http://www.boston.com/news/science/articles/2008/08/28/new_technique_finds_a_faster_way_to_change_one_cell_type_into_another/
New technique finds a faster way to change one cell type into another
By Carolyn Y. Johnson, Globe Staff | August 28, 2008
CAMBRIDGE - Harvard researchers have transformed one type of pancreas
cell in living mice into another - the insulin- producing cells that
are destroyed in type 1 diabetes - potentially giving stem cell
scientists a powerful new way to one day grow replacement tissues for
patients.
The technique, which the researchers said improved diabetic symptoms
in the mice, is faster than another pioneering method, in which
scientists turn mature adult cells into embryonic-like stem cells that
have the capacity to become any cell in the body.
The new technique, re****ted online yesterday in the journal Nature, is
years away from having benefits for diabetic patients, according to
Douglas Melton, a co-author and co-director of the Harvard Stem Cell
Institute. But other researchers said it was an exciting demonstration
that could spur scientists to think more broadly about converting
mature cells of all types into another type in the same organ -
taking, for example, a bit of heart tissue and transforming it into
cardiac muscle.
"The message for those of us working in other organs . . . is it opens
up the possibility of directly forming those different cells, in our
case, heart muscle cells," said Dr. Kenneth Chien, a colleague of
Melton's and director of the Cardiovascular Research Center at
Massachusetts General Hospital.
The work is the latest in a series of advances in stem cell research
that have helped ****ft the focus away from obtaining stem cells from
embryos, a practice that is controversial because it involves the
destruction of embryos. Two years ago, Japanese scientists altered
stem cell science with their re****t that it was possible to reprogram
a cell, turning it into an embryonic-like stem cell called an iPS
cell, which was capable of turning into any cell in the human body.
Melton's team has shown it's possible to skip that stem cell-like
state altogether.
Melton and colleagues painstakingly identified which genes were likely
to trigger the cell switch by sorting through more than 1,000 genes
and winnowing them down to ones that played a role in the development
of insulin-producing cells. They found that by injecting viruses
carrying three genes into mice, they could turn the pancreatic cells
into beta cells that produce insulin.
"It's the first paper that did sort of a systematic approach to
finding the factors that could do reprogramming - as opposed to
guessing," said Dr. Markus Grompe, director of the Oregon Stem Cell
Center at Oregon Health and Science University. He was not involved in
the Harvard study.
In the mice, a fifth of the cells made the jump from one cell type to
another, much higher than the current success rate of less than 1
percent for the creation of iPS cells from adult cells.
Diabetes researchers have long been trying to create the beta cells
that die in type 1 diabetes, which typically starts in childhood and
affects as many as 3 million Americans. Without the cells, which
produce insulin that regulates the level of sugar in their
bloodstream, patients are forced to constantly monitor their blood
sugar levels and take insulin by injection or pump.
The work represents a step forward, but researchers have more work to
do as they try to turn their finding into a cure for the disease. They
have yet to achieve the same transformation in human cells. Type 1
diabetes comes with the additional obstacle that even if the correct
cells are created in people, the patients' immune system will destroy
them.
Carolyn Y. Johnson can be reached at cjohnson@[EMAIL PROTECTED]
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