Synthetic cells as a blood substitute: Researchers have developed artificial red blood cells that have similar characteristics to their natural role models. The cells, which consist of polymers with a membrane coating, have the same cup-shaped shape, move through blood capillaries with similar flexibility and can transport oxygen or other substances through the body, as tests have shown.
Blood is an indispensable elixir of life and at the same time a scarce resource: Especially in times of crisis, blood supplies for operations and the care of accident victims are often scarce. For this reason, researchers have long been trying to synthesize at least the red blood cells that are important for oxygen transport. So far, however, these artificial blood cells have only ever had some of the necessary properties.
Flexible transport artist
Red blood cells are adapted to their task in a variety of ways: They carry the iron-containing molecule hemoglobin, which binds oxygen and thus makes these cells effective oxygen transporters. In addition, their cup-shaped shape and great flexibility allow them to squeeze themselves through narrow capillary vessels. Last but not least, the red blood cells carry proteins on their cell surface that prevent the immune system from destroying them.
Researchers led by Jimin Guo from the University of New Mexico in Albuquerque could have developed a synthetic cell that combines all of these features. “We have produced synthetic red blood cells that fully correspond to natural cells in size, concave shape, deformability, oxygen transport and the long circulation time in the body,” the scientists report.
Polymer structure with real membrane
For their synthetic blood cells, the researchers first created a kind of print of real red blood cells: They covered the blood cells with a thin layer of silicate, giving them a hollow shape. They then attached a multi-layer layer of different polymers to this mold and then etched the silicate structure away again. Finally, they covered the surface of these polymer cells with a cell membrane derived from real red blood cells.
The result was artificial cells that looked similar to red blood cells and had the same proteins on their surface. Tests with artificial capillaries showed that these cells can deform as flexibly and squeeze through thin veins as the real cells: After passing through the constrictions, the blood cells returned to their natural shape.
In tests with chicken chicks and mice, the synthetic blood cells also proved to be long-lived and tolerable: They circulated in the animal’s body for more than 48 hours without the researchers observing clumping or other harmful side effects.
Can be loaded with hemoglobin and other active ingredients
The crucial question now was whether these artificial blood cells could also function as their role models. “We have developed modular processes for this, through which we can load the cells with functional ‘cargo’ such as hemoglobin, medicinal substances, magnetic nanoparticles or biosensors,” report Guo and his colleagues. “This gives the artificial red blood cells different functions. In addition to transporting oxygen, they can also serve as drug transports, display toxins in the body or be controlled magnetically.
Initial tests have shown that this loading works and that the blood cells can perform the desired functions, at least in the laboratory. However, further studies with animals have yet to show how these synthetic cells prove themselves in medical use. However, the researchers are confident that they have made important progress with their artificial blood cells. (ACS Nano, 2020; doi: 10.1021 / acsnano.9b08714)
Source: American Chemical Society
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