One reason these grafts perform so poorly is because of the body’s own inflammatory response. “Not only does scar tissue form around the outside of the implant but a similar process occurs on the inside, re-narrowing the vessel and limiting blood flow,” he says. “For grafts that are already very narrow, like those in the coronaries and legs, this reduces their effectiveness and many can become completely blocked.”
The team, led by Dr Richard Tan and overseen by Dr Wise, sought to solve the problem by developing a surface coating for vascular grafts that switches off the harmful inflammatory responses that lead to their rejection.
“This coating is made from interleukin-4, a naturally occurring molecule found in our own body that is usually involved in resolving inflammatory responses to infection,” Dr Tan says. “When coated onto the surface of a vascular graft, immune cells arrive at the graft surface and interact with this molecule. They are immediately switched into an anti-inflammatory state causing a signaling cascade that stops further inflammation,” he says.
The coating has the tremendous capacity to inhibit the immune responses that drive the growth of these cells. This leads to vascular grafts that remain clear of blockages for longer, improving the performance of the graft, ultimately reducing the need for patient re-intervention, Mr Tan says.
The scientists describe their results as striking, and believe the finding represents a fundamental change to the way our bodies perceive and react to a medical implant.
“Essentially by mitigating the body’s negative responses, we are able to allow devices to perform as they were intended to, increasing their performance for patients whose very lives depend on some of these devices every day,” Dr Wise says. “That’s a hugely significant step forward in an area where there is a desperate unmet need for life-saving scientific innovation.”
Having proven the coating works in the lab, the team now plans to use it in a larger study before moving towards human clinical trials. From here it will likely take three to seven years before it is widely available for use in Australian hospitals.
This work was reported by ABC News online on Thursday, 14 March 2019. Read the article here: New liquid discovery could stop bodies from rejecting medical implants
