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During his time in the trenches of the First World War, Dr. Lawrence Bruce Robertson, a Canadian surgeon who pioneered blood transfusion, three men die from ruptured blood cells, multi-organ damage and eventually organ failure symptoms of a condition called paroxysmal nocturnal hemoglobinuria (PNH).
It was a time before scientists had identified the four major blood groups in humans: A, B, AB and O. The men who had seen Robertson die died as a result of a violent reaction to the blood they received, which was incompatible with their own blood type.
Type O can be safely administered to all blood groups.
We now know that type O blood, which is a recessive trait, the universal donor & # 39; is. If a blood transfusion is required, those with type O blood should receive type O blood; on the contrary, type O can be safely administered to all blood groups. Now, in a new study, researchers report that they have used newly discovered gut bacteria enzymes to convert type A blood at a faster rate to type O than ever before. Ubiquitous blood shortages could soon be gone.
"What we could do, if it meets all safety requirements, is to expand that stock of available blood," Dr. Steve Withers, professor of biochemistry at the University of British Columbia and senior author of the new study, which he presented at the American Chemical Society's National Meeting in Boston on Tuesday.
First developed by the late Jack Goldstein of the New York Blood Center, the idea to convert A-, B- or AB-blood to O has been present for a while, explains Dr. James Blood Services, head scientist. Dana Devine from, who is not involved in the new study. The challenge, she adds, is how to commercialize it.
"He has an enzyme that is much more active and you can use less of it," said Devine van Withers. "He may have the breakthrough to circumvent the costs," she adds, referring to older methods with price tags that prevented becoming marketable.
Some enzymes from bacteria that can be grown in a laboratory – of which there are about 10,000, Withers points – can be used to cut off the antigens, or small sugars or protein molecules, from type A or type B blood, effectively change it to type O. (When an enzyme that feeds with type A antigens is associated with an enzyme that feeds with type B antigens, type AB blood can be converted to O.) In a 2015 study, published in the Journal of the American Chemical SocietyWithers and his team found an enzyme that was able to chew very slowly on type A antigens. While manipulating evolution, the researchers tweaked the enzyme and improved the ability to remove the sugar molecules by a factor of 170.
But Withers, an enzymologist with 35 years of experience, suspected that nature – especially the human intestine – had an even bigger solution.
"The human intestine contains the antigens A and B," he said. "It would be logical that bacteria would evolve to cut them off."
To see if this was the case, Withers and his team started working with Dr. Jayachandran Kizhakkedathu, a pathologist at the Center of Blood Research, and Withers & # 39; University of British Columbia; Steven Hallam, a microbiologist and immunologist whose lab specializes in metagenomics, the study of genetic materials that are recovered directly from nature, in contrast to the materials produced in a laboratory.
Microbes are the environment of the earth and its other organisms, Hallam said, and there are many more than neurons and stars in the universe. "People become more interested in tapping into that huge diversity of life, creating an opportunity to discover enzymes and catalysts to solve global problems," he explains.
With the support of Hallam's laboratory, the Withers team sifted through human excrement to extract their bacterial DNA, the DNA subsequently chopped into very large chunks, containing 20 to 30 genes on average. They have inserted those genes into a notorious host that can easily be grown in the laboratory.E coli. "And then," Withers said with a small smile, "we essentially crossed our fingers and hoped that these genes could be coded."
It worked. The intestinal enzymes were even more efficient than those developed by the team three years ago.
The potential meaning for society is profound, Devine said. "It would enable blood systems to manage their industry much better – they always struggle to get enough O-blood donors -" she said about blood disorders.
In case of emergency transfusion, doctors automatically give blood of type 0 to a patient; taking the time to perform a screening can be life-threatening. The occupations for type O donors are therefore high, especially in the summer months. "People go on holiday and the general blood supply starts to drop," says Devine. "Sometimes you get a rising demand from people who travel, more traffic causes more accidents, and it all comes in the wrong way."
The new research is still in the preparatory phase. By cooperating with the CDC and Canadian Blood Services, the team will have to conduct further in vitro tests to determine whether blood has been converted from type A to O using gut microbes – which researchers would remove from the blood before it would be administered – could cause abnormal reactions in patients. But if it passes safety studies, including a Phase 3 clinical trial, the social significance would be enormous.
"As scientists, we do not often get the chance to make discoveries that have such a big human impact in the world, it's rare, it's a glorious thing, the idea of taking any kind of blood and Any form that can be transformed would have a major impact on health, it would literally save lives, and turning to the human body to find that solution is very elegant, "says Hallam. "It has only just begun."