• 대한의생명과학회지
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• 제21권1호
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• pp.40-49
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• 2015

Mesenchymal stem cells (MSCs) have the ability to self-renew and differentiate into multi-lineage cells, thus highlighting the feasibility of using umbilical cord blood-derived MSCs (UCB-MSCs) for cell-therapy and tissueengineering. However, the low numbers of UCB-MSC derived from clinical samples requires that an ex vivo expansion step be implemented. As most stem cells reside in low oxygen tension environments (i.e., hypoxia), we cultured the UCBMSCs under 3% $O_2$ or 21% $O_2$ and the following parameters were examined: proliferation, senescence, differentiation and stem cell specific gene expression. UCB-MSCs cultured under hypoxic conditions expanded to significantly higher levels and showed less senescence compared to UCB-MSCs cultured under normoxic conditions. In regards to differentiation potential, UCB-MSCs cultured under hypoxic and normoxic conditions both underwent similar levels of osteogenesis as determined by ALP and von Kossa assay. Furthermore, UCB-MSCs cultured under hypoxic conditions exhibited higher expression of OCT4, NANOG and SOX2 genes. Moreover, cells expanded under hypoxia maintained a stem cell immnunophenotype as determined by flow cytometry. These results demonstrate that the expansion of human UCB-MSCs under a low oxygen tension microenvironment significantly improved cell proliferation and differentiation. These results demonstrate that hypoxic culture can be rapidly and easily implemented into the clinical-scale expansion process in order to maximize UCB-MSCs yield for application in clinical settings and at the same time reduce culture time while maintaining cell product quality.

• International Journal of Stem Cells
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• 제16권3호
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• pp.304-314
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• 2023

Background and Objectives: Ear cartilage malformations are commonly encountered problems in reconstructive surgery, since cartilage has low self-regenerating capacity. Malformations that impose psychological and social burden on one's life are currently treated using ear prosthesis, synthetic implants or autologous flaps from rib cartilage. These approaches are challenging because not only they request high surgical expertise, but also they lack flexibility and induce severe donor-site morbidity. Through the last decade, tissue engineering gained attention where it aims at regenerating human tissues or organs in order to restore normal functions. This technique consists of three main elements, cells, growth factors, and above all, a scaffold that supports cells and guides their behavior. Several studies have investigated different scaffolds prepared from both synthetic or natural materials and their effects on cellular differentiation and behavior. Methods and Results: In this study, we investigated a natural scaffold (alginate) as tridimensional hydrogel seeded with progenitors from different origins such as bone marrow, perichondrium and dental pulp. In contact with the scaffold, these cells remained viable and were able to differentiate into chondrocytes when cultured in vitro. Quantitative and qualitative results show the presence of different chondrogenic markers as well as elastic ones for the purpose of ear cartilage, upon different culture conditions. Conclusions: We confirmed that auricular perichondrial cells outperform other cells to produce chondrogenic tissue in normal oxygen levels and we report for the first time the effect of hypoxia on these cells. Our results provide updates for cartilage engineering for future clinical applications.

• 한국동물생명공학회지
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• 제38권3호
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• pp.177-187
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• 2023

Background: The grading of Hanwoo (Korean native cattle) is based on four economic traits, and efforts have been continuously made to improve the genetic traits associated with these traits. There is a technology to predict the expected grade based on the 4 economic genetic SNP characteristics of Korean cattle calves using single nucleotide polymorphism (SNP) technology. Selection of highly proliferative, self-renewing, and differentiating satellite cells from cattle is a key technology in the cultured meat industry. Methods: We selected the Hanwoo with high and low-scored of genomic estimated breeding value (GEBV) by using the Hanwoo 50K SNP bead chip. We then isolated the bovine satellite cells from the chuck mass. We then conducted comparative analyses of cell proliferation, immunocytochemistry, qRT-PCR at short- and long-term culture. We also analyzed the differentiation capability at short term culture. Results: Our result showed that the proliferation was significantly high at High scored GEBV (Hs-GEBV) compared to Low scored GEBV (Ls-GEBV) at short- and long-term culture. The expression levels of Pax3 were significantly higher in Hs-GEBV bovine satellite cells at long-term culture. However, there were no significant differences in the expression levels of Pax7 between Hs- and Ls-GEBV bovine satellite cells at short- and long- term culture. The expression levels of MyoG and MyHC were significantly high at Ls-GEBV bovine satellite cells. Conclusions: Our results indicated that selection of bovine satellite cells by Hanwoo 50K SNP bead chip could be effective selection methods for massive producing of satellite cells.

• 생명과학회지
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• 제26권1호
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• pp.8-16
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• 2016

적절한 농도의 활성산소종(ROS)은 병원체에 대한 세포의 방어, 신호 전달, 세포 성장 및 유전자 발현을 포함한 다양한 정상 세포 기능을 매개한다. 최근의 연구는 ROS와 ROS를 생성하는 NADPH 산화 효소(Nox)가 성인 쥐 뇌의 뇌실 하 영역(SVZ)에 있는 신경 줄기세포의 자가 복제와 신경 세포 분화에 중요하다는 것을 보여 주었다. 본 연구에서 세포 내 ROS가 갓 태어난 쥐의 뇌에서 적출되어 배양된 SVZ 신경 줄기세포에서 검출된 것으로 나타났다. Nox 유사 유전자들 중 Nox4가 배양된 세포에서 주로 발현되었고, Nox1과 Nox2는 거의 발현되지 않았다. 또한, Nox4 유전자는 신경 세포 분화 동안 최대 10배까지 발현이 크게 증가하였다. Immunocytochemistry결과 Nox4 단백질은 신경 세포 특이적인 tubulin인 Tuj1-양성 신경 세포에서 주로 발견되었다. 이와 맥을 같이 하여, 내인성 ROS는 분화 후 축삭돌기를 가지고 있으며 신경 세포로 보이는 세포에서만 검출되었다. 또한, ROS를 제거하는N-acetyl cysteine에 의해 세포 산화 환원 상태가 교란되었을 때, 신경 세포로의 분화가 크게 감소하였다. 마지막으로, shRNA를 이용하 여 Nox4를 knockdown한 세포에서 신경 세포로의 분화가 감소하였다. 이러한 연구 결과는 Nox4가 갓 태어난 쥐의 SVZ 신경 줄기 세포의 주요한 ROS 생성 효소이고, Nox4에 의한 ROS생성이 신경 세포 분화에 중요하다는 것을 암시한다.

• 아동학회지
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• 제1권
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• pp.15-27
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• 1980

PURPOSE This study was intended to analyze the play-form of normal preschool children as related to age, sex, educational experience and social maturity. METHOD 1. Subjects The subjects of this study were eighty seven 3-, 4- and 5-year-old preschool children attending educational institutions in Seoul. 2. Instruments The instruments used in this study consisted of twenty one-minute observations in 5 preschool settings and a questionnaire designed to measure the children's social maturity filled in by their parents. The observations provided information on the children's free play, that is 1) play-form: solitary, parallel and group play 2) use/non-use of toys 3) behavior: play, activity, doing nothing, onlooking 4) stationary/moving dimensions 5) play group size The questionnaire measured such factors as communication, socialization, locomotion, self-help and self-direction. 3. Data Analysis Data analysis consisted of percentage and Chi square. RESULTS 1. Play-Form The relationship between age and play-form proved to be significant at the .05 level. That is, in both boys and girls, solitary play decreased with age and group play increased with age while parallel play maintained a similar position. The relationship between sex and play-form proved to be significant at the .05 level in 3-& 4-year-old children, but not significant in 5-year-old children. That is, in their $3^{rd}$ year boys engage in the solitary play more than girls and in their $4^{th}$ year boys engage in more group play than girls. 2. Toys Without differentiation of sex and age, cases of using toys in play exceed those cases where toys were not used. 3. Behavior The relationship between age and behavior proved to be significant at the .05 level in both boys and girls. That is, with increase of age, play decreased and activity increased in boys while play increased and doing nothing decreased in girls. 4. Moving Status Totally, moving occurred more frequently in play than stationary status. Moving proved not to have a significant relationship with age, but it did Navel a significant relationship with sex at the .05 level. That is, moving tended to increase with the increase in age in both boys and girls, but not at a significant level. Boys moved significantly more than girls in all three age levels. 5. The Relationship between Educational Experience and Play-Form There was a tendency for children with longer preschool experience to engage in less solitary play and more group play than children who had less than one semester of preschool experience, but this difference was not statistically significant. 6. The Relationship between Social Maturity and Play-Form The high social maturity group engaged in less solitary play and more group play than the low social maturity group, but this was not a statistically significant difference. 7. Play Group Size Play group size was 2~10 children, but the majority of play groups consisted of 2~3 children. There was a tendency for play groups composed of 2 children to decrease with age and play groups composed of 3 children to increase with age. No significant difference was found between the sexes in play group size.

• Journal of Plant Biotechnology
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• 제35권4호
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• pp.281-290
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• 2008

식물의 Receptor like kinase (RLK) 단백질들은, 그 기능이 잘 알려져 있지 않지만, signal sequence, single transmembrane region, cytoplasmic kinase 도메인으로 구성되어 있다 RLK gene (RLGs)는 호르몬 반응 경로, 세포 분열, 식물의 성장과 발달, 자가 불수분 그리고 공생과 병원균 인식과 연관되어 있다고 보고되었다. 본 연구에서는 벼의 RLGs 중 RLG1, RLC5, RLG6, RLG#6, RLG8, RLG10, RLG17, RLG18, RLG20의 스트레스에 따른 발현 변화를 real-time PCR을 사용하여 분석하여 분자적 특징을 확인하였다. Threshold cycle ($C_T$) 수치의 변화를 통해 발현 변화를 비교하여 결과적으로, NaCl에 대해서는 모두 감소하는 경향을 확인하였으며, Salicylic acid와 상처에 대해서는 각 RLGs에 따라 발현 변화가 다르게 나타났다. 이에 비교하여 저온에서는 모든 RLGs발현이 증가하였다. 따라서 본 연구에서는 냉해에 의한 벼의 생산성 감소를 벼의 RLK에서 확인된 분자적 특징을 이용함으로써 신 기능성 품종의 개발을 통해 극복 할 수 있을 것이라는 가능성을 보여주었다.