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STEM CELL RESEARCH - Basics
M. Arshad Chaudhry, Ph.D.
Michael Smith Laboratories
UBC, Vancouver
[email protected]
Outline of This Presentation
• Stem cell research
• The nature and promise of stem cell
research
• The ethical debate
What Are Stem Cells?
Stem cells are the raw material from which
all of the body’s mature, differentiated cells
are made. Stem cells give rise to brain
cells, nerve cells, heart cells, pancreatic
cells, etc.
What’s So Special About Stem
Cells?
They have the potential to replace cell tissue that has
been damaged or destroyed by severe illnesses.
They can replicate themselves over and over for a very
long time.
Understanding how stem cells develop into healthy and
diseased cells will assist the search for cures.
Two Kinds of Stem Cells
Embryonic (also called “pluripotent”)
stem cells are capable of developing into
all the cell types of the body.
Adult stem cells are less versatile and
more difficult to identify, isolate, and
purify.
Stages of Early Embryonic Development
Stages of Early Embryonic Development
Embryonic Stem Cells:
Researchers extract stem cells from a 5-7 days old blastocyst.
Stem cells can divide in culture to form more of their own kind,
thereby creating a stem cell line.
The research aims to induce these cells to generate healthy
tissue needed by patients.
Two Sources of
Embryonic Stem Cells
1. Excess fertilized eggs from IVF (in-vitro
fertilization) clinics
2. Therapeutic cloning (somatic cell nuclear
transfer)
Tens of thousands
of frozen embryos
are routinely
destroyed when
couples finish their
treatment.
These surplus
embryos can be used
to produce stem cells.
Regenerative
medical research
aims to develop these
cells into new, healthy
tissue to heal severe
illnesses.
Somatic Cell Nuclear
Transfer
The nucleus of a donated
egg is removed and
replaced with the nucleus
of a mature, "somatic cell"
(a skin cell, for example).
No sperm is involved in
this process, and no
embryo is created to be
implanted in a woman’s
womb.
The resulting stem cells
can potentially develop into
specialized cells that are
useful for treating severe
illnesses.
Adult Stem Cells
• Fundamental feature of adult stem cells
– They maintain the ability to divide throughout
life and give rise to specific cell type
• Blood vessel stem cells can not give rise to brain or heart
muscle cells
– The fact that developmental potential of adult
stem cells is restricted has recently been
challenged
• Why some tissues maintain stem cells and
others don’t is not understood
In favor of ESCR:
The Ethical Debate
Embryonic stem cell research (ESCR) fulfills the ethical obligation to
alleviate human suffering.
• Since excess IVF embryos will be discarded anyway, isn’t it better that
they be used in valuable research?
• SCNT (Therapeutic Cloning) produces cells in a petri dish, not a
pregnancy.
Against ESCR:
In ESCR, stem cells are taken from a human blastocyst, which is then
destroyed. This amounts to “murder.”
• There is a risk of commercial exploitation of the human participants in
ESCR.
• Slippery slope argument: ESCR will lead to reproductive cloning.
Key Ethical Issues
• The blastocyst used in stem cell research is
microscopically small and has no nervous
system. Does it count as a “person” who has a
right to life?
• What do various religions say about when
personhood begins? Does science have a view
on this?
• In a society where citizens hold diverse religious
views, how can we democratically make humane
public policy?
Stem Cell Research Worldwide