UCLA

Neural tissues have long been difficult systems to study. They contain a large variety of cell types organized into complex three-dimensional structures. This complexity has made it challenging to model these systems in vitro using classical tissue culture models. Recent advances have made it possible to take advantage of stem cells’ innate ability to differentiate into a variety of neural cell types to study the developing brain and spinal cord in ways not previously possible. In this thesis I present how I have used these new methods in stem cell biology to further our understanding of neurodevelopment and disease, and my work on further improving these new model systems.First, I used single cell transcriptomics to analyze the earliest stages of mouse dorsal interneuron development in a newly created in vitro differentiation protocol. By using this model system I was able to enrich our dataset for populations of interest, and use pseudotemporal analysis to find genes that may be responsible for helping to specify the different types of dIs present in the mouse spinal cord. I found 9 genes that we were able to verify using in situ hybridization in sections of developing mouse spinal cord. Next, I transitioned from two-dimensional models of spinal cord development into three-dimensional models of brain development. Recent studies in the brain organoid field have highlighted the importance of improving oxygen and nutrient delivery to the developing organoids. We tested both media flow and hyperoxygenation’s effects on brain organoid development, and found that while both have effects, the effect of hyperoxygenation is much larger. This presents a simple method of improving cell stress in current model systems. Lastly, I used classic genetic overexpression methods to try to create a better model of Alzheimer’s Disease using brain organoids. Mouse models and two-dimensional culture models have continually failed to provide effective treatments that translate into human clinical trials, hinting that these models are lacking some key component. By overexpressing mutant tau in brain organoids, we were able to replicate some classical AD pathology. Together these experiments represent a variety of approaches to addressing questions in current neurobiology.