[blindza] Alternative to stem cell use for cell regeneration
- From: "Jacob Kruger" <jacobk@xxxxxxxxxxxx>
- To: "BlindZA" <blindza@xxxxxxxxxxxxx>
- Date: Fri, 29 Aug 2008 06:11:56 +0200
(content below)
http://www.rdmag.com/ShowPR.aspx?PUBCODE=014&ACCT=1400000101&ISSUE=0808&RELTYPE=LST&PRODCODE=00000000&PRODLETT=MZ&CommonCount=0
Jacob Kruger
Blind Biker
Skype: BlindZA
'...Fate had broken his body, but not his spirit...'
---article---
One cell becomes another: no stem cells needed
Aug. 28, 2008
In an unprecedented flourish of genetic alchemy, scientists used a virus to
coax one type of cell to become another, without the intermediate stem cell
step.
Courtesy of Nature, standard beta cells (left) and beta cells produced
by reprogramming (right). In terms of shape and structure, researchers call
them "indistinguishable."
The research, conducted with cells from the pancreas, could soon be used to
treat people with diabetes-but its long-term impacts could be even greater.
"This represents a parallel approach for how to make cells in regenerative
medicine," says Douglas Melton, co-director of the Harvard Stem Cell
Institute. "And now that it's shown that you can turn one of your cells into
another, it makes you think of what other cells you'd like to convert."
Cell transformation has traditionally been accomplished by harvesting and
reproducing stem cells. These are able to become other types of cells,
raising the much-anticipated possibility of replacing disease-damaged and
age-ravaged organs and tissues.
But stem cells are tricky. Using highly-versatile embryonic stem cells
requires embryo destruction, a steady supply of human eggs and potentially
dangerous hormone treatments for the women who produce those eggs. Adult
stem cells, though ethically uncontroversial, are also hard to handle.
Another technique, known as de-differentiation, can turn skin cells to stem
cells-but tends to introduce cancer-causing mutations.
Melton's team avoided stem cells, and their baggage, altogether by using a
virus to tweak three developmental genes in pancreatic tissue cells in mice.
Three days later, these became insulin-producing beta cells, and appear free
from the complications that have frustrated stem cell researchers.
If the technique, described today in Nature, is replicated in humans, it
could be used to treat insulin deficiencies in people with diabetes-and
that's just the start.
start.
"Neurodegenerative diseases come to mind, as does cardiovascular disease,"
says Melton.
Arthur Caplan, a Univ. of Pennsylvania bioethicist who wasn't involved in
the study, called the findings a "breakthrough" for both diabetes and the
field of regenerative medicine.
Pancreas tissue cells transformed into insulin-producing beta cells at
work, courtesy of Nature.
"It's a system that's easier to manipulate than getting a new stem cell to
turn into something you want," he says. "The kind of work done here has the
promise to go into clinical practice in a relatively short time."
Caveats remain, the foremost being the replication of the work in human
tissue. The team managed to cause the transformation inside the mice, but in
humans the transformation will need to be done in a tissue culture,
producing cells than can be injected into recipients. And though Melton's
team used a safe and well-characterized virus to induce the changes, the
long-term safety of the new cells isn't proven.
Melton must also coax the transformed cells into forming groups known as
islets, which produce the insulin used in humans.
"We've made a cell type, but we haven't yet made a whole tissue," says
Melton. "But we're reasonably confident."
Melton's team is also seeing whether the same kind of cell transformation
can be achieved in liver cells, or triggered by drugs.
Other researchers, he says, will apply the technique to other diseases.
"If you've got extra cells of one type and need another, why go all the way
back to a stem cell?" says Melton.
Still a need for human stem cells
The transformation of pancreas cells from one type to another has been
hailed as a breakthrough: until now, such tricks required of
scientifically-and sometimes ethically-tricky stem cells.
But for all its promise, the new technique-like de-differentiation before
it-won't replace embryonic stem cells, and wouldn't have been possible
without them.
"We wouldn't be where we are today without working with human embryonic stem
cells. They provide a unique window into human development and disease. We
still need those," says Melton.
As of now, Melton's technique doesn't appear to have provoked the same
commentary as de-differentiation, in which adult cells are reprogrammed into
an embryonic state. When that feat was announced in November, President Bush
hailed it in his State of the Union address as an alternative to embryonic
stem cells, and many conservatives followed suit.
Scientists soon pointed out that de-differentiated cells were unproven-and,
that aside, de-differentiation wouldn't have been possible without insights
generated from the research that embryonic stem cell critics had condemned.
The same holds true for the latest breakthrough.
"The goal of regenerative medicine is to make useful cells," says Melton.
"I'll use induced pluripotency, embryos, direct reprogramming-if I knew
which path worked best, I'd try it, but I'm not smart enough. So we're
trying all ways. I'm obsessed with beta cells, and I'll try any way of
making them."
The abstract to the study "In vivo reprogramming of adult pancreatic
exocrine cells to b-cells" is available here,
http://www.nature.com/nature/journal/vaop/ncurrent/abs/nature07314.html
----------
To send a message to the list, send any message to blindza@xxxxxxxxxxxxx
----------
To unsubscribe from this list, send a message to blindza-request@xxxxxxxxxxxxx
with 'unsubscribe' in the subject line
---
The 'homepage' for this list is at http://www.blindza.co.za
Other related posts:
- » [blindza] Alternative to stem cell use for cell regeneration
