NEWS: Researchers isolate master cell for bone regeneration

[janet paterson <janet313@xxxxxxxxxxx>]

Researchers isolate master cell for human bone, cartilage regeneration

WASHINGTON (April 1, 1999 3:48 p.m. EST ) -
Researchers have isolated from adult bone marrow a master cell and possibly
have unlocked the secret of bone or cartilage regeneration.

The laboratory discovery now paves the way toward learning to make
replacement parts for ailing or aged bodies, experts say.

The researchers at Osiris Therapeutics in Baltimore report in the journal
Science that they isolated a single cell, called a mesenchymal stem cell,
and then grew it into a colony of more than a million cells that could be
induced to produce bone, cartilage or fat.

Other experts in the rapidly expanding field of stem cell research
applauded the achievement.

"The fact that they can (isolate) a precursor cell like that, and direct it
to produce specific cell types, is quite an advance," said doctor James A.
Thomson of the University of Wisconsin, a noted pioneer in stem cell
research. "It may be that such cells can eventually be used for therapy and
that would be quite exciting."

Stem cells are the body's building blocks. Some, such as pluripotent stem
cells, come only from embryos and their use in research is opposed by many
people.

Other stem cells, such as the mesenchymal cells used by Osiris, are
produced in adults.

But only the pluripotent stem cells from embryos are thought to be capable
of growing into any tissue in the body. The mesenchymal stem cells are the
parent lines for bone, cartilage, fat, tendon and muscle.

The Osiris work helps move stem cell research from the laboratory toward
the clinic, said doctor David J. Anderson, a Howard Hughes Medical
Institute stem cell researcher at the California Institute of Technology.

"If you want to use stem cells to replace damaged tissue, you have to first
know how to differentiate those cells in the lab dish before you put them
into a patient," he said.

In their work, Osiris researchers led by doctor Mark F. Pittenger grew a
single mesenchymal stem cell through more than 20 generations to create
about a million cells.

The researchers then altered the culture medium and added proteins that
caused the specimens to grow into cell families, or lineages, that would
produce bone, tendon or fat, Pittenger said. Other work underway may lead
to producing muscle cell lines.

"We've arrived at conditions that allow us a very strong degree of
control," said Pittenger. "When we direct these cells to the (cartilage)
lineage, almost all of the cells grow to that lineage."

That means it's very likely that researchers will eventually be able to
inject specific types of cells into patients, which then would grow into
replacement bone, tendon or muscle, he said.

Laboratory research on animals is already underway and human studies may be
possible in three years, he said.

If the technique proves successful, researchers predict that precursor
cells for bone could be used to replace tissue lost to cancer,
osteoporosis, injury or dental disease.

Research in rabbits and dogs already has shown that gaps in leg bone caused
by surgery, such as for cancer, can be filled in with tissue grown in the
body from stem cells.

Animal studies also are underway to determine if stem cells injected into
the heart can replace scar tissue caused by heart attack.

The study using adult stem cells is important also because it avoids the
controversy of using stem cells from embryos, Pittenger said.

Congress has banned federal financing of research using human embryos, and
some lawmakers oppose a National Institutes of Health plan to possibly pay
for embryonic stem cell research.

But Thomson, one of the first to isolate stem cells from human embryos,
said that although researchers have proven that some types of stem cells
can be obtained from adults, there is still a scientific need for embryonic
stem cell research.

There are no known adult stem cells for some critical organs, such as
kidney, heart and lung, he noted. If replacements are to be grown for these
parts, Thomson said, it would require embryonic stem cell research.

By PAUL RECER
Copyright 1999 Nando Media
Copyright 1999 Associated Press

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janet paterson - 52 now /41 dx /37 onset - almonte/ontario/canada
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janet313@xxxxxxxxxxx