Here’s news that may offer a ray of hope to the nearly 10 million Americans suffering from peripheral arterial disease (PAD). Recently a team of experts from the UCLA Henry Samueli School of Engineering and Applied Science joined hands with a group of researchers from the David Geffen School of Medicine at UCLA to apparently help combat the hardening of arteries. A new PAD treatment device is apparently being developed by the team to arrest thrombosis in small-diameter blood vessels.
PAD or hardening of the arteries is known to be a familiar circulatory problem that causes narrowed arteries to reduce blood flow to the limbs. A supposed warning signal for vascular disease, heart attack and stroke, the condition and its growth may lead to loss of limbs or even death.
Presently various treatments for PAD are available. These include balloon angioplasty, stenting and bypass surgery. The flipside of the latter two treatments is that the devices used are observed to have caused thrombosis. It is a condition where blood flow is obstructed due to clots formed inside blood vessels and may consequently result in serious complications. With this fortuitous discovery, UCLA engineers and physicians hope to offer patients a treatment while still keeping thrombosis at bay.
The experts focused their research on stents that are integrated with a material called Nitinol. The latter is supposedly a superelastic nickel and titanium alloy which is capable of being deformed and recovering its original shape on heating.
“What we’ve been doing at UCLA for the last five to 10 years now is working with thin-film Nitinol,” mentioned Greg Carman, a professor of mechanical and aerospace engineering and lead investigator for the multidisciplinary research team, which was organized under the umbrella of the UCLA Center for Advanced Surgical and Interventional Technologies.
“Nitinol, discovered back in the 1960s, is a shape-memory material. They thought it was going to revolutionize the engineering field. It wasn’t until 1985 that people began to think this material would probably be great to use in a stent,” Carman added. “The reason they liked it for a stent is because you could bend the material a very large distance and it would return back to its original shape. Other metals, such as surgical steel, do not allow such a large shape recovery and, as such, cannot be used in many stenting devices.”
Carman’s group is stated to have accidentally stumbled on the method to design what they believed to be very high-quality, uniform-composition Nitinol. They had been looking into creating thin-film Nitinol in the early 2000s.
“I immediately saw the promise that thin-film Nitinol had for intravascular and cardiac applications,” commented Dr. Daniel Levi, a pediatric cardiologist at Mattel Children’s Hospital UCLA and a principal investigator on the team. “Greg and I started working together immediately on stents and a heart valve.”
The experts’ team then worked on developing stents that included thin-film Nitinol on the outside. While originally they thought of it as a potential treatment for neural vascular disease, later they found that their thin-film Nitinol could find its place in much smaller tubes or catheters as it was just about 5 microns thick. As against other commercial stents that have a thick covering of around 100 microns, they felt smaller-diameter blood vessels, like those found in limbs could particularly benefit from the stents.
Even though this was an advantage to treatment delivery, their major worry was thrombosis. On further testing the experts found that their innovative stent also bundled in an array of features that could probably help fight thrombosis.
Moving further, the researchers initially uncovered the formation of blood clots on the surface of the thin-film Nitinol which was tested in animals. On additional review, it was found by Youngjae Chun, a student of Carman that thrombosis may be linked to the hydrophobic nature of the material’s surface. And upon measurement the film did apparently reveal a hydrophobic nature.
This led the team to an intricate analysis that investigated the various treatments that could possibly alter the surface of Nitinol. In the course of one such test, Chun spotted a treatment that produced a super-hydrophilic response. In vitro analysis to check if the platelets would adhere to the new chemically treated material that was on the surface was successful.
“With the Challenge Grant, we are beginning to do tests in animals again and have already seen that our film does remain patent,” Carman said. “It’s our understanding that very few, if any, covered stents out there that are put into 3- or 4- millimeter vessels will remain patent. We need to show with statistical relevance that our material stays patent longer than other systems commercially on the market. If we can do that, we would have something that could impact the world quite dramatically.
“At this point, we need to deploy the stent grafts and have them stay open,” said Dr. David Rigberg, a vascular surgeon at the Geffen School of Medicine and the third principle investigator on the team. “We also want to see that under examination many of the things that we look at to determine if something is going to thrombose are decreased. I think the study has a real shot at clinical application.”
With PAD being a huge problem, the researchers intend at expanding the possible uses of thin-film technology.
The National Institutes of Health’s National Heart, Lung and Blood Institute recently awarded the team a $1 million Challenge Grant.