• BMB Reports
• /
• 제48권12호
• /
• pp.668-676
• /
• 2015

Pluripotent stem cells only exist in a narrow window during early embryonic development, whereas multipotent stem cells are abundant throughout embryonic development and are retainedin various adult tissues and organs. While pluripotent stem cell lines have been established from several species, including mouse, rat, and human, it is still challenging to establish stable multipotent stem cell lines from embryonic or adult tissues. Based on current knowledge, we anticipate that by manipulating extrinsic and intrinsic signaling pathways, most if not all types of stem cells can be maintained in a long-term culture. In this article, we summarize current culture conditions established for the long-term maintenance of authentic pluripotent and multipotent stem cells and the signaling pathways involved. We also discuss the general principles of stem cell maintenance and propose several strategies on the establishment of novel stem cell lines through manipulation of signaling pathways.

• 한국수정란이식학회:학술대회논문집
• /
• 한국수정란이식학회 2004년도 제4회 발생공학 국제심포지움 및 학술대회
• /
• pp.88-88
• /
• 2004

• Reproductive and Developmental Biology
• /
• 제32권2호
• /
• pp.105-110
• /
• 2008

The endogenous retrovirus-like elements (HERVs) found on several human chromosomes are somehow involved in gene regulation, especially during the transcription level. HERV-H, located on chromosome Xp22, may regulate gastrin-releasing peptide receptor (GRPR) in connection with diverse diseases. By suppression subtractive hybridization screen on SV40-immortalized lung fibroblast (WI-38 VA-13), we discovered that expression of HERV-HX2, a clustered HERV-H sequence on chromosome X, was upregulated in immortalized lung cells, compared to that of normal cells. Expression of HERV-HX2 was then analyzed in various cell lines, including normal somatic cells, cancer cells, SV40-immortalized cells, and undifferentiated and differentiated human embryonic stem cells. Expression of HERV-HX2 was specifically upregulated in continuously-dividing cells, such as cancer cells and SV40-immortalized cells. Especially, HERV-HX2 in HeLa cells was highly upregulated during the S phase of the cell cycle. Similar results were obtained in hES cells, in which undifferentiated cells expressed more HERV-HX2 mRNA than differentiated hES cells, including neural precursor and endothelial progenitor cells. Taken together, our results suggest that HERV-HX2 is upregulated in cancer cells and undifferentiated hES cells, whereas downregulated as differentiation progress. Therefore, we assume that HERV-HX2 may playa role on proliferation of cancer cells as well as differentiation of hES cells in the transcriptional level.

• Clinical and Experimental Reproductive Medicine
• /
• 제29권2호
• /
• pp.117-127
• /
• 2002

Objective: This study was to investigate the generation of the functional neuron derived from human embryonic stem (hES, MB03) cells on in vitro neural cell differentiation system. Methods: For neural progenitor cell formation derived from hES cells, we produced embryoid bodies (EB: for 5 days, without mitogen) from hES cells and then neurospheres (for $7{\sim}10$ days, 20 ng/ml of bFGF added N2 medium) from EB. And then finally for the differentiation into mature neuron, neural progenitor cells were cultured in i) N2 medium only (without bFGF), ii) N2 supplemented with 20 ng/ml platelet derived growth factor-bb (PDGF-bb) or iii) N2 supplemented with 5 ng/ml brain derived neurotrophic factor (BDNF) for 2 weeks. Identification of neural cell differentiation was carried out by immunocytochemistry using $\beta_{III}$-tubulin (1:250), MAP-2 (1:100) and GFAP (1:500). Also, generation of functional neuron was identified using anti-glutamate (Sigma, 1:1000), anti-GABA (Sigma, 1:1000), anti-serotonin (Sigma, 1:1000) and anti-tyrosine hydroxylase (Sigma, 1:1000). Results: In vitro neural cell differentiation, neurotrophic factors (PDGF and BDNF) treated cell groups were high expressed MAP-2 and GFAP than non-treated cell group. The highest expression pattern of MAP-2 and $\beta_{III}$-tubulin was indicated in BDNF treated group. Also, in the presence of PDGF-bb or BDNF, most of the neural cells derived from hES cells were differentiated into glutamate and GABA neuron in vitro. Furthermore, we confirmed that there were a few serotonin and tyrosine hydroxylase positive neuron in the same culture environment. Conclusion: This results suggested that the generation of functional neuron derived from hES cells was increased by addition of neurotrophic factors such as PDGF-bb or BDNF in b-FGF induced neural cell differentiation system and especially glutamate and GABA neurons were mainly produced in the system.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제38권6호
• /
• pp.343-353
• /
• 2012

Objectives: This aim of this study was to effectively isolate mesenchymal stem cells (hSMSCs) from human submandibular skin tissues (termed hSMSCs) and evaluate their characteristics. These hSMSCs were then chemically induced to the neuronal lineage and analyzed for their neurogenic characteristics in vitro. Materials and Methods: Submandibular skin tissues were harvested from four adult patients and cultured in stem cell media. Isolated hSMSCs were evaluated for their multipotency and other stem cell characteristics. These cells were differentiated into neuronal cells with a chemical induction protocol. During the neuronal induction of hSMSCs, morphological changes and the expression of neuron-specific proteins (by fluorescence-activated cell sorting [FACS]) were evaluated. Results: The hSMSCs showed plate-adherence, fibroblast-like growth, expression of the stem-cell transcription factors Oct 4 and Nanog, and positive staining for mesenchymal stem cell (MSC) marker proteins (CD29, CD44, CD90, CD105, and vimentin) and a neural precursor marker (nestin). Moreover, the hSMSCs in this study were successfully differentiated into multiple mesenchymal lineages, including osteocytes, adipocytes, and chondrocytes. Neuron-like cell morphology and various neural markers were highly visible six hours after the neuronal induction of hSMSCs, but their neuron-like characteristics disappeared over time (24-48 hrs). Interestingly, when the chemical induction medium was changed to Dulbecco's Modified Eagle Medium (DMEM) supplemented with fetal bovine serum (FBS), the differentiated cells returned to their hSMSC morphology, and their cell number increased. These results indicate that chemically induced neuron-like cells should not be considered true nerve cells. Conclusion: Isolated hSMSCs have MSC characteristics and express a neural precursor marker, suggesting that human skin is a source of stem cells. However, the in vitro chemical neuronal induction of hSMSC does not produce long-lasting nerve cells and more studies are required before their use in nerve-tissue transplants.

• 한국발생생물학회:학술대회논문집
• /
• 한국발생생물학회 2004년도 추계학술대회
• /
• pp.21-21
• /
• 2004

• 한국발생생물학회지:발생과생식
• /
• 제12권1호
• /
• pp.87-95
• /
• 2008

만능성 인간 배아줄기세포로부터 확립된 신경줄기세포 또는 신경전구세포는 퇴행성 신경질환 세포치료제로 이용될 수 있는 다양한 종류의 신경세포로 분화 유도될 수 있다. 하지만, 인간 배아줄기세포로부터 신경세포를 생산하기 위한 기술은 아직 많은 장애를 가지고 있다. 인간 배아줄기세포 유래 신경전구세포에서 특징적으로 나타나는 신경관 유사로제트에 대한 이해는 인간 배아줄기세포 신경 분화의 효율을 높이는데 유용한 정보를 제공할 것으로 사료된다. 일반적으로 신경로제트(neural rosette)는 분화 중인 배아체를 부착 배양함으로써 유도하지만, 이 방법은 시간이 걸리고 복잡하다는 단점이 있다. 본 연구에서는 신경로제트가 부착배양을 하지 않고 부유배양으로 형성될 수 있는지 조사하였다. 우선적으로, 배아체 형성 및 신경분화에 인간 배아줄기세포 클럼프(clump) 크기가 영향을 주는지를 조사하였고, 사방 $500\;{\mu}m$ 크기의 인간 배아줄기세포 클럼프가 신경 분화 유도에 가장 효과적임을 확인하였다. 로제트 형성을 유도하기 위해, 사방 $500\;{\mu}m$ 크기의 인간 배아줄기세포 클럼프를 1주일 동안 EB 배양배지에 부유 배양함으로써 균일한 크기의 배아체를 얻은 후, NES 배양 배지에서 부가적으로 $1{\sim}2$주 동안 계속 부유 배양한 결과, $7{\sim}10$일 사이에 신경관 유사 로제트가 형성됨을 확인하였다. 로제트 형성 세포의 신경전구세포로서 특성은 RT-PCR과 면역형광염색법을 이용한 신경전구세포 특이적 마커(vimentivi, nestin, MSI1, MSI2, Sox1, Tuj1) 발현을 통해 확인하였다. 또한, 성장인자를 제외한 NES 배양 배지에서 신경로제트를 $2{\sim}6$주 동안 지속적으로 배양하면 성숙 신경세포로의 말단 분화가 유도됨을 확인하였다. 신경세포 특이적 마커(Tuj1, MAP2, GABA)와 신경아교 특이적 마커($S100{\beta}$, GFAP)는 $2{\sim}3$주 또는 4주 후에 각각 발현이 유도됨을 확인하였고, 희소 돌기아교 특이적 마커(O1과 CNPase)는 $5{\sim}6$주 후에 발현이 증가함을 확인하였다. 본 연구결과는 신경로제트가 부유 배양시스템에서 성공적으로 형성됨을 보여주고 있으며, 이는 인간 배아줄기세포의 신경 분화를 이해하고, 신경전구세포 유도 과정을 단순화하는데 효과적으로 이용될 수 있을 것으로 사료된다.

• Molecules and Cells
• /
• 제42권9호
• /
• pp.617-627
• /
• 2019

Brain organoids are an exciting new technology with the potential to significantly change our understanding of the development and disorders of the human brain. With step-by-step differentiation protocols, three-dimensional neural tissues are self-organized from pluripotent stem cells, and recapitulate the major millstones of human brain development in vitro. Recent studies have shown that brain organoids can mimic the spatiotemporal dynamicity of neurogenesis, the formation of regional neural circuitry, and the integration of glial cells into a neural network. This suggests that brain organoids could serve as a representative model system to study the human brain. In this review, we will overview the development of brain organoid technology, its current progress and applications, and future prospects of this technology.

• Journal of Genetic Medicine
• /
• 제12권1호
• /
• pp.31-37
• /
• 2015

Purpose: We investigated the neurogenic potentials of amniotic fluid-derived stem cells (AFSCs) according to the expression levels of stem cell markers and ingredients in the neural induction media. Materials and Methods: Four samples of AFSCs with different levels of Oct-4 and c-kit expression were differentiated neurally, using three kinds of induction media containing retinoic acid (RA) and/or a mixture of 3-isobutyl-1-methylxanthine/indomethacin/insulin (neuromix), and examined by immunofluorescence and reverse transcription-polymerase chain reaction (RT-PCR) for their expression of neurospecific markers. Results: The cells in neuromix-containing media displayed small nuclei and long processes that were characteristic of neural cells. RT-PCR analysis revealed that the number of neural markers showing upregulation was greater in cells cultured in the neuromix-containing media than in those cultured in RA-only medium. Neurospecific gene expression was also higher in Oct-4 and c-kit double-positive cells than in c-kit-low or -negative cells. Conclusion: The stem cell marker c-kit (rather than Oct-4) and the ingredient neuromix (rather than RA) exert greater effects on neurogenesis of AFSCs.

• Journal of Korean Neurosurgical Society
• /
• 제63권2호
• /
• pp.153-162
• /
• 2020

Spinal cord injury (SCI) is one of the most devastating conditions and many SCI patients suffer neurological sequelae. Stem cell therapies are expected to be beneficial for many patients with central nervous system injuries, including SCI. Adult stem cells (ASCs) are not associated with the risks which embryonic stem cells have such as malignant transformation, or ethical problems, and can be obtained relatively easily. Consequently, many researchers are currently studying the effects of ASCs in clinical trials. The environment of transplanted cells applied in the injured spinal cord differs between the phases of SCI; therefore, many researchers have investigated these phases to determine the optimal time window for stem cell therapy in animals. In addition, the results of clinical trials should be evaluated according to the phase in which stem cells are transplanted. In general, the subacute phase is considered to be optimal for stem cell transplantation. Among various candidates of transplantable ASCs, mesenchymal stem cells (MSCs) are most widely studied due to their clinical safety. MSCs are also less immunogenic than neural stem/progenitor cells and consequently immunosuppressants are rarely required. Attempts have been made to enhance the effects of stem cells using scaffolds, trophic factors, cytokines, and other drugs in animal and/or human clinical studies. Over the past decade, several clinical trials have suggested that transplantation of MSCs into the injured spinal cord elicits therapeutic effects on SCI and is safe; however, the clinical effects are limited at present. Therefore, new therapeutic agents, such as genetically enhanced stem cells which effectively secrete neurotrophic factors or cytokines, must be developed based on the safety of pure MSCs.