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Oct. 16 — Can adult stem cells cure
any diseases?
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Response
by Fernando Camargo
Whitehead Fellow |
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The answer to this question is a resounding yes. Stem
cells within the bone marrow can give rise to all the
cells of our immune system, red cells and platelets.
Therefore, a wide range of genetic diseases, including
immunodeficiencies and anemic disorders, can be treated
successfully with bone marrow transplants.
Additionally, in cancers of the blood and immune system,
such as leukemias or lymphomas, intensive use of chemotherapy
or radiation destroys normal bone marrow along with
tumor cells. Therefore, replacement of blood forming
stem cells is necessary for the patient to survive and
is achieved through transplantation of bone marrow cells
from an immunologically-matched donor. Bone marrow transplants
are FDA-approved and routinely performed. They have
already saved thousands of lives. The Nobel Prize in
Medicine in 1990 was actually awarded to two pioneers
in the field of bone marrow transplants, Donnall Thomas
and Joseph Murray.
Another type of bone marrow adult stem cell, the mesenchymal
stem cell, has recently entered the therapeutic scene.
This cell type can become muscle, bone, cartilage or
fat and has some ability to modify immune function in
certain experimental models. It has therefore become
a cell of intense interest for treating musculoskeletal
abnormalities, cardiac disease and some abnormalities
of immunity (such as graft-versus-host disease after
bone marrow transplant). There are ongoing studies to
test the role of this cell type, some of which have
been quite encouraging. However, mesenchymal stem cell
therapy has not yet been shown to have a clear-cut advantage
over existing therapies, is not considered a standard
of care for any condition and does not have regulatory
approval for the routine treatment of any disease. Therapeutic
use of these cells is currently limited to clinical
research studies.
There is also a significant body of work that suggests
that transplantation of neural stem cells could be very
beneficial for the treatment of some neurodegenerative
diseases such as Parkinson’s. However, most of
these studies have been performed in small animals models
and their results await validation in primate models.
One of the obstacles for performing this procedure is
the source of donor cells. Adult neural stem cells,
unlike bone marrow cells, cannot be obtained from a
simple biopsy, so from a clinical perspective it would
be very difficult to obtain large enough quantities
of them to even perform clinical trials.
In conclusion, adult stem cell therapies are powerful,
but they are not as wide-ranging as claimed. There are
a narrow range of diseases for which the therapies are
extremely valuable, enormously encouraging evidence
for the potential of stem cell research to positively
impact people’s lives.
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