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- Barrier to circulation: scientists have uncovered the mechanism of cancer due to nanoplastics
Barrier to circulation: scientists have uncovered the mechanism of cancer due to nanoplastics
For the first time, Russian scientists have shown using computer modeling how nanoplastics penetrate cell membranes and displace cholesterol from them. This disrupts the rigidity and barrier function of the shell, which can provoke cell death or their malignant degeneration, leading to serious diseases, including cancer. The discovery gives an impetus to the creation of accurate toxicity tests and the development of safe polymers of a new generation, experts noted. However, it remains to be seen which concentrations of nanoplastics in the body are truly dangerous.
What is the importance of cholesterol in cells?
Scientists from Yaroslav the Wise Novgorod State University have used computer modeling to show for the first time how tiny plastic particles entering cell membranes can change the distribution of cholesterol.
— It is the most important building material of cell membranes. It is responsible for their mechanical properties and the phase behavior of the membrane (it makes it strong and at the same time mobile so that the cell works normally. — Izvestia). Cholesterol also indirectly affects the functioning of membrane proteins," Andrey Gurtovenko, chief researcher at the NovSU Microplastics Research Center, told Izvestia.
Microplastic particles on a cotton pad
As the results of the study showed, once in the body, nanoplastics cause cell damage. This, in turn, is fraught with their death or malignant degeneration, which in the future can lead to chronic inflammation and cancer, he added.
Plastic debris is "ground" into small fragments — up to several nanometers in size - under the influence of the sun, wind, water and microorganisms. Such particles also enter the environment from cosmetics, detergents and synthetic clothing during washing. They are found everywhere — in oceans, rivers, soil, plants. Nanoplastics enter the body along with food, water, air and, to a lesser extent, through the skin. Inside, these particles are able to overcome natural barriers, enter the bloodstream, and from there — into internal organs and even into the brain.
How nanoplastics damage the cell membrane
To understand what happens when nanoplastics come into contact with the body, a model of the cell wall was created, said Andrey Gurtovenko. It is a double layer of lipids — fat molecules. The virtual membrane contains 33% of cholesterol molecules, which corresponds to the concentration typical for human cells.
Then spherical particles from two of the most common plastics, polypropylene and polystyrene, were placed in the system. They are usually used to make disposable tableware and packaging. The particle size is about 4-4.5 nm, which is comparable to the thickness of the cell membrane.
According to the scientist, according to calculations, the penetration of such a particle into the cell shell takes from hundredths of a second to several hours. Once inside the membrane, it occupies a position between the layers and displaces cholesterol molecules, resulting in areas devoid of these molecules in the structure. Such zones change the properties of the membrane, making it either excessively fluid, excessively rigid, or brittle.
In addition, nanoplastics can cause cholesterol redistribution between the membrane layers, which makes it lose its ability to effectively withstand mechanical stress. The barrier function of the cell membrane is also disrupted — it begins to let through substances that were previously delayed.
At the same time, the scientist notes that such effects are possible only at extremely high concentrations of nanoplastics in the body. Under what conditions they can occur remains the subject of further research.
Why is it necessary to distinguish between micro- and nanoplastics?
"The described introduction of foreign particles into the structure of cell membranes can affect the functioning of synapses in the nervous system, immune cells, and even metabolic parameters such as blood sugar, insulin sensitivity, and others," explained Sergey Kharitonov, a molecular biologist and researcher at Lomonosov Moscow State University.
However, the results obtained are the result of modeling on a simplified model, and not on living cells, the expert added. In a real organism, the membranes are more complicated: they are covered on the outside with a glycocalyx, a "fluffy" layer of chains of sugars (carbohydrates), and up to 50% of the membrane area is occupied by proteins that can smooth out or prevent the effects predicted by the model.
Nevertheless, the work helps to understand what properties of nanoparticles make them potentially dangerous to cells. This is important for creating accurate systems for testing the toxicity of nanoplastics and for developing new safe materials that, when destroyed, form less biologically aggressive particles.
— Atomic computer simulation is the "gold standard" for studying interactions at the molecular level. The work shows a strict mechanism of how nanoplastics particles displace cholesterol, violating the rigidity of the membrane," commented Evgeny Kurdyukov, Associate Professor of the Department of General and Clinical Pharmacology at Penza State University.
According to him, studying this mechanism can help doctors better understand how nanoplastics are potentially associated with the development of heart attacks and affect neurodegenerative processes. In addition, the results obtained can form the basis for the development of drugs that will promote the aggregation of nanoplastics into large particles that are easily excreted from the body.
In general, the study serves as an argument in favor of the need to distinguish between microplastics and nanoplastics in legislation, since their behavior in the body differs significantly, the specialist emphasized.
"The practical benefit of such studies is that they help to understand which particle sizes, types of plastic, and surface properties are potentially more dangerous and what toxicologists need to look at during experiments: membrane permeability, inflammatory response, cell death, and changes in the functioning of membrane proteins," the head of the Personalized Medicine Center explained to Izvestia. Medicine" of Kazan (Volga Region) Federal University, corresponding member of the Academy of Sciences of the Republic of Tatarstan Albert Rizvanov.
This is useful for risk assessment, the development of safe materials, water and air filtration systems, as well as for future regulation of the turnover of plastic products, he said. At the same time, the study lacks data on the routes of entry and distribution of particles in tissues, taking into account their excretion from the body, comparing different forms, as well as verifying the results on living cells at doses close to real ones.
The authors emphasize that the damaging effect can occur only at high concentrations of nanoplastics, but their level in the body is not yet known, Albert Rizvanov noted. According to him, the study is important as a step towards understanding potential risks, but not as a definitive confirmation of the threat.
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