Transcript Stem Cells and Society: Ethics and Advances

Cristian Aguilar
NSF-GK12
Workshop II
12/4/10
What are Stem Cells?
 Stem Cells have 3 general
properties that make them
unique among other cell
types.
 Unspecialized
 Capable of self-renewal over
long periods of time
 Can give rise to specialized
cell types
What are Stem Cells?
 Unspecialized
 Does not have any tissuespecific structures that allow
it to perform specialized
functions
 Self-renewal
 Dividing into the same nonspecialized cell type over
long periods
 Can give rise to specialized
cell types
 Differentiation to carry out
specific functions
Embryonic Stem Cells
 Derived from embryos that
develop from eggs that have
been fertilized in vitro
 Pre-implantation stage embryo
cells are cultured in the
presence of mouse skin cells
and a special culture medium.
Embryonic Stem Cells
 Diseases that might be treated
by transplanting cells
generated from human
embryonic stem cells include
Parkinson’s disease, diabetes,
traumatic spinal cord injury,
Duchenne’s muscular
dystrophy, heart disease, and
vision and hearing loss.
Adult Stem Cells
 Undifferentiated cells found among differentiated cells in
a tissue or organ
 Can differentiate to yield some or all of the major
specialized cell types of the tissue or organ
 Role: To maintain and repair the
tissue in which they are found
 Stem cells may remain quiescent
for long periods of time until they
are activated by a normal need
for more cells to maintain tissues,
or by disease or tissue injury.
Adult Stem Cells
 There are very small numbers of stem cells in each tissue
 Once removed from the body, their capacity to divide is
limited
Embryonic vs. Adult Stem Cells
 Embryonic Stem Cells
 Can become all cell
types of the body
because they are
totipotent
 Can be grown relatively
easily in culture
 Unknown whether
tissues derived from
embryonic stem cells
would cause transplant
rejection
 Adult Stem Cells
 Thought to be limited to
differentiating into
different cell types of
their tissue of origin
 Rare in mature tissues –
isolation and culture are
challenging
 Believed less likely to
initiate rejection after
transplantation
Induced Pluripotent Stem Cells
 Genetically reprogrammed to an embryonic stem cell–
like state
 Oct4, Sox2, Nanog
 Express stem cell markers and are capable of
generating cells characteristic of all three germ layers
 Hoped to be used in
transplantation medicine
 Viral gene introduction can
lead to cancer formation
 Likely to avoid rejection by the
immune system
The [Potential] Uses for Stem Cells
 hESCs may yield insight into early human
development
 Further understanding of normal cell division and
differentiation
 Testing of new drugs
 Cell-based therapies
Technical Considerations
 Proliferate extensively and generate sufficient





quantities of tissue
Differentiate into the desired cell types
Survive in the recipient after transplant
Integrate into the surrounding tissue after transplant
Function appropriately for the duration of the
recipient's life
Avoid harming the recipient in any way
The Stem Cell Debate
 When does life actually begin?
 The Southern Baptist Convention opposes human embryonic stem
cell research on the grounds that "Bible teaches that human beings are
made in the image and likeness of God (Gen. 1:27; 9:6) and protectable
human life begins at fertilization."
 The Catholic Church affirms that "the killing of innocent human
creatures, even if carried out to help others, constitutes an absolutely
unacceptable act." The Church, however, supports research that
involves stem cells from adult tissues and the umbilical cord, as it
"involves no harm to human beings at any state of development."
 The United Methodist Church stands in "opposition to the creation
of embryos for the sake of research" as "a human embryo, even at its
earliest stages, commands our reverence.”
 The Assemblies of God opposes the "the practice of cultivating stem
cells from the tissue of aborted fetuses" because it "perpetuates the evil
of abortion and should be prohibited.“
 Value of life
 The Pontifical Academy for Life has stated that human blastocysts are
inherently valuable and should not be voluntarily destroyed as they are
"from the moment of the union of the gametes" human subjects with
well defined identities.
The Stem Cell Debate
 When does life actually begin?
 Human potential and humanity
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Survival outside the womb
Undifferentiated
Heart beat, brain activity
 Individuality

Potentially two or half
 Efficiency

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IVF, abortion clinics
Existing stem cell lines