• 생명과학회지
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• 제25권6호
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• pp.724-731
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• 2015

중간엽줄기세포는 성체줄기세포의 한 종류로, 자기재생산능력(self-renwal)과 다분화능(multipotency)을 가지고 있고, 다양한 자양인자(trophic factors)들을 분비한다. 뿐만 아니라, 중간엽줄기세포는 골수, 지방, 탯줄과 같은 조직에서 쉽게 얻을 수 있기 때문에 줄기세포치료에 좋은 도구로 이용되고 있다. 하지만, 줄기세포치료의 효율성을 높이기 위해 추출한 세포의 개체 수를 늘리는 과정에서 중간엽줄기세포는 점차적인 노화를 겪게 되고, 이는 줄기세포 자체의 기능적인 감소를 야기한다. 인체 내에서, 노화된 줄기세포는 조직 내의 항상성 유지에 부정적인 영향 을 미치게 되고, 이러한 상태가 지속되면 대표적인 노인성 질환인 퇴행성 질환의 원인이 된다. 최근 연구들에 의하면 중간엽줄기세포가 노화를 겪을 때, 노화 관련된 DNA 메틸화 패턴의 변화와 히스톤의 변형이 일어남을 확인하였다. 또한, 중간엽줄기세포의 노화에 있어서 DNA 메틸화효소(DNA methyltransferase) 억제제와 히스톤 아세틸화효소(histone deacetylase) 억제제가 부분적으로 노화를 개선하는 효과를 관찰한 연구사례들이 있다. 본 총설에서는, 노화에 따른 후생유전학적인 변화에 의해, 조절되는 노화 관련 유전자들과 중간엽줄기세포의 노화에 대한 연구사례들을 분석하여 서술하고자 한다.

• 과학기술학연구
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• 제12권1호
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• pp.185-207
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• 2012

황우석 사태 이후 한국의 국가는 줄기세포 연구를 장려하고 시험관 아기 산업을 장려하겠다는 입장과 "글로벌 스탠다드"에 부합하는 윤리적 규제를 도입하겠다는, 많은 경우 서로 모순될 수밖에 없는 입장을 표명하여 왔다. 줄기세포 연구에 대한 윤리적 규제가 점점 강화되면서 인간배아세포 연구가 위축되면서, 연구 공동체와 바이오산업, 임상의사와 환자, 그리고 국가 자체를 위기로부터 구원해줄 대안으로 떠오른 것은 체세포 줄기세포였다. 그러나 한국 생명공학기술에 대한 연구들은 주로 배아줄기세포에 초점을 맞추고 있으며, 조혈줄기세포나 지방유래줄기세포와 같은 체세포 줄기세포에 대한 연구에는 상대적으로 관심이 적은 것으로 보인다. 배아줄기세포가 흔히 실험적이고 윤리적으로 논란거리로 여겨지는 반면에, 조혈모 혹은 간엽줄기세포와 체세포 줄기세포는 별다른 공적인 논의 없이 대중들의 일상 속으로 들어와 있다. 한국의 많은 일반인들은 조혈모 줄기세포 치료를 통해 백혈병으로부터 생명을 구한 환자들의 사례에 이미 익숙한가 하면, 다른 한편에서 지방유래줄기세포 치료를 선전하는 의사들의 수가 늘고 있고, 지방유래줄기세포의 개념을 활용하여 만든 화장품이 소비자들의 주목을 받고 있기도 한 현실이 이미 진행되고 있다. 이러한 맥락에서, 본 논문은 배아줄기세포나 국가 정책이나 연구 규제에만 집중되어 시장을 놓치고 있는 윤리적 논의는 한국에서 줄기세포 기술의 정치의 전모를 다루기에 한계가 크다는 사실을 주장하고자 한다.

• 대한의생명과학회지
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• 제19권1호
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• pp.41-47
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• 2013

Pluripotent stem cells (PSCs) have lots of potential in biomedical sciences owing to its potential to differentiate into any kind of cells in the body. However, it is still a challenge to culture PSCs on a large scale for application to regenerative medicine. Herein, we introduce a synthetic polymer that enables large-scale suspension culture of human PSCs. By employing suspension culture, it became unnecessary to use conventional substrata such as mouse embryonic fibroblast (MEF) or Matrigel$^{TM}$, which are believed to be main causative sources of xenogeneic contamination in cultured human PSCs in vitro. Human PSCs were cultured in the medium in which elastin-like polypeptide (ELP) dissolved. The ELP in the medium became harden as temperature increases by transforming the medium into a semi-solid gel that supported growth of human PSCs in suspension. Gel-sol transition temperature of ELP can be adjusted by modifying the peptide sequence in which 5 amino acids, Val-Pro-Gly-Xaa-Gly, repeated sequentially. We constructed 3D suspension media having transition temperature around $33{\sim}35^{\circ}C$ using an ELP consisted of 40, 60, or 80 repeats of a monomer, which was Val-Pro-Gly-Val-Gly. Among the ELPs, ELP80 was chosen as the best ELP to support growth of human PSCs in suspension culture. This result suggests that the ELP80 can be a medium component for culturing human PSCs in large-scale.

• Asian Pacific Journal of Cancer Prevention
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• 제13권7호
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• pp.3103-3107
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• 2012

Osteosarcoma, the most common primary mesenchymal malignant tumor, usually has bad prognosis in man, with cancer stem-like cells (CSCs) considered to play a critical role in tumorigenesis and drug-resistance. It is known that phosphatidylinositol 3-kinase (PI3K) is involved in regulation of tumor cell fates, such as proliferation, cell cycling, survival and apoptosis. Whether and how PI3K and inhibitors might cooperate in human osteosarcoma CSCs is still unknown. We therefore evaluated the effects of LY294002, a PI3K inhibitor, on the cell cycle and apoptosis of osteosarcoma CSCs in vitro. LY294002 prevented phosphorylation of protein kinase B (PKB/Akt) by inhibition of PI3K phosphorylation activity, thereby inducing G0/G1 cell cycle arrest and apoptosis in osteosarcoma CSCs. Further studies also demonstrated that apoptosis induction by LY294002 is accompanied by activation of caspase-9, caspase-3 and PARP, which are involved in the mitochondrial apoptosis pathway. Therefore, our results indicate PI3K inhibitors may represent a potential strategy for managing human osteosarcoma via affecting CSCs.

• 한국발생생물학회지:발생과생식
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• 제20권1호
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• pp.63-71
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• 2016

Human embryonic stem cells (hESCs) have been routinely cultured on mouse embryonic fibroblast feeder layers with a medium containing animal materials. For clinical application of hESCs, animal-derived products from the animal feeder cells, animal substrates such as gelatin or Matrigel and animal serum are strictly to be eliminated in the culture system. In this study, we performed that SNUhES32 and H1 were cultured on human amniotic fluid cells (hAFCs) with KO-SR XenoFree and a humanized substrate. All of hESCs were relatively well propagated on hAFCs feeders with xeno-free conditions and they expressed pluripotent stem cell markers, alkaline phosphatase, SSEA-4, TRA1-60, TRA1-81, Oct-4, and Nanog like hESCs cultured on STO or human foreskin fibroblast feeders. In addition, we observed the expression of nonhuman N-glycolylneuraminic acid (Neu5GC) molecules by flow cytometry, which was xenotransplantation components of contamination in hESCs cultured on animal feeder conditions, was not detected in this xeno-free condition. In conclusion, SNUhES32 and H1 could be maintained on hAFCs for humanized culture conditions, therefore, we suggested that new xeno-free conditions for clinical grade hESCs culture will be useful data in future clinical studies.

• Biomolecules & Therapeutics
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• 제27권1호
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• pp.25-33
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• 2019

Mesenchymal stem cells are classified as multipotent stem cells, due to their capability to transdifferentiate into various lineages that develop from mesoderm. Their popular appeal as cell-based therapy was initially based on the idea of their ability to restore tissue because of their differentiation potential in vitro; however, the lack of evidence of their differentiation to target cells in vivo led researchers to focus on their secreted trophic factors and their role as potential powerhouses on regulation of factors under different immunological environments and recover homeostasis. To date there are more than 800 clinical trials on humans related to MSCs as therapy, not to mention that in animals is actively being applied as therapeutic resource, though it has not been officially approved as one. But just as how results from clinical trials are important, so is to reveal the biological mechanisms involved on how these cells exert their healing properties to further enhance the application of MSCs on potential patients. In this review, we describe characteristics of MSCs, evaluate their benefits as tissue regenerative therapy and combination therapy, as well as their immunological properties, activation of MSCs that dictate their secreted factors, interactions with other immune cells, such as T cells and possible mechanisms and pathways involved in these interactions.

• Molecules and Cells
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• 제45권7호
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• pp.479-494
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• 2022

Human mesenchymal stem cells (MSCs) are multipotent stem cells that have been intensively studied as therapeutic tools for a variety of disorders. To enhance the efficacy of MSCs, therapeutic genes are introduced using retroviral and lentiviral vectors. However, serious adverse events (SAEs) such as tumorigenesis can be induced by insertional mutagenesis. We generated lentiviral vectors encoding the wild-type herpes simplex virus thymidine kinase (HSV-TK) gene and a gene containing a point mutation that results in an alanine to histidine substitution at residue 168 (TK(A168H)) and transduced expression in MSCs (MSC-TK and MSC-TK(A168H)). Transduction of lentiviral vectors encoding the TK(A168H) mutant did not alter the proliferation capacity, mesodermal differentiation potential, or surface antigenicity of MSCs. The MSC-TK(A168H) cells were genetically stable, as shown by karyotyping. MSC-TK(A168H) responded to ganciclovir (GCV) with an half maximal inhibitory concentration (IC₅₀) value 10-fold less than that of MSC-TK. Because MSC-TK(A168H) cells were found to be non-tumorigenic, a U87-TK(A168H) subcutaneous tumor was used as a SAE-like condition and we evaluated the effect of valganciclovir (vGCV), an oral prodrug for GCV. U87-TK(A168H) tumors were more efficiently ablated by 200 mg/kg vGCV than U87-TK tumors. These results indicate that MSC-TK(A168H) cells appear to be pre-clinically safe for therapeutic use. We propose that genetic modification with HSV-TK(A168H) makes allogeneic MSC-based ex vivo therapy safer by eliminating transplanted cells during SAEs such as uncontrolled cell proliferation.

• 생명과학회지
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• 제26권12호
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• pp.1355-1359
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• 2016

인간 중간엽 줄기세포(hMSCs)는 신경세포(neuron-like cells)를 포함한 다양한 세포로 분화할 수 있는 능력을 지닌 성체 줄기세포(adult stem cells)이다. 본 연구에서는 인간의 골수유래-중간엽 줄기세포(bone marrow-mesenchymal stem cells; hBM-MSCs)를 이용한 신경분화에서 신경세포 표지자(neuronal marker)인 NF-M, Tuj-1 뿐만 아니라 성상세포 표지자(glial marker)인 GFAP의 발현 역시 의미 있게 증가함을 real-time PCR, Western blot, and immunocytochemical staining법을 통하여 관찰하였다. 이를 개선하기 위하여, 신경분화에 중요한 신호전달자(signal intermediator)인 PDE4를 억제한 후 신경분화를 유도하였다. PDE4 억제자인 rolipram 혹은 resveratrol를 각각 처리하여 신경분화한 줄기세포(Roli- or RSV-dMSCs)에서 NF-M, Tuj-1의 발현이 증가하였고 반면, GFAP의 발현은 감소함을 real-time PCR, Western blot, and immunocytochemical staining법을 통하여 관찰하였다. 본 연구를 통하여, PDE4를 조절하며 줄기세포의 신경분화를 개선할 수 있음을 보였다.

• Reproductive and Developmental Biology
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• 제36권1호
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• pp.33-37
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• 2012

Differential capacity of the parthenogenetic embryonic stem cells (PESCs) is still under controversy and the mechanisms of its neural induction are yet poorly understood. Here we demonstrated neural lineage induction of PESCs by addition of insulin-like growth factor-2 (Igf2), which is an important factor for embryo organ development and a paternally expressed imprinting gene. Murine PESCs were aggregated to embryoid bodies (EBs) by suspension culture under the leukemia inhibitory factor-free condition for 4 days. To test the effect of exogenous Igf2, 30 ng/ml of Igf2 was supplemented to EBs induction medium. Then neural induction was carried out with serum-free medium containing insulin, transferrin, selenium, and fibronectin complex (ITSFn) for 12 days. Normal murine embryonic stem cells derived from fertilized embryos (ESCs) were used as the control group. Neural potential of differentiated PESCs and ESCs were analyzed by immunofluorescent labeling and real-time PCR assay (Nestin, neural progenitor marker; Tuj1, neuronal cell marker; GFAP, glial cell marker). The differentiated cells from both ESC and PESC showed heterogeneous population of Nestin, Tuj1, and GFAP positive cells. In terms of the level of gene expression, PESC showed 4 times higher level of GFAP expression than ESCs. After exposure to Igf2, the expression level of GFAP decreased both in derivatives of PESCs and ESCs. Interestingly, the expression level of $Tuj1$ increased only in ESCs, not in PESCs. The results show that IGF2 is a positive effector for suppressing over-expressed glial differentiation during neural induction of PESCs and for promoting neuronal differentiation of ESCs, while exogenous Igf2 could not accelerate the neuronal differentiation of PESCs. Although exogenous Igf2 promotes neuronal differentiation of normal ESCs, expression of endogenous $Igf2$ may be critical for initiating neuronal differentiation of pluripotent stem cells. The findings may contribute to understanding of the relationship between imprinting mechanism and neural differentiation and its application to neural tissue repair in the future.

• 한국임상수의학회지
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• 제25권6호
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• pp.458-465
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• 2008

The purpose of this study is to characterize canine mesenchymal stem cells (MSCs) derived from bone marrow (BM) for use in research on the applications of stem cells in canine models of development, physiology, and disease. BM was harvested antemortem by aspiration from the greater tubercle of the humerus of 30 normal beagle dogs. Canine BM-derived MSCs were isolated according to methods developed for other species and were characterized based on their morphology, growth traits, cell-surface antigen profiles, differentiation repertoire, immunocytochemistry results, and neurotrophic factor expression in vitro. The canine MSCs exhibited a fibroblast-like morphology with a polygonal or spindle-shaped appearance and long processes; further, their cell-surface antigen profiles were similar to those of their counterparts in other species such as rodents and humans. The canine MSCs could differentiate into osteocytes and neurons on incubation with appropriate induction media. RT-PCR analysis revealed that these cells expressed NGF, bFGF, SDF-1, and VEGF. This study demonstrated that isolating canine MSCs from BM, stem-cell technology can be applied to a large variety of organ dysfunctions caused by degenerative diseases and injuries in dogs. Furthermore, our results indicated that canine MSCs constitutively secrete endogenous factors that enhance neurogenesis and angiogenesis. Therefore, these cells are potentially useful for treating dogs affected with various neurodegenerative diseases and spinal-cord injuries.