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Source: ONE News -
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Researchers have identified the early master cells that make up
the human heart and said they could someday be used to make patches
to fix damaged hearts.
The discovery, published in the journal Nature, also sheds
surprising light on how human hearts develop in the womb, and how
congenital heart disease develops.
"This cell that we describe is probably not going to be used
directly as cell-based therapy because it has the possibility of
going into too many different cell types," said Kenneth Chien of
the Harvard Stem Cell Institute and Massachusetts General
Hospital.
But Chien said his team is now looking for intermediate cells that
are on their way to becoming beating heart muscle, the cells that
line the arteries, and other heart cell types.
More immediately, it helps in understand what causes heart disease,
Chien told reporters in a telephone briefing.
"The study provides a new way of understanding heart disease as it
appears in children and in adults," Chien said.
Chien's team worked entirely with human cells and found the human
heart develops differently from hearts in mice - a surprising
finding.
"The human heart at birth is more than a thousand times bigger than
the adult mouse heart, yet the size of the initial embryos are
close in size. Humans are just a heck of a lot bigger than mice,
and every organ is bigger. How is that achieved?" Chien
asked.
Early heart stem cells
In mice, the progenitor cells that Chien's team found exist for
just 48 hours.
But a mouse develops from conception to birth in just three
weeks, while humans gestate for nine months.
And it turns out the human heart develops from patches of these
early heart stem cells.
Another surprise - these patches of stem cells tend to
congregate in areas linked with congenital heart disease, including
the heart valves and pumping chambers.
"Congenital heart disease may be a stem cell disease," Chien
said.
Congenital heart disease affects up to two percent of newborns
and often requires surgery within days or weeks of birth.
Chien does not believe it would be possible to grow entire hearts
using the cells - too complicated - but it may be possible to grow
patches to fix areas damaged by heart attacks, or faulty valves, he
said.
Batches of cells could also be used to test drugs for possible
unexpected side-effects on the heart.
"Finding a cell that can make all the parts of the heart, including
the contracting muscle, the smooth muscle and the vessels, brings
us much closer to the possibility of repairing human hearts with
new cells," Dr Doug Melton, who helps direct the stem cell
institute, said in a statement.
Stem cells are the body's master cells, the source of all cells and
tissue in the body.
Chien's team worked with embryonic stem cells, which are found
in days-old embryos and which at first can give rise to every cell
type.
These cells differentiate as an embryo develops, becoming destined
for certain fates as heart cells, nerve cells and so on.
Using human embryonic stem cells is controversial as some people
object to destroying a human embryo.
Some groups have managed to turn ordinary skin cells into stem
cells.
They are called induced pluripotent stem cells or iPS calls and
Chien wants to try and turn iPS cells into the heart progenitor
cells - but says working with true human embryonic stem cells is
important.
Banks of human heart progenitor cells might be grown and used for
treatments eventually, he said, especially if they can be matched
to all the different human tissue and blood types.
