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Stem Cells
What are Stem Cells?
• Stem Cells: Cells that can turn into specific
types of cells (neurons, skin cells, etc.)
– Adult: held somewhere in body; replace
skin, intestinal, and blood cells
– Embryonic: come from fertilized eggs
Adult Stem Cells
• Multipotent: can become only a few cell
types
• Replace constantly dying cells (skin,
intestines, blood)
• Scientists are able to turn adult stem cells
into embryonic stem cells by inserting
genes into them!
– This became necessary when embryonic
stem cell research was banned in 2000
Embryonic Stem Cells
Totipotent: “The Mother of All Stem Cells”
- Can give rise to any cell type
- Fertilized egg or a few divisions later
Pluripotent: “Stem Cell Lines”
- Can give rise to 200 cell types
- Blastocyst (Day 4 after fertilization)
- Stem Cell Lines come from unused
blastocysts from In-Vitro procedures
Day 1 Fertilized Egg:
Totipotent
Day 4 Blastocyst:
Pluripotent
Potential Uses of Stem Cells
• Embryonic Stem Cells could be used for:
– Growing replacement cells and organs
Parkinson’s and Alzheimer’s diseases, spinal
cord injuries, stroke, heart disease, type I
diabetes, arthritis…
Potential Uses of Stem Cells
• Drug Testing: Grow
liver cells to test the
effects of a drug on
the liver, for ex.
• Research how genes
are turned on and
turned into organs,
etc.
– Prevent cancer, birth
defects
U.S. Battle over Stem Cells
• 2000: Gov’t. begins to only fund research
on existing stem cell lines
• 2004: House passes bill to fund research
with new stem cell lines; Bush vetoes
• 2007: House and Senate pass bill to fund
research again; Bush vetoes
• 2009: Obama overturns 2000 decision