Common Food Dye Could Treat Spinal Cord Injury

Brilliant Blue G (BBG), an ordinary food dye, has been found to stop the cascade of molecular events that cause secondary damage that immediately follows a traumatic injury to the spinal cord.

Researchers at University of Rochester Medical Center (URMC, New York, NY, USA) set out to find a substance that blocks P2X7, a purinergic-ligand-gated ion channel receptor that plays a role in regulating the deaths of immune cells such as macrophages. P2X7, which is carried in abundance by neurons in the spinal cord, allows adenosine triphosphate (ATP) to latch onto motor neurons and send them the flood of signals that cause their deaths, worsening the spinal cord injury and resulting paralysis.

The researchers therefore searched for a compound that not only would prevent ATP from attaching to P2X7, but also could be delivered intravenously. Luckily, they discovered that BBG (a known P2X7R antagonist), is both structurally and functionally equivalent to the commonly used blue dye No. 1, which was approved by the U.S. Food and Drug Administration (FDA) as a food additive in 1982. An intravenous injection of BBG proved to significantly reduce secondary injury in spinal cord-injured rats, which improved to the point of being able to walk, though with a limp. Rats that failed to receive the BBG solution never regained the ability to walk. There was one side effect; rats that were injected with BBG temporarily had a blue tinge to their skin. The study was published in the Proceedings of the [U.S.] National Academy of Sciences (PNAS).

"Because BBG is so similar to this commonly used blue food dye, we felt that if it had the same potency in stopping the secondary injury as oxidized ATP, but with none of its side effects, then it might be great potential treatment for cord injury,” said lead researcher Maiken Nedergaard, M.D., D.M.Sc., a professor of neurosurgery and director of the center for translational neuromedicine at URMC. "We were not disappointed.”

ATP, the vital energy source that keeps cells alive, quickly pours into the area surrounding a spinal cord injury shortly after it occurs, and paradoxically kills off what are otherwise healthy and uninjured cells. This surprising discovery marked a milestone in establishing how secondary injury occurs in spinal cord patients, and also laid out a potential way to stop it, by using oxidized ATP, a compound known to block ATP's effects, directly into the injured spinal cord area to achieve its results. However, placing a needle into a spinal cord that has just been severely injured is risky in itself, and oxidized ATP cannot be injected into the bloodstream because of its dangerous side effects.

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University of Rochester Medical Center