Momoko Watanabe - US grants

Project Summary/Abstract It is intriguing how a single fertilized egg divides and gives rise to an organism containing a diverse array of cells, tissues, and organs with beautiful three-dimensional (3D) architecture in a precise manner. The neocortex is of particular interest because it is highly-specialized structure with features that are markedly different between species. For example, the neocortex in primates is enormously increased in size and complexity, which probably endow humans with remarkable sensory activities and intellectual ability such as abstract thinking and creativity. Understanding human corticogenesis is important for not only to gain some evolutionary insights but also to discover the underlying causes of human-specific diseases such as neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. We ideally need a human brain model, given that rodent models sometimes fail to mimic human symptoms and predict clinical outcomes. However, due to limited access to human brain tissue and ethical concerns, it has been challenging to directly study human development. Consequently, considerable attention has been placed on the generation of in vitro models using human pluripotent stem cells (hPSCs) to recapitulate aspects of human development and disease. The cerebral organoid is a 3D cortical tissue derived from hPSCs and recapitulates laminar organization of the developing cerebral neocortex in vivo. The advent of such organoid techniques has opened the door for studies of human specific developmental features and paves the way for disease modeling. However, many organoid differentiation protocols are inefficient and inconsistent and display marked variability in their ability to recapitulate the 3D architecture and course of neurogenesis in the developing human brain. The goal of this proposal is to understand 1) the state of hPSCs that can predict efficient and successful organoid differentiation, 2) to use this robust organoid system to uncover microcircuit formation that has the underlying importance for human brain activities and its malfunction is likely link to neuropsychiatric disorders, such as autism, and 3) to study Fragile X Syndrome, the most common heritable form of cognitive impairment, using human cortical organoids that can give some human-specific insights into mechanisms and cures of this disease.

The human brain is comprised of different regions, including primary, sensory, and motor cortices. These areas are affected in many neurological disorders. It is crucial to reproducibly create brain areas in organoids to better understand early development. This project aims to develop hydrogel-based bioengineering technologies to accurately make different areas of the cerebral cortex in cortical organoids. To accomplish these goals, a multidisciplinary team will leverage expertise in cell and developmental biology, soft materials engineering, and bioinformatics. The broader societal impacts of this project include educational and outreach activities that engage the public and students from underserved communities in partnership with the UCI Stem Cell Research Center, UCI Center for the Neurobiology of Learning and Memory, UCI Office of Access and Inclusion, and OC STEM Initiative. <br/><br/>Direct access to human tissue is indispensable for deep understanding of the mechanisms underlying human brain development and disease. Therefore, cortical organoids that closely mimic many aspects of the fetal cortex have emerged as accessible and promising in vitro tools. However, cortical organoids currently lack arealization – the reproducible cellular diversity and distinct spatial organization within the neocortex. To achieve arealization in cortical organoids, a novel responsive hydrogel platform will be developed that can generate spatial patterning of morphogen sources. This platform will be leveraged for examining gene regulatory networks underlying signaling interactions for specifying different areas, using single-cell and spatial transcriptomics. The approaches and insights developed in this project can be applied towards understanding morphogenesis and generating reproducible organoids in other systems beyond cortical organoids. <br/><br/>This RECODE project is funded by the Engineering Biology and Health Cluster in the Division of Chemical, Bioengineering, Environmental, and Transport Systems.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.