Epithelial cells line the surfaces of many organs in the body, including the inner surface of hollow organs. As such, they often exhibit different functional properties and abilities through the thickness of the cell - something that is called planar cellular polarity (PCP). The biofabrication of fully functional epithelial tissues has a broad application in tissue engineering and regenerative medicine. One of the main obstacles for achieving this goal is that epithelial cells grown in culture dishes typically do not demonstrate this polarity. The epithelial cell polarity within a sheet or plane of cells is tightly regulated by signaling within and between cells. This signaling does not appear to be maintained in cultured cells and, as a result, reestablishing PCP in manufactured tissues has never been achieved. In addition, some congenital abnormalities, such as spina bifida, are due to the failure of epithelial cells to function properly during embryonic development. This Faculty Early Career Development Program (CAREER) project will study the mechanical and biochemical regulatory mechanisms of planar cell polarity in vitro. The project will systematically study the effects of geometrical confinement, matrix stiffness, mechanical strains, and chemical gradients on the initiation and maintenance of PCP, as well as identify the molecules that relay external mechanical signals to the cells for establishing PCP. The educational activities in this project will provide hands-on, project-based experience to a broad audience, with an emphasis on women and underrepresented minorities. Undergraduate and graduate students will be trained in a project-based course in mechanobiology. In addition, a summer program that provides computational scientists and biologists with training in advanced bioengineering tools that are developed through this project will facilitate interdisciplinary communication. By improving understanding of how endothelial cells establish this necessary functional variation, this project will support the development of biomanufacturing and tissue engineering systems to produce layers of epithelial cells that are necessary for normal organ function. In addition, the fundamental knowledge gained will advance understanding with respect to normal and pathological tissue growth and development.
The overall research goal of this project is to expand knowledge about the fundamental mechanisms through which epithelial cells, which are planar polarized, mediate strain-based signaling. This project is focused on neuroepithelial cells that are responsible for the formation of the neural tube during embryonic development, disruption of which can result in neural tube defects (such as spina bifida). This will be accomplished through three research objectives. The first is to investigate the effects of interfacial geometry and matrix stiffness on the asymmetrical distribution of PCP signaling complexes at the single cell level. This objective will use novel patterning techniques to control the areas in which the cells can grow as well as tunable hydrogels to simulate variations in extracellular matrix stiffness. The second objective is to elucidate the role of strains and the Wnt gradient (a set of signal transduction pathways in which proteins pass signals into a cell through cell surface receptors) in the alignment of PCP at the tissue level. This alignment will be evaluated at the molecular, cellular, and tissue-level through molecular assays, live-cell imaging, and tissue phenotype assessment. The final objective is to identify the mechanosensors that relay mechanical signals to the PCP pathway. This will be done through selective knock-down of various key mechanoreceptors in the cultured cells to determine how these changes affect strain-mediated alignment of PCP. The knowledge gained from these experiments will advance fundamental understanding of the development of planar cell polarity in neuroepithelial cells and will be more broadly applicable to epithelial cells in general. In addition to answering fundamental questions that are key to tissue growth and development, this research will support the advancement of biomanufacturing and tissue engineering systems that include layers of epithelial cells, which are important for normal tissue function.
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.