Дисертації з теми "Human Liver Stem Cells"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Human Liver Stem Cells.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Human Liver Stem Cells".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Chen, Shi. "Cryopreservation of human embryonic stem cells and hepatocytes." Thesis, University of Oxford, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.711665.
Повний текст джерела
2
Jennings, Adam Edward. "Control of growth and differentiation of human liver stem cells." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403607.
Повний текст джерела
3
LAI, FEDERICA. "Immunohystochemical markers of stem/progenitor cells in the fetal human liver." Doctoral thesis, Università degli Studi di Cagliari, 2019. http://hdl.handle.net/11584/260751.
Повний текст джерелаАнотація:
The documentation and the characterization of human stem/progenitor cells of the liver is interesting subject of the current scientific literature. Stem/progenitor cells are a heterogenus population characterized by a range of morphological and immunohistochemical features from bile duct cells to hepatocytes. They are typically characterized by the self-renewal ability able to differentiate into diverse lineage after injury or damage.. This study evaluated the immunohistochemical expression of different type of cytokeratins (CK7, CK14 and CK19) at different gestational ages in order to identify stem/progenitor in fetal human liver. Objectives: The aim of this study was to identify the stem/progenitor cell markers, by immunohistochemistry, in order to highlight the immunoreactivity of CK7, CK14 and CK19 in human liver progenitor cells at different gestational ages. Material and Methods: Liver samples were obtained from 14 fetal liver from 7 to 38 weeks of gestation. Liver samples were formalin-fixed routinely processed and stained with with H&E for histology. Section were also immunostained with the following antibodies: anti-CK7, anti-CK14 and anti-CK19. Results: Cytokeratin 7 (CK7): From 7 to 12 weeks of gestation, the positivity for CK7 is evident in the cytoplasm of progenitor cells of hepatocytes. From 15 weeks to 19 weeks, its immunoreactivity is absent. At about 27 weeks up to 38 weeks, we have a moderate positivity than before. The bile ducts in the first 7 weeks of gestation are absent. From 15 weeks onwards, we have a strong positivity of CK7 in ductal cells, remaining until late gestational age. The positivity of CK7 in the bile ducts is cytoplasmic and perinuclear. Cytokeratin 14 (CK14): From 7 weeks to 12 weeks, a cytoplasmic positivity, mainly perinuclear, is present in the cytoplasm of progenitor cells. From 15 weeks to 19 weeks, no immunoreactivity was found in hepatoblasts. From 27 weeks up to 38 weeks, there is a positive recovery. On the other hand, there is no positive effect during the development of the ductal system. Cytokeratin 19 (CK19): From 7 to 12 weeks of gestation, we have an intense cytoplasmic positivity homogeneously spread at the level of progenitor cells. At 15 weeks it is more light and focal and then negativize and start again from 27 weeks. Like CK7, also the CK19 is intensely expressed in the bile ducts from 15 weeks and then maintained until the 38th gestational age studied. Conclusion: Immunohistochemistry with monoclonal anti-cytokeratin antibodies has revelated previously the presence of cytokeratins in embryonic and early fetal hapatocytes. With the differentiation of bile ducts at about the 10th week, cytokeratin, particulary CK19, disappears from liver cells but remains in bile duct cells. This study shows that the immunoreactivity of the analyzed cytokeratins, in particular CK7 and CK19, is well evident from the first weeks of gestation and is maintained even in late age.
4
Hamou, Wissam. "Assessing liver regeneration by human embryonic stem cell-derived hepatocytes." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066374.
Повний текст джерелаАнотація:
Trouver de nouvelles sources de foie pour les transplantations est un vrai enjeu. Les obstacles principaux à la transplantation d'organes sont la pénurie de greffons et les lourds traitements immunosuppresseurs à vie. La possibilité de reprogrammer les cellules du patient et les cultiver donne accès à une quantité virtuellement illimitée de cellules a transplanter, éliminant de ce fait le besoin de donneurs d'organesMon doctorat se divise en deux parties : la première consiste à faire des cellules hépatiques en programmant des cellules souches humaines. La deuxième consiste à transplanter ces dernières dans des foies de souris ayant des insuffisances hépatiques aigues et chroniques pour étudier la régénération du foie. Les nouveautés de ce projet sont le fait d'étudier la première phase d'intégration post transplantation des cellules car cette phase est critique dans la régénération. De plus je comparerai la régénération du foie par les cellules transplantées dans une insuffisance hépatique aigue avec une insuffisance hépatique chronique. Une semaine après transplantation, le foie de ces souris contenait les cellules greffées qui se sont implantées et celles-ci se comportaient comme des cellules de foie bona fide, produisant une protéine, l'albumine humaine. Encore mieux : l'analyse des fonctions du foie a relevé un retour à une fonction normale en 3 jours avec transplantation contre 7 jours sans cellules transplantées. Ces résultats sont très encourageants quant à la possibilité d'utiliser des cellules dérivées de cellules souches à des fins thérapeutiquesFinding new sources for liver transplants is a real issue. The main obstacles to organ transplantation are the shortage of grafts and heavy immunosuppressive treatment for life. The ability to reprogram the patient's cells and grow them gives access to a virtually unlimited amount of transplanted cells, thereby eliminating the need for an organ donor. My doctorate is in two parts: the first is to make liver cells by programming of human stem cells. The second is to transplant those cells in the livers of mice with acute and chronic liver failure to study liver regeneration. The novel parts of this project are to study the first phase of post-integration cell transplantation because this phase is critical in regeneration. Also I would compare liver regeneration by transplanted cells in acute liver failure with chronic liver failure. One week after transplantation, the liver of these mice contained the grafted cells and which are located if they behaved as bona fide liver cells producing a protein, human albumin. Even better: analysis of liver function noted a return to normal function in three days with seven days without transplantation against transplanted cells. These results are very encouraging when the possibility of using cells derived from stem cells for therapeutic purposes
5
Söderdahl, Therese. "Characterization of biotransformation systems in human cells : focus on stem cells and their progeny /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-206-4/.
Повний текст джерела
6
Liu, Chao. "Identification of liver stem-like cells in human derived intrahepatic biliary epithelial cells in vitro." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967345642.
Повний текст джерела
7
Lindton, Bim. "Experimental studies of human fetal liver cells : in regard to in utero hematopoietic stem cell transplantation /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-134-9.
Повний текст джерела
8
Minami, Takahito. "Novel hybrid three-dimensional artificial liver using human induced pluripotent stem cells and a rat decellularized liver scaffold." Kyoto University, 2020. http://hdl.handle.net/2433/253138.
Повний текст джерела
9
Winkler, Sandra, Madlen Hempel, Sandra Brückner, Hans-Michael Tautenhahn, Roland Kaufmann, and Bruno Christ. "Identification of pathways in liver repair potentially targeted by secretory proteins from human mesenchymal stem cells." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-207430.
Повний текст джерелаАнотація:
Background: The beneficial impact of mesenchymal stem cells (MSC) on both acute and chronic liver diseases has been confirmed, although the molecular mechanisms behind it remain elusive. We aim to identify factors secreted by undifferentiated and hepatocytic differentiated MSC
in vitro in order to delineate liver repair pathways potentially targeted by MSC. Methods: Secreted factors were determined by protein arrays and related pathways identified by biomathematical analyses. Results: MSC from adipose tissue and bone marrow expressed a similar pattern
of surface markers. After hepatocytic differentiation, CD54 (intercellular adhesion molecule 1, ICAM-1) increased and CD166 (activated leukocyte cell adhesion molecule, ALCAM) decreased. MSC secreted different factors before and after differentiation. These comprised cytokines involved in innate immunity and growth factors regulating liver regeneration. Pathway analysis revealed cytokine-cytokine receptor interactions, chemokine signalling pathways, the complement and coagulation cascades as well as the Januskinase-signal transducers and activators of transcription (JAK-STAT) and nucleotide-binding oligomerization domain-like receptor (NOD-like receptor) signalling pathways as relevant networks. Relationships to transforming growth factor beta(TGF-beta) and hypoxia-inducible factor 1-alpha (HIF1-alpha) signalling seemed also relevant. Conclusion: MSC secreted proteins, which differed depending on cell source and degree of differentiation. The factors might address inflammatory and growth factor pathways as well as chemo-attraction and innate immunity. Since these are prone to dysregulation in most liver diseases, MSC release hepatotropic factors, potentially supporting liver regeneration.
10
Garg, Abhilok. "In vitro processing of human bone marrow derived mesenchymal stem cells to enhance delivery in liver disease." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4326/.
Повний текст джерелаАнотація:
Currently the only effective treatment for end stage liver disease is transplantation together with immune-modulating drugs. Human bone marrow derived mesenchymal stem cells (MSC) have been shown to suppress inflammation, potentiate regeneration and act as vectors for gene therapy. Thus, MSC infusions offer an attractive potential therapy for treating liver disease. However a number of obstacles exist in MSC delivery before they can be used therapeutically. Although MSC can migrate to sites of injury after in vivo administration, their engraftment within the liver is often poor, potentially limiting their therapeutic action. I have shown that detaching MSC from culture using non-enzymatic methods is superior in retaining surface chemokine receptor expression. Furthermore, I have shown that these receptors are functional in migration and attachment assays both in vitro and in vivo in carbon-tetrachloride induced liver injury. TGFβ1 stimulated MSC were able to further enhance engraftment via up-regulation of surface CXCR3. Additionally the potent immunosuppressive properties of MSC, mediated via Prostaglandin E2, were enhanced after TGFβ1 stimulation. Thus my studies demonstrate that manipulation of MSC through careful choice of detachment methods and exogenous cytokine stimulation can improve their engraftment in injured liver and their immunosuppressive properties with implications for improving the efficacy of MSC therapy.
11
Greuel, Selina [Verfasser]. "Expansion of human induced pluripotent stem cells (hiPSCs) in 3D bioreactors for extracorporeal liver support / Selina Greuel." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2020. http://d-nb.info/1206184132/34.
Повний текст джерела
12
Kia, Richard. "Novel approaches using human induced pluripotent stem cells and microRNAs in the development of relevant human hepatocyte models for drug-induced liver injury." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2010059/.
Повний текст джерелаАнотація:
Drug-induced liver injury (DILI) remains a prominent cause of patient morbidity and mortality, partly due to the lack of relevant in vitro hepatic models for accurate screening for drug-induced hepatotoxicity at the early stages of drug development, and also the lack of sophisticated in vitro model systems to mechanistically understand the pathways that are perturbed following drug exposure. This thesis describes our endeavour to develop more relevant in vitro human hepatocyte models via novel investigative approaches using insights gained from the rapidly advancing research areas of human induced pluripotent stem cells and microRNAs (miRs). An emerging hepatic model is hepatocyte-like cells (HLCs) generated from human induced pluripotent stem cells (hiPSCs), though the functional phenotype of HLCs in general remains limited in comparison with the gold standard in vitro model of human primary hepatocytes (hPHs). As studies have shown that hiPSCs retain transient epigenetic memories of the donor cells despite cellular reprogramming with a resultant skewed propensity to differentiate towards the cell-type of origin, we evaluated the contribution of epigenetic memory towards hepatic differentiation by comparing HLCs generated from hPH- and non-hPH-derived hiPSC lines derived from a single donor. Our findings suggested that they were functionally similar, although comparison using hiPSC lines derived from other donors is still required to be conclusive. Although hPHs remain the gold standard in vitro model for DILI, they are commonly harvested from liver tissue of poor quality and rapidly lose their in vivo phenotype during extended in vitro culture, limiting its utility to acute toxicity studies only. Using an unbiased miR expression profiling approach, we identified a set of differentially-expressed miRs in dedifferentiating hPHs which are associated with many of the previously delineated perturbed pathways and biological functions. However, validation experiments are now required to confirm our findings from the bioinformatics analyses. Another approach taken to develop relevant and functional hepatic models includes efforts to better emulate the in vivo liver tissue environment by using complex hepatic models co-cultured with non-parenchymal cells. However, for the application of these models in the study of drug-induced toxicity, a hepatocyte-specific marker of hepatocyte perturbation is needed to discriminate non-specific cellular toxicity contributed by non-hepatocyte cell types present within the model. We demonstrated that the detection of miR-122 in cell culture media can be applied as a hepatocyte-enriched marker of toxicity in heterogeneous cultures of hepatic cells. In summary, this thesis describes our contribution towards the continuing efforts to develop new and improve on existing hepatic models for DILI by evaluating the contribution of epigenetic memory towards the functional phenotype of HLCs, delineating the changing miR profile of dedifferentiating hPHs, and introduced the concept of using miR-122 as a cell-type specific marker of hepatocyte perturbation with a potential to bridge in vitro and in vivo findings.
13
Essaouiba, Amal. "Development of a liver-pancreas in vitro model using microfluidic organ-on-chip technologies." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2573.
Повний текст джерелаАнотація:
Le diabète mellitus, également désigné comme la maladie du siècle, est une pathologie mortelle qui affecte le système endocrinien. Les mécanismes liés à la rupture de la boucle de rétroaction, qui régule le métabolisme et induit le diabète, ne sont pas entièrement connus. La compréhension des mécanismes d'action de l'insuline est donc essentielle pour le développement de stratégies thérapeutiques efficaces afin du lutter contre cette maladie. Par conséquent, il est impératif de trouver un modèle robuste et fiable, capable de surmonter les limites de la culture cellulaire traditionnelle en 2D et de l'expérimentation animale, pour la recherche sur le diabète. L'objectif de cette thèse est de développer un nouveau modèle de co‐culture foie‐pancréas en utilisant des systèmes microphysiologiques avancés (MPs) afin d’aborder plus efficacement le mécanisme impliqué dans la régulation endocrinienne hépatique et pancréatique. Ce travail met en évidence la capacité des systèmes multi‐organes sur puce qui combinent la compartimentation avancée des cellules en 3D, la microfluidique et la technologie des cellules souches pluripotentes induites (iPSC), pour atteindre une complexité biologique élevée et des fonctions rarement reproduites par une seule de ces technologies d’ingénierie tissulaireDiabetes mellitus (DM) or the so called disease of the century is a life threatening dysfunction that affects the endocrine system. The mechanisms underlying the break in the feedback loop that regulates the metabolism and the consequent diabetes induction are not fully known. Understanding the mechanisms of insulin action is therefore crucial for the further development of effective therapeutic strategies to combat DM. Accordingly, it is imperative to find a robust and reliable model for diabetes research able to overcome the limitations of traditional 2D in vitro cell culture and animal experimentation. The aim of this thesis is to develop a new liver‐pancreas co‐culture model using advanced microphysiological systems (MPs) to tackle more effectively the mechanism involving the hepatic and pancreatic endocrine regulation. This work highlights the power of multi organ‐on‐chip systems that combines the advanced 3D‐cell compartmentalization, microfluidics and induced pluripotent stem cells (iPSC) technology to achieve a high biological complexity and functions that are rarely reproduced by only one of these tissue engineering technologies
14
Amofah, Eunice. "Bone marrow stem cells in liver disease." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497234.
Повний текст джерела
15
Corbineau, Sébastien. "Génération de progéniteurs hépatiques dérivés de cellules souches : application à l’hypercholestérolémie familiale." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA114821/document.
Повний текст джерелаАнотація:
La transplantation d’hépatocytes représente une alternative à la transplantation hépatique pour le traitement de certaines maladies métaboliques dont l’hypercholestérolémie familiale. Les cellules souches embryonnaires (ES) et les cellules souches pluripotentes induites (iPS) humaines représentent de nouvelles sources de cellules hépatiques. Nous avons mis au point une approche de différenciation des cellules souches humaines en cellules hépatiques et généré ainsi des cellules dérivées de cellules iPS de patients atteints d’hypercholestérolémie familialeHepatocyte transplantation represents an alternative to liver for the treatment of metabolic diseases including familial hypercholesterolaemia. Embryonic stem cells (ES) and induced pluripotent stem cells (iPS) represent new sources of hepatic cells. We have developed an approach to differentiate human stem cells into hepatic cells and thus we have generated hepatic cells derived from iPS of familial hypercholesterolaemia patients
16
Harun, Rosliah. "Derivation of trophoblast stem cells from human embryonic stem cells." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414643.
Повний текст джерела
17
Anilkumar, Thapasimuthu Vijayamma. "The pathobiology of hepatic stem cells (oval cells)." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244072.
Повний текст джерела
18
Harrison, Sean. "Liver cell types derived from pluripotent stem cells." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/liver-cell-types-derived-from-pluripotent-stem-cells(7f39c3ec-facd-4c06-ab9a-7c171313eb05).html.
Повний текст джерелаАнотація:
Liver development involves the differentiation and interaction of both endoderm and mesoderm cell types. The role of the liver in drug metabolism makes it an important area of medical research. Mimicking embryonic liver development in vitro using human ESCs is a strategy used to differentiate liver cell types. These can then be used as a model playing a role in the development of drugs and the study of their hepatotoxicity and would also have potential for use in cell therapy and regenerative medicine. Differentiated hepatocyte-like cells were found to have more in common with liver cells than those of other organs, including the secretion of albumin and activity of proteins important in drug metabolism, CYP3A and CYP2D6. However the hepatocyte-like cells were found to more closely resemble fetal rather than adult hepatocytesOrganoid differentiation resulted in cells types which in vivo are both endoderm and mesoderm derived cells of the liver. Culture in this 3D system allowed the spontaneous acquisition of polarity by these cells and their formation into structures reminiscent of liver architecture. After treatment with the toxin 4,4′-diaminodiphenylmethane a cell type and structure specific dose response was observed which matches that described in vivo.
19
Ma, Kwai-yee Stephanie. "Identification and characterization of tumorigenic liver cancer stem/progenitor cells." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557534.
Повний текст джерела
20
Ma, Kwai-yee Stephanie, and 馬桂宜. "Identification and characterization of tumorigenic liver cancer stem/progenitor cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557534.
Повний текст джерелаАнотація:
Li Ka Shing Prizes for best PhD theses in the Faculties of Dentistry, Engineering, Medicine and Science, 2006-2007published_or_final_version
abstract
Pathology
Doctoral
Doctor of Philosophy
21
Al, Echrish Noori H. Jasim. "Liver development and the role of mesenchymal stem cells." Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580160.
Повний текст джерелаАнотація:
Human fetal liver is the major site of haematopoiesis throughout gestation but at around 12 - 13, weeks hepatogenesis becomes prominent. In the first trimester, the fetal liver contains a number of putative stem cell populations in microenvironmental niches. This study was designed to investigate these stem cell populations to determine the origins of hepatogenesis in fetal life and to determine the implications for hepatic regeneration in adults. Mesenchymal stem cells were isolated from fetal liver samples (fIMSC) on the basis of adherence to tissue culture plastic. The phenotype of the adherent population, using flow cytometry was determined as: CD29+ve, CD10S+ve, CD90+ve, CD73+ve, HLA ABC+ve, CD271-ve, CD4S-ve, CD34-ve, CD133-ve, CDllb-ve & HLA DR-ve. Differentiation of flMSC into osteogenic, adipogenic and chondrogenic lineages was also demonstrated as confirmation of the multipotential nature of these cells. Cells which were expanded clonally showed the same characteristics as the primary cell population. Thus, MSC isolated from human fetal liver conformed to criteria stipulated by International Society of Cellular Therapy (ISCT). flMSC were extensively passaged in vitro to relatively large passage numbers (P1S). It was observed that there was a reduction in expression of CD10S associated with a decrease in proliferative and differentiation properties of the cells. These findings appeared to be associated with chromosomal abnormalities and a shortening of telomere length over increasing passage number, which could be considered as a triggering of cell senescence. It was concluded that the early passage numbers of flMSC (P4-P8) are optimum for all studies and that CDi0S is a reliable and accessible surrogate marker for identification of senescent cells. flMSC were cultured in proprietary medium, supplemented with growth factors which are known to stimulate hepatogenesis. A greater degree of hepatogenesis from flMSC was observed when the medium was supplemented with oncostatin M (OSM), in comparison to culture in a medium supplemented with fibroblast growth factor (FGF) or hepatocyte growth factor (HGF). A hepatocyte-specific antibody and gene profiling were used to analyse the development of flMSC in these culture conditions. Hepatic cluster formation (indocyanine green positive) was noted within 3 days when flMSC cultured in the presence of FGF. Then after subsequent adding of OSM, cultured flMSC stained positively by flow cytometric analysis using an optimised hepatocyte-specific antibody and gene expression studies confirmed the presence of albumin, alpha-fetoprotein, factor VIII and tryptophan 2,3 dioxygenase in these cells. The cells acquired a polygonal morphology, similar to that of adult hepatocytes. The flMSC characterised in this study were shown to possess immunomodulatory activity: they do not induce aT-cell response and they have an immunosuppressive effect on T-cells in mixed Iymphocyte culture. flMSC differentiated to hepatocytes have the same immunological properties as undifferentiated fIMSC, despite expression of HLA DR when the cells are exposed to pro-inflammatory cytokines. This study shows that human fetal liver-derived MSC can develop into functional hepatocytes in vitro and that these end-stage cells have immunomodulatory properties. This de novo source of hepatic tissue could have therapeutic utility with potential for transplantation across HLA barriers.
22
Noisa, Parinya. "Characterization of neural progenitor/stem cells derived from human embryonic stem cells." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5712.
Повний текст джерелаАнотація:
Human embryonic stem cells (hESCs) are able to proliferate indefinitely without losing their ability to differentiate into multiple cell types of all three germ layers. Due to these fascinating properties, hESCs have promise as a robust cell source for regenerative medicine and as an in vitro model for the study of human development. In my PhD study, I have investigated the neural differentiation process of hESCs using our established protocol, identified characteristics associated with each stage of the differentiation and explored possible signalling pathways underlying these dynamic changes. It was found that neural differentiation of hESCs could be divided into 5 stages according to their morphology, marker expression and differentiation potencies: hESCs, neural initiation, neural epithelium/rosette, neuronal progenitor cells and neural progenitor/stem cells (NPSCs) and 4 of these stages have been studied in more detail. At the neural initiation, hESCs firstly lose TRA-1-81 expression but retain SSEA4 expression. This transient cell population shows several similar properties to the primitive ectoderm. After neural-tube like structure/neural rosette formation, neural progenitor cells appear as typical bipolar structures and exhibit several properties of radial glial cells, including gene expression and pro-neuronal differentiation. The neural progenitor cells are able to grow in culture for a long time in the presence of growth factors bFGF and EGF. However, they gradually lose their bipolar morphology to triangular cell type and become pro-glial upon further differentiation. In addition, the state of neural progenitor and stem cells can be distinguished by their differential response to canonical Notch effector, C protein-binding factor 1. It was also found that delta like1 homolog (DLK-1) is temporally upregulated upon initial neural differentiation, but becomes undetectable after the neural progenitor stage. Overexpression of DLK-1 in NPSCs enhances neuronal differentiation in the presence of serum by blocking BMP and Notch pathways. These results show that neural differentiation of hESCs is a dynamic process in which cells go through sequential changes, and the events are reminiscent of the in vivo neurodevelopment process. Moreover, I have characterized stably transfected nestin-GFP reporter hESC lines and found that the cell lines maintained the features of hESCs and the expression of GFP is restricted to the neural lineage after differentiation. Therefore, these reporter lines will be useful for the study of factors that regulate neural differentiation and for the enrichment of neural progenitors from other lineages. Taken together, this study has demonstrated that hESCs are a good in vitro model to study the mechanisms and pathways that are involved in neural differentiation. The availability of hESCs allows us to explore previously inaccessible processes that occur during human embryogenesis, such as gastrulation and neurogenesis.
23
Aoi, Takashi. "Generation of Pluripotent Stem Cells from Adult Mouse Liver and Stomach Cells." Kyoto University, 2008. http://hdl.handle.net/2433/124215.
Повний текст джерела
24
Ratanasirintrawoot, Sutheera. "Defining markers and mechanisms of human somatic cell reprogramming." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11236.
Повний текст джерелаАнотація:
Somatic cells can be reprogrammed into induced pluripotent stem (iPS) cells by over expression of the transcription factors OCT4, SOX2, KLF4 and c-MYC. Using serial live cell immunofluorescence imaging of human fibroblasts undergoing reprogramming, we traced the emergence of nascent iPS cell colonies among heterogeneous cell populations and defined the kinetics of marker expression. We identified distinct colony types that morphologically resemble embryonic stem (ES) cells yet differ in molecular phenotype and differentiation potential. By analyzing expression of pluripotency markers, methylation at the OCT4 and NANOG promoters, and differentiation into teratomas, we determined that only one colony type represented bona fide iPS cells, whereas the others represented reprogramming intermediates. Proviral silencing and expression of TRA-1-60, DNMT3B, and REX1 distinguished the fully reprogrammed state, whereas Alkaline Phosphatase, SSEA-4, GDF3, hTERT and NANOG proved insufficient as markers. Reprogramming in chemically defined medium favored formation of bona fide iPS cell colonies relative to partially reprogrammed colonies. These data highlight the need for rigorous characterization and standardization of putative iPS cells.
25
Jurczak, Daniel. "Stemness in human embryonic stem cells." Thesis, University of Skövde, School of Life Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-3509.
Повний текст джерелаАнотація:
Stem cells are cells that have a unique ability to divide for an indefinite period. Additionally, they can give rise to a plethora of specialized cell types. The advent of high-throughput technologies made it possible to investigate gene expression on a large scale. This enabled scientists to perform comprehensive gene profiling studies of stem cells. Several authors have suggested that there might be a common set of genes that control the stemness of stem cells. In this study, we suggest that ”stemness” genes that are related to ”stemness” characteristics show a statistically significant down-regulation between undifferentiated and differentiated cells. For this we have analyzed microarray data from five different cell lines and compared their global expression profiles. Common down-regulated transcripts among those data sets were de- rived by using a well-established gene expression analysis procedure called Significance Analysis of Microarrays. Since all three data sets were provided by Cellartis AB, the derived list of common transcripts was subsequently compared with an external study. Moreover, we also performed a comparison with down-regulated genes derived from mouse embryonic stem cells. This was done to determine if there is a common set of stemness genes even across distinct species. Re- sults were further evaluated using a comprehensive data-set from a study by Skottman et al. (2005). All results where compared uti- lizing using a range of false discovery rate threshold values and the results were subsequently used for gene ontology term enrichment. GO terms where utilized to functionally annotate and classify those embryonic stem cell transcripts, that were found to be common in all data-sets and identify over-represented biological processes related to those genes.
26
Khan, Amir Ali. "Proteomics analysis of human stem cells." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493771.
Повний текст джерелаАнотація:
Stem cells have two characteristics that make them unique from any other cell: they can renew themselves indefmitely and they can be differentiated into other cell types. The aim of this investigation was to employ proteomic techniques (2D-PAGE/mass spectrometry) to compare protein expression profiles between two embryonic cell lines (HI and Hues1) and between Huesl and a multipotent cell line (MSC).
27
Owen-Jones, Catrin Eleri. "Stem cells in human oral epithelium." Thesis, Cardiff University, 2004. http://orca.cf.ac.uk/55544/.
Повний текст джерелаАнотація:
The stratifying epithelia of skin and mucosa continuously renew their structure by cell division, but only a small fraction of proliferative cells, the stem cells, are capable of continuous self-renewal. The staining distribution of various stem cell and differentiation markers were investigated in normal human mucosal epithelium. To determine the extent of regional variation in patterns of stem cell behaviour in human epithelia, human mucosal keratinocytes were amplified in vitro. Using retroviral vectors, a sub-population of these cells were transduced with genes for histochemically detectable markers to permit lineage analyses. Organotypic culture methods were used to generate epithelia with normal patterns of cell kinetics and differentiation and these were examined after maintenance in vitro or after transplantation back to in vivo sites in immune deficient mice. The clonal lineages resulting from stem cell patterns were compared and the number of functional stem cells were assessed from the size of stable clonal units regenerated. The cell cycles of keratinocytes grown on plastic compared to organotypic culture were also investigated by flow cytometry to see if the organotypic cultures provided a suitable stem cell model. Results included the following. Antibody staining in palate revealed that K15 and K19 identified zones of positively stained basal cells at the epithelial rete tips. These K15 and K19 positive regions were negative for differentiation markers K6 and K16, indicating that cells in these regions were undifferentiated and could include stem cells Organotypic cultures gave similar staining profiles to palate, and using retrovirally stained subpopulations of cells and transplantation to SCID mice, clonal units were identified which did not correspond to the primitive rete that had reformed. Flow cytometry work showed that the cell cycles of cells grown in vitro on plastic were faster than the cell cycles of organotypic cultures.
28
Dianat, Noushin. "Cellules souches pluripotentes humaines et modélisation de maladies hépatiques : l'hypercholestérolémie familiale et les cholangiopathies." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA114810.
Повний текст джерелаАнотація:
La thérapie cellulaire pourrait représenter une alternative à la transplantation hépatique dans certaines pathologies comme les maladies métaboliques sévères. Toutefois, la pénurie de donneurs d’organes implique la nécessité de trouver de nouvelles sources de cellules hépatiques comme les cellules souches pluripotentes qui peuvent être amplifiées extensivement et différenciées en tout type cellulaire. Les cellules souches embryonnaires humaines (hESC) et les cellules souches pluripotentes induites humaines (hiPSC) générées à partir des cellules somatiques de patients puis différenciées en hépatocytes représentent une source potentielle d’hépatocytes. Ces cellules permettent en outre d’envisager la transplantation d’hépatocytes autologues génétiquement modifiés comme alternative à la transplantation hépatique pour le traitement de certaines maladies génétiques du foie. L’hypercholestérolémie familiale (HF) est une maladie autosomale dominante due à des mutations dans le gène codant le Récepteur aux Low Density Lipoproteins (RLDL) qui est à l’origine d’un taux élevé de cholestérol sanguin de patients HF. Les patients homozygotes doivent épurer leur sérum par LDL-aphérèse en moyenne deux fois par mois dès le plus jeune âge pour éviter les infarctus mortels survenant dès l’enfance. Les hépatocytes différenciées à partir des iPSC de patients et leur correction in vitro, permettent d'évaluer la faisabilité de la transplantation d'hépatocytes autologues génétiquement modifiés pour le traitement de l’hypercholestérolémie familiale.Au cours du développement du foie, des hépatocytes et des cholangiocytes, les deux types de cellules épithéliales hépatiques, dérivent de progéniteurs hépatiques bipotents (les hépatoblastes). Bien que les cholangiocytes formant les canaux biliaires intrahépatiques ne représentent qu'une petite fraction de la population cellulaire totale du foie (3%), ces cellules régulent activement la composition de la bile par réabsorption des acides biliaires, un processus qui est important dans des maladies choléstatiques du foie. Dans la première partie de cette étude nous avons mis au point une approche de différenciation des cellules souches pluripotentes (hESC et hiPSC) en cholangiocytes fonctionnels. Ces cellules serviront à la modélisation des maladies génétiques touchant les cholangiocytes formant des canaux biliaires. Dans la deuxième partie, nous avons généré des iPSC spécifiques de patients HF (HF-iPSC), différenciées en hépatocytes et corrigé le défaut phénotypique par transfert lentiviral de l’ADNc codant le LDLR dans les HF-iPSCCell therapy can be an alternative to liver transplantation in some cases such as severe metabolic diseases. However, the shortage of organ donors implies the need to find new sources of liver cells such as hepatocytes derived from pluripotent stem cells that can be amplified and differentiated extensively into any cell type. Human embryonic stem cells (hESC) and human induced pluripotent stem cells (hiPSC) generated from somatic cells of patients and then differentiated into hepatocytes represent a potential source of transplantable hepatocytes. These cells now make it possible to consider the transplantation of genetically modified autologous hepatocytes as an alternative to liver transplantation for the treatment of genetic diseases of the liver.Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in the gene encoding the receptor for Low Density Lipoproteins (LDLR), which is the cause of high blood cholesterol in these patients. Homozygous patients should purify their serum LDL-apheresis on average twice a month starting at a young age to avoid fatal myocardial infarction occurring in childhood.Human hepatocytes differentiated from patient’s induced pluripotent stem cells (iPSCs) allow assessing the feasibility to transplant genetically modified autologous hepatocytes as treatment of familial hypercholesterolemia.During the liver development, hepatocytes and cholangiocytes, the two types of hepatic epithelial cells, derive from bipotent hepatic progenitors (hepatoblasts). Although cholangiocytes, forming intrahepatic bile ducts, represent a small fraction of the total liver cell population (3%), they actively regulate bile composition by secretion and reabsorption of bile acids, a process that is important in cholestatic liver diseases. In the first part of this study we developed an approach to differentiate pluripotent stem cells (hESC and hiPSC) into functional cholangiocytes. These cells could be used for the modeling of genetic biliary diseases. In the second part, we generated FH patient specific iPSCs (HF-iPSC), differentiated them into hepatocytes and tried to correct the disease phenotype by lentiviral introduction of LDLR cDNA cassette in HF-iPSC
29
Bird, Thomas Graham. "Liver regeneration by hepatic progenitor cells." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5634.
Повний текст джерелаАнотація:
The liver is the largest solid organ in the body and is frequently the site of injury. During disease, liver injury is usually compensated for by exceptionally efficient regeneration which occurs both from differentiated epithelia and also from an undifferentiated cell population with stem cell like qualities known as hepatic progenitor cells (HPCs). HPCs are particularly active during massive or chronic liver injury and therefore are an attractive target for much needed novel therapies to enhance regeneration in patients for whom the only current effective therapy is liver transplantation. Stem cells in other organs systems are believed to reside in a specialised microenvironment or niche which supports their maintenance and function. To investigate the hypothesis that HPCs are supported by a functional niche and are capable of regenerating hepatocytes, we commenced by establishing a number of murine in vivo models. Having shown a stereotypical niche, consisting of macrophages, myofibroblasts and laminin exists in both animal models and human disease, we investigated the active recruitment of extrahepatic cells into this niche and showed that macrophages are actively recruited from the bone marrow during liver injury. Macrophages were shown to influence HPC behaviour during injury. Furthermore using macrophages as a cellular therapy, induced HPC activation with corresponding changes to liver structure and function. Investigation of signalling pathways revealed and confirmed a TWEAK dependent activation of HPCs following macrophage transfer. Having demonstrated the potential for macrophage therapy via HPC activation, we aimed to study the ability of HPCs to regenerate the hepatic parenchyma. To do so we developed and characterised a novel model of hepatocellular injury and HPC activation. Using the genetic labeling of hepatocytes in this model we were able to show rapid and large scale repopulation of hepatocytes from a precursor source with HPCs being the critical precursor source of hepatocellular regeneration. In addition this process is again dependent on TWEAK signalling, without which HPC mediated regeneration fails resulting in mortality. Therefore HPCs are an attractive biological target for regenerative medicine, and both TWEAK signalling and autologous macrophage infusion offer genuine potential to manipulate these cells as future therapies.
30
Bowles, K. M. "Generation of haematopoietic cells from human embryonic stem cells." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596829.
Повний текст джерелаАнотація:
Culture of hESCs on murine stromal layers or in stromal free conditions as embryoid bodies results in low levels of haematopoietic cells. Here it is demonstrated that overexpression of the transcription factor HOXB4 considerably augments haematopoetic development of hESCs. Stable HOXB4 expressing hESC clones were generated by lipofection and could be maintained in the undifferentiated state for prolonged passages. Moreover, differentiation of hESCs as embryoid bodies in serum containing medium without the use of additional of cytokines led to sequential expansion of first erythroid then myeloid and monocytic progenitors. These cells retained the capacity to develop into formed blood elements during in vitro culture. Consistent with the development of committed haematopoietic cells the expression of transcription factors known to be critical for haematopoietic development was observed. The successful use of enforced gene expression to promote the differentiation of hESCs into a terminally differentiated tissue is thus demonstrated, thereby revealing an important role for HOXB4 in supporting their in vitro development along the haematopoietic pathway. Once a method for producing significant numbers of haematopoietic cells from hESCs in vitro was established, hESCs were used to study the role of stem cell leukaemia gene (SCL) in human blood and endothelial development. hESC lines were generated in which the expression of SCL, under control of an enhancer previously shown in mice to target expression to blood and endothelial progenitors, was evident through green fluorescent protein (GFP) expression. The enhancer directed GFP expression inhuman K562 cells and some differentiated progeny of HOXB4 transfected hESCs. However a more thorough assessment of GFP positive cells was hindered by problems with transgene silencing.
31
Lam, Shuk-pik. "Differentiation of mesenchymal stem cells (MSCs) into hepatocytes in acute liver injury." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43085647.
Повний текст джерела
32
Lu, Wei-Yu. "Defining the liver repopulating capacities of hepatic progenitor cells." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17875.
Повний текст джерелаАнотація:
The liver has the ability to regenerate rapidly during acute liver injury by activating mature hepatocytes to divide and restore the damaged liver mass. In contrast, the liver relies on hepatic progenitor cells (HPCs) which have the ability to differentiate into both hepatocytes and biliary cells for regeneration during chronic liver injuries. Whole organ transplant is the most effective treatment for end stage liver diseases. However, there is a constant shortage of donor organs causing the death of many patients while waiting for suitable donor organs. HPC transplant is a potential alternative for whole organ transplant. However the isolation of HPC which is scarce in the liver and the expansion of these cells to a number that is suitable for transplant have been challenging. To investigate the plausibility of using HPCs as an alternative for liver transplant, I developed a protocol to isolate and expand HPC in vitro. Using this system, I investigated the complex hierarchy of HPCs in aid to select a defined population of HPC that is suitable for transplant. I found the EpCAM+ CD24+ population marks a naïve population of HPC that might be suitable for cell therapy. I further investigate the liver repopulating capacities of these cells by isolating EpCAM+CD24+ HPC population by Fluorescence Activated Cell Sorting (FACS) from a hepatocellular injury model. Surprisingly, a subpopulation of the EpCAM+ CD24+ HPCs which are also CD133+ possesses a higher colony forming capacities has been identified. Most importantly, this population can be expanded to a large scale in vitro and able to repopulate the injured liver after transplant. This defined population of HPCs can also be isolated from a mouse model of fatty liver disease and the isolated HPCs can be expanded in vitro. These cells are able to repopulate the liver after cell transplantation. The presence of HPCs that are capable of being isolated from the fatty liver proved the potential of using HPCs for transplant in a clinical setting by using cells isolated human fatty liver that are from rejected for transplant to overcome the shortage of donor organs.
33
Joannides, Alexis. "Neural differentiation of human embryonic stem cells." Thesis, University of Cambridge, 2009. https://www.repository.cam.ac.uk/handle/1810/252121.
Повний текст джерелаАнотація:
Human embryonic stem cells (hESCs) are a potential source of defined cell types for studying early human development and application in regenerative medicine. Realising this potential requires a number of challenges to be overcome. The experimental findings reported represent a systematic approach in establishing controlled and standardised conditions for differentiating hESCs down the neural lineage, and characterising neural derivatives both in vitro and in vivo. Human embryonic stem cell cultures were established from two independently-derived liens, H9 and UES9. A novel, efficient method for propagating hESCs is described, avoiding the use of enzymatic products which may lead to karyotypic instability. Controlled neuroectodermal differentiation is demonstrated using a chemically defined system over a period of 16 days, and this process is shown to be dependent on endogenous fibroblast growth factor (FGF) signalling. Neural progenitors generated with this system are subsequently expanded for over 180 days and shown to retain neural stem cell (NSC) identity at the clonal level. Evidence is provided that hESC-derived NSCs follow a developmentally predictable timecourse of neurogenesis followed by gliogenesis, and their in vitro and in vivo behaviour is characterised with respect to temporal maturation and phenotypic potential.
34
Conneally, Helen Ann. "Genetic modification of human hematopoietic stem cells." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ27123.pdf.
Повний текст джерела
35
Götherström, Cecilia. "Characterisation of human fetal mesenchymal stem cells /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-139-3/.
Повний текст джерела
36
Rugg-Gunn, Peter. "Epigenetic status of human embryonic stem cells." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614294.
Повний текст джерела
37
Chan, Elcie. "Characterisation of microRNAs in human stem cells." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5476.
Повний текст джерелаАнотація:
In collaboration with David Baulcombe and Attila Molnar we have generated microRNA libraries for human embryonic stem cells (hESCs) before and after differentiation along the neuronal lineage and also from human mesenchymal stem cells (hMSCs). Both cell types are of medical importance and understanding how their proliferation and differentiation is regulated by microRNAs is also of scientific interest. The hMSC library was sequenced by 454 technology and the two subsequent hESC libraries by Solexa sequencing. Approximately a quarter of all currently known microRNAs were identified between the libraries, in addition to 3 novel microRNAs and 25 annotated piRNAs. For the hESC libraries, we verified the presence of embryonic specific microRNAs (miR-302 family) and neuronal specific microRNAs (miR-9/miR-9*), and demonstrated that expression of these miRNAs is regulated at the transcriptional level. Additionally, promoter assessments of miR-9 transcription revealed that multiple upstream regions may be important in neuronal specific expression. Almost half of all known human microRNAs are located within the introns of host genes. We used microarrays to analyse host gene expression and found that there was little correlation with microRNA expression, indicating that many microRNAs are not regulated at the transcriptional level by their host promoter. Furthermore, the expression of microRNAs from the same cluster, and also from the same hairpin precursor, did not always correlate when compared between the stem cell libraries. Taken together, this data indicates that microRNAs are regulated at a variety of levels both pre- and post-transcriptionally. Many microRNA isomers were also detected that differed in expression between human cell types, and upon differentiation of the hMSCs through the osteoblastic lineage. Interestingly, microRNAs and some of their isomers showed different affinities for Argonaute proteins in pulldown assays. We also profiled mRNAs that were immunoprecipitated with Argonaute in order to identify miRNA targets
38
Zhang, Yingying, and 张莹莹. "Functional ion channels in human bone marrow-derived mesenchymal stem cells and human cardiac c-kit+ progenitor cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50567032.
Повний текст джерела
39
Deng, Jie. "Neurogenesis of adult stem cells from the liver and bone marrow." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009700.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--University of Florida, 2005.Typescript. Title from title page of source document. Document formatted into pages; contains 143 pages. Includes Vita. Includes bibliographical references.
40
Vitillo, Loriana. "Focal adhesion kinase regulation of human embryonic stem cells." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/focal-adhesion-kinase-regulation-of-human-embryonic-stem-cells(31052725-50a4-4d34-a1eb-018be57986af).html.
Повний текст джерелаАнотація:
Undifferentiated human embryonic stem cells (hESCs) grow on the extracellular matrix (ECM) substrate fibronectin (FN) in defined feeder-free conditions. The ECM is part of the hESCs pluripotent niche and supports their maintenance, but the contribution to survival remains to be elucidated. Understanding the mechanism of survival is particularly crucial in hESCs, since it affects their expansion in cell culture and ultimately translation of research to the clinic. HESCs bind to FN mainly via alpha5β1- integrin, known to be upstream of important survival cascades in other cell types. However, it is not understood if and how FN/integrin binding supports those molecular pathways in the context of pluripotent hESCs. The aim of this work was to elucidate the survival cascade downstream of the FN/integrin interaction in hESCs. Initially, when hESCs were cultured on a non-integrin activating substrate they initiated an apoptotic response that also occurred when β1-integrin was selectively blocked with antibody, leading the cells to detach from FN. Integrin activation is generally transduced within cells via a complex adhesome of scaffold and kinase proteins, among which the focal adhesion kinase (FAK) plays a key role. Indeed, blocking β1-integrin resulted in dephosphorylation of endogenous FAK in hESCs. When FAK kinase activity was directly inhibited (with small molecule inhibitors), hESCs responded by detaching from FN and activating caspase-3, leading to an increase in apoptosis. Furthermore, flow cytometry analysis showed that the population of hESCs that underwent apoptosis still retained the pluripotency-associated marker NANOG. FAK is a convergent point between growth factor signaling and the PI3K/Akt pathway, with a well-reported role in the maintenance of hESCs. Consistently, FN activated both AKT and its target the ubiquitin ligase MDM2 at the protein levels, while pAkt was reduced after β1-integrin blocking and FAK inhibition. Cell imaging showed that MDM2, which regulates p53 degradation in the nucleus, displayed reduced nuclear localisation after FAK inhibition, opening the possibility for a change in the p53 balance in hESCs. In fact, p53 protein increases after FAK inhibition corresponding also to caspase activation. Further investigation explored if FAK-dependent pathways are also implicated in the maintenance of hESC pluripotency. Inhibition of FAK led the cells that survived apoptosis to lose stem cell morphology, decrease pluripotency-associated markers and change nuclear shape. Moreover, a small pool of FAK was found in the nucleus of hESCs cultured on FN, but decreased after FAK inhibition. FAK was also co- immunoprecipitated with NANOG protein in standard hESC culture while NANOG decreased after sustained FAK inhibition. This data suggests that nuclear roles of FAK could support, together with the cytoplasmic activation of the PI3K cascade, both survival and pluripotency pathways requiring further investigation. In conclusion, the original contribution of this work is to identify in FAK the downstream survival effector of the FN/β1-integrin interaction in hESCs. HESCs survival is maintained by the binding of β1-integrin to FN and activation of FAK kinase and downstream PI3K/Akt, leading to the suppression of p53 and caspase activation. In parallel, promotion of these pathways by FAK is suggested also to support the key pluripotency circuitry, feeding into NANOG. Overall, FAK is proposed here as an important regulator of hESC survival and fate.
41
Viebahn, Cornelia Sabine. "Interaction between the immune system and liver progenitor cells." University of Western Australia. Biochemistry and Molecular Biology Discipline Group, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0055.
Повний текст джерелаАнотація:
Liver progenitor cells (LPCs) play a major role in the regeneration process following chronic liver damage. LPCs can differentiate into hepatocytes and cholangiocytes and thus are capable of replenishing the damaged liver. Due to their plasticity and robust nature in culture systems, they are promising candidates for use in cell therapy. However, to be able to use LPCs as tissue regenerating stem cell-like cells in the clinic, we need to fully understand how they are controlled. Although a strong association between LPCs and inflammation has been shown in many chronic liver diseases, the role of the immune system in LPC-mediated hepatic regeneration is poorly understood. We hypothesise that specific immune cells and mediators are needed to induce the LPC compartment, and that these are common to the LPC response in different injury settings. Therefore, the present study focused on the characterisation of the inflammatory environment in the LPC response, which generates this niche. The aims of this study were (i) to identify the immune cells that are important for the LPC response, (ii) to define the cytokine profile and (iii) to determine the role of the cytokine producing cells during liver regeneration. To study hepatic inflammation following liver injury, a diet-induced model of liver injury (choline-deficient, ethionine-supplemented diet, CDE diet) was compared to two transgenic mouse models of immune-mediated hepatitis (Met-Kb, 178.3). Although all three models are characterised by hepatitis, histological analysis revealed that LPCs were only detectable in the CDE and Met-Kb livers. In the 178.3 model, livers regenerated from proliferating hepatocytes. An LPC response could not be induced in these mice even when liver damage was made more severe. In the other two models, LPC numbers increased over time showing the highest numbers one week after the peak of liver injury. LPCs were often found in close proximity to inflammatory cells, in particular macrophages.
42
Kung, Janet Wui Cheung. "Investigating the liver progenitor cell niche in the developing human liver." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25953.
Повний текст джерелаАнотація:
Liver cirrhosis places an increasing burden on healthcare worldwide. Currently the only treatment is liver transplantation. Whilst liver transplant has a relatively good five-year survival, donor organ shortage costs many lives every year and results in lifelong immunosuppression. Alternative treatments are thus urgently needed. It is with this background that there is understandable interest for the development of stem cell therapies for liver regeneration. The identification of putative liver stem cells has brought closer the previously separate fields of liver ontology, regeneration, and carcinogenesis. Significant overlaps in the regulation of these processes are now being described. For example, studies in embryonic liver development have already provided the basis for directed differentiation of human embryonic stem cells and induced pluripotent stem cells into hepatocyte-like cells. As a result, the understanding of the cell biology of proliferation and differentiation in the liver has been improved. This knowledge can be used to improve the function of hepatocyte-like cells for drug testing, bio-artificial livers, and transplantation. In parallel, the mechanisms regulating cancer cell biology are now clearer, providing fertile soil for novel therapeutic approaches. Recognition of the relationships between development, regeneration, and carcinogenesis, and the increasing evidence for the role of stem cells in all of these areas, has sparked fresh enthusiasm in understanding the underlying molecular mechanisms and has led to new targeted therapies for liver cirrhosis and primary liver cancers. Human liver progenitor cells (LPCs) have therapeutic potential but their in vitro culture results in inadequate differentiation, function, and phenotypic instability reflecting an incomplete understanding of in vivo processes. LPCs can be robustly isolated from second trimester human foetal livers by immunoselection for EpCAM+/CD29+/CD49d+/CD49e–/CD235a–/CD45– cells. Expression profiling of mRNA and microRNA in human foetal LPCs was performed and compared with mature human hepatocytes and human embryonic stem cells undergoing hepatocytic differentiation. Foetal LPCs exhibit a distinct transcriptome profile consistent with a stem cell signature, cell division, and some liver-specific functions. Bioinformatic integration of microRNA and mRNA datasets revealed that microRNAs up-regulated in LPCs targeted genes involved in metabolic processes implying repression of the mature hepatocyte phenotype. Control of LPC gene expression therefore occurs at both transcriptional and, via microRNAs, post-transcriptional levels. Furthermore, transcription factor binding site analyses revealed enriched E2F1 motif in gene and microRNA promoters suggesting feedback control in determining LPC fate. Foetal LPCs were capable of differentiation to a hepatocytic phenotype in the presence of appropriate paracrine signals provided by EpCAM– non-parenchymal cells (NPCs), which consist mainly of endothelial cells and hepatic stellate cells. Fibronectin, despite being produced in abundance by EpCAM– NPCs, had no effect on LPC synthetic function in vitro. The expression of fibronectin in the perisinusoidal space suggests its potential role of modulating cross-talk between hepatoblasts/hepatocytes, liver sinusoidal endothelial cells, and hepatic stellate cells. Fibronectin expression in the portal vein mesenchyme and laminin α5 expression along the ductal plate suggest that both matrix molecules, located in close proximity to LPCs, may be important in supporting the LPC niche. Findings in this work provide insight into the regulation of the human foetal LPC functional phenotype, bringing stem cell-based therapies for liver disease one step closer.
43
Lam, Shuk-pik, and 林淑碧. "Differentiation of mesenchymal stem cells (MSCs) into hepatocytes in acute liver injury." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085647.
Повний текст джерела
44
Tirnitz-Parker, Janina Elke Eleonore. "Primary culture and immortal cell lines as in vitro models to evaluate the role of TWEAK signalling in hepatic oval cells /." Connect to this title, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0039.
Повний текст джерела
45
Gow, Adam George. "Production of canine hepatocyte-like cells from stem cell sources." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/10057.
Повний текст джерелаАнотація:
The cost of drug development is high with many drugs failing during toxicity testing. This is a particular problem in veterinary medicine where the pharmaceutical market size is so small that it may not be economically viable to develop drugs. The liver and specifically hepatocytes have a crucial role in drug metabolism via oxidation by cytochrome enzymes (CYP), conjugation and excretion into the biliary system. This drug metabolism is unpredictable between species as each has unique CYP profiles. Furthermore there is breed variation of CYP profiles within the canine species. The ability to produce an in vitro source of canine hepatocytes to model drug metabolism in this species and in different breeds would greatly reduce the expense of candidate drug testing. If an unlimited supply could be produced in vitro this would reduce the number of animals required in pre-clinical testing. The aim of this thesis was to produce an in vitro supply of canine hepatocyte-like cells from stem cell sources, namely hepatic progenitor cells (HPC), mesenchymal stem cells (MSC) or induced pluripotent stem cells (iPSC). Cultures of canine primary hepatocytes were produced to use as a gold standard, but also to develop and refine tests of hepatocyte characterisation and function. A panel of primers was developed for use in real time polymerase chain reaction (PCR) as well as optimising tests for low density lipoprotein (LDL) and indocyanine green uptake, albumin production, periodic acid- Schiff staining for glycogen and CYP activity using a luciferase-based system. As primary hepatocytes rapidly lost their defining characteristics and function in vitro, methods of maintaining function using CYP inducers and culture substrates were assessed. Isodensity centrifugation and magnetic-activated cell sorting was employed to isolate HPCs. Selection of cells from the non-parenchymal cell fraction with stem cell marker Prominin 1 demonstrated that these were keratin 7 positive, a HPC marker. Cells morphologically consistent with HPC appeared and expanded in culture after 2 weeks. On passaging, these cells failed to continue expanding, despite plating onto collagen, laminin, SNL feeder cells or using Kubota’s medium (known to allow rapid expansion of rodent and human HPCs). Canine adipose (Ad-MSC) and bone marrow-derived mesenchymal stromal cells (BM-MSC) were isolated post mortem. These were characterised as CD45, 105 and STRO-1 positive, CD11b, 19 and 45 negative cells which could be differentiated into adipocytes, chondrocytes and osteocytes based on staining characteristics and relative gene expression. Protocols published for other species were used to differentiate both Ad-MSC and BM-MSC towards a hepatocyte phenotype. Although a dramatic change in morphology and a reduction in vimentin gene expression were noted, suggesting a loss of mesenchymal phenotype, these protocols did not induce a hepatocyte phenotype. Pre-treatment with 5-Aza-2′-deoxycytidine to cause DNA demethylation and valproic acid to inhibit histone deacetylation also failed to allow transdifferentiation. A polycistronic vector containing Oct-4, c-Myc, Sox2 and Klf4 was successfully transfected into canine epidermal keratinocyte progenitor cells which became alkaline phosphatase positive and assumed a morphology consistent with iPSC. After colony selection and expansion, PCR evidence of plasmid presence was lost, colony morphology changed, and alkaline phosphatase activity reduced, consistent with vector expression factor and pluripotency loss. Canine iPSCs produced by lentiviral method were then differentiated towards hepatocyte phenotype using a published protocol for mouse and human iPSC. These cells were then assessed for hepatocyte characteristics using the developed reagents and primers. These cells demonstrated increased gene expression and morphology consistent with differentiation towards a hepatocyte-like phenotype. This thesis demonstrates successful culture of canine primary hepatocytes and validation of tests of hepatocyte phenotype. This provides a basis for optimising primary hepatocyte function in vitro and assessment of the success of differentiation protocols on stem cell sources. Canine mesenchymal stromal cells do not appear to transdifferentiate towards a hepatocyte-like phenotype using published protocols for other species. Canine iPSC are a promising candidate for an in-vitro source of hepatocyte-like cells.
46
Gertow, Karin. "Human embryonic stem cells : a novel model system for early human development /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-749-9/.
Повний текст джерела
47
Kardel, Melanie Dawn. "Analysis of hematopoiesis from human pluripotent stem cells." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33333.
Повний текст джерелаАнотація:
Human embryonic stem (ES) or induced pluripotent stem (iPS) cells have the potential ability to generate all of the cell types in the body. If their differentiation into relevant cell types of interest can be effectively controlled, they are attractive for developmental studies, disease modelling, drug testing, and advancing regenerative medicine. The generation of hematopoietic cells from human ES/iPS cells has been reported, but is highly variable and often inefficient. My specific objective in this thesis was to more fully characterize the process whereby hematopoietic cells are generated from primitive pluripotent precursors, to understand current limitations, and to design improvements that would increase the yield and reproducibility of hematopoietic cell generation. I first examined the effect of the conditions used to maintain the undifferentiated starting population of ES/iPS cells on their hematopoietic cell differentiation ability. The results showed that the initial maintenance conditions used do have a significant influence on the subsequent number and consistency of hematopoietic cells generated. In addition, I found that this process is separately influenced by optimization of sequentially manipulated (early and late) differentiation steps. Analysis of individual EBs revealed a previously unappreciated heterogeneity of hematopoietic output from single EBs in vitro. Even under the most optimal conditions studied, it was found that the majority of EBs did not generate any hematopoietic colony-forming cells (CFCs). This suggested that only a limited number of the initial ES/iPS cells were contributing to the hematopoietic progenitor cell output under these conditions. To investigate this latter phenomenon further, I developed a lentiviral system to track the subsequent hematopoietic progeny of marked undifferentiated or early differentiating ES/iPS cells. The use of this approach confirmed that few of the starting ES/iPS cells contribute to the hematopoietic output of individual EBs. Together these studies suggest that the genesis of hematopoietic progenitors from pluripotent precursors remains limited by multiple factors. Further studies to characterize cell types intermediate between fully pluripotent cells and those with hematopoietic activity are needed to define more rigorously and optimize the use of this strategy for various medical applications.
48
Eirew, Peter. "Detection and characterization of human mammary stem cells." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/34671.
Повний текст джерелаАнотація:
The mammary gland of adult female mice contains undifferentiated epithelial stem cells with in vivo regenerative and self-renewal properties. A biologically similar population likely exists in the human breast but a specific and quantitative methodology to identify and characterize these cells has been lacking. In this study I show that human mammary structures are reproducibly generated when dissociated suspensions of primary human mammary cells are propagated in collagen gels that have been implanted under the renal capsule of highly immunodeficient, hormone-treated mice. These structures contain differentiated cells of both mammary lineages in a spatial organization similar to normal mammary tissue, and display functional maturation into milk-producing glands when the hosts become pregnant. In vitro assays of single cell suspensions prepared from these regenerated glands revealed the consistent presence of mammary progenitor cells able to form adherent bi-lineage as well as pure luminal and myoepithelial colonies. In addition, when these cells are suspended in new gels and transplanted into secondary immunodeficient mice, similar progenitor-containing structures are demonstrable, indicative of a regenerative process that recreates the normal developmental hierarchy. This daughter progenitor production endpoint allows the frequency of these self-renewing human mammary stem cells to be derived from limiting dilution transplant assays as 1 per 10³–10⁴ cells in normal adult human reduction mammoplasty samples, and their phenotype to be established as CD49f⁺EpCAM⁻⁄low CD31⁻CD45⁻. I have also developed methodologies to isolate fractions of cells from mammoplasty tissue that are enriched in cells in different phases of the cell cycle (G0/G1/S/G2/M). Application of functional assays to these fractions indicates that a proportion of stem and progenitor cells in normal adult breast tissue exhibit phenotypes that are associated with actively proliferating cells. These studies support a model of mammary cell production that includes a significant rate of normal turnover of primitive cells, and sets the stage for further work to identify the factors and molecular interactions that regulate this process.
49
Tilgner, Katarzyna. "Derivation of oocytes from human embryonic stem cells." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512211.
Повний текст джерела
50
Adams, William James. "Human Vascular Endothelium from Induced Pluripotent Stem Cells." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10816.
Повний текст джерелаАнотація:
The vascular endothelium is a dynamic cellular interface that displays a unique phenotypic plasticity. This plasticity is critical for vascular function and when dysregulated is pathogenic in several diseases. The development of new human endothelial genotype-phenotype studies, personalized vascular medicine efforts and cell based regenerative therapies are limited by the unavailability of patient-specific endothelial cells. Induced pluripotent stem cells (iPSC) offer great promise as a new personalized source of endothelium; however, the reproducibility, fidelity and functionality of iPSC-derived endothelial cells remains poorly understood.Engineering and Applied Sciences