Most of us have heard of stem cells. Over the last
decade or so, these amazing, changeable cells — among nature's greatest
chameleons — have achieved a certain wistful place in medicine.
The idea is that if these cells can become, or be turned into, other
cells, then maybe one day they could be used to replace vital cells
that are tragically missing in such devastating diseases as Alzheimer's.
Stem cells made in
bone marrow apparently make
house calls. They travel to the
injured organ, and turn into
that organ’s particular cells.
This is not always good.
But new research suggests that stem cells don't
always play the hero. Sometimes, when these cells are injured —
or maybe even simply inflamed — they can progress to become cancer.
"Stem cells are rare, but they're found in each organ in the body,"
says Ganesh S. Palapattu, M.D., a former postdoctoral fellow in
the laboratory of Hopkins scientist William G. Nelson, M.D., Ph.D.,
and now on the faculty at the University of Rochester. Their main
job is to serve as genetic understudies — turning into, and playing
the role of, specific cells if needed, so that an organ can keep
doing its job. "However, if the stem cells present in an organ suffer
genetic damage, these damaged cells may progress to become cancer."
Chameleon cell. This is
a prostate epithelial cell — now. But it began its life as
a stem cell in the bone
marrow. The green area shows the presence of a protein made only
by bone marrow cells. The red shows
a protein made by prostate epithelial cells, and the blue shows
the cell’s nucleus.
Stem cells made in the bone marrow appear to be
even more versatile and generic pinch-hitters. If tissue in certain
organs is injured, bone marrow stem cells apparently make house
calls — they travel to the injured organ, and turn into that organ's
particular cells. Scientists aren't sure how this phenomenon happens
— whether the bone marrow stem cells turn into the specialized cells
directly, or whether they fuse to other cells in the organ — but
it's been seen in several organs. Can stem cells from the bone marrow
form new cells in the prostate? Brady researchers Palapattu, Alan
Meeker, Ph.D., Nelson, and colleagues found out that they can. In
research published in the Journal of Urology, they found that in
mice given a virus that causes inflammatory damage and tissue repair
in the prostate, bone marrow stem cells appeared.
Some of the specific cells they produced were epithelial
cells — cells of the tissue that lines the prostate, and protects
it from the outside. What might these findings tell us about how
prostate cancer develops? In 2004, a research team reported that
bone marrow cells could give rise to epithelial cells in the stomach,
in response to infection with Helicobacter, a form of bacteria that
leads to stomach cancer. In their experiments, the bone marrow-derived
stomach cells were the cells that progressed to become cancerous.
Much of the Brady's research in recent years has turned up increasing
evidence that inflammation and infection play a role in prostate
cancer. The bone marrow-stem cell link may be another piece in this
puzzle. It may be, says Palapattu, "that bone marrowderived prostate
cells appearing in infected or inflamed prostates might be at risk
to progress to prostate cancer."