Microplastics can block blood vessels in mice brains, researchers find | Plastics

Microplastics can move through mice brains and block blood vessels, essentially mimicking blood clots that could potentially be fatal or otherwise disrupt brain function.

The findings are detailed in a peer-reviewed paper for which researchers for the first time used real-time imaging to track bits of plastic as they moved through and accumulated in brain blood vessels. When one piece of plastic got stuck, others accumulated behind it, like a “car crash”, the authors reported.

The authors then found decreased motor function in those mice exposed to microplastics, suggesting impacts on the brain. While mounting evidence has linked microplastics to neurotoxicity, the research is the first to suggest how – it probably reduces blood flow.

“This revelation offers a lens through which to comprehend the toxicological implications of microplastics that invade the bloodstream,” the Peking University authors wrote.

Microplastics are tiny bits of plastic either intentionally added to consumer goods, or which are products of larger plastics breaking down. The particles contain any number of 20,000 plastic chemicals, of which thousands, such as BPA, phthalates and Pfas, present serious health risks.

The substance has been found throughout the human body, and can cross the placental and brain barriers. Recent research found microplastics to be accumulating in human brains at much higher levels than eight years ago. The substance is linked to an increased risk of heart attack and cancer, and is considered to be a neurotoxicant that can cause multiple forms of brain dysfunction, such as Parkinson’s disease.

Until now, very little has been understood about how the bits of plastic move through brains, and why they might cause some disease and neurotoxicity.

To track the plastic in the mice brains in real time, researchers gave them water filled with fluorescent-coated polystyrene, a common material found in household goods and packaging. Using an imaging technique called two-photon microscopy, they were able to watch how, within just a few hours, the fluorescent bits began appearing in the brain.

Researchers suspect that immune cells had, in effect, absorbed the bits of plastic, creating irregular-shaped cells. As the cells traveled the tiny brain cortex vessels where there are generally more and tighter bends, they sometimes became lodged. Larger bits of plastic were more prone to getting stuck.

When cells did get lodged, more cells would pile on, mimicking the effect of cars in a pile-up accident. The blockages reduced blood flow and sometimes broke up after a few days or weeks, but some persisted beyond the closure of the study’s four-week observation period.

In behavioral assessments following exposure to microplastic, the exposed mice traveled slower and shorter distances than those who were not exposed, and performed poorly on a maze test that gauges memory function.

However, the authors stressed that it was unclear if the same effects would happen in a human brain because the vessels are not quite as small as those in mice, and blood volume and flow rate are greater. Still, it strongly pointed to serious cardiovascular and brain health risks, and “increased investment in this area of research is urgent and essential to fully comprehend the health risks posed by microplastics in human blood”, the authors wrote.