In vitro exposure of nasal epithelial cells to particulate matter

Air pollution is a mixture of many types of materials and chemicals that comes in a variety of sizes. Particulate matter (PM) is an air pollution term for a heterogeneous mixture of gases, liquid and solid particles of different origins and sizes in suspension in the air, keeping close physical and chemical interaction. PM is classified as coarse (2.5–10 μm aerodynamic diameter, PM10), fine (0.1–2.5 μm aerodynamic diameter, PM2.5), and ultrafine (≤0.1 μm aerodynamic diameter). Large epidemiological studies in the USA and Europe suggested that air pollution, and especially fine particulate PM, may increase the risk of cancer and other chronic respiratory diseases. A convincing body of evidence has been accumulated on adverse effects of fine PM, but the specific sources, constituents and mechanisms responsible for these effects have not been determined.

The nasal epithelium is a valuable ‘sentinel’ for the human exposure to environmental air. Being the ‘window to the respiratory system’, the nasal epithelium absorbs airborne pollutants which may injure the nasal mucosa. Moreover, fine particles that deposit on the nasal epithelium are subjected to surface forces which may push them through the different tissue compartments till they reach the nasal vasculature, and then translocated by the circulation to other organs. Cultured nasal epithelial cells provide an in vitro model that allows for controlled experiments in order to study their response to a variety of pollutants without dealing with ethical issues, including the use of animals. Analyses of the immediate biological damage, along with the structural and functional response to pollutants exposure, will provide in depth understanding of the process and might enable exploring biomarkers, sensitive to early detection of malignant developments.