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Scientists achieve cellular transformation of bone marrow
stem cells into nerve cells
By Frank Gaglioti
22 August 2000
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Scientists announced on 15 August that they have transformed
adult bone marrow cells into nerve cells by altering the cells'
environment. The implications are that scientists will be able
to obtain a deeper insight into the process of cell specialisation.
On the basis of this development, medical science may be able
to regenerate nervous tissue and ultimately develop a cure for
diseases which involve degeneration or injury to the nervous system,
such as Alzheimer's and Parkinson's disease. The research was
carried out by scientists at the University of Medicine and Dentistry
of New Jersey (UMDNJ) and published in the Journal of Neuroscience
Research. Ira Black, the head of the research team, stated
that hopefully in the future, these stem cells will be useful
for virtually any disorder that destroys neurons, from stroke
to brain trauma to degenerative diseases such as Parkinson's and
Alzheimer's disease to spinal cord injury.
The scientists isolated stem cells from the bone marrow of
a rat. Stem cells are undifferentiated cells found in various
parts of the body such as in bone marrow, the brain and in an
embryo, which then develop into other cell types. The bone marrow
stem cells used usually give rise to bone, muscle and fat cells.
The scientists achieved the transformation by treating the isolated
stem cells with a mixture of antioxidants and growth factors such
as fibroblast growth factor. Each of the stem cells then divided
into two cellsa stem cell and a nerve cell. The research
team has been able to achieve an 80 percent conversion rate in
the laboratory.
The resulting nerve cells were then placed into the brains
of rats where they formed connections with other nerve cells and
have survived within the rat brain for months without any ill
effect. Scientists have detected the formation of various chemicals
within the cells which are only found in normally functioning
nerve cells. Preliminary studies found that the neurons were capable
of migrating to target sites in the rat's brain. Such cells could
be used to repair brain damage in specific areas of the brain.
The results have been confirmed using similar human stem cells.
Further studies are planned to test the nerve cells in rats
with spinal disorders and Alzheimer's and Parkinson's disease.
Previous studies have indicated that damaged cells send out chemical
signals to which stems cells respond by producing new cells which
migrate to the damaged area and replacing the damaged cells. Black
commented, we know that neural stem cells migrate to areas
in the brain that have been damaged. It appears that the cells
can assume regional functions and actually improve function of
the damaged systems.
The current research is part of the burgeoning field of stem
cell research which has the potential to revolutionise medical
science. Leroy Stevens at the Jackson Laboratory in Bar Harbor,
Maine first proposed the existence of stem cells in 1970 after
observing strange cells in mouse embryos which formed teratomas,
a strange growth made up of various tissues such as bone, skin
and teeth after birth. Stevens named the cells as pluripotent
embryonic stem cells. The term pluripotent is used to indicate
embryonic cells with the ability to form other types of cells.
In fact the embryonic stem cells go on to form the tissue and
organs which make up the body.
In 1998, James Thompson of the University of Wisconsin and
John Gearhart of Johns Hopkins University first isolated embryonic
stem cells in independent experiments. Embryonic stem cells have
been used to generate various types of tissue. Thompson has used
such cells to form heart tissue. Ronald McKay of the National
Institute of Neurological Disorders and Strokes was able to use
nerve tissue produced from embryonic stem cells to partially reverse
the effects of Parkinson's disease in rats.
At first it was felt that each organ had its own stem cells
in the mature organism; for example, skin stem cells replenishing
skin cells and bone marrow stem cells replenishing blood. The
implications of the UMDNJ work and similar recent experiments
is that adult stem cells can be stimulated to transform into any
type of cell given a suitable environment. In April, a research
team from StemCells California Inc. announced they had produced
liver cells from blood stem cells. In June, Rajendra Bhatnagar
at the University of California at San Francisco reported transforming
human skin and gum cells into bone and cartilage.
Potentially scientists will have the ability to produce organs
and tissue from cell cultures which would be available for transplant.
Such transplant material will have the advantage of being produced
from cells taken from the patient, thus avoiding complications
of tissue rejection.
On a more fundamental level, the research into the development
of stem cells will provide an invaluable insight into human development.
After fertilisation all the cells in the earliest stages of embryonic
development are identical. Later, however, a differentiation occurs
with the formation of various cell types which make up the human
body. Scientists are not able to explain why such a differentiation
occurs at all, given that all the cells contain identical genetic
information. What determines whether a stem cell ends up being
a muscle or a blood cell or the myriad of other cells which make
up an individual? The stem cell research will enable scientists
to follow the development of the cells from their very earliest
stages to when the differentiation occurs. This will enable a
greater insight into the formation of cancer and various birth
defects, which are due to abnormal cell division and cell differentiation.
Although stem cell research has made enormous strides in the
last few years it has been held back by the refusal of the Clinton
administration to fund any research using embryonic stem cells.
Most of the stem cell research is funded by private sources. Clinton
has capitulated to pressure from religious groups who oppose the
research on the basis that the embryonic stem cells have the potential
to form a living organism, so claiming that the researchers are
in effect performing an abortion. Such claims are based on religious
bigotry and not scientific fact. The embryonic material is obtained
clinically in tissue laboratory cultures and would not exist otherwise.
In December 1999 the National Institute of Health produced
a draft guideline on stem cell research indicating that limited
funds may be made available in the future.
See Also:
Scientists
isolate elusive embryonic stem cells
[4 December 1998]
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