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