New test regime for biomaterial safety

Scientists at Sheffield University have developed a new process for testing biomaterials which could flag threats to human health.

The work was inspired by the vaginal mesh scandal, where thousands of women suffered medical complications following polypropylene mesh surgery. Developed by researchers at Sheffield’s Department of Materials Science and Engineering, the new oxidative stress test acts as an early-warning system to identify biomaterials that are not suitable for clinical use inside the human body. The work is published in RSC Advances.

Compared to current methods, the new approach is claimed to be better at simulating deployment environments and identify cracks and surface degradation in biomaterials. The test subjects biomaterials to oxidation and mechanical stresses, mimicking those experienced inside a patient, and can give scientists a better understanding of how materials will perform over time in clinical use.

The Sheffield team developed their procedure by evaluating a type of surgical mesh made of polypropylene (PP mesh), which has been used to treat pelvic organ prolapse and stress urinary incontinence, a condition that affects 50 per cent of postmenopausal women. The use of PP mesh has caused life-changing complications in thousands of women and led to medical negligence lawsuits.

“The process starts with subjecting the material to conditions which mimic the natural processes of oxidation and mechanical stress experienced within the human body,” said Dr Nicholas Farr, EPSRC Doctoral Research Fellow at Sheffield University. “This is followed by analysis using novel material characterisation techniques to evaluate the nanoscale surface of the material.

“It is envisioned that the process outlined has the potential to form the basis of an ‘early warning’ analysis system which possesses the ability to identify materials which are not suitable for clinical deployment within the human body.

“My hope is that this research can not only aid the development of new implantable materials but also help to update the regulatory standards which govern medical device production.”

According to the University, manufacturers assert that PP material is inert and non-degradable, but an increasing body of evidence reveals PP meshes are subject to oxidative damage, which is supported by explanted material from patients suffering with clinical complications showing evidence of fibre cracking and oxidation.

The researchers found that the stress loaded onto the PP mesh while inside the body is likely to have caused polymer oxidation and chemical reactions in the materials - this oxidation and these reactions are likely to have changed the material’s molecular structure, causing the material to crack and the release of etched oxidised insoluble particles initiating an inflammatory response in the body.