It is estimated that 18 million people worldwide are legally blind from optic neuropathies such as advanced glaucoma. Restoration of vision requires regenerating the optic nerve, a collection of retinal ganglion cell (RGC) axons that have exited the eye to connect with the brain. Although promising, cell transplantation-based strategies alone are inadequate to regenerate the optic nerve, in part, because transplanted RGCs fail to extend an axon out of the eye. Similarly, neuro- regenerative approaches are limited by failure to direct long distance axon growth. In this project, I propose an innovative approach that uses applied electrical fields (EFs) to guide RGC axon growth. Recently, I have demonstrated that RGC axons grow directionally, towards the cathode, when exposed to an EF, in vitro. Whether EFs can direct RGC axon growth in vivo, is unknown, as are the mechanisms through which cells sense and respond to EFs. Preliminary data presented here shows that 1) an EF can be generated along the rat optic nerve, 2) in vivo application of EFs promotes RGC axon regeneration after crush injury, and 3) co-activation of Rac1, a member of the Rho GTPase family, synergistically directs RGC axon growth in vitro. This proposal aims to demonstrate the feasibility of in vivo EF application as a therapeutic modality to guide RGC axon regeneration and test the hypothesis that EFs direct RGC axon regeneration by activating the Rho-GTPase signaling cascade. The K08 Career Development Award will provide me with structured education in research methodology, applied electrical engineering and electrophysiology, and technology transfer as well as structured mentorship to fill in educational and experiential gaps in knowledge, develop skills in leadership, work life balance, and grant and manuscript writing that will allow me to transition to an independent, NIH- funded clinician-scientist who is a world expert in the field of optic nerve regeneration. I have strategically assembled a mentorship team consisting of electrical engineers, material scientists, electrophysiologists, cell biologists, neurosurgeons, neurobiologists, statisticians, and translational scientists to complement my background as a neuro-ophthalmologist and developmental neurobiologist and direct my learning and career trajectory. Successful completion of this project will position me to become a competitive R01 applicant where I plan to test whether EF application, in conjunction with molecular cues, can be used to direct axon growth of transplanted RGCs to regenerate the optic nerve and restore visual function in different animal models of optic neuropathies. If successful, this project has the potential to make large strides in the field of optic nerve regeneration, bringing electrical modulation to the forefront.
Although neuro-regenerative and cell-replacement based approaches for optic nerve regeneration are a promising strategy for restoring vision in patients blinded by optic neuropathies such as advanced glaucoma, these approaches are, in part, limited by the fact that retinal ganglion cells (RGCs) fail to extend an axon out of the eye and into the optic nerve. Here, we propose to develop electric field (EF) application into a technology that can be used to direct the growth of transplanted or regenerating RGC axons towards their synaptic targets in the brain. In demonstrating the feasibility, as well as uncovering the underlying mechanisms, by which EFs direct axon regeneration, the results of this project could fuel the development of a breakthrough clinical technology that will enable cell-replacement based procedures to regenerate the optic nerve.