Carbon monoxide foam in the rectum relieves bowel disease in mice

It’s best known as a deadly poison, but in low doses, carbon monoxide can have therapeutic benefits for conditions like inflammatory bowel disease and cancer. Now researchers may have found a way to deliver the treatment safely in a foam


June 29, 2022

Researchers Made Carbon Monoxide Foam Using Techniques From Molecular Gastronomy

John Traverso

Carbon monoxide foam delivered through the rectum can reduce inflammation and speed tissue recovery in mice and rats.

This colorless and odorless gas is best known as a dangerous poison, capable of causing coma, convulsions and possibly death when it reaches concentrations of 50% or more in the blood.

But it’s not always harmful. Our bodies actually produce small amounts on a regular basis, and about 20 years ago, Leo Otterbein at Harvard Medical School noticed that production increased when we were sick.

Since then, several studies, mostly in animals, have shown that low doses of carbon monoxide can help treat diseases such as cardiovascular disease and even cancer, primarily by reducing inflammation.

The challenge, however, is to develop a safe and effective way to administer it. Safe dosing and storage can be problematic with administration methods such as inhalation and infusion.

Now it turns out whipping the gas into a froth can do the trick.

“We wanted to try an approach that was really outside the box,” says James Byrne at the University of Iowa Health Care, co-author of the new study with Otterbein and John Traverso at Massachusetts Institute of Technology. “So we turned to molecular gastronomy and what they’ve done to push the physical limits of food,” he says.

The researchers placed ingredients commonly found in processed foods, such as xanthan gum, inside pressure vessels containing carbon monoxide. They then trapped the gas inside these materials by whipping them at high speed. The resulting concoction resembles a spoonful of frothed milk. Since all the materials are food grade and the concentration of carbon monoxide is very low, there is no risk of handling the material, says Byrne.

Next, they inserted the foam into the rectums of about 40 mice and rats showing symptoms of one of three conditions: inflammatory bowel disease, radiation-induced bowel injury, or liver failure related to an acetaminophen overdose. In all three cases, treated rodents showed significant reductions in inflammation and tissue damage compared to those given control foam or no treatment at all.

The benefits seen in the liver indicate that once the carbon monoxide is released from the foam, it enters the bloodstream where it can access other organs, Otterbein says. This means that the foam could potentially treat a wide range of conditions such as cardiovascular, kidney or lung disease.

“I don’t know if there is any other foam used to deliver therapeutic gases,” says Traverso. “It opens up a whole new way of thinking about therapeutics.”

Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.abl4135

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Article modified on June 30, 2022

We specified that carbon monoxide foam treats inflammatory bowel disease

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