New research reveals that microplastics are influencing our cellular processes

The study, conducted as part of a PhD project and recognised with the Postgraduate Best Poster Prize, examined how polystyrene microplastics influence human cell behaviour. 

The findings demonstrate that exposure to microplastics can alter cellular morphology, reduce proliferation, increase apoptosis, and impair migration, raising important questions about their potential impact on human health.

The research was highlighted at the Minoritised Life Scientists Future Forum (MLSFF26) at Edinburgh International Conference Centre from March 23 to 25. MLSFF26 is the only major conference in Europe dedicated to supporting and showcasing the contributions of marginalised and underrepresented communities in the life sciences.  

Widespread contaminants

“Microplastics have become widespread environmental contaminants, detected in a wide range of sources, including food, drinking water, air, textiles, and personal care products. Increasingly, they have also been identified in human biological samples, such as blood, urine, faeces, and breast milk. Human exposure occurs primarily through ingestion, inhalation, and dermal contact, making microplastics an unavoidable part of modern life,” said Medah.

“Despite growing awareness of their environmental presence, there remains a significant gap in understanding their biological effects on humans. While numerous studies have focused on marine organisms, relatively little is known about how microplastics interact with human cells, particularly at the cellular and molecular levels. 

“This research was therefore designed to investigate whether polystyrene microplastics, a commonly used polymer in consumer products, can influence cell behaviour, viability, and stress responses in human cell models.”

In vitro model

To investigate these effects, human embryonic kidney (HEK-293) cells were used as an in vitro model system. This cell line is widely used in biomedical research due to its well-characterised properties and relevance to kidney function, particularly in relation to filtration and exposure to circulating substances.

Cells were exposed to 1 µm polystyrene microplastics at concentrations ranging from 2.5 to 200 µg/mL over 24- and 48-hour periods. A range of assays was then conducted to assess key cellular parameters, including proliferation, cytotoxicity, apoptosis, morphology, and migration. Cell migration was evaluated using wound-healing assays, providing insight into the potential effects on cellular repair mechanisms.

To enhance the translational relevance of the study, similar experiments were also conducted in additional human cell lines representing major exposure routes and physiological systems. These included Caco-2 intestinal epithelial cells (ingestion), HepG2 liver cells (metabolism), and BEAS-2B bronchial epithelial cells (inhalation). This multi-model approach allowed for comparison across tissues and provided a more comprehensive assessment of microplastic effects on human biology.

Significant effects

The results revealed consistent and significant effects across all cell models tested. In HEK-293 cells, exposure to polystyrene microplastics resulted in marked alterations in cell morphology, reduced proliferation, and increased apoptosis. Notably, these effects were dose- and time-dependent, becoming more pronounced at higher concentrations and longer exposure durations.

Cell migration was also significantly impaired, as demonstrated by reduced wound closure in exposed cells. This finding suggests that microplastics may disrupt cellular repair processes, which are essential for maintaining tissue integrity following injury or stress.

Importantly, exposure to microplastics induced oxidative stress in all cell lines examined. Oxidative stress arises from an imbalance between reactive oxygen species and antioxidant defences and is known to damage key cellular components, including DNA, proteins, and lipids. This process is strongly associated with inflammation, cellular dysfunction, and the development of various diseases.

Similar patterns of reduced proliferation, increased apoptosis, impaired migration, and oxidative stress were observed in intestinal, liver, and lung cell models, indicating that the effects of microplastics may not be restricted to a single tissue type but could have broader systemic implications.

Progression of effects

“One of the most notable aspects of the study was the clarity and consistency of the dose- and time-dependent responses across all cell models. The progression of cellular effects, from subtle morphological changes at lower concentrations to more pronounced functional impairments at higher doses, was particularly striking,” Medah said.

“These observations emphasise that microplastics are not biologically inert particles; rather, they can actively influence cellular processes in measurable ways. The reproducibility of these effects across different human cell lines further supports the potential significance of the findings.”

The findings of this study contribute to a growing body of evidence suggesting that microplastics may represent an emerging public health concern. Given the widespread and continuous nature of human exposure, the ability of microplastics to disrupt normal cellular function raises important questions about their long-term effects.

The induction of oxidative stress, combined with impairments in cell proliferation and migration, suggests that microplastics could interfere with key biological processes, including tissue repair, immune responses, and cellular homeostasis. Although in vitro findings cannot be directly extrapolated to whole-organism outcomes, they provide essential mechanistic insights that inform risk assessment and guide future research.

Need for deeper understanding

“These results demonstrate the need for a deeper understanding of how environmental contaminants interact with human biology and highlight the importance of considering microplastics within the broader context of environmental health and disease prevention,” Medah said.

“Future work will focus on clarifying the molecular mechanisms underlying the observed cellular effects. This includes investigating gene expression changes, proteomic alterations, and signalling pathways associated with oxidative stress and cellular damage responses.

“Further studies will also explore the effects of long-term and repeated exposure, which may more closely reflect real-world conditions. Expanding comparative analyses across multiple tissue types will be essential to determine whether certain organs are more susceptible to microplastic-induced damage.

“Ultimately, this research aims to contribute to the development of evidence-based strategies for assessing and mitigating the potential health risks associated with microplastics.”

Project background

This research was conducted as part of a PhD project under the supervision of Dr Samireh Jorfi and Dr Erini Meimaridou, whose support and guidance were imperative to the study’s design, execution, and interpretation.

“Winning the Postgraduate Best Poster Prize was a very proud moment for me. It was encouraging to see my work recognised, especially within a forum that celebrates and supports minoritised and underrepresented scientists in the life sciences.

“The award strengthened my confidence in presenting my research and reinforced the importance of communicating science clearly to wider academic and professional audiences. Attending MLSFF was also a valuable opportunity to share my work with other scientists, receive thoughtful feedback, and connect with people working across different areas of life sciences.

“This experience reminded me that science is not only about generating data, but also about communicating research clearly, building connections, and contributing to discussions around emerging public health issues such as microplastics.”

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