Stem Cells: Scientific Potential and Alternatives

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Stem Cells Scientific Potential and Alternatives
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Review of Terminology

• DNA -
• Gene - functional unit of heredity, a segment of
  DNA located at a specific site on a chromosome
  genes direct the formation of proteins.
• Nucleus
• Cell - the basic unit of life, all living
  organisms are made up of cells
• somatic cell -
• germ cell -

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Differentiation of Human Tissues

• Early embryonic cells unspecialized
• Three primary tissue layers
• All tissues develop from here

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Adult Stem Cells

• Stem cells cells that have the ability to
  divide for indefinite periods and
• Remember
• Progenitor cells partially specialized cells
  that can give rise

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Stem Cells of the Bone Marrow
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The Problem of Cell Potency

• Multipotent
• Pluripotent
• Totipotent -

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Derivation of hES Cells

• Excess frozen blastocysts donated from
  fertility clinics
• Inner cell mass (embryo) separated from
  trophoblast (placenta)
• Cells dissociated and cultured in laboratory
• Can be made to differentiate using chemical
  signals

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Blastocyst Diagram
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Applications of Pluripotent Stem Cells

• decision-making genes (birth defects, cancer)
• human cell lines for all cell types
• replacement tissue for degenerative conditions
  (Parkinsons and Alzheimers disease, diabetes,
  heart disease, stroke, arthritis)

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Example Diabetes

• Insufficient insulin production in
• Insulin needed for
• cells derived from stem
  cells produce insulin
• Eliminates need for insulin injections

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Scientific Challenges Remaining

• Understanding of cellular events that lead to
  and
• - Can stem
  cells be modified to minimize tissue
  incompatibility?
• Time of development and expense of treatments

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Rejection Possible Solutions

• Genetic engineering
• Somatic cell nuclear transfer (
  )
• develops into a
• Dolly the sheep

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Alternatives to hES Cells

• Umbilical cord blood
• Contains and
  stem cells (lower potency than
  hES)
• Patient specific
• Cord blood banks
• 2000 collection and 125/year storage fees
• Some public banks for donated cells

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Alternatives to hES Cells

• Induced Pluripotent Stem Cells (iPS)

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Alternatives to hES Cells

• Induced Pluripotent Stem Cells (iPS)
• Show potency than cord
  cells
• Low efficiency (recent improvements)
• Other problems

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Alternatives to hES Cells

• Direct Cell Reprogramming - 2011
• Turns one cell
• (ex. Skin cell ? Neuron)
• Uses RNA, no virus DNA needed
• Eliminates need for
• Potential and problems are uncertain

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Autologous Stem Cell Therapies

• Self-donation of
• Injected (with or without chemical treatment)
  into
• Not FDA approved
• Clinical trials underway (heart attack, spinal
  cord injury, etc.)
• Many Americans seek overseas options

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Questions?

• The United States has been criticized by some for
  being too restrictive to stem cell-based research
  and therapies. Should U.S. laws be relaxed to be
  more accommodating to those wishing treatment?
• A recent study by Duke University predicted that
  by the year 2050, regenerative procedures based
  on stem cell and other biotechnologies could
  extend an average human life span by up to 100
  years. Is this a desirable goal?
• Many biotechnologies are vastly expensive, yet
  much of the basic research supporting these
  developments is paid for by taxpayers. Who
  should benefit?