differentiated parts of hESC colony were cut off using finely drawn-out dissecting pipette, which is mechanical separation method. Results: After separating of spontaneously differentiated cells, we observed that removed parts were recovered by undifferentiated cells. Furthermore, mechanical separation method was more efficient for hESCs expansion after thawing when we repeated this method. The recovery rate after removing differentiated parts of hESC colonies were 55.0%, 74.5%, and 71.1% when we have applied this method to three passages. Conclusion: Mechanical separation method is highly effective for rapidly collecting and large volumes of undifferentiated cells after thawing of cryopreserved early passage hESCs.

• Laboraroty Animal Research
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• v.34 no.4
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• pp.257-263
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• 2018

Trefoil factor 1 (TFF1, also known as pS2) is strongly expressed in the gastrointestinal mucosa and plays a critical role in the differentiation of gastric glands. Since approximately 50% of all human gastric cancers are associated with decreased TFF1 expression, it is considered a tumor suppressor gene. Tff1 deficiency in mice results in histological changes in the antral and pyloric gastric mucosa, with severe hyperplasia and dysplasia of epithelial cells, resulting in the development of antropyloric adenoma. Here, we generated Tff1-knockout (KO) mice, without a neomycin resistant ($Neo^R$) cassette, using the clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease 9 (CRSIPR/Cas9) system. Though our Tff1-KO mice showed phenotypes very similar to the previous embryonic stem (ES)-cell-based KO mice, they differed from the previous reports in that a reduction in body weight was observed in males. These results demonstrate that these newly established Tff1-KO mice are useful tools for investigating genetic and environmental factors influencing gastric cancer, without the effects of artificial gene insertion. Furthermore, these findings suggest a novel hypothesis that Tff1 expression influences gender differences.

• Development and Reproduction
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• v.14 no.2
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• pp.123-129
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• 2010

Embryonic stem (ES) cells can self-renew maintaining the undifferentiated state. Self-renewal requires many factors such as OCT4, SOX2, and NANOG. It is previously known that OCT4 and SOX2 can bind to NANOG promoter and support Nanog gene expression in mouse ES cells by the detailed studies using the mouse Nanog promoter. Here, we constructed serial deletion mutant promoter-reporter constructs to investigate the human Nanog gene promoter in detail. The highest promoter activity was obtained in the 0.6 kb (-253/+365) promoter-reporter construct which includes the binding sites of OCT4 and SOX2. To further confirm contribution of OCT4 and SOX2 in Nanog gene expression, we introduced site- directed mutation(s) in the OCT4 and/or SOX2 binding sites of the human Nanog promoter 0.6 kb (-253/+365) and checked the influence of the mutation on the promoter activity using human EC cell line NCCIT. Mutation either in OCT4 binding site or SOX2 binding site significantly reduced the activity of Nanog promoter which directly confirmed that OCT4 and SOX2 binding is essential in human Nanog gene expression.