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Commencement:Looking
Outward • Feeling
Smart •
Filling Bass Chairs
Student Affairs VP Picked •
Christensen Honored •
Bigger, Better
Bookshelves
Dancing Feats and Feasts
• Accepted
for Admission •
A
Dean for Medicine
Scholars and Fellows
•
Math Champs •
Healing Damaged Hearts •
Backing a Digital Future
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Healing Damaged
Hearts
fter demonstrating in 1998 that muscle cells taken from a rabbit’s
leg could replace severely damaged heart muscle cells in the animals,
Duke Medical Center researchers plan to see whether their novel approach
will work in humans with damaged hearts.
Safety trials set to begin soon at the University Hospital Dykzigt
in Rotterdam will be using an approach pioneered by Duke molecular
biologist and heart researcher Doris Taylor. Another trial using a
different delivery approach is under way at Hospital Bichat in Paris.
Taylor says it is likely that similar human trials could begin later
this year at Duke and elsewhere in the United States.
In Taylor’s approach, muscle cells (myoblasts) are taken from
the leg, grown in significant quantities outside the body, and then
returned to damaged areas of the heart, in this case through a catheter.
In all animal models to date, the injected cells have behaved just
like heart muscle cells and improved cardiac function. She outlined
the procedure in a “state-of-the-technology” address delivered
in May at the annual Paris Course on Revascularization, where more
than 10,000 European clinicians discussed the latest in cell-based
treatments for heart disease.
Taylor chronicled how quickly her findings in the laboratory are being
translated into clinical trials in humans and how this approach has
a major head-start over the latest scientific rage, which uses stem
cells to repair ailing hearts in animals. “Stem cell technology
today is where we were with myoblasts five years ago,” she says.
“While stem cells have an exciting future, there are many challenges
to be overcome.”
The main differences between the two sources of cells involve quantity
and behavior of the cells. Myoblasts can be grown in practically limitless
quantities, while there are only finite amounts of stem cells in a
potential patient. It is important that cells be taken from the individual
whose heart is being repaired to avoid the immune system responses
seen in organ transplantation. “The other major difference is
what happens when the cells are actually introduced into the damaged
heart,” she says. “Myoblasts quickly start acting like the
muscle cells they are and begin contracting like those around them.
If stem cells are injected into normal heart, they act like normal
heart cells; if they are injected into damaged and scarred heart muscle,
they act like damaged or scarred muscle cells.”
There is a great need for a new approach to repairing heart damage,
says Taylor, since more than 3.5 million people worldwide suffer an
acute heart attack each year. Those who survive are usually left with
areas of severely damaged heart muscle, which leaves them at risk
for further heart attacks. Damaged muscle can also progress to a condition
known as congestive heart failure, where the heart gradually loses
its ability to pump blood throughout the body.
Taylor envisions that, in the near future, a patient would come to
the emergency room with a heart attack and doctors would remove a
small plug of cells from the leg and grow them in the laboratory for
about two to four weeks, which also is long enough to assess damage
to the heart. Then the cells would be delivered to damaged areas of
the heart with a catheter, a device now commonly used to clear blocked
arteries.
Currently there is no way to reverse damage done to the heart during
an extended period of low oxygen, as occurs in a severe heart attack.
Although the remaining healthy heart muscle cells grow larger to compensate,
that only makes the heart more inefficient, ultimately leading to
heart failure, which kills more than 410,000 people annually in the
United States and Europe.
“Treatments for severe heart failure are currently limited either
to making the remaining heart work better or performing a heart transplantation,”
Taylor says. “You are born with all the heart cells you’ll
ever have. Once you damage the heart muscle, it’s gone forever.”
Based on the pre-clinical studies carried out in Taylor’s lab
at Duke, as well as others in Europe, she is encouraged that a new
age of treatment for heart disease is on the horizon. “This is
the first time we actually have a hope for recovery, not just stabilizing
and then managing heart patients. We might actually be able to regain
lost heart function, which would improve the quality and quantity
of life. Now, only the sickest heart failure patients get heart transplants.
With myoblast therapy, there are no limitations on whose quality and
quantity of life can be improved.”
According to Taylor, should the new approach be shown to be safe and
effective in clinical trials, it should become widely available, though
every center would not likely be able to handle all aspects of the
procedure. “The process is straightforward, but not simple,”
she says. “Our clinicians can get cells to anywhere, that’s
the easier part; growing the cells is more difficult. Unless hospitals
want to get into the business of growing cells, it is likely that
they will partner with another center or company with that expertise.”
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