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For the 10 million Americans suffering from a condition called peripheral vascular disease (PVD), novel research from the creative team at the Indiana Center for Vascular Biology and Medicine may soon help ease the discomfort associated with the disease.
The human body is a pulsing, thriving network of blood vessels that, when working properly, circulates blood to and from the heart and lungs, delivering oxygen and nutrients to all the organs and tissues of the body. But when clogged due to atherosclerosis, blood vessels in the legs, for example, are unable to deliver oxygen and nutrients, resulting in pain when walking or at rest, severely limiting quality of life.
The primary therapies used today to address PVD are medication, surgical bypass, and angioplasty. Several companies have developed drug-eluting stents using medications to prevent re-blockage, or restenosis, of the coronary arteries. Drug-eluting stents specifically designed for treating PVD are also under intense investigation.
Two leading researchers on the topic--Dongming Hou, M.D., Ph.D., an investigator at the Indiana Center for Vascular Biology and Medicine, and the InstituteÕs director, Keith March, M.D., Ph.D.--are developing an innovative technique that uses a stent releasing an endogenous, or naturally occurring, body chemical called nitric oxide (NO) to help treat PVD. The researchers hope that this dynamic combination may better address the most common problem that occurs after opening a blocked artery-restenosis.
“Restenosis in peripheral vessels occurs in up to 40 percent of cases,” Dr. Hou told NHW. This is the key reason why the use of stents in the legs has not been as successful in avoiding invasive procedures as it has been in the heart vessels, he adds.
“NO is synthesized normally by endothelial cells (which line the inside of the vessel surface) and plays a critical role in maintaining vascular health and regulating vascular tone via vessel wall relaxation,” continued Dr. Hou. “The effects of NO on vessel response to injury include the inhibition of platelet aggregation (clotting), inflammatory cell adhesion, and vessel wall cell proliferation--all of which play a major role in restenosis. These biological actions of NO make it an important component in the endogenous defense against vascular damage.”
In ongoing animal studies, ICVBM researchers have already shown significant reduction in restenosis after implanting the nitric oxide drug-eluting stent. While stents have demonstrated positive effects in reducing restenosis by providing a mechanical scaffold in the artery, forcing the artery to remain open, researchers hope that by adding nitric oxide, they will reduce a process called proliferative neointimal formation that contributes largely to restenosis.
“Our study is designed to examine whether a NO-eluting teflon-covered stent called Med-aSpireª from Vascular Architects, Inc., can prevent restenosis in peripheral arteries,” explains Dr. Hou. “In our models, we showed a significant reduction in restenosis. Currently, a long-term study is ongoing. As NO has many favorable influences on endothelium and platelet function, this new drug-eluting stent holds promise with good initial results in animal studies. Further studies with such stents and compounds are warranted in humans.”
By reducing the rate of restenosis in the legs, researchers hope to substantially improve quality of life for the millions living with PVD.
The first human trials on this NO-releasing stent for the treatment of PVD will be launched in Europe this fall. Trials in the United States may begin in early 2004.
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