Stem cell advance offers hope for heart treatments
AFP, PARIS
Monday, Sep 03, 2007, Page 1
Surgeons will soon be able to literally mend a broken heart using
live tissue grown from a patient's very own stem cells, top
cardiologists said.
The whole procedure -- harvesting cells from bone marrow, growing
tissue and surgically implanting the heart muscle or valve -- could
take as little as six weeks and could become routine within three-to-
five years, they reported.
Their findings were published in a special issue of the Philosophical
Transactions of The Royal Society B in Britain.
One reason heart attacks are so debilitating, even when they are not
fatal, is because the human heart does not regenerate. Damaged tissue
stays damaged.
Most problems occur with age, when the heart begins to wear out.
"But the highest medical need for tissue-engineered heart valves is
in the treatment of congenital heart malformation,
nearly 1 percent of all newborns, Simon Hoeurstrup, lead author of
one of the studies, said.
Artificial heart valves currently available must be periodically
replaced as children grow, leading to suffering and higher death
rates than in adults.
Bio-engineered heart muscle that could be grafted onto a patient's
living tissue without fear of rejection by the immune system has long
been a holy grail of cardiovascular medicine.
Artificial replacements "do the job and save people's lives," said
heart surgeon Magdi Yacoub, who coordinated the studies. "But they
cannot match the elegant, sophisticated functions of living tissues."
While durable, mechanical hardware increases the risk of bacterial
infection in the heart's inner lining, as well as abnormalities in
blood flow. Recipients must also take medication to prevent blood
clots, boosting the chances of internal bleeding and embolisms.
There are currently two broad techniques for making bio-prosthetic
heart valves, and both have serious drawbacks.
Animal grafts, especially from pigs, are readily available, but
differ in structure and tend to wear out. Human valves from donors
work much better, but are in chronically short supply and can easily
provoke immune reactions.
In the tissue engineering approach favored by Yacoub and Hoerstrup,
the patient's own stem cells -- taken from bone marrow -- are
isolated and expanded in the laboratory using standard cell culture
techniques.
They are then "seeded" onto a special matrix in the shape of a heart
valve that is positioned in a device called a "bioreactor" which
tricks the cells into growing in the right shape.
Once mature, the living-tissue heart valves can be implanted in the
patient.
This procedure has already been extensively tested in sheep, but
several years of follow-up are required before it can be deemed
effective and safe, Hoerstrup said.
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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