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Götherström, Cecilia. "Characterisation of human fetal mesenchymal stem cells /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-139-3/.
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Gupta, Gunjan. "Effect of chondrocyte-stem cell interactions on chondrogenesis of mesenchymal stem cells." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1465607.
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Thesis (M.S.)--University of California, San Diego, 2009.<br>Title from first page of PDF file (viewed August 11, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 128-134).
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Li, Jing. "Effects of intrinsic & extrinsic factors on the growth and differentiation of human mesenchymal stem cells." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36434450.
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dos, Anjos Afonso Fernando. "A step towards identifying the true adult murine Mesenchymal Stem Cell." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1444628/.
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Research spanning over a few decades has contributed to the discovery and understanding of a population of cells that are precursors of connective tissue cell-types. These cells currently referred as Mesenchymal Stem Cells (MSCs), have also been shown by some researchers to have the capacity to give rise to neuron- and muscle-like cells in vitro, making them very attractive as cellular source for clinical application in regenerative medicine. Despite the intense focus on therapeutic research on going in the MSC field, the biology of these cells remains elusive, especially at its hierarchical organisation. Although some data suggest that MSCs are composed of different sub-populations of progenitors or cells that are prompted to differentiate preferentially into one or few different cell-types in vitro, there is no defined hierarchy proposed yet, especially at the most primitive level. The initial aim of this project was to characterise the adult murine MSC (muMSCs) compartment since most of the studies performed to date were conducted with human cells. During the process of such, a new cell type was found. Under a conventional isolation/culture system a minor sub-population of muMSCs was identified and then characterised (based on the expression of SSEA-1 antigen Stage Specific Embryonic Antigen-1). The data presented strongly suggest that this new sub-population is not only the founder of the MSC compartment but also they are multipotent both in vitro and in vivo. Moreover, this new cell-type can be directly identified from fresh bone marrow thus confirming its true existence in vivo. Detailed study on SSEA-1 pos-MSCs revealed that these cells present several common features with Embryonic Stem Cells (ES) and therefore suggests that a group of cells with embryonic features might persist throughout adult life. The identification/characterisation of these adult murine SSEA-1pos cells should facilitate the identification of a similar cell-type in the human MSC compartment. Furthermore, this study opens new questions on the developmental origin and importance of adult tissue-specific stem cells in the maintenance of tissue homeostasis.
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Kemp, Kevin Charles. "The role of mesenchymal stem cells in stem cell transplantation for haematological malignancies." Thesis, University of the West of England, Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495521.
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Haemopoietic recovery after high dose chemotherapy (HOC) in the treatment of haematological disease may be slow and/or incomplete. This is generally attributed to progressive haemopoietic stem cell failure, however we hypothesize that HOC induced defective haemopoiesis may be in part due to poor stromal function. Although chemotherapy is known to damage mature bone marrow stromal cells in-vitro, the extent to which marrow mesenchymal stem cells (MSC) are damaged by HOC in-vivo and in-vitro is unknown. To firstly address this question the physical characteristics and functional properties of marrow MSC derived from patients who have received chemotherapeutic treatment for various haematological diseases were investigated. Subsequently a suitable in-vitro treatment culture model was developed and the effects of chemotherapy exposure in-vitro using cell culture and proteomic techniques were shown. Results of this study demonstrate proliferative and phenotypic changes to patient MSC caused by HOC regimens. In contrast, the differentiation capacity, and ability to form functional marrow stroma after exposure to HOC in-vivo was equal to that of patient MSC studied prior to HOC. Chemotherapeutic exposure to MSC cultures in-vitro have confirmed changes seen in-vivo, with abnormalities evident in MSC proliferation, differentiation and also in their ability to support haemopoietic stem cell migration and repopulation after treatment. A reduced C044 expression on MSC, after exposure to cyclophosphamide, was also observed and the importance of this molecule shown through con-focal microscopy demonstrating its interaction with C034+ haemopoietic stem cells. Using proteomic techniques differences in protein expression by MSC, relating to changes in their function after chemotherapy exposure, were also observed after treatment with cyclophosphamide or melphalan. Finally the role of keratinocyte growth factor as a potential cyto-protective agent to MSC against damage caused by chemotherapy exposure was tested. Results indicated there was significant evidence to indicate that KGF was able to preserve reductions in C044 expression levels after MSC exposure. It was concluded that marrow MSC sustain prolonged injury due to recurrent courses of HOC in-vivo and in-vitro. However, the clinical importance of the chemotherapy induced defects we have observed must be determined through the initiation of prospective randomized trials of the effects of MSC co-transplantation on haemopoietic recovery in the setting of HOC with and without haemopoietic stem cell rescue.
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Lin, Wenyu. "Investigating the immunomodulatory properties of human embryonic stem cell-derived mesenchymal stem cells." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/7060.
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The immunosuppressive property of mesenchymal stem cells (MSC) has been utilised to ameliorate autoimmune reactions such as graft-versus-host disease. However, variation exists in primary MSC isolated due to differences in donor age and tissue of origin. Alternatively, human embryonic stem cells (hESC) can be differentiated to homogeneous populations of MSC (hESCMSC), thus providing an unlimited source of MSC for cell therapy. In this study, the immunomodulatory properties of two hESC-MSC lines, hESC-MSC1 and hESC-MSC2, were compared with adult bone marrow-derived MSC (BM-MSC) and neonatal foreskin fibroblast (Fb). hESC-MSC were able to suppress the proliferation of anti-CD3/CD28-stimulated CD4+ T cells in contact and transwell systems. The immunosuppression was demonstrated by both the carboxyfluorescein diacetate succinimidyl ester (CFSE) and [3H]- thymidine proliferation assays. However, hESC-MSC were less potent and twice the number of adherent hESC-MSC (as measured by IC50) compared to BM-MSC and Fb were required to suppress T cell proliferation by 50%. Supernatants collected from transwells of MSC or Fb with T cells were shown to suppress T cell proliferation, suggesting that suppressive factors were only produced in the presence of activated T cells. Among several candidates, endothelial monocyte-activating polypeptide-II (EMAP-II) was identified as a potential suppressive factor. T cells also induced indoleamine-2,3- dioxygenase (IDO) expression in MSC and Fb. IDO led to the depletion of tryptophan, an essential amino acid, and/or the production of tryptophan metabolites (kynurenines), thereby inhibiting T cell proliferation. Interestingly, blocking of IDO with 1-methyltrytophan reversed the suppressive effect, implicating IDO as a potential mediator in T cell suppression. Concomitantly, several candidate suppressive factors in the supernatants have also been identified using antibody arrays. However, their functions require validation. In conclusion, hESC-MSC share similar suppressive properties as BM-MSC and represent a potential cell source for clinical purposes.
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Okolicsanyi, Rachel K. "Mesenchymal stem cells as mediators of the neuronal cell niche." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/84485/1/Rachel_Okolicsanyi_Thesis.pdf.
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This study examined the role of heparan sulfate proteoglycans (HSPGs) in neural lineage differentiation of human mesenchymal stem cells (hMSCs). Several HSPGs were identified as potential new targets controlling neural fate specification and may be applied to the development of improved models to examine and repair brain damage. hMSCs were characterised throughout extended in vitro expansion for neural lineage potential (neurons, astrocytes, oligodendrocytes) and differentiated using terminal differentiation and intermediate sphere formation. Brain damage and neurological disorders caused by injury or disease affect a large number of people often resulting in lifelong disabilities. Multipotent mesenchymal stem cells have a large capacity for self-renewal and provide an excellent model to examine the regulation and contribution of both stem cells and their surrounding microenvironment to the repair of neural tissue damage.
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Rasmusson, Ida. "Immune modulation by mesenchymal stem cells /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-384-1/.
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Gow, Adam George. "Production of canine hepatocyte-like cells from stem cell sources." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/10057.
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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.
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Neale-Edwards, Emma C. "Manufacturing of human mesenchymal stem cells : the analytical challenges." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33283.
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It has been repeatedly proven that cell therapies can address many current unmet clinical treatment needs and also improve on current treatment options for various diseases, from neurological disorders to bone repair (Rosset et al. 2014; Corey et al. 2017). Though the potential of cell therapies has been demonstrated at a relatively small scale, the realisation of bringing cell based treatments to a larger market is hindered by the complexity of the product along with safety concerned and high production cost. Safety concerns can be informed with more in-depth analytical analysis of the product, however this in turn increase the costs involved in producing a cell therapy (Davie et al. 2012). Consequently the cost of analytical techniques also needs to be reduced, to address this need the area of microfluidic based bioanalytics holds much promise (Titmarsh et al. 2014). The culturing of human mesenchymal stem cells (hMSC) was used as a proof of concept model to demonstrate where improved bioanalytical and bioassay methods could be utilised in the production of cell therapies. Cells from four donors were cultured under three different oxygen environments and the conditioned medium assessed for pro-angiogenic capabilities using a tube formation bioassay and a proportion of the cytokine secretome profile measured using Luminex technology. Thorough secretome analysis it was shown that predicting cytokine levels based solely on the donor was not possible as the handling of the cells also had an influence on the secretome profile. The donor expression profiles did not behave in the same manner across all oxygen environments, for example in some donors IL-8 levels increased per cell at lower oxygen where as other donors showed a decrease per cell. While the tube formation assay showed some differences between donors in pro-angiogenic capabilities it also highlights the challenges with interpreting large data sets. The feasibility of using a microcapillary film (MCF) based enzyme-linked immunosorbent assay (ELISA) to detected two relevant cytokines, IL-8 and hepatocyte growth factor (HGF) was investigated. Following on from this work the development of a combined MCF ELISA assay with hMSC cell culture to produce a fully closed cell screening system was initiated. It was shown that it was feasible to measure IL-8 and HGF using the MCF ELISA platform but further work would need to be done to make the system more compatible with the manufacturing environment. In order to adapt the MCF to also be an hMSC culture platform the first challenge was to functionalise the Fluorinated Ethylene Propylene (FEP) surface of the MCF. It was concluded that a poly (vinyl- alcohol) (PVA) and gelatin mixture produced a homogenous coating to which a consistent level of hMSC would attach. This work was carried out on a flat surface; therefore steps were taken to adapt this knowledge into the MCF, while there was evidence of hMSCs present inside the MCF more work will need to be done to bring this concept to an established platform.
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Yu, Jiaole, and 于皎乐. "Intrinsic and extrinsic factors affecting the migratory mechanisms of human mesenchymal stem cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/197130.
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The potential applications of mesenchymal stem cells (MSCs) have been widely advocated, however, many barriers hinder their clinical utilization. Enhancement of the homing of human MSCs (hMSCs) to the target tissues remains a clinical challenge. To overcome this hurdle, the mechanisms responsible for migration and engraftment of hMSCs have to be defined. My study aimed to explore both the underlying mechanisms and means of enhancing the migration of hMSCs.
A graft versus host disease (GvHD) injury model and a novel orthotopic neuroblastoma model were established to delineate the distinct property of hMSCs homing towards either injured or cancerous tissues. This highly specific homing process was further revealed to be in a CXCR4-dependent manner.
Notably, a novel gene, exchange protein directly activated by cAMP (Epac), was demonstrated to be actively involved in the hMSCs homing process. hMSCs expressed functional Epac and its activation significantly enhanced the migration and adhesion of hMSCs. Furthermore, Epac activation directly contributed to the chemotactic response of hMSCs to SDF-1, suggesting that Epac is linked to the stromal cell derived factor-1 (SDF-1) signaling cascades. Importantly, the homing of hMSCs towards injured tissues in vivo could be dramatically increased by Epac activation.
hMSCs are adherent cells and their migration to distant tissues thus requires detachment into a suspension state. This disruption of cell-extracellular matrix interaction, known as anoikis stress, triggers programmed cell death, leading to a marked decrease in the efficiency of cell trafficking and engraftment. Anoikis stress induced massive cell death has emerged as the major challenge in the application of hMSCs. How some of the hMSCs can overcome this adversity and migrate towards distant destinations remains largely unexplored. It was observed that the surviving hMSCs circumvented anoikis stress by forming self-supporting cellular aggregates. Compared to adherent hMSCs, aggregated-hMSCs had better migratory response to both SDF-1α and SDF-1α analogue (CTCE-0214). Such enhanced migratory effect was proven to be CXCR4-dependent both in vitro and in vivo by using a CXCR4 specific antagonist (AMD3100). Although the viability of hMSCs under anoikis stress dramatically decreased, CTCE-0214 could promote cell survival and facilitate the migration of hMSCs towards injured targets. This phenomenon could be partially explained by the increase in anti-apoptosis effect via up-regulated Bcl-2 expression and autophagy activation under CTCE-0214 treatment.
The exact effects of hMSCs on tumor growth and progression have long been controversial. Significant fasten growth and promoted metastasis of neuroblastoma in vivo was observed in hMSCs co-transplanted mice in this study. Reciprocally, hMSCs could not only be recruited by primary tumor, but also be selectively attracted by metastatic loci. This recruitment was significantly reduced when hMSCs were pre-treated with AMD3100, suggesting that the SDF-1/CXCR4 axis was a prime mover in this process.
In summary, my study demonstrated that the migratory property of hMSCs could be enhanced by novel intrinsic and extrinsic factors using both in vitro and in vivo models. This study provides a new prospective on MSCs biology during the ex vivo manipulation process and I proposed means to overcome some of these hindrance so we can maximize the efficacy of clinical MSCs application in the future.<br>published_or_final_version<br>Paediatrics and Adolescent Medicine<br>Doctoral<br>Doctor of Philosophy
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Qiao, Bin. "Epithelial-Mesenchymal Transition and Mesenchymal-Epithelial Transition in Oral Stem Cell Carcinogenesis." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/367467.
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Oral squamous cell carcinoma (OSCC), derived from normal oral epithelium transformation, remains a major public health problem world-wide. The prognosis of OSCCs that occur on lips is good, while other sites of oral mucosa where OSCC appears are more progressive, invasive and metastatic. A small subset of cells within a malignant neoplasm, named cancer stem cells (CSCs) or tumour initiating cells are thought to be capable of initiating the neoplasm itself, and of driving its growth and recurrance after treatment. The precise origin of CSCs is an ambiguous issue at present. The first proposal of the origin of CSCs is that CSCs develop from tumour cells themselves via cellular dedifferentiation. The secondary hypothesis for the origin of CSCs proposes that CSCs are the product of malignant transformation of adult stem cells. In this Ph.D thesis, we tried to demonstrate that CSCs in OSCC may be produced from those pathways.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Medicine<br>Griffith Health<br>Full Text
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Nie, Yingjie. "Defective dendritic cells and mesenchymal stromal cells in systemic lupus erythematosus and the potential of mesenchymal stromal cells as cell-therapy." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43278681.
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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.
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Che, Mohamad Che Anuar. "Human embryonic stem cell-derived mesenchymal stem cells as a therapy for spinal cord injury." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/7047/.
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Traumatic injury to the spinal cord interrupts ascending and descending pathways leading to severe functional deficits of sensory motor and autonomic function which depend on the level and severity of the injury. There are currently no effective therapies for treating such injuries and the adult central nervous system has very limited capacity for repair so that recovery is very limited and functional deficits are usually permanent. Cell transplantation is a potential therapy for spinal cord injury and a range of cell types are being investigated as candidates. Mesenchymal stem cells (MSCs) obtained from bone marrow are one cell type quite extensively studied. When transplanted into animal models of spinal cord injury these cells are reported to affect various aspects of repair and in some cases to improve functional outcome according to behavioural measures. However, the use of these cells has several limitations including the need for an invasive harvesting procedure, variability in cell quality and slow expansion in culture. This project therefore had two main aims: Firstly to investigate whether MSC-like cells closely equivalent to bone marrow derived MSCs could be reliably and consistently differentiated from human embryonic stem cells (hESCs) in order to provide an “off the shelf” cellular therapy product for spinal cord injury and secondly, to transplant such cells into animal models of spinal cord injury in order to, determine whether hESC-derived MSCs replicate or improve on the repair mechanisms reported for bone marrow MSCs.
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Zhang, Jiao, and 张姣. "Regulation of cell proliferation and modulation of differentiation in human induced pluripotent stem cell-derived mesenchumal stem cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49617503.
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Functional mesenchymal stem cells (MSCs) derived from human induced pluripotent stem cells (iPSCs) may represent an unlimited cell source with superior therapeutic benefits for tissue regeneration to somatic tissue, such as bone marrow (BM)-derived MSC. In the first part of this project, I investigated whether the differential expression of ion channels in iPSC-MSCs was responsible for their higher proliferation capacity than that of BM-MSCs. The expression of ion channels for K+, Na+, Ca2+ and Cl- currents was assessed by reverse transcription-polymerase chain reaction (RT-PCR). The functional role of these ion channels were then verified by patch clamp experiments to compare the electrophysiological properties of iPSC-MSCs versus BM-MSCs. I detected significant mRNA expression of ion channel genes including KCa1.1, KCa3.1, KCNH1, Kir2.1, SCN9A, CACNA1C and Clcn3 in both human iPSC-MSCs and BM-MSCs; while Kir2.2 and Kir2.3 were only observed in human iPSC-MSCs. Furthermore, I identified five types of currents (BKCa, IKDR, IKir, IKCa and ICl) in iPSC-MSCs, while only four of them (BKCa, IKDR, IKir and IKCa) were observed in BM-MSCs. The rate of cell proliferation was 1.4 fold faster in iPSC-MSCs as compared to BM-MSCs. Interestingly, the proliferation rate of human iPSCMSCs was significantly reduced when inhibiting IKDR with shRNA and hEAG1 channel blockers, 4-AP and astemizole. Though to a lesser extent, the proliferation rate of human BM-MSCs also decreased by IKDR blockage. These results demonstrated that hEAG1 channel plays a crucial role in controlling the proliferation rate of human iPSC-MSCs but to a lesser extent in BM-MSCs.
Next, I examined whether forced expression of a transcription factor- myocardin in iPSC-MSC using viral vectors (adenovirus or lentivirus) can further enhance their trans-differentiation to cardiomyocytes and improve their electrophysiological properties for cardiac regeneration. My results on RT-PCR and immunofluorescent staining revealed that myocardin induced the expression of several cardiac and smooth muscle cell markers, including α-MHC, cTnT, GATA4, α-actinin, and cardiac MHC, smooth muscle cell markers MYH11, calponin, and SM α-actin, but not the more mature cardiac markers such as β-MHC and MLC2v in iPSC-MSCs. These findings indicate that forced expression of myocardin in iPSC-MSC resulted in partial trans-differentiation into cardiomyocytes phenotype. Furthermore, I also discovered that myocardin altered the electrophysiological properties of iPSC-MSCs when examined by RT-PCR and patch clamp experiments. Forced expression of myocardin in iPSC-MSC enhanced the expression of Kv4.3, SCN9A and CACNA1C, but reduced that of KCa3.1 and Kir 2.2 in iPSC-MSCs. Moreover, BKCa, IKir, ICl, Ito and INa.TTX were detected in iPSC-MSC with ectopic expression of myocardin; while only BKCa, IKir, ICl, IKDR and IKCa were noted in iPSC-MSC transfected with green florescence protein. Furthermore, as measured by multi-electrode arrays recording plate, the conduction velocity of the neonatal rat ventricular cardiomyocytes cocultured iPSC-MSC monolayer was significantly increased after ectopic expression of myocardin. Taken together, I have demonstrated that hEAG1 channel is important in the regulation of iPSC-MSC proliferation and forced expression of myocardin in iPSC-MSC resulted in their partial transdifferentiation into cardiomyocytes phenotype and improved the electrical conduction during integration with mature cardiomyocytes.<br>published_or_final_version<br>Medicine<br>Doctoral<br>Doctor of Philosophy
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Leung, Ho-yan, and 梁可昕. "A study of membrane-bound neuregulin in mediating fate commitment of Schwann cell-like cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193482.
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Central nervous system injuries often lead to devastating consequences due to an unfavourable environment created after the injury. Current treatments have yet to address the environment for improved prospects of functional recovery. Transplantation of Schwann cells into the lesion site could in part address the issue, promoting nerve regeneration and enhancing functional recovery. Bone marrow stromal cells (BMSCs) promise to be a viable, autologous source for Schwann cell derivation. Fate-committed Schwann cells derived from BMSCs through co-culture with purified dorsal root ganglia (DRG) neurons suggest that the DRG neurons present juxtacrine cues that direct commitment to the Schwann cell fate. We hypothesize that Neuregulin 1 type III (NRG1(III)) is one such juxtacrine cue to which BMSC-derived Schwann cell-like cells (SCLC) respond in the switch to fate commitment. In this study, NRG1(III) was found to be expressed on freshly isolated DRG neurons and that SCLCs expressed both the ErbB2 and 3 receptors. Western blot analysis for phosphorylated Akt and MAPK provided indicators of downstream signalling of NRG1/ErbB complexes. We then tested if both the soluble and membrane bound forms of NRG1 mediate SCLC differentiation towards fate commitment. In contrast to the membrane-bound form on DRG neurons, soluble NRG1 failed to direct the SCLCs towards the Schwann cell fate. HEK293T cells that stably overexpress NRG1(III) were generated and tested as a neuronal surrogate that presents NRG1(III) on the cell surface. In a 5-day co-culture system with HEK293TNrg1(III) cells, SCLCs were found to develop elongated processes, acquiring either unipolar or bipolar morphology that resembles that of Schwann cells. Screening for marker expression by RT-PCR suggested that at this stage of morphological transition, SCLCs were not yet committed to the Schwann cell fate. The co-culture system will be pursued to find ex vivo conditions that direct differentiation of BMSC-derived SCLCs to fate-committed Schwann cells.<br>published_or_final_version<br>Biochemistry<br>Master<br>Master of Philosophy
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Karystinou, Alexandra. "YAP in mesenchymal stem cells." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=192255.
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MSCs are the most studied subtype of adult stem cells and have been derived from most postnatal organs and tissues. MSCs are defined as having the capacity to self-renew and to differentiate into both mesodermal and non-mesodermal lineages, and are immunosuppressive. For these properties, MSCs have been considered ideal candidates for regenerative medicine and have been used in several clinical trials. The difficulty, however, to preserve the potency of the cells during culture expansion and to monitor differentiation are obstacles in their use in the clinic and have emphasized the need to investigate molecular pathways underlying stem cell fate-decisions during differentiation in more detail. Hippo pathway was recently identified in Drosophila melanogaster and mammals, and controls organ size by regulating cell proliferation, apoptosis and differentiation. It is composed of a core of serine/threonine kinases and scaffold proteins that when activated, phosphorylate and inhibit yes-associated protein (YAP) transcriptional co-factor. Inactivation of YAP in some stem and progenitor cells by this pathway is required for their differentiation. In contrast, failure to inhibit YAP enhances proliferation and may cause oncogenic transformation. In the present study, the expression of multiple YAP variants was confirmed in human and mouse MSCs. In both human and mouse, YAP was inhibited in response to cell-contact inhibition and remained unchanged during in vitro chondrogenic differentiation. Overexpression of human (hYAP1) variant in C3H/10T1/2 cells did not appear to affect colony formation, cell cycle distribution or cell size, but increased cell proliferation, induced cell transformation and reduced the in vitro differentiation capacity of the cells towards the chondrogenic, adipogenic and osteogenic lineages. The effects of hYAP1 overexpression are hypothesized to be either a result of a nuclear co-factor function or indirectly via protein interactions in the cytoplasmic compartment. Hippo pathway and YAP are possible pharmacological targets for modulation of MSC function.
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Hahnel, Mark. "Trafficking of mesenchymal stem cells." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/14559.
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In adult life mesenchymal stem cells (MSCs) reside primarily in the bone marrow and are defined according to their ability to self-renew and differentiate into tissues of mesodermal origin. Due to their immuno-modulatory properties and ability to form cartilage and bone, MSCs have clinical potential, for the treatment of autoimmune diseases and tissue repair. This project determines the chemokine receptor profile on murine bone marrow MSCs at early and late passage and on human MSCs derived from a range of fetal tissues including fetal blood, bone marrow, amniotic fluid and placenta. The overwhelming result from this analysis is the consistency across species and tissue source with respect to chemokine receptor profiles. In addition it is clear that expression of specific chemokine receptors defines sub-populations of MSCs. Currently, clinical trials using MSCs have relied on continued in vitro culture in order to obtain sufficient numbers for treatment. Here, MSCs have been shown to lose external chemokine receptor expression and associated chemotactic ability, whilst growing in size upon continued culture. All cultured MSCs investigated in this thesis were shown to be a heterogeneous population of stem cells and progenitors that contained ‘true’ MSCs within its number. This thesis investigates a pharmacological approach to mobilise endogenous MSCs from the bone marrow, increasing their numbers in the blood. It has previously been reported that administration of VEGF-A over 4 days followed by a single dose with a CXCR4 antagonist (AMD3100) causes selective mobilisation of MSCs into blood. The VEGF biology of this response has been interrogated. MSCs were shown to express high levels of VEGFR-1 and lower levels of VEGFR-2 on the cell surface but do not express VEGFR-3. By blocking VEGFR-1 with mAbs during VEGF-A165 treatment, a ten-fold increase in MSC mobilisation in response to AMD3100 was recorded, while treating with VEGFR-2 blocking mAbs had no effect. Using VEGF isoforms specific for VEGFR-1 and VEGFR-2 (PlGF and VEGF-E respectively), it was determined that MSC mobilisation was dependant on activation of VEGFR-2 and not VEGFR-1. PαS cells are a subset of MSCs found in the murine bone marrow that are PDGFRα+, Sca-1+, CD45-, Ter119-. Further characterisation of mobilised mMSCs by flow cytometric analysis of PαS cells, now provides a way to investigate the biology of MSCs, both in their steady state in vivo and in models of injury and inflammation. Molecular mechanisms lying downstream of VEGFR-2 have been explored and it has been shown that MMPs play a critical role in mobilisation. The use of drugs to mobilise MSCs into the blood may provide a cost effective, non-invasive treatment to promote tissue repair.
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Yao, Hsin-Lei Reid Lola M. "The hepatic stem cell niche and paracrine signaling by mesenchymal cells in support of human hepatic stem cells." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1270.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.<br>Title from electronic title page (viewed Mar. 26, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biomedical Engineering." Discipline: Biomedical Engineering; Department/School: Medicine.
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Sottile, Francesco 1988. "Mesenchymal stem cells generate distinc functional hybrids via cell fusion or entosis." Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/565598.
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Homotypic and heterotypic cell-cell fusion are key processes during development and tissue regeneration. On the other hand, aberrant heterotypic cell fusion between cancer and normal cells can contribute to tumor initiation and metastasis. Additionally, a form of cell-in-cell structure called entosis has been observed in several human tumors. Here we investigate cell-cell interaction between mouse mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs). MSCs have a great potential for regenerative medicine, but they are also involved in cancer progression. Here we report that MSCs can either fuse forming thereby heterokaryons, or be invaded by ESCs through entosis. Importantly we show that hetero-to-synkaryon transition occurs through a mitotic cell division and not by nuclear membrane fusion. Moreover, we also observe that the ROCK-actin/myosin pathway is required for both fusion and entosis in ESCs but only for entosis in MSCs. Overall, we show that MSCs can undergo fusion or entosis in culture by generating distinct functional cellular entities. Therefore, we conclude that both cellular processes should be explored for possible therapeutic application of MSCs.<br>Las fusiones célula-célula homotípica y heterotípica son procesos clave durante el desarrollo y la regeneración de tejidos. Por otro lado, la fusión celular heterotípica aberrante entre células tumorales y células normales puede contribuir a la tumorigénesis y a la metástasis. Además, una forma estructural donde una célula esta dentro de la otra llamada entosis se ha observado en varios tumores humanos. Aquí estudiamos la interacción célula-célula entre las células madre mesenquimales (MSCs) de ratón y las células madre embrionarias (ESCs). Las MSCs no solo tienen un gran potencial para la medicina regenerativa, sino que también están involucradas en la progresión del cáncer. Aquí mostramos que las MSCs pueden fusionarse formando de este modo heterokaryons, o ser invadidas por las ESCs a través de entosis. Es importante destacar que la transición desde el heterokaryon al synkaryon se produce a través de una división celular mitótica y no por la fusión de la membrana nuclear. Por otra parte, también se observa que se requiere de la vía ROCK-actina/miosina tanto para la fusión como para la entosis en ESCs, pero solo para entosis en MSCs. En definitiva, se muestra que las MSCs pueden someterse a la fusión o entosis en cultivo mediante la generación de distintas entidades celulares funcionales. Por tanto, concluimos que ambos procesos celulares deben ser explorados para una posible aplicación terapéutica de las MSCs.
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Gullo, Francesca. "Mesenchymal stem cell subsets from human synovium." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=195745.
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Youngstrom, Daniel W. "Mesenchymal Stem Cell Mechanobiology and Tendon Regeneration." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/64422.
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Tendon function is essential for quality of life, yet the pathogenesis and healing of tendinopathy remains poorly understood compared to other musculoskeletal disorders. The aim of regenerative medicine is to replace traditional tissue and organ transplantation by harnessing the developmental potential of stem cells to restore structure and function to damaged tissues. The recently discovered interdependency of cell phenotype and biophysical environment has created a paradigm shift in cell biology. This dissertation introduces a dynamic in vitro model for tendon function, dysfunction and development, engineered to characterize the mechanobiological relationships dictating stem cell fate decisions so that they may be therapeutically exploited for tendon healing.
Cells respond to mechanical deformation via a complex set of behaviors involving force-sensitive membrane receptor activity, changes in cytoskeletal contractility and transcriptional regulation. Effective ex vivo model systems are needed to emulate the native environment of a tissue and to translate cell-matrix forces with high fidelity. A naturally-derived decellularized tendon scaffold (DTS) was invented to serve as a biomimetic tissue culture platform, preserving the structure and function of native extracellular matrix. DTS in concert with a newly designed dynamic mechanical strain system comprises a tendon bioreactor that is able to emulate the three-dimensional topography, extracellular matrix proteins, and mechanical strain that cells would experience in vivo. Mesenchymal stem cells seeded on decellularized tendon scaffolds subject to cyclic mechanical deformation developed strain-dependent alterations in phenotype and measurably improved tissue mechanical properties. The relative tenogenic efficacies of adult stem cells derived from bone marrow, adipose and tendon were then compared in this system, revealing characteristics suggesting tendon-derived mesenchymal stem cells are predisposed to differentiate toward tendon better than other cell sources in this model.
The results of the described experiments have demonstrated that adult mesenchymal stem cells are responsive to mechanical stimulation and, while exhibiting heterogeneity based on donor tissue, are broadly capable of tenocytic differentiation and tissue neogenesis in response to specific ultrastructural and biomechanical cues. This knowledge of cellular mechanotransduction has direct clinical implications for how we treat, rehabilitate and engineer tendon after injury.<br>Ph. D.
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San, Khin MiMi. "tRNA Profiling of Mesenchymal Stem Cell Exosome." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5638.
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Background: Exosomes have great potential in regenerative medicine through the
transfer of their bioactive cargos, such as RNA. tRF RNA and tiRNA are tRNAderived
non-coding RNA. Here, we sought to identify the tRF/tiRNA profile in human
mesenchymal stem cell (hMSC) exosomes. Methods: Bone marrow hMSCs were
cultured with/without osteogenic differentiation medium and exosomes were
harvested. RNA was extracted from: 1) control cells (Cell-NT); 2) control exosomes
(EXO-NT); 3) differentiated cells (Cell-OM); 4) exosomes produced by differentiated
cells (EXO-OM). RNA was sequenced to profile the small RNA with a focus on
tRF/tiRNA. Results: tRF/tiRNA was highly enriched in hMSC exosomes. Less
diversity was seen in the tRF/tiRNA profile in exosomes than that in parent cells.
Selective tRF/tiRNA were packed into MSC exosomes and their profile is dependent
on the cell maturation status. Conclusions: Our results suggest that tRF/tiRNA may
play a role in mediating the function of exosomes in tissue regeneration.
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Li, Chuen-wai, and 李鑽偉. "Dynamic compression and exogenous fibronectin regulates cell-matrix adhesions and intracellular signaling proteins of human mesenchymal stem cells in 3D collagen environment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197553.
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The fundamental principle of tissue engineering is to use appropriate cell source, combined with scaffolds and bioactive factors to develop tissue constructs which restore, maintain or improve tissue function. There is increasing data emphasizing the importance of mechanical signals and extracellular matrix (ECM) proteins presented by the scaffold in determining stem cell fate/functions which are critical to tissue construct maturation and success of stem cell-based therapies. Cell-matrix adhesions are one of the major mechanosensing machineries cells use to convert information provided by ECM ligands and mechanical signals presented by scaffolds into intracellular biochemical signaling cascades which lead to particular functional responses. Therefore, understanding how ECM ligands and mechanical signals regulate cell-matrix adhesion formation and activation of associated intracellular signaling proteins is fundamental to rational design of biomaterial and loading protocol for optimal cell functional responses in tissue constructs.
In this study, we attempted to understand the regulatory effects of external mechanical signal and exogenous ECM protein on cell-matrix adhesion formation and associated intracellular signaling proteins of human mesenhymal stem cells, and in particular, to test the hypothesis that mechanical stimulation or exogenous ECM protein can lead to adhesion maturation into 3D-matrix adhesions in 3D collagen environment. We used microencapsulation technique to embed cells in 3D collagen environment, forming disc-shaped hMSC-collagen constructs. By immunofluorescent staining and confocal microscopy, we visualized changes in size, morphologies and molecular composition of the adhesions.
First of all, 2D adhesions of hMSCs were characterized. We showed that hMSCs form well-organized αv integrin-based focal adhesions and fibrillar adhesions in 2D culture. To investigate the regulatory effects of mechanical signals on adhesion signaling and maturation, we used micromanipulator-based loading device to impose dynamic compression to hMSC-collagen constructs. We found that dynamic compression lead to enlargement of integrin αv adhesions which recruit focal adhesion kinase (FAK), vinculin and extracellular signal-regulated kinase (ERK). In addition, FAK was activated at enlarged integrin αv adhesions and translocated to peri-nuclear region after compression, suggesting that loading induces activation of FAK signaling pathways through increased integrin αv clustering. Moreover, we demonstrated that dynamic compression can induce 3D-matrix adhesion formation, indicating the role of external force in integrin α5-based adhesion maturation in 3D collagen environment.
We explored the effect of exogenous ECM proteins on adhesion maturation of hMSCs by adding fibronectin into cell-collagen mixture during fabrication of collagen constructs. Our results demonstrated that the exogenous fibronectin can induce α5 integrin-based adhesion maturation into 3D-matrix adhesions in our collagen constructs in a dose-dependent manner.
This study demonstrated that the effect of external mechanical signals and exogenous ECM ligands on adhesion signaling and maturation of hMSCs in 3D collagen environment. Our findings contribute towards mechanobiology of hMSCs in 3D context. In particular, our results showed that exogenous proteins or external loading can lead to 3D-matrix adhesion formation, which may serve as a potential way to enhance biological functions of hMSCs in collagen constructs, facilitating stem cell-based therapies.<br>published_or_final_version<br>Mechanical Engineering<br>Doctoral<br>Doctor of Philosophy
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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.
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Duffy, Cairnan Robert Emmett. "New culture systems for mesenchymal stem cells." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/21044.
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Mesenchymal stem cells are the stem cells that replace the bone, fat and cartilage tissues of the human body. In addition, these cells can form muscles, ligaments and neurons. This wide multipotency has made mesenchymal stem cells of particular interest in the fields of tissue engineering and regenerative medicine. Furthermore, mesenchymal stem cells can modulate the immune system by reducing factors that increase inflammation and immune recognition. This immune recognition suppression has resulted in their application as part of bone marrow transplantation in the prevention of 'graft versus host‘ disease. There are hundreds of on-going clinical trials using these cells for the treatment of autoimmune diseases such as type I diabetes, arthritis and multiple sclerosis. The increasing importance of these cells has brought in to focus the culture methods used to for their expansion and manipulation. Currently, animal derived components are used as surfaces for their growth and as components in the culture media. This exposes these cells to animal pathogens and antigens that can be passed to the recipients of these cells. In the first part of this thesis, polymer microarrays were employed to identify alternatives to the biological surfaces currently used for mesenchymal stem cell culture. This platform allowed hundreds of polyacrylates/acrylamides and polyurethanes to be simultaneously scrutinised to identify surfaces that could support their growth and maintain their stem cell characteristics. Identified polymer surfaces were monitored in long-term culture (10 passages) and were shown to retain the cell phenotype and capacity to differentiate, thus providing chemically defined substrates for long-term mesenchymal stem cell culture. In the second part of this thesis, a 'smart‘ polymer microarray of hydrophilic cross-linked polymers (hydrogels) were used to remove another key biological component of culture, trypsin. These 'smart‘ hydrogels modulated their properties depending on the temperature. Hydrogels that could trigger mesenchymal stem cell release after a reduction in temperature were identified. A unique passaging system using a modest temperature reduction for 1h was developed as a passaging method. Cells were maintained and monitored for 10 passages using this novel enzyme free passaging method. Analysis of the mesenchymal stem cell phenotype and differentiation capacity revealed this method superior than conventional culturing methods. In the final part of this thesis, a 'knowledge-based‘ small molecule library was designed, which could potentially yield small molecules to manipulate/enhance the mesenchymal stem cell state without the use of biological components. The key protein pathways that control the stem cell state were examine with the bioinformatics tool GeneGo was used to identify compounds that affected these pathways, resulting in selection of 200 small molecules. The effect of the small molecules on the mesenchymal phenotype was examined and 5 small molecules were identified that enhanced the phenotype of these cells. The anti-inflammatory properties associated with the hit compounds led to the investigation of their effects on key surface proteins associated with the immune-modulatory state of the cells. In this preliminary study, two of the small molecules, estriol and spermine, increased the expression of a key mesenchymal stem cell marker STRO-1 and down regulated ICAM-1, a critical component of the immune modulation capacity of this cell type.
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Lin, Paul. "Engineered Tracking and Delivery of Mesenchymal Stem Cells (MSCs)." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1355278573.
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Ackema, K. B. "Hox genes and mesenchymal stem cells." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2008.
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Popielarczyk, Tracee. "Homing and Differentiation of Mesenchymal Stem Cells in 3D In Vitro Models." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78789.
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Mesenchymal stem cells (MSCs) have great potential to improve clinical outcomes for many inflammatory and degenerative diseases through delivery of exogenous MSCs via injection or cell-laden scaffolds and through mobilization and migration of endogenous MSCs to injury sites. MSC fate and function is determined by microenvironmental cues, specifically dimensionality, topography, and cell-cell interactions. MSC responses of migration and differentiation are the focus of this dissertation. Cell migration occurs in several physiological and pathological processes; migration mode and cell signaling are determined by the environment and type of confinement in three-dimensional (3D) models.
Tendon injury is a common musculoskeletal disorder that occurs through cumulative damage to the extracellular matrix (ECM). Studies combining nanofibrous scaffolds and MSCs to determine an optimal topographical environment have promoted tenogenic differentiation under various conditions. We investigated cellular response of MSCs on specifically designed nanofiber matrices fabricated using a novel spinneret-based tunable engineered parameters production method (STEP). We designed suspended and aligned nanofiber scaffolds to study cellular morphology, tendon marker gene expression, and matrix deposition as determinants for tendon differentiation.
The delivery and maintenance of MSCs at sites of inflammation or injury are major challenges in stem cell therapies. Enhancing stem cell homing could improve their therapeutic effects. Homing is a process that involves cell migration through the vasculature to target organs. This process is defined in leukocyte transendothelial migration (TEM); however, far less is known about MSC homing. We investigated two population subsets of MSCs in a Transwell system mimicking the vasculature; migrated cells that initiated transmigration on the endothelium and nonmigrated cells in the apical chamber that failed to transmigrate. Gene and protein expression changes were observed between these subsets and evidence suggests that multiple signaling pathways regulate TEM.
The results of these experiments have demonstrated that microenvironmental cues are critical to understanding the cellular and molecular mechanisms of MSC response, specifically in homing and differentiation. This knowledge has identified scaffold parameters required to stimulate tenogenesis and signaling pathways controlling MSC homing. These findings will allow us to target key regulatory molecules and cell signaling pathways involved in MSC response towards development of regenerative therapies.<br>Ph. D.
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Guyette, Jacques Paul. "Conditioning of Mesenchymal Stem Cells Initiates Cardiogenic Differentiation and Increases Function in Infarcted Hearts." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-dissertations/32.
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Current treatment options are limited for patients with myocardial infarction or heart failure. Cellular cardiomyoplasty is a promising therapeutic strategy being investigated as a potential treatment, which aims to deliver exogenous cells to the infarcted heart, for the purpose of restoring healthy myocardial mass and mechanical cardiac function. While several cell types have been studied for this application, only bone marrow cells and human mesenchymal stem cells (hMSCs) have been shown to be safe and effective for improving cardiac function in clinical trials. In both human and animal studies, the delivery of hMSCs to infarcted myocardium decreased inflammatory response, promoted cardiomyocyte survival, and improved cardiac functional indices. While the benefits of using hMSCs as a cell therapy for cardiac repair are encouraging, the desired expectation of cardiomyoplasty is to increase cardiomyocyte content that will contribute to active cardiac mechanical function. Delivered cells may increase myocyte content by several different mechanisms such as differentiating to a cardiomyocyte lineage, secreting paracrine factors that increase native stem cell differentiation, or secreting factors that increase native myocyte proliferation. Considerable work suggests that hMSCs can differentiate towards a cardiomyocyte lineage based on measured milestones such as cardiac-specific marker expression, sarcomere formation, ion current propagation, and gap junction formation. However, current methods for cardiac differentiation of hMSCs have significant limitations. Current differentiation techniques are complicated and tedious, signaling pathways and mechanisms are largely unknown, and only a small percentage of hMSCs appear to exhibit cardiogenic traits. In this body of work, we developed a simple strategy to initiate cardiac differentiation of hMSCs in vitro. Incorporating environmental cues typically found in a myocardial infarct (e.g. decreased oxygen tension and increased concentrations of cell-signaling factors), our novel in vitro conditioning regimen combines reduced-O2 culture and hepatocyte growth factor (HGF) treatment. Reduced-O2 culturing of hMSCs has shown to enhance differentiation, tissue formation, and the release of cardioprotective signaling factors. HGF is a pleiotropic cytokine involved in several biological processes including developmental cardiomyogenesis, through its interaction with the tyrosine kinase receptor c-Met. We hypothesize that applying a combined conditioning treatment of reduced-O2 and HGF to hMSCs in vitro will enhance cardiac-specific gene and protein expression. Additionally, the transplantation of conditioned hMSCs into an in vivo infarct model will result in differentiation of delivered hMSCs and improved cardiac mechanical function. In testing our hypothesis, we show that reduced-O2 culturing can enhance hMSC growth kinetics and total c-Met expression. Combining reduced-O2 culturing with HGF treatment, hMSCs can be conditioned to express cardiac-specific genes and proteins in vitro. Using small-molecule inhibitors to target specific effector proteins in a proposed HGF/c-Met signaling pathway, treated reduced-O2/HGF hMSCs show a decrease in cardiac gene expression. When implanted into rat infarcts in vivo, reduced-O2/HGF conditioned hMSCs increase regional cardiac mechanics within the infarct region at 1 week and 1 month. Further analysis from the in vivo study showed a significant increase in the retention of reduced-O2/HGF conditioned hMSCs. Immunohistochemistry showed that some of the reduced-O2/HGF conditioned hMSCs express cardiac-specific proteins in vivo. These results suggest that a combined regimen of reduced-O2 and HGF conditioning increases cardiac-specific marker expression in hMSCs in vitro. In addition, the implantation of reduced-O2/HGF conditioned hMSCs into an infarct significantly improves cardiac function, with contributing factors of improved cell retention and possible increases in myocyte content. Overall, we developed a simple in vitro conditioning regimen to improve cardiac differentiation capabilities in hMSCs, in order to enhance the outcomes of using hMSCs as a cell therapy for the diseased heart.
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Li, Jing, and 李靜. "Effects of intrinsic & extrinsic factors on the growth and differentiation of human mesenchymal stem cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37238310.
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Nili, Ahmadabadi Elham. "Development of a novel mesenchymal stromal cell (MSC) therapy for repairing the cornea." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/122897/1/Elham_Nili%20Ahmadabadi_Thesis.pdf.
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This thesis has produced advances in our understanding of the biology and potential clinical application of stem cells to aid the treatment of patients with severe eye injuries. This research evaluated the therapeutic potential of a stem cell (called Mesenchymal Stromal Cells (MSCs)) isolated from the peripheral margin of the cornea, known as the limbus. Firstly, a method for routinely isolation and propagation of human limbal MSCs was optimized. Subsequently, the performance of those cells on a silk fibroin membrane was examined.
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Richardson, Lucy Elizabeth. "Extracellular matrix cues for mesenchymal stem cell differentiation." Thesis, Royal Veterinary College (University of London), 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444369.
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Tassoni, Alessia. "Retinal glial responses to mesenchymal stem cell transplantation." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709042.
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Wong, Andrew P. "REGENERATIVE POTENTIAL OF MESENCHYMAL STEM CELL DERIVED EXOSOMES." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5856.
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Bone defects are a pervasive complication arising from many clinical conditions, both mechanical and pathological. Current treatments for large bony defects focus on applying bone grafts or synthetic materials to the defect area. Cell-based—and especially stem-cell—therapies have advanced greatly thanks to increasing attention focused on their ability to generate new tissues in situ with biomechanical properties approaching that of native tissue, but they suffer from their own shortcomings as well. Exosomes have been shown to play critical roles in cell-signaling and tissue regeneration and are therefore potentially ideal therapeutic vehicles for treating bone defects. Exosomes are small microvesicles counted amongst stem cells’ paracrine factors capable of delivering nucleic acid and enzymatic protein cargoes in a targeted 2 manner. Our previous studies have shown that hMSC-Exosomes are both proliferative and chemotactic, inhibit inflammatory cytokine production, and suppress osteoclast differentiation. Our long term goal is to develop hMSC-Exosome as a clinical therapy for bone regeneration. The objectives of this study were to determine the ability of hMSC-Exosome to enhance bone healing in a rat calvarial defect model, and to further investigate the integrity of the exosome under certain storage conditions. The specific aims of this study were: 1) To determine the osteogenic potential of hMSC-Exosomes in rat calvarial defects, and 2) To determine the impact of variable storage conditions on the integrity of exosomes. To investigate in vivo regenerative potential, rats with surgically-created craniotomy defects were treated with hMSC-Exosome suspension via a collagen gel matrix. After 4 weeks, the calvaria were harvested and analyzed via micro-CT. Volumetric micro-CT analysis showed that hMSC-Exosome could significantly enhance center healing, structural integrity, and growth uniformity in a calvarial defect model. Western blot and TEM showed thorough destruction of surface protein markers and decreased membrane integrity in lyophilized exosome fraction; moderate progressive surface protein marker loss and aggregation were observed with increasing freeze-thaw cycles. In summary, hMSC-Exosome is a promising therapeutic for treatment of bone defects.
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Lemieux, Justin Michael. "Mechanisms of Hematopoietic-Mesenchymal Cell Activation." Yale University, 2009. http://ymtdl.med.yale.edu/theses/available/etd-03112009-191829/.
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As the prevalence of osteoporosis is expected to increase over the next few decades, the development of novel therapeutic strategies to combat this disorder becomes clinically imperative. These efforts draw extensively from an expanding body of knowledge pertaining to the physiologic mechanisms of skeletal homeostasis. To this body of knowledge, we contribute that cells of hematopoietic lineage may play a crucial role in balancing osteoblastic bone formation against osteoclastic resorption. Specifically, our laboratory has previously demonstrated that megakaryocytes can induce osteoblast proliferation in vitro, but do so only when direct cell-to-cell contact is permitted. To further investigate the nature of this interaction, we have effectively neutralized several adhesion molecules known to function in the analogous interaction of megakaryocytes with another cell-type of mesenchymal origin - the fibroblast. Our findings implicate the involvement of fibronectin/RGD-binding integrins including á3â1 (VLA-3) and á5â1 (VLA-5) as well as glycoprotein IIb (CD41), all of which are known to be expressed on megakaryocyte membranes. Furthermore, we demonstrate that IL-3 can enhance megakaryocyte-induced osteoblast activation in vitro, as demonstrated in the megakaryocyte-fibroblast model system. Taken together, these results suggest that although their physiologic and clinical implications are very different, these two models of hematopoietic-mesenchymal cell activation are mechanistically analogous.
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Lim, Jeremy James. "The development of glycosaminoglycan-based materials to promote chondrogenic differentiation of mesenchymal stem cells." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44849.
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Tissue engineering strategies represent exciting potential therapies to repair cartilage injuries; however, difficulty regenerating the complex extracellular matrix (ECM) organization of native cartilage remains a significant challenge. Cartilaginous ECM molecules, specifically chondroitin sulfate (CS) glycosaminoglycan, may possess the ability to promote and direct MSC differentiation down a chondrogenic lineage. CS may interact with the stem cell microenvironment through its highly negative charge, generation of osmotic pressure, and sequestration of growth factors; however, the role of CS in directing differentiation down a chondrogenic lineage remains unclear. The overall goal of this dissertation was to develop versatile biomaterial platforms to control CS presentation to mesenchymal stem cells (MSCs) in order to improve understanding of the interactions with CS that promote chondrogenic differentiation.
To investigate chondrogenic response to a diverse set of CS materials, progenitor cells were cultured in the presence of CS proteoglycans and CS chains in a variety of 2D and 3D material systems. Surfaces were coated with aggrecan proteoglycan to alter cell morphology, CS-based nano- and microspheres were developed as small particle carriers for growth factor delivery, and desulfated chondroitin hydrogels were synthesized to examine electrostatic interactions with growth factors and the role of sulfation in the chondrogenic differentiation of MSCs. Together these studies provided valuable insight into the unique ability of CS-based materials to control cellular microenvironments via morphological and material cues to promote chondrogenic differentiation in the development of tissue engineering strategies for cartilage regeneration and repair.
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Tseng, Paulina, and Oscar Hedlund. "Dental Mesenchymal Stem Cells’ Effect on Glioma Cells." Thesis, Umeå universitet, Institutionen för odontologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-131189.
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Glioma is a malignant tumor with a high mortality rate within few years of diagnosis. Due to limited effect of currently available cancer therapies, alternative therapies are investigated. Studies have shown that mesenchymal stem cells (MSCs) may have a therapeutic potential in glioma treatment. The objective of this in-vitro study was to examine the effect of three different human dental MSCs (D-MSC) on rat glioma cells. We utilized three experimental set ups in order to study the effect of D-MSC on glioma cell survival: unstimulated conditioned medium, stimulated conditioned medium, and direct co-culture. Unstimulated conditioned medium showed an inhibitory effect of 10-30 % on cell survival. Stimulated conditioned medium showed no statistically significant inhibition of glioma cell survival. Direct co-culture immunofluorescence microscopy revealed propidium iodide absorption, indicating cell death, in glioma. Results indicate that D-MSC has a negative influence on glioma proliferation but secreted/expressed factors mediating this effect are unidentified. This is a screening of D-MSCs potential therapeutic effect in treating glioma.
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Wong, Mei Mei. "Effects of Cell Death and Phagocytosis on Mesenchymal Stem Cell Function." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511852.
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Wu, Pensée. "Muscular dystrophy cell therapy : an in utero approach using human fetal mesenchymal stem cells." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4726.
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Duchenne muscular dystrophy (DMD) is the most prevalent genetic neuromuscular disorder and affects 1 in 3,500 live male births. Lack of the protein dystrophin in muscle fibres causes permanent muscle damage, is lethal and despite various potential therapeutic strategies aimed at restoring dystrophin expression, has no cure. As DMD affects all skeletal muscles as well as the heart, a systemic treatment would be necessary and in utero stem cell transplantation is a promising way of achieving this. The identification of human fetal mesenchymal stem cells (hfMSC) in early gestation fetal blood offers the prospect of allogeneic or autologous cell therapy, while intrauterine administration would capitalise on ontological opportunities unique to the developing fetus. The aim of the study was to improve hfMSC engraftment and contribution to skeletal muscle fibres following intrauterine transplantation (IUT) in a mouse model of DMD. My project demonstrated that hfMSCs are easily isolated and expandable with the ability to undergo myogenesis in vitro. HfMSCs differentiated into mature myotubes following exposure to galectin-1 conditioned medium, while galectin-1 transduced hfMSCs showed significantly higher expression of myogenic markers compared to non-transduced hfMSCs. Co-culture experiments provided an in vitro model to explore the underlying mechanism for muscle differentiation of hfMSCs following IUT. HfMSCs were able to form chimeric myotubes by fusing with myoblasts isolated from E15 mouse embryos, evidence that they should be able to fuse with developing muscle fibres in vivo. Engraftment and differentiation into muscle fibres of hfMSCs injected intra-peritoneally into E15 mouse embryos in vivo was enhanced by using immunodeficient dystrophic host mice, postnatal muscle injury and additional neonatal hfMSC transplantation following IUT. In conclusion, my thesis supports the use of hfMSC as an attractive source for cell therapy and provides the background for further studies to optimise their engraftment and differentiation to underpin future clinical applications.
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O'Donoghue, Keelin. "Fetomaternal tracking of fetal mesenchymal stem cells." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/11850.
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Branch, Matthew James. "Mesenchymal stem cells and the ocular surface." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665484.
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Interest in Mesenchymal Stem Cells for ophthalmic regenerative medicine is increasing. These cells have an increasing array of abilities that allow them to promote wound healing through a number of different mechanisms. The area of mesenchymal stem cell research is large and complex, with many differing names, criteria, sources and culture techniques. Thorough characterisation is crucial if they are to be developed for therapeutic use. Research into fetal liver mesenchymal stem cells represents a small proportion of what is known about these cells although some evidence points to important differences between those found in the bone marrow of adults. These cells may be able to aid corneal regeneration or provide a suitable model for other mesenchymal stem cells. Detailed characterisation of plastic adherent fetal liver was carried out. These cells successfully met the International Society of Cellular Therapy's minimal criteria for mesenchymal stem cells. Their phenotype and genotype (karyotype and telomere length) were assessed over extended passaging. Marker expression was found to decrease in correlation with telomere shortening and increasing cytogenetic anomalies. Fetal liver mesenchymal stem cell colony forming abi lities were investigated and although colonies proliferated substantially marker profiles in each varied and did not conform to the minimal criteria. Mesenchymal stem cells do not generate an immune response and most are also reported to suppress the cellular immune system. Although fetal liver mesenchymal stem cells did not generate an immune response when incubated with lymphocytes they did not possess the ability to suppress stimulation by third party antigens. Fetal liver mesenchymal stem cell interaction with amniotic membrane, as a potential candidate for a culture substrate and carrier was also analysed. Amniotic membrane allowed attachment and proliferation whilst retaining a mesenchymal stem cell phenotype after 21 days in culture.
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Vaghjiani, Rasilaben Jethalal. "Isolation and characterisation of mesenchymal stem cells." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/4416.
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MSCs have great therapeutic potential and are currently used in various clinical trials. However, the extremely low frequency of MSCs and the absence of a known cell-specific marker have made their purification and identification a highly challenging goal. Our hypothesis is that identification of a MSC specific cell surface marker would facilitate isolation of a pure population of MSCs, which in clinical studies may enhance the subsequent regenerative effect in comparison to a heterogeneous MSC population. Our aim therefore was to attempt to identify such MSC-specific markers using a transcriptomics approach. Individual clones were isolated after seeding bone marrow mononuclear cells from BALB/b and BALB/c mice in 5% oxygen tension. All clones had the ability to differentiate into adipocytes, chondrocytes, and osteoblasts, and to self-renew, and were therefore functionally characterised as MSCs. All murine MSC clones consistently expressed very high levels of Sca-1. Cytogenetic analysis of clones revealed an abnormal karyotype of 69 chromosomes and transplantation of cells into immuno-compromised SCID mice revealed no evidence of tumour formation after 7 months indicating that cells were not malignant. A rigorous genome-wide supervised microarray analysis revealed six genes were differentially expressed on the MSC clones in comparison to various controls - STEAP1, STEAP2, ly6f, versican, vitamin D receptor, and H2-M9. Two-dimensional hierarchical clustering of 28 different arrays revealed both STEAP genes and vitamin D receptor also had a similar expression pattern to Sca-1. Thus STEAP1 and STEAP2 were the only two cell membrane protein encoding genes identified by both analysis methods. Importantly, flow cytometry analysis revealed STEAP2 was differentially expressed in normal diploid multipotent human bone marrow stromal cells (hBMSCs) compared to fibroblasts and freshly isolated bone marrow cells. Furthermore, western blot analysis revealed STEAP1 was significantly expressed in hBMSCs, but not by human fibroblasts or human chondrocytes. STEAP1 depletion by RNA interference resulted in decreased cell adherence to tissue culture plastic. Results suggest STEAP1 and STEAP2 may be novel MSC markers in murine and in human cells. Further work is needed to elucidate their role in MSCs and to establish their usefulness as potential cell-specific markers.
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Stoianovici, Charles. "Directing Mesenchymal Stem Cells for Periodontal Regeneration." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5335.
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Background: Directing autogenous Mesenchymal Stem Cell (MSC) to defect sites has a great promise in bone regeneration. We designed a MSC specific, bone affinity peptide (E7HA7) by conjugating E7 with a polyglutamate hydroxyapatite (HA) binding motif. We sought to characterize the in-vivo releasing pattern and bioactivity of E7HA7. Methods: HA discs were coated with fluorescent labeled peptides E7HA7, E7HA2 or E7 were subcutaneously implanted in Sprague Dawley rats. In an ectopic bone formation model was used to test the in-vivo bioactivity of E7HA7 conjugated to DBM. Results: E7HA7 showed slower peptide release from scaffolds in comparison to other groups, being statistically significant at week 2 compared to E7, and to E7HA2 at week 4 and 8. In ectopic model, the medians for new bone formation in each group were: iDBM=0.041mm3, iDBM-E7=0.071mm3, aDBM=0.138mm3, and aDBM-E7=0.192mm3. Conclusions: Conjugation of E7 to polyglutamate bone binding domain showed slow releasing kinetics and osteoinductive potential.
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Zhang, Yuelin, and 張月林. "Mesenchymal stem cells derived from pluripotent stem cells for cardiovascular repair and regeneration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196438.
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Despite major advances in pharmacological and surgical treatments of cardiovascular diseases (CVDs), clinical outcomes of patients with severe CVDs remain very poor. Most of medication and interventions currently available are only playing roles of preventing further damage to myocardium, declining the risk of on-going cardiovascular events, lifting the cardiac pumping efficiency and lower early mortality rates, none of these treatments can regenerate or repair damaged cardiac tissue or restore heart function. As a result, several new strategies have been explored to overcome limitations of current therapeutic approaches. One prospective is to replace dead cardiac vascular cells with young and green cells to repair or regenerate damaged heart myocardium.
Several types of stem cells, including bone marrow hematopoietic stem cells, mesenchymal stem cells (MSCs), embryonic stem cell (ESCs)and induced pluripotent stem cells (iPSCs),have been tested as the candidates for treatment of CVDs. Among a myriad of types of stem cells, bone marrow derived MSCs(BM-MSCs) has received great attention based on several unique properties such as easy isolation and expansion, stable genetic background and low immunogenicity. However, the therapeutic efficacy of BM-MSCs derived from aging or diseased donors is impaired. The differentiation potential of BM-MSCs is gradually reduced with the increased culture time. Thus, it is urgent to identify some novel alternative sources for MSCs. Moreover, the potential mechanisms of MSCs therapy have not been understood totally. This thesis is designed to investigate the therapeutic efficacy and potential mechanisms of several novel types of MSCs, including hESC-MSCs and hiPSC-MSCs and Rap1-/--BM-MSCson several types of CVDs, including pulmonary arterial hypertension (PAH), dilated cardiomyopathy (DCM)and myocardial infarction (MI).
In Chapter 4, it disclosed that hESC-MSCs have a better therapeutic efficacy than BM-MSCs in attenuation of PAH induced by monocrotaline in mice. The greater therapeutic potential of hESC-MSCs on PAH was not only attributed to the higher capacity of differentiation into de-novo vascular cells, but also attributed to higher cell survival rate and greater paracrine effects post-transplantation.
In Chapter 5, it demonstrated that compared with BM-MSCs, iPSC-MSCs have a better therapeutic effect on doxorubicin-induced cardiomyopathy. Several potential mechanisms of action were involved in iPSC-MSCs-based therapy for cardiomyopathy. It demonstrated that iPSC-MSCs transplantation not only attenuated the generation of reactive oxygen species(ROS)and the level of inflammation, but also restored depletion of cardiac progenitor cells and promoted endogenous myocardial regeneration against doxorubicin induced cardiomyopathy. Moreover, mitochondrial transfer and paracrine actions of iPSC-MSCs played critical roles in the rescue for doxorubicin-induced cardiomyopathy.
In Chapter 6, it uncovered that compared with wild type BM-MSCs,Rap1-/--BM-MSCs transplantation achieved a better benefit to MI induced by ligation of left anterior descending (LAD)coronary artery. Rap1-mediated NF-κB activity plays a key role in regulation MSCscytokine secretion profiles. The absence of Rap1 in MSCs leads to reduced pro-inflammatory cytokines secretion and enhanced MSCs survival capacity, thus yielding a better therapeutic efficacy.
In conclusion, findings presented in this thesis provide important new insights regarding different novel types of MSCs, including those derived from ESC and iPSC. They have distinct mechanisms of action from BM-MSCs and provide superior therapeutic efficacy in various form of severe CVDs, including PAH and DCM. The safety and efficacy of these novel types of MSCs for treatment of CVDs deserve further investigations.<br>published_or_final_version<br>Medicine<br>Doctoral<br>Doctor of Philosophy
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Awaya, Tomonari. "Selective Development of Myogenic Mesenchymal Cells from Human Embryonic and Induced Pluripotent Stem Cells." Kyoto University, 2013. http://hdl.handle.net/2433/180602.
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Saleh, Fatima. "Regulation of mesenchymal stem cell activity in an in vitro model of the stem cell niche." Thesis, University of York, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547374.
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Wang, Longlong. "A mesenchymal stem cell (MSC) niche in mouse incisor." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/a-mesenchymal-stem-cell-msc-niche-in-mouse-incisor(8f92b75d-f90f-4c58-ab06-682af9f90e95).html.
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Mesenchymal stem cells (MSCs) are heterogeneous cell populations that are identified by their in vitro characteristics while their biological properties and in vivo identities are often less understood. Different from human teeth, mouse incisors grow and erupt continuously throughout their lives and compensate for daily abrasions with the existence of stem cells. However, the precise location of the mesenchymal stem cells (MSCs) in the incisor is unclear. Generally, the MSCs in the mouse incisor are believed to be located in the mesenchyme close to the epithelium cervical loops, since the growth and differentiation of the incisor always initiates at the apical end and extends towards the incisal end. The utilization of label-retaining experiments and transgenic reporter mouse lines has enabled further understanding of the less established identities and properties of dental pulp stem cells in vivo. The work described in this thesis demonstrates that the mesenchymal stem cell niche located at the apical end of mouse incisor contains three distinct but connected cell populations: 1) a slow cycling cell population containing Thy-1+ cells essential for tooth dental pulp and odontoblast formation 2) a Ring1/Bcor-associated fast cycling cell population crucial for maintaining tissue growth and homeostasis of epithelium stem cells in labial cervical loop 3) a quiescent long-term cell population marked by Flamingo homologue Celsr1 might respond to generate new stem cells when the stem cells become depleted.
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Michalopoulos, Efstathios. "Guided human mesenchymal stem cell differentiation by physical stimulation." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444057.
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