Microplastics in the bloodstream can induce cerebral thrombosis by causing cell obstruction and lead to neurobehavioral abnormalities
January 22, 2025 | ScienceAdvances
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Introduction
Microplastics (MPs) are plastic particles with a diameter of less than 5 mm (1, 2). These particles originate from small plastic pellets produced for specific purposes, as well as from the degradation, weathering, and fragmentation of larger plastic products in the environment (3–5). MPs are ubiquitous worldwide, present in various environments ranging from oceans to land and from Antarctic ice to human settlements (4). Pollution from MPs is particularly notable in the oceans, where marine organisms such as fish, shellfish, and plankton ingest them, thereby introducing them into the human food chain (4–6). Substantial amounts of MPs have also been found in freshwater systems, including rivers, lakes, and reservoirs, allowing for contamination of human water sources. In addition, MP particles can be transported through the atmosphere and disseminated into the air, eventually entering the human respiratory system (7). Recent studies have indicated that MPs can directly enter the human bloodstream through the use of plastic medical supplies (8).
MPs have been found in human feces and various tissues, including the liver, kidney, placenta, and blood (9–11). Accumulation of MPs in organisms can result in tissue dysfunctions and chronic diseases such as respiratory diseases, immune system disorders, chronic inflammation, endocrine gland effects leading to hormone imbalance, and metabolic dysfunctions (12–15). In particular, the presence of MPs in the bloodstream poses a substantial health challenge. As the blood circulates, these MPs may be carried to any organ, especially the distal branch vessels. Studies have shown that blood MPs can lead to acute cardiovascular diseases (16–17). Furthermore, in a study, patients with carotid artery plaque in which MPs and nanoplastics (NPs) were detected had a higher risk of a composite of myocardial infarction, stroke, or death from any cause in 34 months (18). These potential threats can be life-threatening compared to the chronic diseases caused by MPs. In addition, MPs can cause brain dysfunction. Nanosized plastic particles can penetrate the blood-brain barrier (BBB) and enter brain tissue (19, 20). The interaction between NPs and a-synuclein fibrils can exacerbate the spread of a-synuclein pathology in vulnerable brain regions, potentially triggering or worsening conditions such as Parkinson’s disease and other neurologically related dementia diseases (21). However, how micron-sized plastics affect brain function remains unclear. Even several studies have proved that treatment with MPs affects behavior and induces phenotypes such as anxiety in mice (22, 23). It is supposed that micron-sized plastics break down into nanosized plastic particles in the body and then enter the brain to exert their effects. It has also been suggested that the impact of MPs on the brain may be mediated through their effects on peripheral tissues, including the modulation of immune inflammation and glycolipid metabolism (24–27). What is the mode of MPs affecting the brain and the mechanisms that they exert their effects remain uncertain.
The development and innovative application of previously unknown research techniques often open new avenues, providing researchers with fresh perspectives and facilitating a deeper understanding of scientific principles. In this study, we applied miniature two-photon microscopy (mTPM) and imaged MPs in the mouse brain in vivo while the animal was awake. With the high-depth imaging capability, we observed MPs in the blood vessels of the mouse cerebral cortex. We tracked the high-speed movement of MP particles in the blood vessels, revealing a mechanism by which MPs can induce brain dysfunction and neurological impairment.
