Browsing by Subject "Cell Therapy"

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    Deciphering Heterogeneities in Cellular Decision Making
    (2023-12) Kang, Jennifer
    This thesis presents a multifaceted exploration into the complexities of cellular decision making, integrating experimental, computational, and engineering approaches to unravel the intricacies of heterogeneous cellular responses to noisy and conflicting extracellular cues. At the core of this research lies the investigation of how cells resolve conflicts in signaling, particularly when exposed to competing stimuli, and how this understanding can be harnessed to engineer novel therapeutic strategies.In the first segment of our study, we explore the intricate dynamics of cellular signaling and conflict resolution using rat pheochromocytoma (PC12) cells as a model. Challenging the traditional understanding, our research uncovers that both low and high concentrations of epidermal growth factor (EGF) can induce sustained extracellular signal-regulated kinase (ERK) activation, propelling cells towards differentiation, a role previously attributed exclusively to nerve growth factor (NGF). This is a significant deviation from the established paradigm where EGF is known to drive proliferation through transient ERK activation, and NGF is associated with sustained ERK activation leading to differentiation. Our findings are bolstered by both population-level and single-cell measurements. To further elucidate this phenomenon, we employed an enhanced mechanistic model. This model reveals a critical aspect: attenuated EGF receptor degradation due to reduced receptor phosphorylation is a key factor driving the sustained ERK activity at both low and high EGF concentrations. Moving beyond the qualitative labels of 'transient' and 'sustained', the model introduces a quantitative metric for ERK activation – its time integral. This metric, governed by receptor-ligand binding and degradation rates, is predictive of cell fate in cultures co-stimulated with EGF and NGF. It facilitates an ultrasensitive switch between proliferation and differentiation, leading to distinct and predictable cell fate outcomes. Building on these findings, the thesis then explores the design of self-assembling multivalent protein constructs. These constructs demonstrate the ability to create synthetic signaling hubs that precisely control kinase activities with spatial accuracy, offering a novel approach to manipulate cellular decision making processes. This advancement opens up possibilities for designing novel signaling paradigms, moving beyond conventional approaches in cell signaling. The third aspect of the research applies machine learning to optimize T cell expansion in immunotherapy. By analyzing kinase activities and signaling pathways, we identify key determinants for enhancing the proliferation and stemness during T cell expansion in vitro, crucial for effective T cell therapy. This approach integrates systems biology, which focuses on the complex interactions within biological systems, with computational analytics, a field that applies algorithmic and statistical techniques to biological data. Together, this synergy enhances our ability to predict and optimize therapeutic outcomes. Collectively, this thesis underscores the importance of a systems biology approach in understanding cellular heterogeneity and decision making. The integration of cellular biology, molecular biology, computational modeling, synthetic biology, and machine learning illustrates the potential for innovative research in controlling and guiding cellular behavior, particularly in the realm of targeted cancer therapies. The findings and methodologies presented here not only advance our knowledge of cellular signaling dynamics but also provide foundational insights for the development of more effective and precise cellular therapies.
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    Mechanisms of Thymic Involution and Therapies to Prevent or Treat the loss of Thymic Epithelial Cells
    (2016-09) Smith, Michelle
    The thymus has great importance to human health as naïve T cells cannot be generated in its absence. The composition and organization of its specialized microenvironment are the foundation of the function of the thymus. In particular, thymic epithelial cells and the segregation of their subtypes, cortical thymic epithelial cells and medullary thymic epithelial cells, into distinct areas are required for positive and negative selection of developing thymocytes. However, these cells can be lost over time through natural age-related processes and through acute injury such as chemotherapy or radiation. The purpose of this thesis is to increase the understanding of how these losses can occur and to investigate therapies which may prevent or treat these losses. We first focus on a stem cell-based therapy for the improvement of thymopoiesis following radiation-based injury to the thymus. In it are discussed findings which describe different outcomes which may be achieved by selection of specific input populations. The disruption which the radiation-induced damage has on intrathymic migration of progenitors is also highlighted as well as the temporary nature of their stimulatory effects on thymic epithelial cells. Next, we also focus on thymic epithelial cell loss, but precipitated by advancing age. To facilitate these studies, a model of accelerated aging caused by deficiency in the gene klotho was used. We found that klotho deficiency did not impart an intrinsic defect in TEC longevity but that elements of the systemic aging environment were responsible for accelerated TEC loss in a TEC non-autonomous fashion. Specifically, high levels of vitamin D which accumulate in these mice were implicated in the induction of abnormal TEC apoptosis. Together the findings presented here advance the understanding of mechanisms which may be responsible for the loss of thymic epithelial cells, either age-related or clinically induced. Two strategies for the prevention or treatment of TEC loss are also discussed.