People have four blood groups, among which there is only one universal, that is, suitable for absolutely all people — this is the I(O) group. Even though this is a common group, donor blood is often still in short supply. Therefore, scientists have been working for several decades to create artificial universal blood that could be transfused to all patients. However, a positive result has only now been achieved. In a new study, scientists have found a way to make blood universal using gut bacteria.
Scientists have found a way to create universal blood
Why it is difficult to create universal donor blood
Transfusion of the wrong blood type can lead to a fatal immune reaction. The reason is that the immune system recognizes foreign sugar molecules, also called “antigens,” on the surface of red blood cells and begins to attack them. We have previously talked about why different people have different blood types. Only blood group I does not contain antigens, so it is universal.
From all of the above it follows that by removing antigens, it is possible to make blood universal, that is, make it group I. Scientists have been working on this for decades, using different enzymes. For example, back in the 80s, enzymes from unroasted coffee beans were used to remove antigens from groups II and III.
Since then, experiments have been carried out using various other, more efficient enzymes that removed antigens in both group II and group III blood. After purifying the red blood cells in the blood of both groups, at the molecular level they looked exactly like group I red blood cells. But when the treated blood was mixed with group I blood plasma, the latter reacted positively, indicating incompatibility. That is, it was not possible to create universal blood.
The blood group is determined by the type of antigens on red blood cells
Like intestinal bacteria helped create universal blood
In a new study published in Nature Microbiology, scientists discovered, in addition to antigens, long chains of sugar molecules that make the blood of all groups (except the first) incompatible with each other. Most likely, it was because of them that previously all attempts to create universal blood ended in failure.
To remove these chains from red blood cells, scientists used a set of enzymes from intestinal bacteria. As the researchers themselves explain, the mucus in our intestines is similar to the surface of red blood cells. So they decided to simply borrow enzymes from bacteria that metabolize this mucus and applied it to red blood cells.
The intestinal bacteria Akkermansia muciniphila were used for the study. Their enzymes break down long sugar chains in the mucus lining the intestines, which means they can do the same on the surface of red blood cells. The experiment was generally successful. Once the antigens themselves are removed from group III blood, it becomes 80% compatible with group I plasma. But after removing sugar chains, compatibility increased to 91-96%.
Scientists were able to purify red blood cells using enzymes from intestinal bacteria
But, unfortunately, the result was not so noticeable when treating blood group II. After removing the antigens, the compatibility of this blood with type I was only 20%, but when scientists removed the sugar chains, this figure increased to only 50%. Obviously, blood group II is “biochemically” more complex. Therefore, scientists will have to find another cocktail of enzymes to purify red blood cells.
But, in any case, we can already talk about some success in this area. Of course, it will take a long time before this technology can be put into practice. It must be proven that it is safe and that purified red blood cells survive normally in the circulation. But, the most important thing is that the first step has already been taken, and good results have been achieved, especially for group III.
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As the authors of the work say, “the hunt for the magic enzyme or enzymes is already underway, and they will appear very soon. This means that scientists will be able to solve the problem of shortage, or at least incompatibility, of human blood. True, it is important not only that the technology is effective, but also inexpensive. Otherwise, it will not be in great demand in practice.