Potentially deadly gas in foam form found to soothe inflammation
Despite the toxic and dangerous effects of carbon monoxide gas, a team of researchers has discovered that, when incorporated into stable foams, carbon monoxide can reduce inflammation and aid tissue regeneration. Researchers from Massachusetts Institute of Technology (MIT), Brigham and Women’s Hospital, the University of Iowa, and Beth Israel Deaconess Medical Center have developed a novel delivery method to safely feed carbon monoxide into the digestive tract to address inflammatory conditions such as colitis.
The method could feasibly be used to deliver other therapeutic gases into the gastrointestinal system for the same treatment purpose.
Past research into carbon monoxide has shown small doses of the gas is beneficial in preventing rejection of transplanted organs, reducing tumour growth, and even modulating inflammation and acute tissue injury.
Conversely, when inhaled at high concentrations, carbon monoxide binds to the iron component in the blood and prevents the body from obtaining enough oxygen, which can lead to serious health effects and death.
In order to safely deliver the gas, the researchers came up with the idea of incorporating the gas into a foam, much like the way that chefs use carbon dioxide to create foams infused with fruity flavours. These culinary foams are usually created by adding a thickening agent to a pureed liquid or a solid, and then incorporating air either by whipping it or using a specialised siphon to inject gases.
The MIT team created a modified siphon to incorporate carbon monoxide into their foams, made from food additives such as alginate, methyl cellulose, and maltodextrin. Xantham gum was also added to stabilise the foams – by varying the amount of xantham gum, the researchers could control how long it would take for the gas to be released once the foams were administered.
In animal experiments, the foams were found to reduce inflammation including radiation-induced proctitis (inflammation of the rectum that can be caused by radiation treatment for cervical or prostate cancer), and also helped to reverse acute liver failure caused by acetaminophen overdose.
“We think that with the foam used in this study, we’re not even coming close to the levels that we would be concerned about,” said Leo Otterbein, a professor of surgery at Harvard Medical School and Beth Israel Deaconess Medical Center. “What we have learned from the inhaled gas trials has paved a path to say it’s safe, as long as you know and can control how much you’re giving, much like any medication. That’s another nice aspect of this approach — we can control the exact dose.”
Current treatments for inflammatory conditions involve drugs that suppress the immune system, which can make patients more susceptible to infections. Treating these conditions with a foam that can be applied directly to inflamed tissue, or delivered orally or rectally, offers a potential alternative to immunosuppressive treatments.
[Previous studies in humans have shown that small amounts of carbon monoxide can be safely inhaled. A healthy individual has a carbon monoxide concentration of about 1% in the bloodstream, and studies of human volunteers have shown that levels as high as 14% can be tolerated without adverse effects.]
The researchers are working on testing different carbon monoxide-containing compounds in further trials.
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