Microplastics are everywhere, including our arteries. And although their presence there is correlated with cardiovascular issues such as heart attacks and stroke, doctors were eager to learn more about how to manage the disease process.
To that end, a team of scientists led by the University of California, Riverside (UCR) fed microplastics to laboratory mice and discovered that these insidious particles seem to dramatically increase the accumulation of plaque known as atherosclerosis in the arteries – but curiously only in male mice, which they detailed in a new study published in the journal. International Environment.
When they analyzed the clogged arteries of these male mice, they found that the microplastics triggered changes within the cells that line the blood vessels for the worse, and led their genes to activate the accumulation of plaque lesions. That’s terrible news for anyone trying to maintain their heart health, because these ubiquitous particles seem to be sabotaging a vital organ system.
“Our study provides some of the strongest evidence yet that microplastics may directly contribute to cardiovascular disease, not just correlate with it,” said Changcheng Zhou, the study’s principal investigator and professor of biomedical sciences at the UCR School of Medicine, in a statement about the research. “Although the precise mechanism is still unknown, factors such as sex chromosomes and hormones, particularly the protective effects of estrogen, may play a role.”
For the study, the team took laboratory mice that were bred to be predisposed to develop atherosclerosis and then put them on a low-cholesterol, low-fat diet for nine weeks – along with feeding them microplastics at 10 milligrams per kilogram of body weight; The scientists came up with this ratio of microplastic because they determined that it was “at levels considered to be environmentally relevant and similar to what humans can encounter through contaminated food and water,” they said in the statement.
While on this diet, the mice maintained their lean figures, while the extra helping of microplastics did not appear to have an impact on their total cholesterol. But the scientists noticed that the aortic root of the male mice, the first section of the aorta, experienced a 63 percent increase in plaque build-up – while their brachiocephalic artery, another important vessel that supplies blood to the head and heart, saw a 624 percent build up of plaque. Female mice did not experience any significant accumulation.
In addition, the scientists carried out a genetic analysis on the aorta of these male mice and found that the microplastics seem to have activated certain genes that promote the growth of plaque lesions in the endothelial cells, which cover the inside of the blood vessels. They also exposed cultured human endothelial cells to microplastics and observed the same phenomenon.
“We found that endothelial cells were most affected by exposure to microplastics,” Zhou said in the statement. “Since endothelial cells are the first to encounter circulating microplastics, their dysfunction can initiate inflammation and plaque formation.”
Couple these findings with the fact that the mice were not obese or had high cholesterol, typical risk factors for atherosclerosis, and the scientists concluded that the chemicals in the microplastics are responsible for the plaque that increases in these important blood vessels.
Besides the importance of the findings to the scientific community, it raises some important questions for the rest of us. Microplastics are essentially everywhere; how the heck do we avoid them?
Unfortunately, there is no way to get rid of microplastics in humans at the moment. Instead, all you can really do is avoid single-use plastics, highly processed foods, not reheating food in plastic containers, and avoid bottled water.
Meanwhile, this team of researchers is already talking about next steps beyond this study.
“We would like to investigate how different types or sizes of microplastics affect vascular cells,” Zhou said. “We will also look at the molecular mechanisms behind endothelial dysfunction and explore how microplastics affect male and female arteries differently. As microplastic pollution continues to increase worldwide, understanding its impacts on human health – including heart disease – is becoming more urgent than ever.”
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