Fern inspires new stent

The innovation described as a ‘flow-diverting intracranial stent’ is being developed by Dr Zhong You, an expert on motion structures from Oxford University’s department of engineering science, and colleagues in the field of neurosurgery.

When inserted at the site of the aneurysm in the brain, the stent is designed to unfurl. Its structure consists of tiny fern-like metal leaves that allow blood to pass through.

Project manager Brijesh Roy, who is helping commercialise the device through Oxford’s spin-out company Isis Innovation, explained that existing aneurysm treatments involve either open-brain surgery to clip the aneurysm or insertion of a metal wire coil to fill the aneurysm cavity.

While these treatments prevent and stem bleeding, Roy said they also cause blood clots to form. These clips and coils prevent blood clots from escaping and breaking down and being reabsorbed, he said. This means, the blood clots maintain constant pressure on the surrounding brain area.

Roy said, ‘The small gaps in our device allow clots to be slowly, slowly broken down and reabsorbed.’

The Oxford team believe this stent could be inserted into the brain using the same minimally invasive techniques used for endovascular coiling.  Roy explained this method involves inserting a small plastic tube into the femoral artery–located near the groin–and steering it through the vascular system, to the patient’s head and then site of the aneurysm. He added that a stent is used at the neck of the aneurysm to keep the coil in place during treatment.

Roy said the idea to use only a stent itself as a treatment is a relatively new idea and the Oxford researchers are one of few in the world trying to commercially develop it.

Most of their work is almot done, he said. The team has decided on a design for the device and its material, which is made of a popular biocompatible material known as nitinol, which is a metal alloy of nickel and titanium.

Roy said the team have also developed a manufacturing process using high precision laser cutting tools.

The remain challenges is developing a method for opening up the stent once it reaches the aneurysm site because in a minimally invasive procedure it would be navigated through the body in a folded state, he said. However there are already some options currently being used in the surgical field that could be applied. 

The Oxford team hope to begin animal trials next year and shortly follow that with clinical trials.

Roy said these stents could potentially be widely used for brain aneurysm treatments in five years time following successful trials on patients.