Researchers at ETH Zurich have developed a cellulose membrane to cover and protect implantable devices, such as pacemakers. The material can reduce fibrotic build up and make subsequent surgical removal of implants much easier. So far, the pouch-like device has been tested successfully in pigs, and the researchers hope to apply for clinical trials in conjunction with an ETH spin-off company called Hylomorph, with the eventual goal of commercializing the technology.
The foreign body response is a significant issue for a variety of implantable medical devices. Pervasive immune attack leads to fibrosis and the development of a fibrotic capsule that can restrict device function and longevity. A variety of coatings and drug treatments have been tested to reduce or mitigate the foreign body response to implantable devices, so far with mixed or limited success.
This latest technology is intended to protect cardiac pacemakers from the growth of fibrotic tissue. Fibrosis is a serious issue for pacemakers, which are intended for long-term implantation. “Every pacemaker has to be replaced at some point. When this time comes, typically after about five years when the device’s battery expires, the patient has to undergo surgery,” said Aldo Ferrari, a researcher involved in the study. “If too much fibrotic tissue has formed around the pacemaker, it complicates the procedure.”
Surgeons often need to cut the excess fibrotic tissue away, increasing the chance of complications during and after surgery. Consequently, there is a need to develop new strategies to reduce the build-up of a fibrotic capsule around pacemakers.
To address this, these researchers have developed a cellulose membrane that can cover pacemakers, and which significantly reduces fibrosis. Ironically, the fibrous nature of the membrane is a factor in its inhibition of fibrosis. “When fibrotic tissue forms, the first stage is the deposition of proteins on the surface. A fibrous membrane surface impedes this process,” explained Francesco Robotti, another researcher involved in the study.
The membrane was also designed to contain numerous honeycomb-like surface indentations. “These indentations make it difficult for the cells that form fibrotic tissue to adhere to the surface – the second stage in the formation processes,” added Robotti.
To test the membrane, the researchers implanted membrane-coated pacemakers in pigs and left them in situ for up to a year. They found that the membranes were well-tolerated and that the fibrotic layer that formed on the membrane was only one third as thick as that on uncovered pacemakers. Based on these promising results, the researchers are planning to conduct a clinical trial at three large cardiac centers in Germany.
Study in journal Biomaterials: Microengineered biosynthesized cellulose as anti-fibrotic in vivo protection for cardiac implantable electronic devices
Via: ETH Zurich