A novel way to accelerate functional recovery after central nervous system (CNS) injuries could one day restore vision for patients with optic nerve damage from diseases such as glaucoma.
For the first time, researchers at City University of Hong Kong (CityU) have identified and demonstrated a therapeutic small molecule, M1, that can restore visual function in the mammalian CNS. Traumatic injuries to the CNS, including the optic nerve, the brain, and the spinal cord, are the leading causes of disability worldwide and there is no available treatment.
M1 stimulates the fusion and motility of mitochondria (often referred to as the powerhouse of a cell, responsible for generating energy that the cell can use) and induces robust axon regeneration by enhancing the intrinsic growth capacity of injured neurons.
Research lead Assoc Prof Eddie Ma Chi-him said the research breakthrough heralds a new approach that could address unmet medical needs in accelerating functional recovery within a limited therapeutic time window after CNS injuries.
Assoc Prof Ma, from the Department of Neuroscience, and a Director of the Laboratory Animal Research Unit at CityU, explained: “Photoreceptors in the eyes (retina) forward visual information to neurons in the retina. To facilitate the recovery of visual function after injury, axons of neurons must regenerate through the optic nerve and relay nerve impulses to visual targets in the brain via the optic nerve for image processing and formation.
“M1 treatment sustains long-distance axon regeneration from the optic chiasm, i.e. midway between the eyes and target brain region, to multiple subcortical visual targets in the brain. Regenerated axons elicit neural activities in target brain regions and restore visual functions after M1 treatment. Our study highlights the potential of a readily available and non-viral therapy for CNS repair.”
The seven-year study, which builds on the team’s previous research on peripheral nerve regeneration using gene therapy, delivers M1 via intravitreal injection. “Successful restoration of the visual function, such as pupillary light reflex and responses to looming visual stimuli, e.g., visually induced innate defensive responses to avoid predator, was observed only in M1-treated mice four to six weeks after the optic nerve had been damaged,” said Dr Au Ngan-pan, Research Associate in the Department of Neuroscience.
To evaluate the potential clinical application of M1, the research team is now developing an animal model for treating glaucoma-related vision loss using M1. They may also develop a model for treating other common eye diseases and vision impairments, such as diabetes-related retinopathy, macular degeneration, and traumatic optic neuropathy.
References:
Pan Bennett Au, N., Chand, R., Kumar, G., et al., A small molecule M1 promotes optic nerve regeneration to restore target-specific neural activity and visual function. PNAS Vol 119, No 44. doi.org/10.1073/pnas.2121273119.
