The impact of clay particles on lung cells: An analysis at the single-cell level

Date

2021-08

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Abstract

Dust particles make up to 40% of the aerosols in the atmosphere. Exposure to large concentrations of dust particles (e.g., clay minerals) during dust storms represents a health concern. Coarse dust particles (diameter between 10 and 2.5 µm) cause coughing, sneezing, eye and nose irritation. Fine dust particles (diameter ≤ 2.5 µm) penetrate deeper into the lungs, reach the alveoli and expose epithelial and macrophage cells to toxic minerals, causing inflammation, cell death, and, consequently, acute and chronic respiratory and cardiopulmonary diseases. During dust storms, the demand for hospitalization due to asthma, respiratory complications, and cardiovascular emergencies increases.

This project examined the impact of different clay minerals on alveolar epithelial A549 and macrophages RAW 264.7 cells at the single-cell level by continuously monitoring cells individually for 48 hours.

Cell viability and exact time of death were calculated for different clay compositions, particle sizes (Ground and Unground), and concentrations (control, 25, 50, 100, 250, and 500 µg mL-1). The clay minerals Na-rich Montmorillonite and Illite were found to be the most toxic type, while Kaolinite was the least toxic one. Ground samples, which had more smaller particles, were found to be more toxic than Unground samples, which had fewer small particles. Analysis of the exact time of death revealed that cell death varies on time depending on clay composition and concentration.

The effect of Na-rich Montmorillonite on RAW 264.7 macrophages was quantified, and results showed that this cell line was more sensitive to clay minerals than the A549 cells. Three experiments were performed, obtaining images at different time intervals (15, 30 and 60 minutes) to evaluate the impact of the microscope fluorescent light on the cells, but it was found that varying time intervals between images did not affect cell’s death.

Finally, the effect of co-cultured A549 with RAW 264.7 cells which were exposed to Na-rich Montmorillonite particles, was tested. Without exposure to particles, mono-cultured A549 cells showed higher death percentages than co-cultured A549 cells. When the cells were exposed to 10 or 500 µg mL-1, co-culture experiments showed a higher death rate than mono-cultured experiments.


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Keywords

Single-Cell, Cell Death, Dust Storm Particles, Clay Particles

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