Circulating Microplastics in Acute Ischemic Stroke: Feasibility, Variability, and Exploratory Comparisons with...

Microplastics (MPs) have been detected in human tissues and implicated in vascular injury in preclinical models, but evidence on circulating MPs in humans is scarce. Surgical and autopsy samples have provided most data to date but are unsuitable for large-scale biomonitoring to clarify potential cardiovascular relevance.

We conducted a prospective pilot study applying a contamination-controlled, plastic-free protocol to quantify MPs in whole blood. Thirty-five participants were enrolled: 20 with ischemic stroke and 15 healthy controls. Samples were analyzed by micro-Fourier transform infrared spectroscopy to determine particle counts, polymer types, and size distributions. To contextualize findings, we performed an exploratory pooled comparison with a reference of healthy individuals derived from two published datasets using weighted combination of reported means and standard deviations.

Overall, MPs were detected in 94% of participants (median 11.0 MPs/mL; IQR 4-22; mean ± SD, 12.6 ± 9.7; range 0-35). Within this pilot cohort, median MP counts were numerically higher in stroke (13.5 MPs/mL [IQR 6-23]) than in healthy controls (7.0 MPs/mL [IQR 2-18]), but group differences were not statistically significant in direct, within-study comparisons (p = 0.21, Mann-Whitney U). In an exploratory analysis, stroke patients exhibited significantly higher mean MP concentrations than a pooled healthy reference derived from external datasets (13.95 ± 8.73 vs 5.11 ± 7.31 MPs/mL; Welch's t = 3.69, p = 0.0016). Polyethylene, polypropylene, and polyethylene terephthalate were the most abundant polymers, and smaller particles (20-100 µm) predominated. MP burden showed no consistent association with age, sex, or vascular risk factors.

This proof-of-concept study demonstrates the feasibility of blood-based MP quantification under clinical conditions and provides a preliminary, hypothesis-generating observation that circulating MP levels may be elevated in acute ischemic stroke. Because the apparent difference relied on an exploratory pooled comparison across heterogeneous datasets, confirmation in larger, harmonized studies is essential before any inference about disease-specific elevation or clinical relevance is justified.