The role of optic nerve lamina region stem cells in age-related optic nerve disease

The most common age-associated optic nerve (ON)-related causes of vision loss are non-arteritic
anterior ischemic optic neuropathy (NAION) and primary open-angle glaucoma (POAG). Optic nerve head
(ONH) defects contribute to NAION and POAG susceptibility, but the mechanisms responsible for this are
incompletely understood, contributing to a lack of effective treatments. My lab recently discovered that the optic
nerve-laminar region (ONLR) within the ONH, contains a CNS neural stem cell/neural progenitor cell
(NSC/NPC) niche which is depleted during aging. Increased CNS-NPC activity has been shown to improve
baseline CNS activity in aged mice, and NPC depletion impedes CNS recovery following injury.
NPCs secrete extracellular vesicles (‘exosomes’) that mediate many of the positive effects of CNS-
NPCs. We find that administering human ONLR-NPC-secreted exosomes enhance RGC survival ex vivo and
stimulates RGC-neuritigenesis. Depleting ONLR-NPCs in a mouse transgenic model increases markers of
RGC stress, using an RGC stress-marker panel. I hypothesize that ONLR-NPCs support RGC survival, and
they do this in part by vesicle secretion. I predict their loss increases RGC stress and susceptibility to death
after axonal ischemic stress, and supplementing RGCs with ONLR-NPC-extracellular vesicles will enhance
RGC survival after axonal stress. We will prove this with two rodent species and two specific aims.
Specific aim 1: Demonstrate that mouse ONLR-NPC loss results in RGC stress and increases
RGC death in ON disease. We will couple a mouse transgenic model enabling selective ONLR-NPC
depletion, the rodent model of NAION rNAION model, and stereology (statistically robust cell quantification).
We will utilize molecular and cell biological techniques for identifying RGC cell stress and apoptosis. We will
then: A) Determine whether acute ONLR-NPC depletion results in RGC stress, via stress marker analysis and
B) Whether this depletion enhances RGC death after rNAION-induced RGC ischemic axonal stress. I predict
increased RGC stress, demonstrable by increased RGC-pJun expression and increased RGC loss.
Specific aim 2. Confirm that rat ONLR-NPC ‘exosomes’ protect RGCs in culture and in vivo during
ischemic ON stress. We will isolate rat ONLR-NPC secreted vesicles and confirm their ability to enhance
RGC survival, by: A) Administering rat ONLR-NPC vesicles and their dissociated components to cultured rat
RGCs, we will quantify their ability to enhance RGC survival and neuritigenesis. I predict improved RGC
survival and increased neuritigenesis. B) Using the rNAION model, we will intravitreally inject rat ONLR-NPC
derived exosomes and their components and determine whether these vesicles improve RGC survival and
reduce stress-related markers such as CRF and pJun. I predict reduced stress levels and improved long-term
RGC survival. Our innovative approach will identify the factors that contribute to RGC stress resistance and
generate new, improved approaches to treatment of optic nerve diseases.

Grant Number: 5R01EY032519-04
NIH Institute/Center: NIH
Principal Investigator: STEVEN BERNSTEIN