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Mary Parker
JO 723
10/1/10
Deadline story
There are many invasive medical treatments. Pills, surgery, chemotherapy, and
many other practices are used to fix symptoms and cure diseases. But through the use of
stem cells, future doctors may be able to trick the body into healing itself.
Stem cells are some of the earliest cells in human development. From their basic
template, every cell in the body is formed from skin to bone. Since stem cells have the
potential to grow into any kind of healthy adult cell, they are studied for their potential to
turn diseased cells into healthy versions of the same cell. However, some groups have
raised questions on the morality of using discarded embryos for studies, and a series of
protests and lawsuits has hindered embryonic stem cell research for many years.
In a new study from the Harvard Stem Cell Institute and Children’s Hospital
Boston, researchers have discovered a new way to create stem cells from fully grown
adult skin cells. The researchers, led by Derrick Rossi, introduced stealthy RNA into
adult cells with the intention of reverting them back to stem cells. The RNA carried four
key proteins into the adult cell, causing it to reprogram itself. Their findings were
published in the September 30 online issue of Cell Stem Cell.
“Our cells have this potential within them to repair tissue,” said Doug Melton, codirector of the Harvard Stem Cell Institute, who was not involved in the work. “This
paper is a major paper in the field of regenerative medicine.”
However, both Melton and Rossi admit that they are still a long way from not
needing embryonic stem cells. Although the modified adult cells may have the ability to
be specifically tailored to each patient, researchers still need to compare the modified
cells with true stem cells in order to see how close they can get to the real thing.
“We wouldn’t have known we had produced a nice pluripotent cell if we hadn’t
compared it to embryonic stem cells. They’re the gold standard,” said Rossi.
The research into modifying adult cells began in Japan in 2006 with Shinya
Yamanaka, who used a DNA-based virus to achieve similar results. Unfortunately, that
technique was slow, extremely inefficient, and caused mutations in the cell that could
lead to cancer if they were injected back into the patient. According to Melton, the
Yamanaka method could manage at best to convert one in a thousand adult cells into
stem cells. This is especially a problem when only a limited amount of material can be
taken from a patient. Once you had those few new stem cells, you risk making the patient
worse if the DNA virus causes cancer.
“It doesn’t take a rocket scientist to say, ‘well, let’s use RNA,’” said Rossi.
When Rossi and his team began the project, the most they hoped for was to solve
one or two of the problems with virus-based cellular reprogramming. They hit a snag
early on, when the adult cells rejected the introduced RNA with a violent immune
response. In most of the early tests, the adult cells self-destructed.
Rossi’s team would not be deterred. They spent the next year chemically
modifying the RNA until it could sneak past the cell’s defenses and begin building
proteins without eliciting an immune response. The result was a new stem cell, which
further research found to be very close to a real embryonic stem cell.
By getting around the DNA method, Rossi’s team created stem cells faster, more
efficiently, and without the danger of viral mutations that could lead to cancer. The next
step will be to develop ways of making the new stem cells useful for clinical therapies.
Melton has been using the basic virus and chemical method to coax new stem cells to
develop back into different kinds of healthy adult cells. Rossi’s team successfully grew
muscle cells with their RNA method, but they still have a long way to go before they can
start human trials.
Yamanaka himself sees the potential in this new method for someday moving
stem cell research forward into hospitals. However, he warns that the quality of the cells
made through Rossi’s method needs to be closely examined, since they can vary
depending on where they are taken from. Rossi’s research involved skin cells, but the
type of cell they start with could have an effect on the type of cell they end with.
Rossi is confident that future research will discover a way to turn his modified
cells into useful medicine. He has already patented the research and established a new
company, ModeRNA Therapeutics, to bring his findings to the next level.