The biological impact of nanoplastics on human health and liver disease

As part of the Hepatology Research Group
Illustration of a tree in the shape of a liver, credit: Cinemanikor, courtesy of Shutterstock
 
Using the latest analytical techniques in plastics analytics, the research team aim to be the first to quantify the burden of micro-and-nanoplastics in blood and fresh human liver tissue in order to determine their biological impact on health and liver disease.
Established in-vitro cell culture models are being used to understand the toxicity and impact of micro-and-nanoplastics on human cells and tissue. The biological effects of the pollutant are being explored by analysing exposed cells for highly sensitive endpoints including bioenergetics, oxidative stress and genotoxicity analysis. Ex vivo instrumental analysis for evidence of plastic polymers in healthy volunteers and patient liver samples are being undertaken under the collaborated group's supervision.
Plastics shown through a microscope

Plastic and the risk to human health

Microplastic and nanoplastics are abundantly present in aquatic, marine and terrestrial ecosystems and with fish and other animals ingesting them, these particles have entered the human food chain. Nanoplastics have been reported in packaged drinking water – a single plastic bottle is estimated to contain 250,000 particles – supermarket packaged meat and seafood items. Nanoplastics inhaled from polluted air also enter the gut.
Micro-and-nanoplastics have been reported in various human tissues including stools, breast milk, placenta, blood, carotid plaque, brain and liver. So far, ecotoxicological models have helped to explore the mechanism of action of micro-and-nanoplastics, with many plastics having associated chemical additives, the focus is now to determine the potential harm to humans.

Confirming the presence of nanoplastics in human tissues

Nanoplastics are small enough to cross the gut, enter the portal circulation and be transported to the liver, but because of their size (<1 µm) and physical properties, reliable identification using light, infra-red or electron microscopy is not possible. So, what then happens when they enter the liver remains unknown, but they are likely to be taken up into the hepatocytes where they may remain or be excreted in bile and returned to the gut.
Researchers are using pyrolysis gas chromatography mass spectroscopy (Py-GCMS) – a cutting-edge technology that can confirm trace amounts of plastic within human tissue – to analyse human liver tissue.

Defining the biological importance of micro and nano-plastic on live health

The research team have established proof-of-concept of nanoplastic uptake in hepatocytes, even in lower concentrations through experiments, on HepG2 cell culture model exposed to an increasing concentration (0.1 – 10 μg/ml) of commercially available polystyrene nano-plastic particles.
HepG2 cells were exposed to red fluorescently labelled 20nm nano-polystyrene particles for 24 hours, washed to remove non-internalisted nano-polystyrene particles and imaged. The results showed a concentration-dependent cytoplasmic uptake of nano-polystyrene particles in the HepG2 cells.
Using assays for oxidative stress and metabolic capacity, researchers are investigating the effects of plastic on cell function and changes in gene expression. With this, is an investigation to understand the intra-cellular localisation of nanoplastics in hepatoyctes with gold core PMMA (poly methyl methacrylate) particles using electron microscopy, and measure the precise cellular uptake of nanoplastics in HepG2 using plasma-mass spectrometry (ICP-MS).
Human liver, anatomy illustration
Precision cut liver slice model will also be used to visualise fluorescent labelled nanoplastics in different cell types.

Hepatology Research Group

The Hepatology Research Group is dedicated to improving the understanding and treatment of liver disease. It utilises state-of-the-art laboratory facilities based in the Derriford Research Facility, and the world class clinical research strengths of the Faculty of Health and University Hospitals Plymouth NHS Trust.
Working in unison with the South West Liver Unit, at University Hospitals Plymouth NHS Trust, the Group provides a full range and secondary, tertiary and community Hepatology services to the South West region, including assessment for liver transplantation, TIPS and liver cancer therapy.
Liver image edited hepatology