CONTACT: JENNIFER BROWN
Iowa City IA 52242
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Release: Aug. 30, 2000
UI study uses blood cells to restore blood flow to damaged tissue in mice
IOWA CITY, Iowa -- University of Iowa researchers have found a way to improve
circulation in the limbs of mice with diabetes. The findings have implications
for the treatment of diabetes in humans. Poor circulation is the cause of
many dangerous health problems in people with diabetes.
The research team led by Gina C. Schatteman, Ph.D., a research scientist
in the UI department of anatomy and cell biology, discovered that injecting
certain types of blood cells into the circulation-deficient limbs of mice
with diabetes accelerated the restoration of blood flow to the limbs. The
results were published in the Aug. 15 issue of the Journal of Clinical Investigation.
The UI study showed that a critical subset of blood cells, called angioblasts,
taken from non-diabetic humans, helps to form new blood vessels in diabetic
mice, and the rate of restoration of blood flow was faster than for untreated
In humans, restoring blood flow to damaged tissue, generally a slow process,
is made even slower by diabetes. People with diabetes do not grow new blood
vessels in their limbs as well as people without the disease. The length of
time it takes for a patient with diabetes to grow new blood vessels to replace
damaged ones is a real problem; during this time the patient is in severe
pain and at an increased risk of infection and gangrene, which can lead to
"The faster good blood flow can be restored to the limb, the faster
you can alleviate pain and the more you can reduce the risk of the complications
that arise from poor circulation," Schatteman said.
People with diabetes are also particularly susceptible to atherosclerosis
(clogging of the arteries). The constricted blood vessels result in reduced
blood flow to the limbs. This condition brings with it a host of problems
such as poor wound healing ability.
In mice, where blood flow is normally restored relatively rapidly, the benefits
of accelerated revascularization may not be obvious. However, in larger animals
and humans, where restoration of flow is much slower, this acceleration may
be of profound importance and could mean the difference between saving and
losing a limb. Schatteman said that her team is currently investigating the
use of these blood cells to restore flow in larger animal models.
Angioblasts are precursor cells that go on to become endothelial cells,
the cells that line the walls of large blood vessels and form the walls of
smaller blood vessels. Although the question of whether angioblast function
is impaired in people with diabetes remains open, Schattemans study
suggests that it is. Angioblasts from people with type I diabetes form fewer
endothelial cells in culture than angioblasts from people without the condition.
These findings suggest that the inability of these blood cells to become blood
vessel wall cells contributes to certain vascular problems associated with
Diabetes is a paradoxical disease. While people with this condition are
less able to grow new blood vessels in the limbs than control subjects, they
tend to grow more blood vessels in the eyes and kidneys. Too many blood vessels
can be as problematic as too few, so any increase in revascularization needs
to be targeted to the limbs.
"Our approach is designed to localize the revascularization to the
limbs," Schatteman said. "We hope this approach will lead to fewer
problems than a systemic approach, which would affect the whole body."
Schatteman cautioned that there are still many steps remaining to determine
whether angioblasts may someday be useful therapeutic agents. An important
first step will be to investigate the distribution of injected cells and examine
the possible consequences of their incorporation into tissues beyond the site
While the current study focused specifically on restoring blood flow to
a limb with damaged circulation, it is possible that the findings may be significant
with respect to rapidly restoring blood flow to infarcted regions of the heart
or to the brain after a stroke.
Researchers in the Department of Molecular Medicine at the University of
Texas Health Science Center in San Antonio were also involved in this study.
The research was supported by an American Heart Association-Texas Affiliate
Grant-In Aid and a joint National Institutes of Health and Juvenile Diabetes
Foundation International Grant.
University of Iowa Health Care describes the partnership between
the UI College of Medicine and the UI Hospitals and Clinics and the patient
care, medical education and research programs and services they provide.