Erythrocytes of the universal group
Impersonal blood will suit anyone
Alla Solodova, Infox.ruCanadian scientists have camouflaged molecules that give blood belonging to a particular group.
Such blood is useful in critical situations when doctors do not have time to look for a suitable donor.
Erythrocytes (red blood cells) are the most numerous blood cells adapted for the transport of oxygen and carbon dioxide. The whole body breathes with these cells. Red blood cells are somewhat "deprived" compared to other cells: there is no nucleus in erythrocytes and mitochondria and other organelles are quantitatively lacking. On the surface membrane of erythrocytes there are molecules by which doctors determine the blood group and Rh factor. These characteristics (AB0/Rh) play a key role in determining the compatibility of blood (organs) of the donor and recipient. If the blood is mixed incorrectly, incompatible red blood cells stick together, which leads to life-threatening renal failure and hemolytic anemia. And immune cells, recognizing surface molecules-antigens, begin to attack strangers. In addition to proteins and carbohydrates of the AB0/Rh system, there are more than a dozen unstable specific molecules in the blood that can cause an immune conflict between the donor and the recipient. So even the blood of the same name may be incompatible.
In cases of large-scale disasters and wars, doctors simply have no time to look for and wait for the right blood or plasma. Since the blood is constantly being updated (the life span of red blood cells does not exceed 120 days, the rate of appearance of new red blood cells is 2.3 million cells per second), then in critical situations when any delay can cost lives, it makes sense to transfuse "neutral" blood. That is, one in which red blood cells and plasma do not contain specific surface molecules-antigens. On the surface of red blood cells, these are agglutinogens (A and B), and in plasma — agglutinins (alfa and beta). With the help of "impersonal" blood, it is possible to support the patient's life at a critical moment – until the body restores the lost blood.
Camouflage instead of circumcision
Previously, scientists have already proposed using an enzymatic method to "trim" the molecular "tails" of erythrocytes and remove agglutinins from the plasma. Such depersonalization of blood turned out to be not unsuccessful, but too complicated and expensive. Canadian researchers led by Dr. Sania Mansouri from McGill University in Montreal have created universal red blood cells whose molecular tails were not cut off, but camouflaged with several layers of polymer. The relatively simple procedure of piece-by-piece packaging of cells, not only did not require expensive reagents, but also did not deprive the blood cells of their basic functions.
For the experiment, the scientists used red blood cells isolated from the blood of healthy volunteers. Biopolymers were added to the suspension of erythrocytes in buffer solution to pack living cells. Their molecules independently envelop each of the red blood cells. By the end of the procedure, each blood cell was packed into a separate multilayer "pouch", which includes three organic molecules: alginate, chitosan-phosphorcholine and polylysine-polyethylene glycol. The researchers tested the mobility and functional usefulness of camouflaged red blood cells. It turned out that the packed red blood cells did not lose their ability to carry oxygen and carbon dioxide. And in standard laboratory tests to determine the blood group, experimental red blood cells turned out to be "faceless": the antibodies did not react to them.
"The results of our experiment are an important step in creating a "universal" blood that can be used in critical situations. But for the practical application of the proposed technique, additional research will be required," the authors of the study write in the article Investigation of Layer—by-Layer Assembly of Polyelectrolytes on Fully Functional Human Red Blood Cells in Suspension for Attenuated Immune Response, published in the journal Biomacromolecules.
Portal "Eternal youth" http://vechnayamolodost.ru15.03.2011