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Stem cells heal hearts
27/08/2007 13:21 - (SA)
Washington - A nutritious cocktail
helped human embryonic stem cells thrive and repair the damaged
hearts of rats, US researchers reported on Sunday.
The experiment provides the best evidence yet that the
powerful but controversial stem cells might be used to repair
the ravages of heart attacks and heart failure, the researchers
said.
Biotechnology company Geron Corp said it would try
to develop the cells into a product. "We're developing our
cardiomyocyte product, GRNCM1, to address the large unmet need
in heart failure," said Dr Thomas Okarma, president and chief
executive officer of Geron.
Stem cells are the body's master cell, acting as a source
for the various cells and tissues in the body. Those taken from
days-old embryos, called embryonic stem cells, are the most
malleable and can produce all of the cell types.
Their use is controversial because some people oppose the
destruction of a human embryo. US President George W Bush
has kept strict limits on federal funding of human embryonic
stem cell research. There are no restrictions on privately
funded researchers.
Okarma said embryonic stem cells were the only human stem
cells that had been shown to form cardiomyocytes - heart
muscle cells.
Because embryonic stem cells are so immature, it is very
difficult to control what kinds of cells they produce, and the
fear is that a tooth could grow inside a heart, for instance.
"We got stem cells to differentiate into mostly cardiac
muscle cells, and then got those cardiac cells to survive and
thrive in the damaged rat heart," said Dr Chuck Murry of the
University of Washington's Institute for Stem Cell and
Regenerative Medicine, who worked on the study.
A survival cocktail
But the cells died when they injected them into the hearts
of the rats, the researchers reported in the journal Nature
Biotechnology.
"This problem is not unique to our system. Death of
transplanted cells is slowing research progress in cell therapy
for diabetes, Parkinson's disease and muscular dystrophy, among
other diseases," they wrote.
So the team developed what they dubbed a "survival
cocktail" that included various proteins and other compounds to
stop the cells from dying.
It worked. When they caused heart attacks in the rats and
then injected the new heart muscle cells, every graft survived
and integrated into the hearts of the rats.
They beat in rhythm and improved the heart function of the
rats, they reported.
"This is one of the most successful attempts so far using
cells to repair solid tissues - every one of the treated
hearts had a well-developed tissue graft," Murry said.
This is key to treating someone after a heart attack, known
medically as a myocardial infarction, said Dr Michael
Laflamme, who also worked on the study.
"This sort of treatment could help the heart rebound from
an infarction and retain more of its function afterwards,"
Laflamme said in a statement.
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