Advancing safer treatments in women’s pelvic health
Stress urinary incontinence affects up to one in three women worldwide, but the most commonly used treatment has led to serious problems for many patients. Researchers at Sheffield have created a new medical device that could be a safer option, offering hope to those living with the condition.
Stress urinary incontinence (SUI) is a condition where everyday movements, like coughing, sneezing, or running, place pressure on the bladder and cause urine to leak unexpectedly. It affects up to 30 per cent of women globally and can significantly reduce quality of life, leading to physical discomfort as well as emotional and social distress.
Until relatively recently, the standard surgical treatment for SUI has involved inserting a polypropylene mesh (PPM) sling beneath the urethra. This material, which is traditionally used in abdominal hernia repair, was adapted to support the urethra and relieve the symptoms of SUI.
But, for many women, the results of this procedure have been far from ideal. A proportion of patients experienced pain, persistent inflammation, and erosion of the mesh into surrounding tissues. When these complications arise, even simple daily activities can become difficult. In response, regulators in several countries, including the UK, banned the use of PPM for the treatment of SUI and over 100 women in England with complications from the implants were given pay-outs as part of a group settlement. However, a key question remained: why does a material that performs well in abdominal hernia repair fail in the pelvic floor?
Developing a safer material to treat women suffering with SUI
Professor Sheila MacNeil, from the University’s School of Chemical, Materials and Biological Engineering, is an expert in the engineering of soft tissues such as skin, oral mucosa, urethra and cornea. Her work focuses on translating scientific research into treatments that deliver real benefits for patients.
Over the past decade, Professor MacNeil has worked closely with NHS urologist Professor Chris Chapple to develop safer materials that offer enhanced support for weakened pelvic floor tissues. Driven by a shared commitment to improving patient outcomes, the research grew from a collaboration between NHS urologists and scientists at the University of Sheffield, with Professors MacNeil and Chapple leading a multidisciplinary team to investigate why PPM - the material at the centre of the vaginal mesh controversy - behaves differently in the pelvic floor and to develop a safer and more effective alternative.
After reviewing the existing evidence on the use of PPM in the pelvic floor, Professors MacNeil and Chapple co-created a new device made from an FDA-approved polyurethane material. This material closely replicates the structure and flexibility of human connective tissue, remaining soft, dynamic, and elastic once implanted. Unlike polypropylene, the polyurethane material stretches and rebounds more naturally and causes only a short-lived, mild immune response instead of ongoing inflammation.
“Our research is all about developing a better material to treat the problem of stress urinary incontinence in women. The PPM material, originally used for hernia repair in men, was adapted for treating stress urinary incontinence in women. Initially, it seemed suitable, but it performed very differently in the pelvic floor. The material was too strong and rigid, causing excessive inflammation in some patients. This led to a high reoperation rate, and the mesh is actually very difficult to take out" explains Professor MacNeil.
“A few years ago, my colleague, Professor Chris Chapple, gathered a group of surgeons, urologists, urogynaecologists, and gynaecologists together to reach a consensus: the type of operation that we're doing is probably the right one, but the material isn't up to it. We then thought we needed to design something that's closer to the patient’s own pelvic floor tissue - and that’s exactly what we did. We made it out of a material that would be stretchy and bounce back, but still hold some resilience”.
“We obtained funding from the British Urology Foundation, which supported research fellowships for young urologists in training, and an EU grant was awarded to Professor Chapple. This funding enabled the doctoral research of Sabi Roman, who developed a lot of the key research” explains Professor MacNeil.
Once the material was developed, the team tested the new polyurethane device in the lab by subjecting it to repeated stretching, comparing its performance with existing polypropylene meshes under the same conditions. While the polypropylene fibres were strong, they proved relatively brittle, and after a few days they stretched permanently without bouncing back. However, the polyurethane fibres handled the repeated stretching very well, with no loss of strength or elasticity.
Testing the safety and performance of the polyurethane material
To further compare the performance of traditional polypropylene meshes with the more patient-friendly, distensible polyurethane material, the Sheffield-led team implanted both materials into a sheep model using the same surgical techniques that would be used in a patient. Sheep were chosen because their pelvic anatomy closely resembles that of humans. Their study, published in the journal Biomaterials (A Critical Comparison of Polypropylene and Polyurethane Sling Materials After Implantation in a Suburethral Sheep Model), was the first to show clear evidence of surface damage to PPM after three months under the urethra, while the polyurethane device showed no such damage.
“To assess how the material would be tolerated by the immune system, we used a number of accredited preclinical tests in rats for seven days, rabbits for 90 days and sheep for six months - looking at adjacent tissue responses and immune cell activity around the implants. Polypropylene consistently caused persistent inflammation, whereas the polyurethane device triggered only a mild immune response that resolved within a few weeks” explains Professor MacNeil.
What interests me the most about this project is that when one goes looking for problems you find them - and applying new surface detection techniques to look at what happens really paid dividends.
Professor Sheila MacNeil
Emeritus Professor of Tissue Engineering at the University of Sheffield
Bringing the new technology to market
Confident in the safety and performance of their polyurethane device, Professors MacNeil and Chapple began working with the University of Sheffield’s Commercialisation team to explore routes for taking their innovation to market.
“The University’s Commercialisation team gave us access to some seed funding and were incredibly supportive, especially when we needed the resources to take the next step in our research. This included a collaboration with the Advanced Manufacturing Research Centre (AMRC) on the detailed design of the device and the associated surgical tools. It also allowed us to collaborate with The Electrospinning Company on the industrial manufacturing of the devices” explains Professor MacNeil.
“The University’s commercialisation funding helped us get to a point at which we were able to work with Venture Builder NLC Health Ventures to found Audaxis Medical” adds Professor MacNeil.
NLC Health Ventures is a Netherlands-based organisation that identifies promising healthcare technologies, builds start-ups around them, and helps scale them through global partnerships. NCL has supported Audaxis Medical by appointing a CEO and helping them to build a team.
Marta Scali, Senior Venture Development Associate at NLC, said: “Even at the very beginning, I had a feeling that the team’s work had real value. Their strong combination of clinical and scientific expertise, the approach they were taking, and their deep understanding of the problem all stood out. They were, and still are, very humble and critical about their own work. They aren’t focused on ‘selling it’, but more on highlighting its strengths and acknowledging what still needs to be done. Meeting them in person in Sheffield was a great experience. Different levels of expertise and cultures all coming together to create something that could help many patients in the future. Knowing that I was part of this is really special”.
Moving forward
Audaxis Medical is currently preparing FDA documentation seeking approval for a first-in-woman study with the PU device. The next step will be to gain regulatory clearance for a small clinical trial using the new, softer, and more resilient material.
“We are all very much aware that translating research from the laboratory to the clinic in a way which is transparent and well-regulated is a challenge - but it's one we are all very committed to undertake” adds Professor MacNeil.
Written by Anna Blagg (Marketing and Communications Officer, Research)
For further information please contact: mediateam@sheffield.ac.uk.