Micro- and nanoplastics are elevated in femoral atherosclerotic plaques compared with undiseased arteries.

OBJECTIVE: As plastic production continues to accelerate, the byproducts increasingly fill the environment. Once degraded into micronanoplastics (MNPs), particles may circulate into food, drinking water, or air. Nascent literature has demonstrated MNP bioaccumulation within human tissues, such as the blood, brain, and solid organs. Only recently have MNPs been identified within thrombi and atherosclerotic plaques of diseased blood vessels, and these findings have been associated with adverse clinical outcomes. Data on MNP content in infrainguinal arterial occlusive disease is currently lacking, however. We investigated MNP presence within femoral artery plaques and examined patient clinical variables to characterize their associations in a territory commonly affected by peripheral arterial disease.

METHODS: Common femoral artery plaques were collected from patients undergoing common femoral endarterectomy for medically refractory lower extremity peripheral arterial disease. These samples were then sectioned, frozen, and analyzed using pyrolysis gas chromatography/mass spectrometry for MNP content by polymer. A total of 12 polymers were investigated in triplicate. A group of decedent patients without clinical atherosclerosis served as control with whole carotid artery tissue used for a similar analysis.

RESULTS: A total of 10 plaques from 8 patients were collected for the plaque group, and 30 whole carotids were gathered from decedents and age matched to the plaque group. The total MNP concentration was 80-fold higher in femoral plaque compared with the control group 3234 μg/g tissue vs 40.68 μg/g tissue for control arteries (P = .0001). By polymer, polyethylene, polystyrene, acrylonitrile butadiene styrene, styrene-butadiene, polyvinylchloride, polyethylene terephthalate, poly(methyl methacrylate), polycarbonate, nylon 66, and nylon 6 were all significantly elevated compared with control tissue. No differences in sex were detected in either group. Polypropylene content was positively correlated with age (P = .011). Within the plaque group, patients undergoing revascularization for chronic limb-threatening ischemia had a greater than three-fold concentration of PP (247 ± 113.6 μg/g vs 71.9 ± 73.5 μg/g) and 10-fold concentration of polyurethane (17.4 ± 12.1 μg/g vs 1.69 ± 2.9 μg/g) compared with those with claudication (P = .0381 and P = .0238, respectively).

CONCLUSIONS: This study demonstrates a greater accumulation of MNPs in common femoral artery plaques compared with nonatherosclerotic artery tissue. This finding further supports the premise that, despite similarities in age between groups, MNPs tend to be represented heavily in atherosclerotic tissues. Patients with chronic limb-threatening ischemia showed a greater concentration of some polymers compared with those with claudication, raising the question of differential disease severity associations with different individual polymers.

CLINICAL RELEVANCE: This work demonstrates high levels of micronanoplastics (MNPs) in human femoral artery atherosclerotic plaques as compared with healthy, nondiseased human carotid arteries. No clear associations between age and MNP levels were demonstrated amongst limb ischemia or control patients. Some individual polymers are associated with advanced atherosclerotic disease (chronic limb-threatening ischemia) compared with claudication. These data add to the growing literature suggesting that MNP particles accumulate in atherosclerotic lesions. Future work should investigate what mechanistic role, if any, MNPs may play in the pathophysiology of vascular atherosclerotic disease.