Breakthrough new drug can restore human vision loss, study finds

Myelin, the protective sheath around nerve fibers, plays a crucial role in brain communication. It ensures fast and efficient transmission of electrical signals. When damaged, this insulation breaks down, causing neurons to misfire or fail entirely.

This disruption, known as demyelination, impairs movement, sensory perception, and cognitive function. It is a defining feature of multiple sclerosis (MS) and other neurodegenerative diseases. Aging, stroke, and traumatic brain injuries can also lead to myelin loss, further complicating recovery.

The body attempts to repair myelin, but the process is often incomplete. Oligodendrocytes, specialized brain cells, generate new myelin to restore function. However, in many cases, the repair falls short, leaving neurons vulnerable to further damage. Scientists have long sought treatments to enhance this process.

Now, researchers at the University of Colorado Anschutz Medical Campus have identified a promising drug, LL-341070, that accelerates myelin repair. Their findings could offer new hope for people with MS and other conditions linked to demyelination.

Oligodendrocytes wrap nerve fibers in lipid-rich layers, forming myelin. This insulation allows neurons to send signals at high speeds, maintaining seamless brain function. When myelin deteriorates, signals slow down or stop, leading to widespread neurological issues. Without effective repair, neurons become more susceptible to degeneration, worsening symptoms over time.

Demyelination affects both white and gray matter in the brain. In MS, damage to neocortical gray matter strongly correlates with physical and cognitive decline. The brain responds with remyelination, attempting to replace lost myelin. Unfortunately, this natural repair mechanism often fails, especially when damage is widespread or severe.

Despite progress in understanding myelin regeneration, no FDA-approved treatments currently exist. Some experimental compounds show promise, but none have made it to clinical use. Unlocking the factors that limit remyelination remains a top priority for researchers working to develop effective therapies.

To better understand myelin repair, scientists focused on the visual cortex, a region highly sensitive to myelin changes. They used advanced imaging techniques, including longitudinal two-photon microscopy, to track remyelination over time. High-density electrical recordings provided additional insights into how repaired myelin impacts neural function.

The experiment induced demyelination using cuprizone, a toxin that selectively targets oligodendrocytes, and tested two potential remyelination drugs: LL-341070, a thyroid hormone mimetic, and clemastine, an existing FDA-approved antihistamine.

Results revealed that cuprizone exposure caused significant oligodendrocyte loss and delays in visual response times. The brain initiated a rapid remyelination process, but its effectiveness varied based on the extent of damage.

Mild demyelination led to substantial recovery, whereas moderate to severe damage overwhelmed the repair mechanisms, leaving oligodendrocyte numbers depleted even after seven weeks.

LL-341070 significantly enhanced the remyelination process, outperforming clemastine in restoring oligodendrocytes and expediting neural recovery. The drug proved especially effective following severe damage, eliminating the natural remyelination deficit and restoring myelin levels to those found in healthy, age-matched mice.

The findings, published in Nature Communications, suggest that LL-341070 could serve as a breakthrough therapy for demyelinating diseases. By enhancing the brain’s innate repair mechanisms, the drug may help restore vision, motor function, and cognitive abilities in individuals with MS and related disorders.

“This research brings us closer to a world where the brain has the capacity to heal itself,” said Ethan Hughes, PhD, co-lead author and associate professor at the University of Colorado School of Medicine. “By harnessing this potential, we hope to help people with diseases like MS by potentially reversing some of the damage, offering people the opportunity to regain their vision and cognitive function."

The study demonstrated that even partial myelin repair significantly improved vision-related brain functions, reinforcing the critical role of myelin in neurological health.

“We've known for years that myelin plays a crucial role in brain function,” said Daniel Denman, PhD, co-lead author of the study and assistant professor at the University of Colorado School of Medicine. “This study highlights the role of cortical myelin in visual function. The drug could be a game-changer because it accelerates the brain’s natural repair mechanisms.”

The research team plans to test LL-341070 in other brain regions and refine the treatment to enhance its effectiveness. While the drug has shown promise in animal models, further studies are needed before human clinical trials can begin.

“This discovery is just the beginning,” Hughes said. “We are optimistic that LL-341070 and similar therapies could one day provide real, tangible benefits to patients by improving overall brain function and quality of life.”

The findings underscore the urgent need for targeted remyelination therapies. By accelerating myelin repair, treatments like LL-341070 could offer new hope for individuals facing the debilitating effects of demyelination.

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