Abstract Body: Introduction: Plastics production has accelerated globally, with most terminating in the environment. Plastics degrade over time into micro (<5mm) and nano (<1000nm) plastic particles (MNP) that are ingested. MNPs are implicated in atherosclerosis but mechanisms remain obscure. Studies have shown MNPs in dissected ascending aortas, but data on abdominal aortic aneurysm and occlusive plaques has not been reported.
Hypothesis: Aortoiliac occlusive plaques and aortic aneurysm walls contain more MNPs than healthy control.
Methods: MNP content from aortic aneurysm and aortic occlusive plaques was measured in triplicate using pyrolysis-gas chromatography/mass spectroscopy including polyethylene (PE), polypropylene (PP), polystyrene, acrylonitrile butadiene styrene (ABS), styrene-butadiene (SBR), poly(methyl methacrylate), polycarbonate, polyvinylchloride (PVC), polyurethane (PU), polyethylene terephthalate, nylon 6, and nylon 66. Healthy fresh cadaveric abdominal aortic wall was used for comparison. Scanning Electron Microscopy (SEM)/Energy Dispersive X-ray (EDX) visualized MNPs directly. Fourier Transform Infrared (FTIR) confirmed composition.
Results: Nine aneurysm walls (n=9 male, mean age of 71 years), 6 occlusive plaques (n=4 male, mean age 67 years), and 12 undiseased aortas (n=4 male, mean age 35 years) were collected. In control aortas, the most prevalent polymers were PE (33.7 μg/g tissue), PP (23.3 μg/g) and PVC (33.5 μg/g). For aneurysms, the most prevalent polymers were PE (129 μg/g), SBR (127.4 μg/g), and PVC (72.1 μg/g). For plaques, most prevalent polymers were PE (1118.3 μg/g), PVC (47.5 μg/g), and SBR (40.3 μg/g). Total MNP concentration was not different between undiseased aortas, aneurysmal walls, or plaques (165 μg/g, 480.5 μg/g, and 1003 μg/g, respectively, p =0.4) but PE was 33-fold greater in plaque than undiseased aorta (33.7 μg/g vs. 1118 μg/g, p = 0.0099). SEM/EDX demonstrated shard-like MNPs surrounded by crystalline structures high in calcium and phosphorus, suggesting MNPs in plaque calcifications. FTIR showed MNP fragments also contained polyacrylamide and polyacetylene.
Conclusion: Aortic atherosclerotic occlusive disease is associated with elevated PE concentrations while aneurysm disease is associated with trends toward elevations in several polymers. Nanoplastics densely associate with vessel calcifications. Further study is needed to better define the role MNPs play in atherosclerosis or aneurysm pathophysiology.