Microplastic Exposure: Time-Dependent Effects on Oxidative Stress, Apoptosis, and Cellular Internalization in Fibroblast Cells

Microplastics (MPs) are emerging environmental contaminants regarding their potential hazards to human health. Polyethylene terephthalate (PET) is a commonly used plastic in many products that cause public health concerns, and the impact of these plastics on skin is still mainly unknown. The study intends to prove the toxicological profile of PET MPs in fibroblast cells depending on exposure duration in terms of oxidative damage, lipid accumulation, apoptosis and their potential to interact with cells. PET MPs demonstrated cytotoxic effects, with 48-h exposure resulting in considerably greater toxicity compared to 24-h exposure by water-soluble tetrazolium salt (WST-1) and lactate dehydrogenase (LDH) assays. Depending on the concentration and time, the percentage of living cells decreased, while early apoptosis predominated at 24-h exposure, late apoptosis, and necrosis rates increased significantly at 48-h. A dose-dependent reactive oxygen species (ROS) formation was higher at 48-h exposure duration, and malondialdehyde (MDA) levels were significantly increased. The lipid droplets were significantly higher during the 48-h exposure, which indicates the accumulation of lipids. Time-dependent internalization of PET MPs was observed with increasing red fluorescence intensity. As a conclusion, PET MPs are relevant to potential health risks, emphasizing the need for further toxicological evaluation, especially for a longer time before their biomedical or environmental use.