Embryonic Stem Cells and Therapeutic Cloning
Matthew B. Wheeler Department of Animal Sciences University of Illinois
Definitions
STEM CELL: • Primordial or progenitor cell that is capable of differentiating or changing in to one or more different cell types. Examples: • Hemapoetic stem cells produce all the blood cells • Neuronal stem cells produce all nerve cell types • Spermatogonia produce sperm • One-cell embryo produces all cells of the body
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Definitions
EMBRYONIC STEM (ES)CELLS: • Stem cells derived from the inner cell mass of embryos approximately 7 days after fertilization, also know as blastocysts. • Produce all the cells of the body
Embryonic Stem Cell Utility
• Can be mixed with other cells including ES cells to make chimeras • Can be differentiated to make cells and tissues for tissue engineering or tissue repair • Can be genetically altered to repair genetic defects or genetic diseases
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Definitions
CHIMERA: • An animal from Greek mythology that has the head of a lion, body of a goat and tail of a serpent. • An individual with a mixture of at least two genetically different cell types, a mosaic.
Examples of Chimeras
Nature and Medicine: - fraternal twins - blood transfusion - bone marrow or organ transplant - a virus-infected cell, “chicken-pox”, or cold sore - a cancerous tumor Experimental: - chimeric animals - tissue engineering - gene therapy - cancer models
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A photograph of a sheep - goat chimera.
- This animal contains cells from both a sheep and a goat embryo. - Cells from two genetically distinct species can work together for the good of the individual animal.
Embryo Development and Embryonic Stem (ES) Cell Isolation
EIGHT-CELL EMBRYO EIGHT-CELL EMBRYO MORULA MORULA BLASTOCYST BLASTOCYST
CHIMERA CHIMERA
ISOLATED ISOLATED ES CELLS ES CELLS
INNER CELL INNER CELL MASS (ICM) MASS (ICM)
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Swine Embryonic Stem (ES) Cells on a Mouse Embryonic Fibroblast (STO) Feeder Layer
ES Cell Colony
Fibroblasts
Blastocyst Injection of Embryonic Stem (ES) Cells
Trophoblast Micropipette
* * * * * * * * * * * * *
Inner Cell Mass (ICM)
Transformed ES cells
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Injection of Porcine Embryonic Stem Cells into a Day 7 Pig Embryo
A Litter Containing 7 Chimeric Piglets
Chimeric Pigs
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Example of a Porcine Chimera Produced from Embryonic Stem Cells
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ES Cell Colony
Human Embryonic Stem (ES) Cells on a Fibroblast Feeder Layer
Fibroblasts
Now a reality!
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Cloning
• Producing genetically identical copies
Which one is not a clone?
d. a. f.
b.
e. g. h.
c.
f.
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Cloned early-stage human embryos—and human embryos generated only from eggs, in process called parthenogenesis—now put therapeutic cloning within reach.
From Cibelli et al., Sci. Am. January 2002, 44-51.
From Cibelli et al., Sci. Am. January 2002, 44-51.
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From Cibelli et al., Sci. Am. January 2002, 44-51.
From Cibelli et al., Sci. Am. January 2002, 44-51.
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Tissue Engineering With Stem Cells
Photographs of Porcine Adipose-Derived Stem Cells(ADSCs) Cultured In Vitro.
Panel A: Second passage ADSCs. Panel B: Osteogenic differentiation was confirmed with alkaline phosphatase staining. Panel C: Osteogenic nodule staining for calcium using von Kossa staining. Panel D: Chondrogenic differentiation was confirmed with toludine blue staining. Panel E: Early differentiated adipose unstained. Panel F: Adipogenic differentiation was confirmed with Oil Red O staining.
Stem cells Bone
Bone
Cartilage
Adipose
(Early)
Adipose
(Mature)
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Derivation of many cells and tissues may be possible.
Biomedical devices are an alternative to tissue engineering. Such devices may also complement engineered tissues and cells.
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The key question is how fast and how carefully we will embrace biotechnology? The breathtaking speed of its introduction is part of what’s stirring up much of the apprehension.
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