• 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.

• 한국발생생물학회지:발생과생식
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• 제21권1호
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• pp.47-54
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• 2017

Unlike mouse results, cloning efficiency of nuclear transfer from porcine induced pluripotent stem cells (piPSCs) is very low. The present study was performed to investigate the effect of cell cycle inhibitors on the cell cycle synchronization of piPSCs. piPSCs were generated using combination of six human transcriptional factors under stem cell culture condition. To examine the efficiency of cell cycle synchronization, piPSCs were cultured on a matrigel coated plate with stem cell media and they were treated with staurosporine (STA, 20 nM), daidzein (DAI, $100{\mu}M$), roscovitine (ROSC, $10{\mu}M$), or olomoucine (OLO, $200{\mu}M$) for 12 h. Flow Cytometry (FACs) data showed that piPSCs in control were in G1 ($37.5{\pm}0.2%$), S ($34.0{\pm}0.6%$) and G2/M ($28.5{\pm}0.4%$). The proportion of cells at G1 in DAI group was significantly higher than that in control, while STA, ROSC and OLO treatments could not block the cell cycle of piPSCs. Both of viability and apoptosis were affected by STA and ROSC treatment, but there were no significantly differences between control and DAI groups. Real-Time qPCR and FACs results revealed that DAI treatment did not affect the expression of pluripotent gene, Oct4. In case of OLO, it did not affect both of viability and apoptosis, but Oct4 expression was significantly decreased. Our results suggest that DAI could be used for synchronizing piPSCs at G1 stage and has any deleterious effect on survival and pluripotency sustaining of piPSCs.

• 마이크로전자및패키징학회지
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• 제28권3호
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• pp.17-24
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• 2021

페로브스카이트 태양전지는 용액공정으로 제작되어 공정 중 전구체 조성제어를 통해 밴드갭을 용이하게 조절할 수 있다. 탠덤 태양전지의 상부셀로 활용하여 실리콘 태양전지와 접합 시 30% 이상의 효율 달성이 가능하지만, 페로브스카이트 태양전지의 낮은 안정성이 상용화의 걸림돌로 작용하고 있다. 아이오딘 이온 및 전극 물질 확산이 주된 열화기구로 알려져 있어 장기 안정성을 확보하기 위해서는 이러한 이온 이동의 방지가 필요하다. 본 연구에서는 층간소재와 페로브스카이트 광활성층 사이의 이온이동에 의한 열화현상을 관찰하고, 이를 억제하기 위해 페로브스카이트 소재와 은전극 사이에 버퍼층을 도입하여 소자의 안정성을 확보하였다. 85℃에서 300시간 이상 보관 시 버퍼가 없는 소자는 페로브스카이트 층이 PbI₂ 및 델타상으로 변화하며 변색되었으며 AgI가 형성되는 것을 확인했다. LiF와 SnO₂ 버퍼 도입 시 이온이동 억제 효과를 통해 페로브스카이트 태양전지의 열안정성이 향상되었다. LiF버퍼층 적용 및 봉지를 한 소자는 85℃-85%RH damp heat 시험 200시간 후 효율감소가 발생하지 않았으며 추가로 AM 1.5G-1SUN 하에서 최대출력점을 추적하였을 때 200시간 후 초기 효율의 90% 이상 유지하는 것을 확인했다. 이 결과는 버퍼층 형성을 통한 층간 물질이동 억제가 장기안정성을 확보하기 위한 필요조건임을 보여준다.

• Molecules and Cells
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• 제41권7호
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• pp.613-621
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• 2018

The capacity of differentiation of human pluripotent stem cells (hPSCs), which include both embryonic stem cells and induced pluripotent stem cells, into cardiomyocytes (CMs) in vitro provides an unlimited resource for human CMs for a wide range of applications such as cell based cardiac repair, cardiac drug toxicology screening, and human cardiac disease modeling. However, their applicability is significantly limited by immature phenotypes. It has been well known that currently available CMs derived from hPSCs (hPSC-CMs) represent immature embryonic or fetal stage CMs and are functionally and structurally different from mature human CMs. To overcome this critical issue, several new approaches aiming to generate more mature hPSC-CMs have been developed. This review describes recent approaches to generate more mature hPSC-CMs including their scientific principles, advantages, and limitations.

• BMB Reports
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• 제48권5호
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• pp.256-265
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• 2015

Cardiovascular and neurodegenerative diseases are major health threats in many developed countries. Recently, target tissues derived from human embryonic stem (hES) cells and induced pluripotent stem cells (iPSCs), such as cardiomyocytes (CMs) or neurons, have been actively mobilized for drug screening. Knowledge of drug toxicity and efficacy obtained using stem cell-derived tissues could parallel that obtained from human trials. Furthermore, iPSC disease models could be advantageous in the development of personalized medicine in various parts of disease sectors. To obtain the maximum benefit from iPSCs in disease modeling, researchers are now focusing on aging, maturation, and metabolism to recapitulate the pathological features seen in patients. Compared to pediatric disease modeling, adult-onset disease modeling with iPSCs requires proper maturation for full manifestation of pathological features. Herein, the success of iPSC technology, focusing on patient-specific drug treatment, maturation-based disease modeling, and alternative approaches to compensate for the current limitations of patient iPSC modeling, will be further discussed. [BMB Reports 2015; 48(5): 256-265]

• International Journal of Stem Cells
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• 제16권4호
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• pp.394-405
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• 2023

The differentiation of pluripotent stem cells has been used to study disease mechanisms and development. We previously described a method for differentiating human pluripotent stem cells (hPSCs) into salivary gland epithelial progenitors (SGEPs). Here, cystic fibrosis transmembrane conductance regulator (CFTR) knockout hPSCs were differentiated into SGEPs derived from CFTR knockout hESCs (CF-SGEPs) using the same protocol to investigate whether the hPSC-derived SGEPs can model the characteristics of CF. CF-a disease that affects salivary gland (SG) function-is caused by mutations of the CFTR gene. Firstly, we successfully generated CFTR knockout hPSCs with reduced CFTR protein expression using the CRISPR-Cas9 system. After 16 days of differentiation, the protein expression of CFTR decreased in SGEPs derived from CFTR knockout hESCs (CF-SGEPs). RNA-Seq revealed that multiple genes modulating SG development and function were down-regulated, and positive regulators of inflammation were up-regulated in CF-SGEPs, correlating with the salivary phenotype of CF patients. These results demonstrated that CFTR suppression disrupted the differentiation of hPSC-derived SGEPs, which modeled the SG development of CF patients. In summary, this study not only proved that the hPSC-derived SGEPs could serve as manipulable and readily accessible cell models for the study of SG developmental diseases but also opened up new avenues for the study of the CF mechanism.

• Molecules and Cells
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• 제41권11호
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• pp.971-978
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• 2018

The stem cell factor (SCF)/c-KIT axis plays an important role in the hematopoietic differentiation of human pluripotent stem cells (hPSCs), but its regulatory mechanisms involving microRNAs (miRs) are not fully elucidated. Here, we demonstrated that supplementation with SCF increases the hematopoietic differentiation of hPSCs via the interaction with its receptor tyrosine kinase c-KIT, which is modulated by miR-221 and miR-222. c-KIT is comparably expressed in undifferentiated human embryonic and induced pluripotent stem cells. The inhibition of SCF signaling via treatment with a c-KIT antagonist (imatinib) during hPSC-derived hematopoiesis resulted in reductions in the yield and multi-lineage potential of hematopoietic progenitors. We found that the transcript levels of miR-221 and miR-222 targeting c-KIT were significantly lower in the pluripotent state than they were in terminally differentiated somatic cells. Furthermore, suppression of miR-221 and miR-222 in undifferentiated hPSC cultures induced more hematopoiesis by increasing c-KIT expression. Collectively, our data implied that the modulation of c-KIT by miRs may provide further potential strategies to expedite the generation of functional blood cells for therapeutic approaches and the study of the cellular machinery related to hematologic malignant diseases such as leukemia.

• 한국발생생물학회지:발생과생식
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• 제26권4호
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• pp.155-163
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• 2022

Human pluripotent stem cells (hPSCs) can give rise to a vast array of differentiated derivatives, which have gained great attention in the field of in vitro toxicity evaluation. We have previously demonstrated that hPSC-derived alveolar epithelial cells (AECs) are phenotypically and functionally similar to primary AECs and could be more biologically relevant alternatives for assessing the potential toxic materials including in fine dust and cigarette smoking. Therefore, in this study, we employed hPSC-AECs to evaluate their responses to exposure of various concentrations of diesel particulate matter (dPM), cigarette smoke extract (CSE) and nicotine for 48 hrs in terms of cell death, inflammation, and oxidative stress. We found that all of these toxic materials significantly upregulated the transcription of pro-inflammatory cytokines such as IL-1α, IL-β, IL-6, and TNF-α. Furthermore, the exposure of dPM (100 ㎍/mL) strongly induced upregulation of genes related with cell death, inflammation, and oxidative stress compared with other concentrations of CSE and nicotine. These results suggest that hPSC-AECs could be a robust in vitro platform to evaluate pulmotoxicity of various air pollutants and harmful chemicals.

• 한국태양에너지학회 논문집
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• 제31권4호
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• pp.57-65
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• 2011

This study proposes a Passive Solar Chamber System (PSCS) as a passive method for reduction of building energy consumption. Through numerical analysis, the study quantitatively analyzes system performance and aims to provide foundational data for system design. For this purpose, the study configures different system operation modes seasonally and also computes thermal and ventilation performance of the system in accordance with design factors(solar radiation, air channel height and distance). System and ventilation efficiency increases along with increase in solar radiation and air channel distance; however, as the air channel height increases, the efficiencies showed a tendency to decrease. Upon installation of PSCS, an average of $98.23W/m^2$ of heat flux was introduced in the daytime for the month of January in comparison to walls with no PSCS installed. For the month of August, natural ventilation of $56.68m^3/h$ was shown to be supplied to the room.

• Molecules and Cells
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• 제45권12호
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• pp.923-934
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• 2022

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have great potential in applications such as regenerative medicine, cardiac disease modeling, and in vitro drug evaluation. However, hPSC-CMs are immature, which limits their applications. During development, the maturation of CMs is accompanied by a decline in their proliferative capacity. This phenomenon suggests that regulating the cell cycle may facilitate the maturation of hPSC-CMs. Aurora kinases are essential kinases that regulate the cell cycle, the role of which is not well studied in hPSC-CM maturation. Here, we demonstrate that CYC116, an inhibitor of Aurora kinases, significantly promotes the maturation of CMs derived from both human embryonic stem cells (H1 and H9) and iPSCs (induced PSCs) (UC013), resulting in increased expression of genes related to cardiomyocyte function, better organization of the sarcomere, increased sarcomere length, increased number of mitochondria, and enhanced physiological function of the cells. In addition, a number of other Aurora kinase inhibitors have also been found to promote the maturation of hPSC-CMs. Our data suggest that blocking aurora kinase activity and regulating cell cycle progression may promote the maturation of hPSC-CMs.