March 4, 1999
New Source Of Cells For Transplants Found
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Researchers said Thursday they had managed to
find and grow stem cells -- cells that can give rise to a variety of
tissues -- from living nerve tissue for the first time ever.
Such a handy source of the elusive stem cells might make it much easier
to cultivate them for transplants to treat brain diseases such as
Parkinson's and spinal cord injuries, the researchers said.
David Anderson and colleagues at the Howard Hughes Medical Institute in
Pasadena, California used a method that has been used in the past to
isolate stem cells from the blood -- which are used to treat a range of
diseases including leukemia and sickle cell anemia.
Blood stem cells give rise to all the different kinds of cells in the
blood, including immune cells that fight infection and cancer. They can
replace cells destroyed by harsh cancer treatments, for instance.
Similarly, neural stem cells should be useful for treating Parkinson's
disease, an incurable and fatal illness caused by the loss of cells that
produce the chemical dopamine in the brain, or for mending nerve
injuries.
But neural stem cells have been harder to find.
``All of us who work on neural stem cells have previously obtained these
cells by putting pieces of tissue into Petri dishes and waiting for
cells to grow out of the tissues,'' Anderson said in a statement.
``But that has always left the worry that maybe these cells behave
differently in the animal.''
Scientists have long known there are ``nursery cells'' throughout the
body that retain the ability to become any kind of cell, unlike the vast
majority of cells which divide to become identical clones of themselves.
Thus most neurons can give rise only to other neurons.
These stem cells are different from the embryonic stem cells that have
made news lately because of their controversial source -- aborted
fetuses or embryos left over from fertility treatments.
Embryonic stem cells are pluripotent -- they can give rise to any kind
of cell in the body at all. But differentiated stem cells, such as the
neural cells, can usually only become nerve cells -- although one
researcher said recently he had coaxed them into becoming
blood-producing stem cells.
Finding these stem cells has not been easy, because they look very much
like normal cells.
But writing in the journal Cell, Anderson's team said they used a method
that has succeeded in teasing out blood stem cells by finding certain
markers on their surfaces.
``The key is that we can now study these stem cells in a way that they
haven't been studied before,'' Anderson said.
And they found some strange things about the stem cells. For one thing,
they stay around for a long time -- long enough to possibly be involved
in some kinds of cancers such as neurofibromatosis or ``Elephant man
disease''.
``The more we understand about stem cells and why they persist, the more
likely we'll be able to stop them from growing if they become
cancerous,'' Anderson said.
--
Judith Richards, London, Ontario, Canada
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