UCLA

The cerebral cortex, the outermost portion of the brain, is a highly organized 6-layered structure with local and long-distance connectivity to different parts of the brain. Proper functioning is essential for higher cognitive tasks such as thinking, speech, fine motor control, and sensory processing. However, genetic mutations or environmental disruptions in the development or maintenance of such a complex system can lead to a variety of neurological disorders and a suitable model is needed to identify and develop novel therapeutics. Model organisms, such as mice, provide valuable insight into conserved processes underlying development and disease, but fail to recapitulate hallmark features of the human brain. Studying human-specific features remains challenging due to the inaccessibility of fetal tissue, therefore, an in vitro model is needed.Recent studies have shown human pluripotent stem cells (PSCs) have the ability to form 3D structures, called brain organoids, that can self-organize into brain-like tissue. In Chapters 2, 3, 4, and 6 optimized protocols are presented to create dorsal, ventral, and fused cortical organoids that mimic structural, transcriptional, and functional aspects of human brain development. In Chapter 3, cortex and ganglionic eminence brain organoids are fused to model inhibitory neuron migration to the cortex and neuronal network activity. In Chapter 4, sources of variability in brain organoid differentiations are identified and RNA sequencing is used to determine a cocktail of growth factors that can improve organoid formation in difficult cells lines. In Chapter 6, WNT/TGFB inhibitors, and a SHH agonist are used to optimize ventral cortical organoid differentiation. Chapters 2 and 7, pathology associated with viral infections of the central nervous system such as Zika virus (ZIKV) and Human immunodeficiency virus type-1 (HIV) are investigated. The development of antivirals and vaccines has remained difficult due to the lack of suitable a model that mimics human disease. In Chapter 2, brain organoids are used to model the effects of ZIKV exposure in developing brain and test possible drug candidates. In Chapter 6, hPSC-derived microglia are used to determine the effects of HIV infection on microglial function. Chapters 3 and 5, use hPSC-derived brain organoids or developing mouse cortices are used to determine the function of genes associated with autism spectrum disorder (MECP2 and FOXP1).