Synthetic tendons

Athletes with Achilles heel injuries could be treated in the future with bioresorbable synthetic tendons. The technology is the planned result of research being conducted by Manchester University and regenerative medicine company Neotherix.

The group hopes to develop process control techniques for the electrospinning of bioresorbable polymers that can be used to make synthetic tendons.

Sandra Downes, a materials scientist at Manchester, said that, at the moment, it is difficult to achieve consistency with the electrospinning process.

The process, she explained, involves putting a solvent in a syringe and applying a high voltage. As the polymer squeezes out of the syringe, it is caught on a collecting plate that is rotated. The rotation produces fine polymer fibres that mimic the natural collagen fibres in healthy tissue.

Downes said that the diameters of the fibres, which are on the microscopic scale, can range depending on a variety of factors, such as temperature or humidity in the room.

‘We’re making these fibres for living tendon cells to grow on so they can heal,’ she said. ‘A very small difference in a fibre’s diameter would make a huge difference to cell behaviour.’

Downes said that unless these fibres can be produced consistently over and over again, they cannot be sold as a biomedical device.

‘It could never be used in the human body because one batch of tendons would be different to another batch,’ she said. ‘We’d never get away with it. If you have an aspirin, you expect it to be the same dose as the one you had the month before.’

Downes and her colleagues are preparing to build an environmental chamber to electrospin the polymers in. They will then experiment with biodegradable polymers such as polyesters and electrospin them under different conditions.

The team will attempt to control and monitor parameters such as the molecular weights of the polymers, the velocity the polymers are squeezed out of the syringe, the distance from the syringe to the collecting plate and the speed at which the polymers are spun.

The resulting fibres will then be analysed using microscopic techniques such as scanning electron microscopy to examine and quantify the consistency. According to Downes, when successful process control techniques are developed, York-based Neotherix will use them to develop synthetic tendons for the medical device market.

‘At the moment, there is no synthetically biodegradable medical device tendon available,’ she said. ‘Surgeons either suture a damaged tendon together, and that can end up as scar tissue, or sometimes surgeons will remove a healthy tendon from one part of the body and put that in the damaged area.

‘Surgeons have told us it would be fantastic to have a medical device they could just pick up off the shelf, take out of its wrapper and use on the patient in the trauma clinic,’ added Downes.

She is currently looking for a PhD student to help in her research for the next three-and-a-half years. Downes hopes that process control techniques can be developed and used on a commercial level.

Siobhan Wagner