Researchers use new stem cell method to treat mice
By Julie Steenhuysen
CHICAGO (Reuters) - Using a new type of stem cells made from ordinary
skin cells, U.S. researchers said on Thursday they treated mice with
sickle cell anemia, proving in principle that such cells could be
used as a therapy.
U.S. and Japanese researchers last month reported they had
reprogrammed human skin cells into behaving like embryonic stem
cells, the body's master cells. They call the cells induced
pluripotent stem cells, or iPS cells for short.
The Japanese team had previously done the reprogramming work in mouse
skin cells.
A team at the Whitehead Institute of Biomedical Research in
Cambridge, Massachusetts, has now used the new cells to treat mice
engineered to have sickle cell anemia, a disease of the blood caused
by a defect in a single gene.
"This is the first evaluation of these cells for therapy," said Dr.
Jacob Hanna, who worked on the study. "The field has been working for
years on strategies to generate customized stem cells," he added in a
telephone interview.
Creating stem cell therapies from a person's own cells would make
them genetically identical, eliminating the need for immune
suppression or donor matching, Hanna said.
"Now, with the breakthrough of this new method for generating stem
cell-like cells, can we try to substitute a diseased tissue in a
living animal?"
Hanna and colleagues working in Rudolf Jaenisch's lab at Whitehead
Institute took skin cells from diseased mice and inserted four genes
that reprogram the cells into becoming iPS cells.
"We call it the magic four factor," Hannah said.
Pluripotent or multipurpose cells, such as embryonic stem cells and
the new cells, can morph into any type of cell in the human body.
The researchers then coaxed these mouse master cells into becoming
blood-forming stem cells and substituted the faulty gene that causes
sickle cell anemia with a working one.
FAR FROM PERFECTED
When they transplanted these cells into the diseased mice, tests
showed normal blood and kidney function, they report in Friday's
issue of the journal Science.
"This demonstrates that iPS cells have the same potential for therapy
as embryonic stem cells, without the ethical and practical issues
raised in creating embryonic stem cells," Jaenisch said in a
statement.
But the technique is far from perfected.
The four genes needed to turn skin cells into master cells are
delivered using a type of virus called a retrovirus.
"Once they enter the genome, there is the danger that they can
silence some genes that are important or they can activate some
dangerous genes that shouldn't be activated," Hanna said.
Another obstacle is that one of the four genes used is c-Myc, which
is known to cause cancer.
Hanna and colleagues got around that by removing the c-Myc gene after
it had done its job of converting the skin cells into iPS cells. "It
is far from solving the problem," he said.
Scientists hope to use stem cells to treat a host of diseases like
diabetes, Parkinson's disease and spinal injuries. And the new
technique for making stem cells will make them easier to study.
But many researchers including Hanna say human embryonic stem
research paved the way for such discoveries and should continue.
"They are the gold standard for what is normal and how a stem cell
should behave," he said.
(Editing by Maggie Fox and Xavier Briand)
http://www.sciam.
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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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