Defense Date


Document Type


Degree Name

Doctor of Philosophy


Physiology and Biophysics

First Advisor

James P. Bennett, Jr. MD, PhD


Human pluripotent stem cells (hPSCs), including human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) hold great promise in the fields of drug development and regenerative medicine. If iPSCs reprogrammed from patient cells replicate what is seen in vivo they may be used as a model of disease. A process that is disrupted in many neurodegenerative diseases is mitochondrial biogenesis. One of these diseases is amyotrophic lateral sclerosis (ALS), which is characterized by loss of motor neurons in the brain and spinal cord. Differentiation of hPSCs into motor neurons offers a way to study a previous unavailable cell type and may further our understanding of human motor neuron biology. The aims of the present study were to differentiate motor neurons from hESCs and iPSCs in low oxygen conditions and to explore mitochondrial biogenesis and electrical maturation during this process. After three weeks of treatment with retinoic acid and purmorphamine, a sonic hedgehog agonist, cells increased expression of post mitotic spinal motor neuron markers. One week later electrophysiological analysis revealed voltage-gated currents and action potential generation. Mitochondrial biogenesis signaling and expression of respiratory chain proteins increased with motor neuron differentiation. Respiration analysis revealed a decrease in glycolysis in motor neurons compared to neural stem cells. Interestingly, this was not accompanied by an increase in basal respiration or mitochondrial mass. These findings enhance our understanding of motor neuron mitochondrial biogenesis, a process impaired in ALS.


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