stemcells notes
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Morality of Stem Cells
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Stem Cells
Definition of stem cells Stem cells are pluripotent cells that can produce
many different kinds of cells. A fertilized egg isomnipotent, i.e. can produce all cells.
Different kinds of stem cells Embryonic stem cells come from embryos ( 6 weeks)
Stem cells are present in some adult tissues,including brain, spinal cord, and bone marrow.
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Embryonic vs. Adult Stem Cells
Embryonic stem cells
Embryonic cells are
pluripotent and virtually
immortal. Embryonic stem cells can
form tumors called
teratomas.
Several methods are now
available to controlgrowth of embryonic
stem cells.
Adult stem cells Adult stem cells also
have the capacity to
produce many differentcell types, includingneurons.
A persons own stemcells should be the bestsource of cells for
transplantation Adult stem cells will
eventually substitute forembryonic stem cells.
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Embryonic Stem Cells
Adapted from the New York Times
18 December 2001
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Fetal Stem Cells
Neurosphere
from rat brain
Nestin stain BRDU stain
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The Stem Cell Debate
On August 9, 2001, President George Bush announced that NIHwill fund human embryonic stem cell (HESC) research for thefirst time. The research will be restricted to 72 cell lines derivedfrom surplus fertilized embryos before August 9.
Both opponents and supporters of HESC research are unhappywith the ruling. Opponents believe that federal funding ofhuman ESC research will open a Pandoras box leading to babyand organ factories. Supporters believe that the restrictions willhold back crucial research that will benefit millions of people.
Researchers have recently found that they can create clonedembryos. Stem cells derived from such embryos have the samegenes and are an ideal source of stem cells for transplantation.Congress, however, is considering a bill that would outlawmaking of cloned embryonic stem cells.
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Importance of Stem Cells
Studies of human embryonicstem cells will lead to majoradvances in human biology
Embryonic stem cell
research will provide criticalinsights into mechanisms ofcell differentiation, growth,and death.
Understanding stem cellsmay provide keys to why
people age. Limitations on the study of
human embryonic stem cellresearch will hold backbiomedical research.
Human embryonic stem celltherapies can save lives andrestore function of people
Human embryonic stem cell
can replace damaged or lostcells
These include diabetes,degenerative neurologicaldiseases, demyelinativediseases, brain & spinal
cord injury. These conditions are the
most common and costlycauses of disability in theUnited States.
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Opposition to HESC Research
Killing human embryos isunacceptable
Use and study of humanembryonic stem cells will
require destruction ofhuman embryos.
Killing human embryos isunacceptable, no matterhow much good suchresearch will bring about.
The facts that embryos willdie anyway and that manypeople would benefit fromthe therapies do not justifykilling embryos. The enddoes not justify the means.
Embryonic stem celltherapies are not necessary
Adult and other sources ofstem cells, i.e. umbilical
blood or bone marrow stemcells can be used.
Many studies suggest thatstem cells from thesesources are beneficial inanimal disease models
Embryonic stem cells mayform tumors whereas adultstem cells have limitedgrowth potential and areless likely to producecancers.
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Common Misconceptions
Human embryonic stem cellresearch encourages abortions.
The proposed NIH research willuse frozen fertilized eggs, not
aborted fetuses. The fertilized eggs are used
with permission of the parentswho would otherwise discardthem.
Availability of human embryonic
stem cells should reduce thecurrent need for and use ofhuman fetal tissues to treatParkinsons disease and otherconditions.
The research will increasekilling of human embryos.
The proposed NIH researchwill not create or clone
human embryos. Only fertilized eggs that
were already been createdfor the purposes ofin vitrofertilization are used.
Availability of this source of
stem cells should reducecurrent unrestricted creationand destruction of humanembryos for their stem cells.
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More Misconceptions
Embryonic stem cells comefrom embryos that canbecome adults
Thousands of fertilized eggs
are being discarded fromfertility and not being usedfor research or therapy
Many fertilized eggs havebeen stored beyond thetime when they are suitable
for producing embryos. Many parents do not want
their eggs to be adoptedby others.
Embryonic stem cells comefrom embryos withrecognizable body parts
Embryonic stem cells come
from blastocysts (2 weeks),little round balls of cells withno discernible organs orbody parts.
The blastocysts are neverimplanted into a uterus.
Embryos form only after thenotochord appears at about2 weeks. Embryos becomefetuses at 6 weeks.
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Current Situation
Current laws do not regulate
embryo production or use by
private companies
Many companies producestem cells from human
embryos created for this
purpose.
Some private organizations
are developing stem cells
from aborted fetuses. Some companies are even
cloning human embryos to
develop stem cell lines.
Most human embryonic stem
lines belong to private
companies.
Companies therefore mustdevelop their own lines if
they want to do human stem
cell research.
A public source of human
embryonic stem cells should
significantly reduce thenumber of embryos that are
created and destroyed for
their stem cells.
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Stem Cells vs non-Stem Cells
Stem cell therapies willrevolutionize medicine.
The current generation ofdoctors will be the first to
use stem cell transplants torepair and replace tissues.
Genetically modified stemcells can deliver molecules.For example, insulin-secreting cells may replace
life-time insulin injections. Stem cells are important
class of transplantable cellsbecause they are robustand produce many celltypes.
Non-stem cells may bebetter for some purposes
Genetically modifiedfibroblasts, for example,
have already been shown todeliver gene products
Mixtures of progenitor cellsthat produce only one kindof cell may be more easy tocontrol than stem cells.
Some specialized cells mayhave advantages over stemcells. For example, Sertolicells have anti-immuneproperties.
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Human Cloning
http://news.bbc.co.uk/hi/english/sci/tech/newsid_371000/371378.stm
First human clone by
placing human nucleus into
a cows egg and growing itto 32-cell stage.
Nov 1997
Scientific American article reporting the
first cloned human embryo showing a
fertilized cloned oocyte and cumuluscells. Advanced Cell Technology
Nov 24, 2001
http://www.sciam.com/explorations/2001/112401ezzell/
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Religious Positions
Human embryonic stem cells are immoral The Catholic and Greek Orthodox Churches believe that
embryos are potential humans. Even if embryos are being
destroyed for other reasons, their use is immoral. Research and use of early embryos is not immoral
The Synod (Protestant) believes that human embryonicresearch is not immoral if it occurs before implantation
Islamic schools do not recognize early embryos as moral
persons and have no difficulty with use and study of them. Life-saving research is a moral obligation
The Jewish faith believes that saving human lives is a moralobligation and a divine mandate as long as care is taken toensure that the process is fair to all parties involved.
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Philosophical Positions
The wisdom of repugnance argument Dr. Leon Kass applied this phrase to therapeutic cloning,
meaning that we know, deep down, that it is immoral tocreate human embryos to use them.
The sanctity of life argument Some philosophers have invoked the sanctity of life as an
argument against using embryonic stem cells. This reducesthe question to our definition of life and a person.
The respect for the embryo argument Human life demands respect. While it is not disrespectful to
use an organ from a dead person, some argue that it isdisrespectful to create an embryo and kill it for its stem cells
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A Better Compromise
Allow NIH to use stem cells derived from fertilizedeggs under a strict guideline of demonstrated need. This provides sufficient diversity for therapy.
It will reduce the embryos use by private companies. Ban implant of non-fertilized eggs into human uterus
This ban on reproductive cloning is eminently enforceable.
It would allow cloning of eggs for infertile women.
Allow therapeutic cloning with a sunset clause This provides a temporary solution until adult stem cells and
other alternatives can be developed
It will prevent the flight of stem cell and cloning researchoverseas
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Conclusions
Both sides of the debate share the same goal:minimize creation and destruction of human embryoswhile accelerating stem cell therapies
The current policy of limiting stem cells createdbefore August 9, 2001 will encourage unregulateduse of embryos while delaying stem cell therapies
Proposed anti-cloning legislation banning therapeuticcloning is not enforceable, delays stem cell therapies,and will drive scientists and companies overseas
A better policy would be to allow NIH to use newstem cell lines, ban reproductive cloning, and allowtherapeutic cloning with a sunset clause