Microplastics can help promote the spread of cancer

Researchers estimate the weekly intake of plastic particles at a maximum of five grams, which is approximately the weight of a credit card. However, how the now unavoidable plastic behaves in the body is often still unknown. A Viennese research team from the University of Vienna and MedUni Vienna now reports in the journal “Chemosphere” on evidence that miniparticles can be passed on even during cell division and promote the spread of cancer.

Placed where plastic usually ends up
The focus was on the gastrointestinal tract, where swallowed plastic particles often end up. One of the central questions here is whether, for how long and in what numbers they can potentially stay there and what consequences this will have.

To do this, the scientists focused on four cell types that occur in colorectal tumors – a form of colon cancer – in humans. The team then exposed these different cell lines to plastic particles of different sizes, the paper said.

Organelles grit their teeth
Other research has already shown that very small particles with a diameter of two or one micrometer – from the latter range we speak of nanoplastics – can penetrate cells well, explains research leader Verena Pichler. As part of their research, it has now been shown that MNPs, like other waste products in the body, are taken up by small “organs” within the cells – the lysosomes.

These so-called organelles are actually responsible for breaking down foreign bodies. But the microplastic particles – the scientists used polystyrene beads – were difficult for them.

The research is still in its infancy
The fact that such small particles can implant themselves into cells so easily was “not surprising” to Pichler. The researcher comes from the field of medical drug design, where the approach of using nanoparticles to specifically deliver drugs to cells has been pursued for some time.

It is not necessarily clear why nanoplastics and nanoparticles should differ from each other here. This also applies to the fact that the two relevant research areas currently hardly communicate with each other, because the topic of ‘microplastics in human health’ has only been in development for about five years, says Pichler.

Plastic is passed into the body
Accordingly, the scientist and colleagues now describe “for the first time” that the plastic can even be passed on to newly formed cells during cell division. Due to the high absorption and long residence in the examined tissue, “the examined particles meet two of the three characteristics in toxicology classified as substances of concern under the EU chemicals regulation REACH,” says the neurochemist.

Facilitates the “free swimming” of tumor cells
In addition, the team found the first signs that plastic-contaminated tumor cells can migrate more easily into the body and therefore help form cancer outgrowths (metastases). Initial laboratory data from follow-up research support the hypothesis that the nature of the cells changes slightly.

The invading or trapped plastic particles appear to make the outer skin of the cells – the cell membrane – less sturdy. This, in turn, makes it harder for the cells to grow together and makes it easier for the tumor cells to “swim freely” in the body, Pichler explains.

Researchers: “Further research is urgently needed”
“Against the backdrop of the ubiquity of plastics in the environment and the continued exposure of people to even the smallest plastic particles, further studies are urgently needed, especially to investigate the long-term effects,” says Lukas Kenner from MedUni. According to Pichler, given the findings, “MNP can be assumed to cause chronic toxicity.”