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Harvard
University scientists have made lines of stem cells able
to turn into any other cell in the body from bits of
skin or blood of 10 patients with genetic diseases,
including muscular dystrophy and juvenile diabetes.
The
findings will help researchers decipher the workings of
these diseases, enabling them to study what happens as
cells that carry a condition’s genetic seeds develop and
age. The lines will be made available for a “nominal
fee” to researchers around the world, the Harvard
scientists said.
Teams at
the Harvard Stem Cell Institute in Cambridge,
Massachusetts, created the lines using a technique that
reprograms cells to give them the same power as those
from embryos to become any of the roughly 210 cell types
in the body. Their advance was described in a paper in
the journal Cell.
Harvard University Stem
Cell Institute researchers (from left) George Melton and
Kevin Eggan speak to the media about their plan to
proceed with somatic-cell nuclear transfer in embryonic
stem cells in this 2006 photo.
--Harvard University
Gazette
The
advance will “allow researchers for the first time to
get access” to cells that are defective in a particular
disease “and to watch the disease progress in a dish, to
watch what goes right or wrong,” said Doug Melton, a
Harvard cell biologist and codirector of the institute.
The
Harvard teams created the new lines from tissue taken
from 10 patients who ranged in age from a
three-month-old child with a form of immune deficiency
sometimes known as “bubble-boy disease” to a 57-year-old
with Parkinson’s.
Last
week another Harvard team said they’d performed the same
feat using the skin of two patients in their 80s with
the neurodegenerative condition known as Lou Gehrig’s
disease.
Yamanaka
technique
The
technique used to create the stem cells, developed by
Shinya Yamanaka of Kyoto University in Japan, has
captivated scientists and transformed the research
they’re performing. The method involves using viruses to
insert four different genes into skin cells. The genes
turn on a process that causes the cells to revert to a
primordial state similar to embryonic stem cells.
Yamanaka
announced his breakthrough two years ago at a scientific
meeting in Toronto, when he described how he had been
able to endow skin cells from mice with the power of
those from embryos. Other advances followed rapidly. In
November two research teams, one led by Yamanaka and the
other by James Thompson of the University of Wisconsin
in Madison, announced independently that they’d done the
same thing with the skin of living people.
Research
teams around the world have rushed to use Yamanaka’s
technique for creating what he calls induced pluripotent
stem cells, or IPS cells, for two key reasons. It is
relatively easy and inexpensive to perform and it
doesn’t require the use of human embryos or unfertilized
eggs, both of which can be difficult to obtain.
Ethical
concerns
Because
human embryos aren’t used or harmed to create the IPS
cells, the method sidesteps ethical concerns that have
dogged researchers. Religious and political leaders,
including President George W. Bush, have objected to
traditional stem-cell research because embryos are
destroyed in the process of creating the lines.
Still,
because Yamanaka’s technique uses viruses and genes that
are known to cause cancer, lines created with this
method can’t be used as treatments. They will allow
researchers to peer into the complex molecular and
genetic processes that occur in defective cells as they
develop, giving them a greater understanding of how and
why disease begins.
“We are
so ignorant at the moment, we don’t even know if when
patients get diabetes, they all get it the same way,”
Melton said in a conference call with reporters. “There
could be 50 different ways of getting Type 1 diabetes.”
Next
steps
George
Daley, the lead author of the paper and a researcher at
Children’s Hospital in Boston who studies blood
diseases, said he and his colleagues will now take the
newly minted stem cells and coax them to become blood
cells of various types.
He said
he hopes that by comparing them with normal healthy
blood, “we can find the particular development points
where the defects arise and we can look at gene-repair
strategies.”
He and
other scientists also will be able to test thousands of
existing drugs to see whether any of them remedy the
defects, he said.
Daley
said the new lines, and those developed in the future,
will be maintained in a new laboratory at Massachusetts
General Hospital in Boston. Setting up the lab will
enable other researchers to obtain the Harvard cells for
their own experiments, something that didn’t happen
quickly after embryonic-stem cells were first isolated
in 1998, he said. |
