Anti-inflammatory drug reduces foreign body reaction to medical device implants

Researchers in England may have found a way to overcome the challenge of foreign body rejection of surgical implants, such as pacemakers. Photo by falco/Pixabay
Researchers in England may have found a way to overcome the challenge of foreign body rejection of surgical implants, such as pacemakers. Photo by falco/Pixabay

March 14 (UPI) -- Treatment with a new anti-inflammatory can help people fitted with pacemakers, cochlear implants and other devices by preventing their bodies from rejecting them, a study published Monday by the Proceedings of the National Academy of Sciences found.

The study, conducted in mice, showed that instilling the anti-inflammatory, called MCC950, into the silicone coating surrounding these implants reduces the risk for the reaction, the researchers said.


The long-term performance of these implantable electronic medical devices often is adversely affected by the body's reaction to foreign bodies, they said.

"Combining these drugs with different materials and softer coatings for devices could transform the lives of individuals who need long-term implants to overcome serious disability or illness," study co-author Clare Bryant said in a press release.

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"In particular, this could make a huge difference to ... prosthetics that connect to the nervous system," said Bryant, a professor of veterinary medicine at the University of Cambridge in England.


This technology, called neuroprosthetics, exists, but has not been used widely because of the difficulties surrounding foreign object rejection, she said.

Implantable electronic medical devices are used for a number of medical conditions, from pacemakers for people with heart problems to neural electrical stimulators for those with spinal injuries, according to Bryant and her colleagues.

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However, in some cases, the human body recognizes these implants and attacks and surrounds them with a dense capsule of scar tissue that prevents electrical stimulation from reaching the nervous system, condition called fibrosis, research has found.

This "foreign body reaction" is caused by an inflammatory response against the implant in which immune cells called macrophages attack and try to destroy the device before a collagen-rich capsule is formed that separates it from the surrounding tissue, she said.

This response then persists until the implant is removed from the body, limiting the effectiveness of the device over the long-term, she added.

No effective methods exist to prevent foreign body reaction without interfering with other important immune responses, according to Bryant and her colleagues.

"Foreign body reaction is currently an unavoidable complication of implantation and is one of the leading causes of implant failure," study co-author Dr. Damiano Barone said in a press release.


"At the moment, the only way we have of preventing it is to use broad-spectrum anti-inflammatory drugs such as dexamethasone, but [while] they may stop the scarring ... they also stop the repair," said Barone, a professor of clinical neurosciences at the University of Cambridge.

For this study, the researchers implanted an electrical device into mice to compensate for sciatic nerve damage and compared the response within the surrounding tissue to that in mice who did not receive an implant.

In addition to using normal mice, the researchers used mice whose genes controlling the inflammatory response had been "knocked out," preventing a response and allowing them to see how the foreign body reaction is generated and which genes were involved, they said.

The researchers then added MCC950 to the device coating and tested its effect in the mice and found that this prevented the foreign body reaction without affecting tissue regeneration.

Drugs such as MMC950 are being developed as potential treatments for a variety of inflammatory diseases, including cancer, sepsis, Alzheimer's disease and Parkinson's disease, according to the researchers.

These new drugs already are being tested in clinical trials in humans for certain conditions, the researchers said.

"There's a lot of excitement around this new class of anti-inflammatory drugs," Bryant said.


"Once they've been through clinical trials and have been shown to be safe to use, we should be in a good position to integrate them into the next generation of implantable devices," she said.

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