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Stem Cells. What is a Stem Cell?. General. Specific. Unspecialized cells Give rise to more than 250 specialized cells in the body Serve as the body’s repair system. Self-Renewal Differentiation (specialization). http://www.nih.gov/news/stemcell/figure5.jpg. Two “types” of stem cells. - PowerPoint PPT Presentation
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What is a Stem Cell?What is a Stem Cell?
General Specific Unspecialized cells Give rise to more
than 250 specialized cells in the body
Serve as the body’s repair system
Self-Renewal Differentiation
(specialization)
4http://www.nih.gov/news/stemcell/figure5.jpg
Two “types” of stem cellsTwo “types” of stem cells
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•Embryonic (ES)
•Adult (non-embryonic) (AS)
Stem Cells differ byStem Cells differ by Origin
Embryonic Adult
Different “potentials” Totipotent Pluripotent Multipotent
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Origin determines potential
PotentialsPotentials
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Totipotent - having unlimited capability. Totipotent cells have the capacity to specialize into extraembryonic membranes and all cells of the embryo. Pluripotent -capable of giving rise to most tissues of an organism. Multipotent -capable of giving rise to many tissues of an organism.
DefinitionsDefinitions
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Stem cells – undifferentiated cells that have the ability to: divide for indefinite periods in culture to become specialized cells
Differentiation – the process whereby cells become
specialized Produces stems cells with decreasing
potential
Embryonic Stem Cells Embryonic Stem Cells (ESC)(ESC)1. Embryos are the result of In Vitro
Fertilization (IVF)2. Cells are taken from the Inner Cell Mass
(ICM) of a blastocyst3. ICM cells are nourished in a petri dish in an
incubator4. Cells are given different types of
Factors/chemicalsThese cells can give rise to most types of cells
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In Vitro Fertilization In Vitro Fertilization (IVF)(IVF)1. Eggs are removed from ovary of female 2. Sperm is obtained from male3. Egg and sperm are combined in test
tubes/Petri dish4. Fertilized eggs (zygotes) are allowed to
divide for a few days.5. Blastocysts are then transferred to uterus
of womanWhat happens to left over embryos?
Frozen until used again Discarded*
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In Vitro FertilizationIn Vitro Fertilization
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Fertilization
+
The zygote dividesThe zygote divides
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Each cell is totipotent
Blastocyst formationBlastocyst formation
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The 1st sign of differentiation
Blastocyst
BlastocystBlastocyst
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Inner Cell Mass (ICM)
TrophoblastGives rise to an embryo under proper conditionsThese are
now Pluripotent stem cells
Embryonic Stem CellsEmbryonic Stem Cells
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Cell differentiationCell differentiation
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Pluripotent stem cell
(Embryonic stem cell)
Multipotent stem cells
(Adult stem cell)
Differentiated cells(muscle, nerve, skin, fibroblast, etc)
Differenti
ationDifferentiation
Can divide
Differentiation
Differentiation
Can divide
Can divide
Adult Stem CellsAdult Stem Cells
Adult tissues reported to contain stem cells include: brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin and liver.
There are a very small number of stem cells in each tissue
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Why is research on Why is research on embryonic stem embryonic stem cells important?cells important?
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Current IssuesCurrent Issues
Derivation Induced-
pluripotent stem cells
Ethics Challenges
Controlling specialization
Donor acceptance
Importance of Stem CellsImportance of Stem Cells
Perhaps the most important potential application of human stem cells is the generation of cells and tissues that could be used for cell-based therapies.
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http://stemcells.nih.gov/index.asp
Importance of Stem CellsImportance of Stem Cells
Today, donated organs and tissues are often used to replace ailing or destroyed tissue, but the need for transplantable tissues and organs far outweighs the available supply.
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Importance of Stem CellsImportance of Stem Cells
Parkinson’s Disease Loss of dopaminergic
producing nerve cell in substantia nigra
Severe motor disturbance Fetal brain cells and iPS
(reprogramming) http://www.youtube.com/
watch?v=1yCgLythe00
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Importance of Stem CellsImportance of Stem Cells
Alzheimers Disease Dementia Death brain tissue, protein
placques, hippocampus http://www.youtube.com/
watch?v=zgvm_vvqq3I&feature=related
http://www.youtube.com/watch?v=TZA3QFliteA&feature=related
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Importance of Stem CellsImportance of Stem Cells
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http://www.youtube.com/watch?v=vwCrxomPbtY
http://www.youtube.com/watch?v=ADchGO-0kGo&feature=related