• International Journal of Stem Cells
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• v.17 no.2
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• pp.182-193
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• 2024

To address the limitations of animal testing, scientific research is increasingly focused on developing alternative testing methods. These alternative tests utilize cells or tissues derived from animals or humans for in vitro testing, as well as artificial tissues and organoids. In western countries, animal testing for cosmetics has been banned, leading to the adoption of artificial skin for toxicity evaluation, such as skin corrosion and irritation assessments. Standard guidelines for skin organoid technology becomes necessary to ensure consistent data and evaluation in replacing animal testing with in vitro methods. These guidelines encompass aspects such as cell sourcing, culture techniques, quality requirements and assessment, storage and preservation, and organoid-based assays.

• BMB Reports
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• v.51 no.10
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• pp.500-507
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• 2018

Cell reprogramming has been considered a powerful technique in the regenerative medicine field. In addition to diverse its strengths, cell reprogramming technology also has several drawbacks generated during the process of reprogramming. Telomere shortening caused by the cell reprogramming process impedes the efficiency of cell reprogramming. Transcription factors used for reprogramming alter genomic contents and result in genetic mutations. Additionally, defective mitochondria functioning such as excessive mitochondrial fission leads to the limitation of pluripotency and ultimately reduces the efficiency of reprogramming. These problems including genomic instability and impaired mitochondrial dynamics should be resolved to apply cell reprograming in clinical research and to address efficiency and safety concerns. Sirtuin (NAD+-dependent histone deacetylase) has been known to control the chromatin state of the telomere and influence mitochondria function in cells. Recently, several studies reported that Sirtuins could control for genomic instability in cell reprogramming. Here, we review recent findings regarding the role of Sirtuins in cell reprogramming. And we propose that the manipulation of Sirtuins may improve defects that result from the steps of cell reprogramming.

• BMB Reports
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• v.54 no.9
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• pp.464-469
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• 2021

Cardiomyocyte differentiation occurs through complex and finely regulated processes including cardiac lineage commitment and maturation from pluripotent stem cells (PSCs). To gain some insight into the genome-wide characteristics of cardiac lineage commitment, we performed transcriptome analysis on both mouse embryonic stem cells (mESCs) and human induced PSCs (hiPSCs) at specific stages of cardiomyocyte differentiation. Specifically, the gene expression profiles and the protein-protein interaction networks of the mESC-derived platelet-derived growth factor receptor-alpha (PDGFRα)⁺ cardiac lineage-committed cells (CLCs) and hiPSC-derived kinase insert domain receptor (KDR)⁺ and PDGFRα⁺ cardiac progenitor cells (CPCs) at cardiac lineage commitment were compared with those of mesodermal cells and differentiated cardiomyocytes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that the genes significantly upregulated at cardiac lineage commitment were associated with responses to organic substances and external stimuli, extracellular and myocardial contractile components, receptor binding, gated channel activity, PI3K-AKT signaling, and cardiac hypertrophy and dilation pathways. Protein-protein interaction network analysis revealed that the expression levels of genes that regulate cardiac maturation, heart contraction, and calcium handling showed a consistent increase during cardiac differentiation; however, the expression levels of genes that regulate cell differentiation and multicellular organism development decreased at the cardiac maturation stage following lineage commitment. Additionally, we identified for the first time the protein-protein interaction network connecting cardiac development, the immune system, and metabolism during cardiac lineage commitment in both mESC-derived PDGFRα⁺ CLCs and hiPSC-derived KDR⁺PDGFRα⁺ CPCs. These findings shed light on the regulation of cardiac lineage commitment and the pathogenesis of cardiometabolic diseases.

• BMB Reports
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• v.52 no.6
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• pp.349-359
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• 2019

After the first research declaring the generation of human induced pluripotent stem cells (hiPSCs) in 2007, several attempts have been made to model neurodegenerative disease in vitro during the past decade. Parkinson's disease (PD) is the second most common neurodegenerative disorder, which is mainly characterized by motor dysfunction. The formation of unique and filamentous inclusion bodies called Lewy bodies (LBs) is the hallmark of both PD and dementia with LBs. The key pathology in PD is generally considered to be the alpha-synuclein (${\alpha}$-syn) accumulation, although it is still controversial whether this protein aggregation is a cause or consequence of neurodegeneration. In the present work, the recently published researches which recapitulated the ${\alpha}$-syn aggregation phenomena in sporadic and familial PD hiPSC models were reviewed. Furthermore, the advantages and potentials of using patient-derived PD hiPSC with focus on ${\alpha}$-syn aggregation have been discussed.

• Journal of Life Science
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• v.30 no.4
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• pp.394-401
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• 2020

As embryonic stem cells become pluripotent, they may cause tumor development when injected into a host. Therefore, researchers are focusing heavily on the therapeutic potential of tissue-specific stem cells (adult stem cells) without resultant tumor formation. Adult stem cells can proliferate for a limited number of generations and are restricted to certain cell types (multipotent). Mature tissue cell types in mammals cannot be intrinsically dedifferentiated or transdifferentiated to adult stem cells. Hence, the technology of induced pluripotent stem cells (iPSCs) for reprogramming adult somatic cells was introduced in 2006, ushering in a new era in adult stem cell research. Although iPSCs have been widely used in the field, the approach has several limitations: instability of the reprogramming process, risk of incomplete reprogramming, and exposure to transgenes integrated into the cell genome. Two years before the introduction of the iPSC technique, the synthetic small molecule 2,6-disubstituted purine, called reversine, was introduced. Reversine can induce the dedifferentiation of committed cells into multipotent progenitor-type cells by reprogramming and converting adult cells to other cell types under appropriate stimuli. Thus, it can be used as a chemically induced multipotent cell agent to overcome the limitations of iPSCs. Also, as an alternative therapeutic approach for treating obesity, it can be used to generate beige cells by browning white adipocytes. While reversine has the potential to act as an anti-cancer agent, this review focuses on its role in differentiation, dedifferentiation, and transdifferentiation in somatic cells.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2001.11a
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• pp.40-46
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• 2001

The use of pluripotent stem cells has tremendous advantages for various purposes but these cell lines with proven germ-line transmission have been completely established only in the mouse. Embryonic germ (EG) cell lines are also pluripotent and undifferentiated stem cells established from primordial germ cells (PGCs). This study was conducted to establish and characterize the chicken EG cells derived from gonadal primordial germ cells. We isolated gonadal PGCs from 5.5-day-old (stage 28) White leghorn (WL) embryos and established chicken EG cells lines with EG culture medium supplemented with human stem cell factor (hSCF), murine leukemia inhibitory factor (mLIF), bovine basic fibroblast growth factor (bFGF), human interleukin-11 (hIL-11), and human insulin-like growth factor-I (hIGF-I). These cells grew continuously for 4 months (10 passages) on a feeder layer of mitotically active chicken embryonic fibroblasts. These cells were characterized by screening with the Periodic acid-Shiff＇s reaction, anti-SSEA-1 antibody, and a proliferation assay after several passages. As the results, the chicken EG cells maintained characteristics of undifferentiated stem cells as well as that of gonadal PGCs. When cultured in suspension, the chicken EG cells successfully formed an embryoid body and differentiated into a variety of cell types when re-seeded onto culture dish. The chicken EG cells were injected into blastodermal layer at stage X and dorsal aorta of recipient embryo at stage 14 (incubation of 53hrs) and produced chimeric chickens with various differentiated tissues derived from the EG cells. The germline chimeras were also successfully induced by using EG cells. Thus, Chicken EG cells will be useful for the production of transgenic chickena and for studies of germ cell differentiation and genomic imprinting.

• BMB Reports
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• v.48 no.5
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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]

• Experimental and Molecular Medicine
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• v.50 no.12
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• pp.5.1-5.15
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• 2018

Targeting hair follicle regeneration has been investigated for the treatment of hair loss, and fundamental studies investigating stem cells and their niche have been described. However, knowledge of stem cell metabolism and the specific regulation of bioenergetics during the hair regeneration process is currently insufficient. Here, we report the hair regrowth-promoting effect of a newly synthesized novel small molecule, IM176OUT05 (IM), which activates stem cell metabolism. IM facilitated stemness induction and maintenance during an induced pluripotent stem cell generation process. IM treatment mildly inhibited mitochondrial oxidative phosphorylation and concurrently increased glycolysis, which accelerated stemness induction during the early phase of reprogramming. More importantly, the topical application of IM accelerated hair follicle regeneration by stimulating the progression of the hair follicle cycle to the anagen phase and increased the hair follicle number in mice. Furthermore, the stem cell population with a glycolytic metabotype appeared slightly earlier in the IM-treated mice. Stem cell and niche signaling involved in the hair regeneration process was also activated by the IM treatment during the early phase of hair follicle regeneration. Overall, these results show that the novel small molecule IM promotes tissue regeneration, specifically in hair regrowth, by restructuring the metabolic configuration of stem cells.

• BMB Reports
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• v.51 no.2
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• pp.85-91
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• 2018

Pluripotent stem cell (PSC) variations can cause significant differences in the efficiency of cardiac differentiation. This process is unpredictable, as there is not an adequate indicator at the undifferentiated stage of the PSCs. We compared global gene expression profiles of two PSCs showing significant differences in cardiac differentiation potential. We identified 12 up-regulated genes related to heart development, and we found that 4 genes interacted with multiple genes. Among these genes, Gata6 is the only gene that was significantly induced at the early stage of differentiation of PSCs to cardiomyocytes. Gata6 knock-down in PSCs decreased the efficiency of cardiomyocyte production. In addition, we analyzed 6 mESC lines and 3 iPSC lines and confirmed that a positive correlation exists between Gata6 levels and efficiency of differentiation into cardiomyocytes. In conclusion, Gata6 could be utilized as a biomarker to select the best PSC lines to produce PSC-derived cardiomyocytes for therapeutic purposes.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.5
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• pp.357-365
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• 2022

Simultaneous myofibril and mitochondrial development is crucial for the cardiac differentiation of pluripotent stem cells (PSCs). Specifically, mitochondrial energy metabolism (MEM) development in cardiomyocytes is essential for the beating function. Although previous studies have reported that MEM is correlated with cardiac differentiation, the process and timing of MEM regulation for cardiac differentiation remain poorly understood. Here, we performed transcriptome analysis of cells at specific stages of cardiac differentiation from mouse embryonic stem cells (mESCs) and human induced PSCs (hiPSCs). We selected MEM genes strongly upregulated at cardiac lineage commitment and in a time-dependent manner during cardiac maturation and identified the protein-protein interaction networks. Notably, MEM proteins were found to interact closely with cardiac maturation-related proteins rather than with cardiac lineage commitment-related proteins. Furthermore, MEM proteins were found to primarily interact with cardiac muscle contractile proteins rather than with cardiac transcription factors. We identified several candidate MEM regulatory genes involved in cardiac lineage commitment (Cck, Bdnf, Fabp4, Cebpα, and Cdkn2a in mESC-derived cells, and CCK and NOS3 in hiPSC-derived cells) and cardiac maturation (Ppargc1α, Pgam2, Cox6a2, and Fabp3 in mESC-derived cells, and PGAM2 and SLC25A4 in hiPSC-derived cells). Therefore, our findings show the importance of MEM in cardiac maturation.