Microplastics in the body are passed on during cell division

The gastrointestinal tract is already recognised as a major storage site for micro- and nanoplastic particles (MNPs) in the human body. Now, a study of cancer cells in the gastrointestinal tract has found that MNPs remain in the cell for much longer than previously assumed, as they are passed on to the newly formed cell during cell division. The work has been published in the journal Chemospheres.

Besides respiration, ingestion is the most important route for MNPs into the organism, with plastic particles up to the weight of a credit card entering the gastrointestinal tract every week. A research consortium consisting of the University of Vienna, the Medical University of Vienna and other partners under the leadership of CBmed investigated the interactions between MNPs and various colon cancer cells. They were not only able to show how MNPs enter the cell and where exactly they are deposited, but also to observe their direct effects: the MNPs are taken up into lysosomes like other ‘waste products’ in the body.

Lysosomes are cell organelles that are also known as the ‘stomach of the cell’ and break down foreign bodies in the cell. However, the researchers observed that, unlike foreign bodies of biological origin, the MNPs are not degraded due to their foreign chemical composition. Depending on various factors, the MNPs are even passed on to the newly formed cell during cell division and are therefore likely to be more persistent in the human body than originally assumed.

In addition, there are initial indications that MNPs increase the migration of cancer cells to other regions of the body and thus possibly promote the metastasis of tumours. This effect is now to be investigated further in a follow-up study.

The altered behaviour of colorectal cancer cells in relation to cell migration was primarily observed as a result of interaction with plastic particles that are smaller than 1 µm. Particles of this size are usually referred to as nanoplastics, which occur 10 to 100 times more frequently than microplastics in a water bottle, for example. It is understood that the smaller the plastic particles are, the more harmful they are.

The latest results and earlier studies show a high uptake and long retention of MNPs in tissues and cells, thus fulfilling two of three characteristics in toxicology that are used to classify substances as being of concern under the EU Chemicals Regulation (REACH). The new study also confirms recent findings that MNPs can influence cell behaviour and possibly contribute to the progression of diseases, according to research team co-leader Lukas Kenner.

“Given the ubiquity of plastics in the environment and the persistent exposure of even humans to the smallest plastic particles, further studies are urgently needed to investigate long-term effects in particular,” said Kenner, from the Medical University of Vienna, CBmed and Vetmeduni Vienna.

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