Date of Graduation
9-2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Cell & Molecular Biology (PhD)
Degree Level
Graduate
Department
Biological Sciences
Advisor/Mentor
Shilpa Iyer
Committee Member
Kartik Balachandran
Second Committee Member
Michael Lehmann, Walter Bottje
Third Committee Member
Walter Bottje
Keywords
mitochondria
Abstract
Mitochondrial disorders are complex diseases that involve multiple systems and result from mutations and deletions in the mitochondrial genome. Leigh syndrome (LS) is a rare and devastating primary mitochondrial disorder characterized by progressive neuromuscular degeneration. Despite its severe consequences, the clinical genotype pathophysiological underlying LS remains elusive, posing significant challenges for the development of effective therapies. The current study aims to advance our understanding of the pathology and phenotype correlation of LS by evaluating mitochondrial dynamics and bioenergetics in patient-derived human induced pluripotent stem cells (hiPSCs) and their differentiated derivatives, which serve as a reliable model of the disease. Key parameters, including mitochondrial membrane potential, mitochondrial respiration, and morphology, were analyzed using a range of techniques such as fluorescent live-cell imaging and respiratory measurements with extracellular flux Analyzer. To achieve this, we focused on generating patient-specific hiPSCs from control and LS fibroblasts, demonstrating the potential of using hiPSCs to assess key bioenergetics parameters, such as maximal respiration and spare respiratory capacity, in a targeted developmental stage and variant-specific manner to better understand their bioenergetic function. We then analyzed mitochondrial dynamics in patient-derived hiPSCs containing different mutations associated with LS such as (m.8993T>G, m.9185T>C, m.10158T>C, m.12706T>C) affecting the function of complex V and complex I of the respiratory chain. The morphology analysis shows that subtle alterations in mitochondrial morphologies are specific to the mtDNA variant, providing insight into unique morphological signatures of mitochondrial disorders during early embryonic development. We also presented the Mitochondrial Cellular Phenotype (MitoCellPhe) tool for quantifying mitochondrial morphologies and demonstrated its utility in delineating differences in morphologies between healthy and diseased fibroblasts and hiPSCs. We differentiated LS-hiPSCs into cardiomyocytes and investigated the associated mitochondrial and cardiac dysfunction. The differentiated cells were validated and characterized for the expression of cell-specific markers to ensure their proper lineage commitment. This comprehensive evaluation of mitochondrial dynamics and bioenergetics in patient-derived hiPSCs and differentiated derivatives provide a robust platform for the identification of potential therapeutic targets and the development of novel treatment strategies. Furthermore, the use of patient-derived hiPSCs allows for the assessment of individual variability, offering personalized medicine approaches. Ultimately, this research aims to pave the way for improved patient outcomes and quality of life for those affected by this debilitating mitochondrial disorder.
Citation
Meshrkey, F. (2023). Evaluating Mitochondrial Dynamics and Bioenergetics in Patient-Derived Human Induced Pluripotent Stem Cells and Differentiated Derivatives Modeling Leigh Syndrome. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/4838