New Medical Breakthroughs Real Progress or False Promises Stem Cells

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New Medical Breakthroughs -Real Progress or
False Promises? Stem Cells

• Naomi Kleitman, Ph.D.
• National Institute of Neurological Disorders
  Stroke / NIH

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Characteristics of Stem Cells
Embryonic stem (ES) cells Derived from embryo
around time of implantation
Blastocyst
Stem cell
1. Self-Renewal Cells divide indefinitely
without differentiating
Progenitors
2. Pluripotency Cells give rise to different
cell types (3 germ layers)
Ectoderm Mesoderm Endoderm 3
Germ Layers
For example Nerve cell Blood cells
Liver cell
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The Promise of Stem Cell Research
Grow large quantities
As a model of disease Identify drug
targets, test new therapeutics, toxicity testing
As a research tool 1. Understand birth defects
2. Study how cells develop
?
3.
Tissues / cells for transplantation Replacement
or support of host cells
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Will Transplants Fulfill the Promise?

• What are the cells doing?
• Do they survive? Where do they go? Fuse with host
  cells?
• If the cells have an effect, what is it?
• Replacing or supporting host cells?
• Are stem cells the best therapeutic in the long
  run?
• Issues in moving to human testing
• Proof of principle, quality of disease model
• Source of cells, purity, potency
• Are they safe?
• Inflammation, rejection, tumor formation
• Controlling cell fate and release of factors
• Safest to graft cells with limited fate choices

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Selected Examples

• Testing in human diseases
• Blood leukemia, lymphoma, bone marrow
• Heart, skin, cornea
• Issue of underlying disease process
• Nervous system -- animal studies
• Spinal cord examples

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• Stimulate adult progenitors in brain
• hES bridges or myelin
• Replace motor neurons in spinal cord
• ES cells plus 3 strategies

These are complex strategies and long-term goals,
not miracle cures.
Modified from P. Reier
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Further Reading

• NIH - Regenerative Medicine 2006
• http//stemcells.nih.gov/info/scireport/2006report
  .htm
• FAQs http//stemcells.nih.gov/info/faqs.asp
• Selling the Stem Cell Dream
• Science, 14 July 2006, v.313 pg.160-3
• Ready or Not? Human ES Cells Head Toward the
  Clinic
• Science, 10 June 2005, v.308 pg.1534-8
• Its more than just injecting cells
• E.g., replacing spinal cord motor neurons
• http//www.nih.gov/news/pr/jun2006/ninds-20.htm