When lacking in blood for transfusions, going with your gut might do the trick.
The storms that ravaged the U.S. East Coast this year also drained the Red Cross’ stocks of blood — so it issued an urgent call for donors. They were especially in need of O-type blood since it can be administered to any patient, increasing their chances of survival in emergency cases.
One workaround this issue is to turn other types of blood into O-type. While possible, it’s a very slow process. However, a research team plans to use enzymes secreted by bacteria in your gut to turn A and B type blood into O at much greater speeds than anything previously possible.
“We have been particularly interested in enzymes that allow us to remove the A or B antigens from red blood cells,” says Stephen Withers, Ph.D. and paper coauthor.
“If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood.”
The prospect of turning donated blood to a common type — O, the universal donor type — is understandably quite appealing to researchers and medical professionals. However, we’ve yet to find any process that works fast, safe, and cheaply enough to feasible.
In their new paper, which will be presented today at the 256th National Meeting & Exposition of the American Chemical Society (ACS), Withers and his team will present an assessment of several new enzyme candidates for the job. The conference will be broadcast live on youtube:
The paper drew on metagenomics — Withers describes it as taking “all of the organisms from an environment and extract[ing] the sum total DNA of those organisms all mixed up together” — to quickly asses the potential of enzyme candidates more quickly. It allowed Withers’ team to sample genes of millions of different organisms without having to grow individual cultures.
They then used a strain of E. coli bacteria to select genes that code enzymes appropriate for the task (enzymes that can remove sugar molecules from red blood cells).
“This is a way of getting that genetic information out of the environment and into the laboratory setting and then screening for the activity we are interested in,” Withers says.
While the researchers planned to start by sampling DNA from mosquitoes and leeches — both organisms that degrade blood — they ultimately found likely candidates in the human gut flora. A certain family of proteins called mucins line the intestinal wall and provide sugars for bacteria that assist in digestion. These sugars serve as both attachment points and feed for said bacteria.
Some of these sugars closely resemble the structure of antigens in A- and B-type blood. The team identified which enzymes bacteria use to absorb these sugars off mucin molecules, and report that they are 30 times as effective in removing red blood antigens compared to any previous candidate.
Withers is now collaborating with colleagues at the Centre for Blood Research at UBC to test these enzymes on a larger scale; depending on the results, they may be then selected for clinical testing. He also plans to use directed evolution, a method that simulates natural evolution, to create more efficient versions of the enzymes.
“I am optimistic that we have a very interesting candidate to adjust donated blood to a common type,” Withers says. “Of course, it will have to go through lots of clinical trails to make sure that it doesn’t have any adverse consequences, but it is looking very promising.”
The paper “Discovery of CAZYmes for cell surface glycan removal through metagenomics: Towards universal blood” will be presented today, Tuesday 21st August, at the 256th National Meeting & Exposition of the American Chemical Society (ACS).
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