Researchers find technology that may make lifesaving implanted devices last longer
Glucose-level sensors. Pacemakers. Chemotherapy ports. Catheters.
New blood vessels (which appear black) on top of an implanted medical device. Where the blood vessels actually penetrate into the surface of the device, they appear "fuzzy."
Implanted medical devices such as these and others add quality of life, deliver lifesaving medicine or protect the lives of patients who need them, but those same devices are at risk from the patients themselves.
"One of the biggest problems with any kind of implanted device is the body's natural reaction to recognize it as foreign and form a scar around it," said Stuart Williams, PhD, scientific director of the University of Louisville/ Jewish Hospital's Cardiovascular Innovation Institute (CII).
Scars, he explained, limit blood flow, and a limited blood supply compromises the function of implanted devices over time. If a device does not function properly, a person's health is at risk.
But Williams, along with co-principal author and CII director of cardiovascular therapeutics James Hoying, is part of a team that has found a way to protect implanted devices. They have engineered a unique system of blood vessels to interact with the tissue surrounding such devices and prevent scarring.
In a study using animal models, the researchers suspended tiny blood vessel fragments in a collagen gel around devices just before implanting them. They call this a microvascular construct (MVC).
Collagen is a naturally occurring protein in the flesh and connective tissue of animals and humans. It provides an environment that resists the formation of scar tissue around the implanted device, Williams said.
The team also implanted devices with collagen gel and no blood vessel fragments. When they compared the two, they found that the MVCs both promoted and maintained circulation in the area around the implant, according to Williams, a senior researcher on the study.
Because there was so much blood vessel activity, "the MVCs and collagen altered the way tissue formed around the implants," he said. Formation of scar tissue was restricted, and the number of white blood cells that stimulate inflammation in the implant area was reduced.
The vessels in the implant area were able to sustain good blood flow over time, indicating that implanted devices might work better for a longer time.
Williams and colleagues now are working to design an operating room-compatible device that could bring this technology to patients.
"This could have implications for patients who have any number of implantable devices," he said.
The National Institutes of Health-funded study was published early online on Aug. 23 in the Journal of Biomedical Materials Research.
Other investigators involved in this study include Gabriel Gruionu, Alice Stone and Mark Schwartz, all of the University of Arizona, Tucson.