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 tissue specific structures that allow it to perform specialized functions  Self-renewal  Dividing into the same non specialized 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

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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

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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?

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Human potential and humanity

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Survival outside the womb Undifferentiated Heart beat, brain activity

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Individuality

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Potentially two or half

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Efficiency

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IVF, abortion clinics Existing stem cell lines