Deadly gas could treat diabetic blindness, according to AU study

Carbon monoxide from engine exhaust kills hundreds of people each year. But a tiny controlled amount might be a potential therapy for a leading cause of blindness.

That is the working premise of a partnership between researchers at Augusta University and a California start-up company. Their work is funded by a $300,000 innovative grant from the National Institutes of Health meant to promote public-private partnerships.

Carbon monoxide is an odorless, colorless gas that kills at least 430 people and sends 50,000 to the Emergency Room each year, according to the National Center for Environmental Health. But in very small doses, it could have some benefit. The AU researchers and Hillhurst Biopharmaceuticals of Montrose, Calif., are studying it in diabetic retinopathy, the leading cause of adult blindness. 

The disease is a complication of diabetes where uncontrolled blood sugar damages small blood vessels in the light-sensitive area in the back of the eye. More than half of diabetics will develop some form of it over time, according to the National Eye Institute. There is no cure and most of the treatments for advanced stages, such as surgery or injections into the eye, have significant drawbacks.

Hillhurst has come up with a way to take carbon monoxide gas and turn it into something that can be given in a pill, said Dr. Ravirajsinh Jadeja of the AU Department of Biochemistry and Molecular Biology, who is co-principal investigator on the grant.

"Basically, they came up with a liquid formulation that can carry a gas, which can deliver a controlled amount of carbon monoxide," he said. "In a very very controlled environment, we can time how much carbon monoxide we want it to release."

In this case, "we’re talking about a very ultra-low dose of carbon monoxide," Jadeja said.

That's important, said Dr. Pamela Martin of AU Biochemistry and Molecular Biology, who is also co-principal investigator. 

"Dose is everything when we are talking about the benefits vs. the bad effects of carbon monoxide, and any other therapy for that matter." 

The approach potentially would have a couple of advantages over the current therapy, she said.

"This treatment would meet both of those criteria we hope, to be more effective and less toxic," she said. "And additionally have the potential to be employed earlier."

Much of that early damage can be attributed to oxidative stress and inflammation harming the fine blood vessels in the eye, Martin said. The tiny amounts of carbon monoxide seek to trigger natural antioxidant forces in the body to counter that, she said.

"That should give some protection in preventing or at least delaying the effects of diabetic retinopathy," Martin said.

In addition, carbon monoxide appears to help protect the mitochondria, the powerhouse of the cells, Jadeja said.

"That’s a very basic thing to have cells working properly," he said.

Being able to take it by mouth would be a clear advantage over current treatments, Martin said.

"When you look at treatment, it is very difficult to get something into the eye without injecting it directly," she said. "So if you can take something orally that could potentially treat an eye condition, that’s huge."