Stem cells: general information and perspectives

We are now in the middle of stem cell war. Each country is trying to invest a large amount of funds into stem cell research. This is due to a potentiality of stem cells. Stem cells are capable of proliferating in an undifferentiated manner and are able to differentiate into a desired cell lineage under certain conditions. These abilities make stem cells an appealing source for cell replacement therapies (regenerative medicine), the study of developmental biology and drug/toxin screening. In addition to embryonic and adult stem cells, induced pluripotent stem (iPS) cells has been recently generated through reprogramming from adult tissue cells such as fibroblasts. This technique has opened up new avenues to generate patient- and disease-specific pluripotent stem cells. Human iPS cells may be useful for gaining valuable insight into the pathophysiology of disease, as well as for discovering for new prognostic biomarkers and drug screening. Moreover, the iPS cell technology may play a major role in immune-matched clinical application in the future. In this chapter, we introduce general characteristics of various stem cells, clinical application of stem cells and future perspectivesope

Disease-specific induced pluripotent stem cells: a platform for human disease modeling and drug discovery.

The generation of disease-specific induced pluripotent stem cell (iPSC) lines from patients with incurable diseases is a promising approach for studying disease mechanisms and drug screening. Such innovation enables to obtain autologous cell sources in regenerative medicine. Herein, we report the generation and characterization of iPSCs from fibroblasts of patients with sporadic or familial diseases, including Parkinson's disease (PD), Alzheimer's disease (AD), juvenile-onset, type I diabetes mellitus (JDM), and Duchenne type muscular dystrophy (DMD), as well as from normal human fibroblasts (WT). As an example to modeling disease using disease-specific iPSCs, we also discuss the previously established childhood cerebral adrenoleukodystrophy (CCALD)- and adrenomyeloneuropathy (AMN)-iPSCs by our group. Through DNA fingerprinting analysis, the origins of generated disease-specific iPSC lines were identified. Each iPSC line exhibited an intense alkaline phosphatase activity, expression of pluripotent markers, and the potential to differentiate into all three embryonic germ layers: the ectoderm, endoderm, and mesoderm. Expression of endogenous pluripotent markers and downregulation of retrovirus-delivered transgenes [OCT4 (POU5F1), SOX2, KLF4, and c-MYC] were observed in the generated iPSCs. Collectively, our results demonstrated that disease-specific iPSC lines characteristically resembled hESC lines. Furthermore, we were able to differentiate PD-iPSCs, one of the disease-specific-iPSC lines we generated, into dopaminergic (DA) neurons, the cell type mostly affected by PD. These PD-specific DA neurons along with other examples of cell models derived from disease-specific iPSCs would provide a powerful platform for examining the pathophysiology of relevant diseases at the cellular and molecular levels and for developing new drugs and therapeutic regimens.ope

인간 전능성 줄기세포에서 유전자 손상과 세포사멸에 있어서 Sirtuin(Sirt1, Sirt2)의 역할

Dept. of Medical Science/박사Sirtuin (Sirt1/2) NAD+ dependent deacetylase plays an important role in cell survival under stress conditions. Sirt1 recently has been found to be highly-expressed in embryonic stem cells and Sirt1/2 may play a key role in survival of pluripotent stem cells (PSCs, embryonic stem cells and induced pluripotent stem cells).1,2 In this study, the roles of Sirt1/2 were investigated in pluripotent stem cell survival by chemical inhibitions. Sirt1/2 inhibitors: Sirtuin, Salermide, and Teniovin-6 were tested in survival of PSCs. While Sirt1/2 inhibition led to apoptosis of undifferentiated PSCs, it did not affect differentiated cells. PSCs have similar characteristics with cancer cells especially in cell cycle.3,4 p53 in PSCs and cancer cells is not activated. To prove Sirt1/2 inhibition-mediated apoptosis in PSCs, the author tested DNA damage and p53-related pathway regulation by Sirt1/2 deacetylation. Sirt1/2 down regulation led to DNA damage increment and reactivation of p53 followed by over-expression of p53 target genes: PUMA and BAX. In the end, cleaved caspase-3 was clearly detected in PSCs treated with Sirt1/2 inhibitors. Pro-apoptotic gene (PUMA, BAX) up-regulations and caspase3 activation imply that the apoptosis is p53-mediated event in Pluripotent stem cells. Thus, PSCs are susceptible to Sirt1/2 inhibition-mediated DNA damage and p53 activation that leads to apoptosis of PSCs, but not of differentiated cells. To validate the PSC-specific apoptosis induction by Sirt1/2 inhibitors, embryoid bodies containing partial differentiated cells and undifferentiated cells and PSC survival was examined by PSC marker (Oct4, SSEA4) expressions. In day 4 EBs, Sirt1/2 inhibitors dramatically reduced Oct4 levels and activated caspase-3 was mostly detected in SSEA4+ cells within the partially differentiating cells. Our findings provide a novel strategy to eliminate undifferentiated cells by Sirt1/2 inhibition in the process of in vitro differentiation.ope

자가통증조절법의 시작시점이 술 후 진통효과 발현시간에 미치는 영향

학위논문(석사)--서울대학교 대학원 :의학과 마취과학전공,2004.Maste

MiFS(Multi Functional Storage) 운전전략에 따른 액비의 품질과 악취발생 특성에 관한 연구

학위논문(석사) --서울대학교 대학원 :농생명공학부, 2008.2Maste

Induced pluripotent stem cell models from X-linked adrenoleukodystrophy patients

OBJECTIVE: Because of a lack of an appropriate animal model system and the inaccessibility of human oligodendrocytes in vivo, X-linked adrenoleukodystrophy (X-ALD)-induced pluripotent stem cells (iPSCs) would provide a unique cellular model for studying etiopathophysiology and development of therapeutics for X-ALD. METHODS: We generated and characterized iPSCs of the 2 major types of X-ALD, childhood cerebral ALD (CCALD) and adrenomyeloneuropathy (AMN), and differentiated them into oligodendrocytes and neurons. We evaluated disease-relevant phenotypes by pharmacological and genetic approaches. RESULTS: We established iPSCs from the patients with CCALD and AMN. Both CCALD and AMN iPSCs normally differentiated into oligodendrocytes, the cell type primarily affected in the X-ALD brain, indicating no developmental defect due to the ABCD1 mutations. Although low in X-ALD iPSCs, very long chain fatty acid (VLCFA) level was significantly increased after oligodendrocyte differentiation. VLCFA accumulation was much higher in CCALD oligodendrocytes than AMN oligodendrocytes but was not significantly different between CCALD and AMN neurons, indicating that the severe clinical manifestations in CCALD might be associated with abnormal VLCFA accumulation in oligodendrocytes. Furthermore, the abnormal accumulation of VLCFA in the X-ALD oligodendrocytes can be reduced by the upregulated ABCD2 gene expression after treatment with lovastatin or 4-phenylbutyrate. INTERPRETATION: X-ALD iPSC model recapitulates the key events of disease development (ie, VLCFA accumulation in oligodendrocytes), provides new clues for better understanding of the disease, and allows for early and accurate diagnosis of the disease subtypes. X-ALD oligodendrocytes can be a useful cell model system to develop new therapeutics for treating X-ALD.ope