• Molecules and Cells
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• v.44 no.8
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• pp.541-548
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• 2021

The discovery of human pluripotent stem cells (PSCs) at the turn of the century opened the door to a new generation of regenerative medicine research. Among PSCs, the donors available for induced pluripotent stem cells (iPSCs) are greatest, providing a potentially universal cell source for all types of cell therapies including cancer immunotherapies using natural killer (NK cells). Unlike primary NK cells, those prepared from iPSCs can be prepared with a homogeneous quality and are easily modified to exert a desired response to tumor cells. There already exist several protocols to genetically modify and differentiate iPSCs into NK cells, and each has its own advantages with regards to immunotherapies. In this short review, we detail the benefits of using iPSCs in NK cell immunotherapies and discuss the challenges that must be overcome before this approach becomes mainstream in the clinic.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.1-9
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• 2012

Because the average human life span has recently increased, the number of patients who are diagnosed with neurodegenerative diseases has escalated. Recent advances in stem cell research have given us access to unlimited numbers of multi-potent or pluripotent cells for screening for new drugs for neurodegenerative diseases. Neural stem cells (NSCs) are a good model with which to screen effective drugs that increase neurogenesis. Recent technologies for human embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) can provide human cells that harbour specific neurodegenerative disease. This article discusses the use of NSCs, ESCs and iPSCs for neurodegenerative drug screening and toxicity evaluation. In addition, we introduce drugs or natural products that are recently identified to affect the stem cell fate to generate neurons or glia.

• BMB Reports
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• v.45 no.5
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• pp.299-304
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• 2012

The ubiquitin-proteasome system is a major proteolytic system for nonlysosomal degradation of cellular proteins. Here, we investigated the response of mouse embryonic stem (ES) cells under proteotoxic stress. Proteasome inhibitors induced expression of heat shock protein 70 (HSP70) in a concentration- and time-dependent manner, and also induced apoptosis of ES cells. Importantly, more apoptotic cells were observed in ES cells compared with other somatic cells. To understand this phenomenon, we further investigated the expression of HSP70 and pluripotent cell markers. HSP70 expression was more significantly increased in somatic cells than in ES cells, and expression levels of pluripotent cell markers such as Oct4 and Nanog were decreased in ES cells. These results suggest that higher sensitivity of ES cells to proteotoxic stress may be related with lower capacity of HSP70 expression and decreased pluripotent cell marker expression, which is essential for the survival of ES cells.

• BMB Reports
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• v.54 no.10
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• pp.505-515
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• 2021

Human pluripotent stem cells (hPSCs) include human embryonic stem cells (hESCs) derived from blastocysts and human induced pluripotent stem cells (hiPSCs) generated from somatic cell reprogramming. Due to their self-renewal ability and pluripotent differentiation potential, hPSCs serve as an excellent experimental platform for human development, disease modeling, drug screening, and cell therapy. Traditionally, hPSCs were considered to form a homogenous population. However, recent advances in single cell technologies revealed a high degree of variability between individual cells within a hPSC population. Different types of heterogeneity can arise by genetic and epigenetic abnormalities associated with long-term in vitro culture and somatic cell reprogramming. These variations initially appear in a rare population of cells. However, some cancer-related variations can confer growth advantages to the affected cells and alter cellular phenotypes, which raises significant concerns in hPSC applications. In contrast, other types of heterogeneity are related to intrinsic features of hPSCs such as asynchronous cell cycle and spatial asymmetry in cell adhesion. A growing body of evidence suggests that hPSCs exploit the intrinsic heterogeneity to produce multiple lineages during differentiation. This idea offers a new concept of pluripotency with single cell heterogeneity as an integral element. Collectively, single cell heterogeneity is Janus-faced in hPSC function and application. Harmful heterogeneity has to be minimized by improving culture conditions and screening methods. However, other heterogeneity that is integral for pluripotency can be utilized to control hPSC proliferation and differentiation.

• Clinical and Experimental Pediatrics
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• v.53 no.8
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• pp.786-789
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• 2010

Induced pluripotent stem (iPS) cells are generated by epigenetic reprogramming of somatic cells through the exogenous expression of transcription factors. Recently, the generation of iPS cells from patients with a variety of genetic diseases was found to likely have a major impact on regenerative medicine, because these cells self-renew indefinitely in culture while retaining the capacity to differentiate into any cell type in the body, thereby enabling disease investigation and drug development. This review focuses on the current state of iPS cell technology and discusses the potential applications of these cells for disease modeling; drug discovery; and eventually, cell replacement therapy.

• BMB Reports
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• v.52 no.8
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• pp.482-489
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• 2019

Reproductive biotechnology has developed rapidly and is now able to overcome many birth difficulties due to infertility or the transmission of genetic diseases. Here we introduce the next generation of assisted reproductive technologies (ART), such as mitochondrial replacement technique (MRT) or genetic correction in eggs with micromanipulation. Further, we suggest that the transmission of genetic information from somatic cells to subsequent generations without gametes should be useful for people who suffer from infertility or genetic diseases. Pluripotent stem cells (PSCs) can be converted into germ cells such as sperm or oocytes in the laboratory. Notably, germ cells derived from nuclear transfer embryonic stem cells (NT-ESCs) or induced pluripotent stem cells (iPSCs) inherit the full parental genome. The most important issue in this technique is the generation of a haploid chromosome from diploid somatic cells. We hereby examine current science and limitations underpinning these important developments and provide recommendations for moving forward.

• Journal of Animal Reproduction and Biotechnology
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• v.38 no.1
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• pp.26-31
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• 2023

Chicken embryonic stem (ES) cells have great potential and provide a powerful tool to investigate embryonic development and to manipulate genetic modification in a genome. However, very limited studies are available on the functional characterization and robust expansion of chicken ES cells compared to other species. Here, we have developed a method to generate chicken embryonic stem cell-like cells under pluripotent culture conditions. The chicken embryonic stem cell-like cells were cultivated long-term over several passages of culture without loss of pluripotency in vitro and had the specific expression of key stem cell markers. Furthermore, they showed severe changes in morphology and a significant reduction in pluripotent genes after siRNA-mediated NANOG knockdown. Collectively, these results demonstrate the efficient generation of chicken embryonic stem cell-like cells from EGK stage X blastoderm-derived singularized cells and will facilitate their potential use for various purposes, such as biobanking genetic materials and understanding stemness in the fields of animal biotechnology.

• Molecules and Cells
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• v.46 no.4
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• pp.209-218
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• 2023

In induced pluripotent stem cells (iPSCs), pluripotency is induced artificially by introducing the transcription factors Oct4, Sox2, Klf4, and c-Myc. When a transgene is introduced using a viral vector, the transgene may be integrated into the host genome and cause a mutation and cancer. No integration occurs when an episomal vector is used, but this method has a limitation in that remnants of the virus or vector remain in the cell, which limits the use of such iPSCs in therapeutic applications. Chemical reprogramming, which relies on treatment with small-molecule compounds to induce pluripotency, can overcome this problem. In this method, reprogramming is induced according to the gene expression pattern of extra-embryonic endoderm (XEN) cells, which are used as an intermediate stage in pluripotency induction. Therefore, iPSCs can be induced only from established XEN cells. We induced XEN cells using small molecules that modulate a signaling pathway and affect epigenetic modifications, and devised a culture method which can produce homogeneous XEN cells. At least 4 passages were required to establish morphologically homogeneous chemically induced XEN (CiXEN) cells, whose properties were similar to those of XEN cells, as revealed through cellular and molecular characterization. Chemically iPSCs derived from CiXEN cells showed characteristics similar to those of mouse embryonic stem cells. Our results show that the homogeneity of CiXEN cells is critical for the efficient induction of pluripotency by chemicals.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.5
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• pp.488-498
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• 2015

Research on stem cells can be divided into three categories : pluripotent stem cell, adult stem cell, and induced pluripotent stem cell. Technology life cycle (TLC) on research stage is analyzed for the three stem cell categories based on diffusion model. Three diffusion models-logistic, Bass, and Bass model with integration constant (BMIC)-are applied to the number of articles related to each stem cell category in SCOPUS lists. Two different parameter estimation methods is used for each of logistic and Bass model. Results show that (1) the current year, 2015, lies in growth period at pluripotent stem cell and adult stem cell, and lies in growth period or maturity period at induced pluripotent stem cell. (2) Model fitness is the highest at BMIC model. (3) Imitation effect works best at the research area of induced pluripotent stem cell.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.10
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• pp.1447-1460
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• 2009

Myogenic satellite cells have been isolated and identified by several recently elucidated molecular markers. Furthermore, knowledge about the precise function of these markers has provided insight into the early and terminal events of satellite cells during proliferation, differentiation, transdifferentiation, specification and activation. Recently, quiescent myogenic satellite cells have been associated with possession of Pax 3 and 7 that represent pluripotent stem cells capable of differentiating into other lineages. However, the mechanism by which myogenic satellite cells attain pluripotent potential remain elusive. Later, transdifferentiating ability of these cells to another lineage in the absence or presence of certain growth factor/ or agents has revolutionized the scope of these pluripotent myogenic satellite cells for manipulation of animal production (in terms of quality and quantity of muscle protein) and health (in terms of repair of skeletal muscle, cartilage or bone).