Browsing by Subject "stem cell"

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    Engineering functional muscle tissues and modeling muscular diseases using myogenic cells differentiated from human pluripotent stem cells or human fibroblasts
    (2019-09) Xu, Bin
    The advances in efficient generation of myogenic cells using human pluripotent stem cells (hPSCs) offer unlimited opportunities for translational applications, such as the study of muscle development and diseases, drug screening, and regenerative medicine. Functional muscle constructs tissue-engineered from these myogenic cells prove excellent tools for those applications. However, these myogenic cells are developmentally immature, and the protocol to derive them is time-consuming. In this thesis, we aim to model muscle diseases and to improve the maturity of muscles using hPSC-derived myogenic cells. We also develop transdifferentiation as an alternative method to obtain myogenic cells more quickly. We modeled Duchenne Muscular Dystrophy (DMD), a genetic disorder leading to muscle wasting and death. We fabricated nanogrooved substrate immobilized with muscle basement membrane mimicking materials and discovered that non-diseased and DMD muscles derived from hPSCs exhibit substantial differences in cell alignments on nanogrooved substrates when these substrates are functionalized with laminin. To improve the maturity of the muscles, we generated hPSC-derived muscle constructs in customized devices and discovered that addition of the endothelial growth medium-2 supplements in the first two weeks of differentiation leads to substantial increases in contractile forces. These constructs show wider myotubes and higher gene expression levels for skeletal muscle-specific myosin heavy chain isoforms, suggesting that a more mature differentiation stage of the cells. Those tissue-engineered constructs were also used to validate the screening of small molecules for enhancing the function and maturation during myogenic differentiation. We found a significant increase in contractile force generation when treated with a cocktail of four small molecules (SB431542, DAPT, Dexamethasone, and Forskolin). To explore an alternative approach to generating functional human muscles more quickly, we chose to transdifferentiate normal human dermal fibroblasts (NHDF) transduced with inducible MyoD. We demonstrated that myogenic transdifferentiation of NHDF could be enhanced by using small molecules CHIR99021 and DAPT when coupled with MyoD induction. We further proved that muscle constructs engineered from transdifferentiated NHDF can generate contractile forces in response to electrical stimuli after 2-week 3D culture. Temporal expression of MyoD in the first week boosts twitch and tetanic forces significantly, and small molecule (CHIR and DAPT) treatment could further improve force generation.
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    Investigation into the use of Pulsed Focused Ultrasound as a Method of Facilitating Homing of Umbilical Cord Blood Stem Cells after Systemic Administration in Ischemic Stroke Rat Models
    (2016-04) Hamborg, Joshua
    Stroke is a leading cause of mortality with no current therapies for chronic stroke victims. Our work investigates how to help chronic stroke patients regain function lost due to their stroke. This was accomplished by exploring how the use umbilical cord blood stem cells (UCBSCs), used in conjunction with pulsed focused ultrasound (pFUS), could provide a safe, efficient, and relatively non­invasive method for providing neuroregenerative therapy. Using rat stroke models that have undergone unilateral MCA occlusion, we propose that tail vein injections of UCBSCs, followed immediately afterwards by pFUS targeted to regions of ischemic damage, will result in functional improvements due to engraftment and neural differentiation of the stem cells. Initial immunohistochemical analysis of control rat brain tissue investigated how the local neuro­environment may become therapeutically favorable after transcranial pFUS treatments. Results obtained so far are preliminary.
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    Self-affirming values: Defensive processing of information about human embryonic stem-cell (hESC) research
    (2020-07) Jordan, Joshua
    Self-affirmation research suggests that affirming important values can reduce defensive responses to threatening information. However, whether this holds in the context of information about the life sciences is not clear. Integrating self-affirmation and values drawn from science communication research, the objective was to better understand core values associated with hESC research and to exclude these values from a subsequent self-affirmation intervention focusing on information about hESC research; and to test the hypothesis that self-affirming a value unrelated to hESC research would reduce defensive processing of information about it. Data were obtained from a pretest study survey and a main study experiment. In the pretest study (n = 315), several values were found to correlate with a favorable view of hESC research, but not opposition to it, since the sample was primarily individuals with a favorable view. A new list of values was thus adopted for the main study, which focused specifically on individuals opposed to hESC research. The main study (n = 113) showed that affirming a value unrelated to hESC research does not reduce defensive processing of information about it. The implications of these findings for science communication are discussed.