Vision loss in glaucoma and optic neuropathies results from the loss of retinal ganglion cells (RGCs) that is irreversible. Regardless of etiology, once cells are lost, RGCs cannot regrow and blindness is considered permanent. Retinas derived from pluripotent stem cells (PSCs) offer a source of tissue to address some of the mechanism(s) of human optic nerve cell loss at the level of the retina, however, one limitation to laboratory grown retinas is that they lack integration with higher order Lateral geniculate nucleus (LGN) and Superior colliculus (SC) neurons which ultimately connect with the visual cortex, thus they are not physiologic and retinal synapses might not form properly. As a first step towards understanding how to repopulate the eye with new RGCs and make those new connections, we propose to develop an optic nerve model to study axon outgrowth and pathfinding which will lead to improved engraftment of projections to the brain. Therefore, we propose to (1) develop a 3D printed scaffold that is permissive to axonal outgrowth, (2) improve the optic nerve by reconstructing the cellular components of the optic nerve, and (3) study cues to control proper connections through the optic chiasm. The optic chiasm represents the first relay station in the transmission of visual signals to the brain and thus is an important first step. We hypothesize that many developmental features of non- human mammalian models will also apply to developing human retinas. These features include neurite outgrowth and guidance towards the optic nerve head (stage I), axon guidance towards the optic chiasm (stage II), and decussation of ipsilateral and contra-lateral RGC axons [1-4]. We further hypothesize that human RGC axons emanating from PSC derived 3D organoids in hydrogel scaffolds will recapitulate these important features and thereby provide an experimentally tractable model for the study of glaucoma and other optic neuropathies. More importantly it will also provide a critical readout for testing therapeutic approaches aimed at restoring vision through cell replacement. We propose to develop a microprinted scaffold for 3D retinal organoids that will facilitate retinal ganglion cell (RGC) axon outgrowth and targeting and improve the organization of optic nerve cells and axon outgrowth by reconstructing the cellular components (including oligodendrocytes, astrocytes and microglial cells) of the human optic nerve.
PROJECT NARATIVE A laboratory grown optic nerve that merges human pluripotent stem cell technology with 3D printed scaffolds could offer a reliable model for understanding human retinal degenerative eye disease, such as glaucoma and could assist researchers in replacing retinal connections to the brain that have been lost due to disease. In this application, we propose to use human stem cell derived 3D retinas to explore how to grow a new optic nerve which will aid in developing therapeutic strategies aimed regenerating retinal ganglion cells.
