Physicians at Emory University School of Medicine are conducting a clinical trial using stem cells generated within the bone marrow to grow new blood vessels that could improve circulation in patients with blockages in the arteries of their legs -- a condition called peripheral vascular disease (PVD). Individuals with PVD have decreased blood flow to the muscles of the legs, especially during exercise, which causes pain, aching, cramping or fatigue in the muscles of their legs when they walk. This condition also is called "intermittent claudication". The Emory team, led by cardiologist Arshed A. Quyyumi, MD, and cardiology fellow Veerappan Subramaniyam, MD, is using colony stimulating factors (growth factors), to prod the bone marrow to release a type of stem cells called endothelial progenitor cells, which are used by the body to form new blood vessels or to repair damaged ones.
Decreased
blood flow in the legs is caused by the blockage or narrowing of the
arteries due to build-up of cholesterol. Normally, with exercise, the
blood vessels dilate (get bigger), but clogged blood vessels constrict
during exercise. In some individuals the vascular system corrects the
problem on its own either by forming new blood vessels, called
"collaterals," that bypass the blockages, or by repairing the diseased
blood vessels. This repair process results in improved circulation even
during exercise. Some people are not able to repair their own vessels,
however, and physicians don't completely understand the reasons why.
Recent studies show that when muscles do not receive enough blood, the
body makes growth factors that stimulate the bone marrow to release
stem cells that "home" to the muscle that is not getting enough blood.
These stem cells include endothelial progeni
tor cells (EPCs), which is
the type of cell needed to make new blood vessels and to repair damaged
ones.
Patients in the clinical trial will be given an injection of either a
growth factor called GM-CSF (granulocyte-macrophage colony stimulating
factor) or placebo (sterile salt water) three times a week for two
weeks. The level of EPCs in the volunteers' blood will be measured
before, during and after administration of the drug or placebo. The
study is randomized and blinded, which means that volunteers will not
know whether they are receiving the study drug or the placebo.
The goal of the study is to determine if and how much GM-CSF will
increase the number of circulating EPCs in patients with peripheral
vascular disease. Another goal is to find out whether or not increasing
the number of circulating EPCs results in improved blood flow to the
leg, improved blood vessel function and improvement of patients'
symptoms.
Currently, GM-CSF is approved by the FDA for several uses, including in
cancer patients to increase the number of white blood cells to fight
infection after chemotherapy; in healthy individuals serving as bone
marrow donors to stimulate the bone marrow to release stem cells; and
in patients who have had a bone marrow transplant to increase the
number of white blood cells. It is still considered experimental,
however, for use to increase the level of EPCs in patients with
peripheral vascular disease.
The investigators are seeking patients in whom prior treatments,
including surgery or angioplasty, have been unsuccessful, or patients
for whom those treatments are not options. To find out more about the
study and eligibility, call 404-712-0170.
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Source:Woodruff Health Sciences Center
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