SUMMARY
Retinal ganglion cells (RGCs) are the projection neurons of the retina that serve as the connection between the
eye and the brain. In this role, they allow for the transmission of visual information to thalamic targets, with
damage to this pathway in injury or disease leading to vision loss or blindness. Glial cells, particularly astrocytes
and microglia, are found adjacent to RGCs within the optic nerve, where they maintain homeostatic conditions
for RGCs to ensure proper health and functionality. Conversely, neuroinflammatory conditions occur when
astrocytes and microglia are induced to adopt a reactive state, leading to the degeneration of RGCs.
Neuroinflammation has been associated with a variety of neurodegenerative diseases, but the pathology of
neuroinflammation in glaucoma is unique due to the highly localized nature of glial reactivity in the optic nerve
head as RGC axons exit the eye, correlated with the initial site of injury along RGC axons in glaucoma. While
animal models have demonstrated the importance of glia in neuronal development and degeneration, important
differences exist between animal models and human patients, including low conservation of RGCs as well as
numerous functional differences in glia. As such, the development of a human model of these cellular interactions
would further expand our understanding of how glia provide support for RGCs, as well as how glia respond
during neuroinflammatory conditions leading to the degeneration of RGCs in glaucoma. Human pluripotent stem
cells (hPSCs) can serve as powerful in vitro models for the study of retinal development and disease, with
previous studies demonstrating the ability to model RGC neurodegeneration in vitro. However, these studies
have not focused upon the compartmentalized nature of RGCs, nor how reactive glia disproportionally affect the
axons of RGCs in neuroinflammatory conditions. Thus, to address the shortcomings of existing hPSC-based
models of glaucoma and to better recapitulate interactions between RGCs and glia, the current application
leverages a robust and reproducible in vitro model to recreate the spatial interactions of glia upon human RGC
axons relevant to the neurodegenerative phenotypes observed in glaucoma. Interactions between glia and RGC
compartments will be analyzed in quiescent and reactive states, and the functional consequences of reactive
glia upon RGC axons will be assessed phenotypically, transcriptionally, and functionally to identify the extent to
which reactive glia modulate RGC neurodegeneration. The successful pursuit of the following aims will leverage
a powerful microfluidic platform for the analysis of RGC axons to include the neuroinflammatory effects of glia
and will provide opportunities to further elucidate fundamental neurodegenerative mechanisms in human RGCs,
as well as to develop novel therapeutic approaches to slow or reverse neurodegeneration.
