Blood compatibility is a determining factor in medical procedures for blood transfusion, dialysis, and organ transplantation. In defining typing, we are scientifically categorized into specific groups, each of which has a series of characteristic antibodies in its plasma.
This means, by having a different set of antibodies and cellular characteristics in your blood, a type B donor is not compatible with a type A receptor and vice versa. And the concern around that is clear: unless a patient receives blood (or compatible with his), a transfusion procedure can lead to the rupture of his red blood cells, resulting in death.
In a paper published in the journal Nature Microbiology last Monday (10), scientists at the University of British Columbia in Canada were able to do an innovative job in microbiology and physiology: converting, using natural enzymes from the human intestine, blood type A in a universal donor – that is, it is possible to make blood A have the same characteristics as type O blood.
The major drawback of the research is that O-type blood cells do not have any sugar on their surfaces, which gives them the universal compatibility feature. Regardless of Rh factor, such sugars, usual carbohydrates like galactose, are directly attached to the surface of blood cells A, B, and AB.
This is why it is so important to have a good supply of blood bags in emergency rooms because when the patient’s blood type is not identified at the time of an accident or need for intervention, the chances of success in the transfusion are real.
The main idea in this research was to transform blood A, the second most common type among humans, into a material compatible with all other blood types in the emergency rooms, since blood banks suffer daily from the lack of stock of blood bags, mainly of type O.
For this, the attempt was to remove the incompatible carbohydrates (sugars) from the red blood cells and to make them as neutral as those of a blood O, the famous universal donor. But there is one: the current techniques of blood conversion have a very high cost that makes their application unfeasible.
Thanks to a type of enzyme present in natural bacteria in our gut, scientists were able to find a light at the end of the tunnel. For years, they have been working to find an enzyme that is widely available and able to break down sugars from less-compatible blood cells – and thanks to our intestinal flora, researchers have discovered the digestion response of some bacteria present there.
What happens is that such bacteria digest mucins (sugars and proteins) from the intestinal tract and the carbohydrates present in these substances are quite similar to those found in blood cells type A.
To put the experiment into practice, the team had to isolate the bacterial DNA from a sample of human feces. Thus, technically, it would be possible to extract the genes that encode the enzymes responsible for the breakdown of mucins.
Using a genetic engineering technique, the researchers were then able to cut the DNA fragment to reproduce it in in vitro copies of Escherichia coli bacteria. The next step was to observe the digestion of these bacteria in the laboratory: would they be able to digest the sugars in the mucins, to the point of breaking them completely?
If positive, it would be more than halfway to eliminating sugars from type A blood cells.
After several attempts, the scientists discovered that the enzymes come from another intestinal bacterium, called Flavonifractor plautiique. Two of the enzymes resulting from the digestion process were able to efficiently break down the sugars from Type A blood cells provided they worked simultaneously.
This process of digestion of carbohydrates in vitro was accompanied by the use of markers, substances that, when viewed under microscopy, color certain cell structures and show the scientist what is happening and the path taken in certain reactions.
The enzyme pair was also able to break off the offending sugars bound to blood cells type A, but not type B.
The possibility of doubling the supply of blood in blood banks and hospitals is real, but we still need to improve the technique, since type A blood represents almost 30% of all types in the world, by allying the supply of blood A with that of blood O, blood supply can potentially double in size.