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Stem Cell News
Blood Vessels Created Using Adult Bone Marrow Stem
Cells
By Ed Susman, United Press International, July 8,
2007
Using a person's own bone marrow, doctors were able
to grow new blood vessels. However, in order for
patients with diseased arteries to benefit from the
test-tube grown vessels, a few more years of research
will be required said researchers. Still, the
accomplishment is yet another large step for adult
stem cells and demonstrative of their therapeutic
potential.
"Our studies show that bone marrow is an
excellent source of stem cells that can be coaxed into
creating blood vessels," Stelios Andreadis,
associate professor in the University at Buffalo
department of chemical and biological engineering,
told United Press International.
Andreadis said that endothelial and smooth muscle
cells make up the test tube created blood vessels.
"These stem cells can be used in regenerative
medicine for cardiovascular applications," he
said.
Especially for those found in and around the heart,
the main reason for creating new blood vessels is for
use in arteries said Andreadis. However, the blood
vessels created in his laboratory are capable of being
used, at the very least as, veins in humans right now.
The new blood vessels should be engineered to
withstand internal pressures as high as 1,200
millimeters of mercury in order to have the strength
to be used to replace diseased coronary arteries. This
is 10 times above the normal limit. Having a top
strength of about 200 mmHg, bone marrow stem cell
derived blood vessels are not yet strong enough.
"We need to improve the matrix around which
the cells grow in order to have strong enough blood
vessels for replacing human arteries," he said.
The researchers have already used tissue engineered
vessels in animals such as sheep with good results, he
said.
Cardiovascular Research recently published
Andreadis' preliminary work. Providing a desirable
alternative to the venous grafts now routinely done in
patients undergoing coronary bypass operations, the
paper demonstrated the potential for eventually
growing tissue-engineered vessels out of stem cells
harvested from the patients who need them.
A high 10-year failure rate, discomfort and pain at
the donor site, and the limited availability of
vessels are some of the disadvantages of venous
grafts.
Using a tissue-specific promoter for alpha-actin (a
protein found in muscles that is responsible for their
ability to relax and contract) in conjunction with a
fluorescent marker protein, Andreadis reported on a
novel method for isolating functional smooth muscle
cells from bone marrow.
One of the most important properties of blood
vessels is their ability to proliferate and the
ability to contract in response to vasoconstrictors.
In their expression of several smooth muscle cell
proteins, the tissue-engineered vessels performed
similarly to native blood vessels.
Critical to the functioning of artificial blood
vessels, both elastin and collagen are produced by the
vessels. These components also give tissue their
elasticity and strength.
The John R. Oishei Foundation of Buffalo and the
Integrative Research and Creative Activities Fund in
the Office of the Vice President for Research at the
University at Buffalo, part of the State University of
New York funded Andreadis' research.
"The work in Buffalo shows the promise that
stem cells have in their ability to produce different
structures," said S. Chiu Wong, associate
professor of medicine at the Weill Medical College at
Cornell University. "This pre-clinical work shows
again that stem cells can be a rich source for
development. It certainly remains a fruitful area of
research."
Working on producing more coronary blood vessels is
another aspect of stem cell research which Wong and
his colleagues are working on. In an attempt to
generate blood vessel growth, stem cells are injected
directly into heart muscle. Wong and his team are part
of a multicenter clinical trial involved to this
particular study which has been funded by Baxter.
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