{HYPERLINK "http://dailynews.yahoo.com/h/ap/20000829/sc/stem_cell_primer_1.html"}The researchers say studies of both adult and embryonic stem cells are
needed.
The following is from:
http://dailynews.yahoo.com/h/ap/20000829/sc/stem_cell_primer_1.html
Although there is a copyright notice, yahoo.com has an option to "Email
this story to a friend'', so, assuming this is ok, here it is.
Please let me know if I have harped on this topic for too long!
Phil Tompkins
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Tuesday August 29 5:56 PM ET
Experts: Maintain Stem Cell Research
By PAUL RECER, AP Science Writer
WASHINGTON (AP) - Despite a papal condemnation of embryonic stem
cell research, scientists say it cannot be abandoned because it could lead
to such great medical benefits for millions of patients.
Pope John Paul II said Tuesday that any research that results in the death
or injury of a human embryo is "not morally acceptable'' even though the
work may eventually offer important medical boons.
The Pope urged researchers, instead, to concentrate on stem cells from
adults. Some studies have suggested adult stem cells can be as medically
useful as the stem cells taken from embryos. The adult cell research does
not involve the death of a human embryo.
But American researchers who are studying both the adult cells and the
embryonic cells say that both paths must be followed if the medical
miracles possible from stem cells are to be achieved.
Stem cells became an extremely active area of medical research after early
studies in mice suggested the so-called "master cells'' could restore
damaged nerves, correct some brain diseases, strengthen ailing hearts
and, perhaps, even cure diabetes.
Stem cells are biological building blocks. They are the ancestral cells for all
the body's tissue. Stem cells differentiate, or evolve, into the heart, lung,
skin and all the other organs in the body.
Researchers believe that by learning to direct or control the direction of
change in stem cells they will eventually be able to grow new organs or to
renew ailing body parts with injections of special stem cells.
There are three basic types of stem cells:
-Totipotent stem cells: The single cell formed when an egg is fertilized by
sperm. This cell can develop into a complete individual.
-Pluripotent stem cells: Four days after fertilization, a totipotent cell
develops a hollow sphere called a blastocyst. Within the blastocyst is a
cell mass that includes pluripotent stem cells. Removing pluripotent stem
cells kills the embryo. These cells can be grown in great numbers and
directed to form cells that, in turn, make the tissues in the body, but not a
complete individual.
-Multipotent, or "adult,'' stem cells. These develop from pluripotent stem
cells and some types appear to be produced throughout life. These cells
convert into specific cell types that form organs. Adult stem cells have been
found for blood, nerves and other tissues.
The Pope and other abortion foes oppose research with the pluripotent
stem cells because it requires the death of embryos. A U.S. federal law
forbids government funding of research that results in the death of an
embryo.
However, the National Institutes of Health recently published guidelines that
would permit funding of embryonic stem cell research provided the funds
were not used to kill the embryo. In effect, private researchers would extract
the stem cells from surplus fertility clinic embryos and then pass the cells
along to federally funded researchers.
Some recent studies in mice have shown that adults stem cells are more
flexible than previously believed. Blood stem cells, for instance, have been
converted into nerve, muscle and bone cells. The Pope and others believe
that the promise of this adult stem cell research makes the embryonic
stem cell studies unnecessary.
Most researchers disagree.
"My work deals with adult stem cells,'' says Dr. Bryon Peterson, a
University of Florida, Gainesville, researcher who has grown liver cells from
mouse bone marrow stem cells. "I feel they will eventually be the most
beneficial for patients. But right now we don't know if they will have the
same plasticity (flexibility) as embryonic stem cells.''
Until more is known, said Peterson, "we need to pursue all aspects'' of
stem cell research.
Dr. Ronald D.G. McKay, an adult stem cell researcher at NIH, said recent
studies in mice show that embryonic stem cells can be converted to nerve
or brain cells to treat Parkinson's disease, Alzheimer's disease and other
central nervous system disorders.
"These experiments show that we can get cells of therapeutic interest from
embryonic stem cells, but we don't know if we can get those cells from
another source,'' he said. "In the future, we might be able to get these cells
from other places, and we are looking - really looking.''
Until then, said McKay, "it would be foolish to abandon'' research that offers
such great promise to relieve human misery. "`We can't turn our backs'' on
embryonic stem cell research, he said. "It is just too important.''
Dr. Johnny Huard, a University of Pittsburgh adult stem cell researcher,
said that even if adult stem cells could be used for medical treatment,
embryos may still be the preferred source of stem cells because they are
"of much higher quality.''
"We have compared the number of stem cells from adult mice and from
newborn mice,'' he said. "The quality of the adult stem cells is not as good
as the newborns and we find the number declines over time.''
Also, said Huard, the adult stem cells are more difficult to keep alive and
growing in the laboratory.
"If are going to use stem cells for therapy, we are going to need quality
cells that can grow quickly,'' he said. "I don't think that cells we get from
adults will be able to do what we need them to do.''
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The information contained in the AP News report may not be published,
broadcast, rewritten or redistributed without the prior written authority of The
Associated Press.
