Stem cells (and how to make your own)
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Transcript of Stem cells (and how to make your own)
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Stem cells Stem cells (and how to make your own)(and how to make your own)
Mr DareTSI Friday
Feb 111.30 in S1
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What are stem cells?What are stem cells?
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What can they do?What can they do?
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Why can’t all our cells do this?Why can’t all our cells do this?
• Pluripotency genes are switched off• Why?• So you get…• How?• Epigenetics!
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Transcription is controlled by chemically changing the DNA
• Transcription is controlled by promoter regions of DNA
• A protein called a transcription factor binds allowing transcription
• Promoter regions for pluripotency genes are turned off in two ways;
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1 – methylating the DNA
• Genes are switched off by methylation of the DNA at the TF binding site
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2 – wrapping the DNA around the histones more tightly
• DNA is negatively charged – keeping positive charges on the histones locks up the DNA
Acetyl groups remove the positive charge from the histones
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So…So…• Our cells can’t
go back uphill• They lose
pluripotency – the master switches are turned off
• But is it gone for good?
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Dr Shinya Yamanaka
New master New master switchesswitches
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What effect did this have?What effect did this have?MEF cells – stem cells for skin
Mouse embryonic stem cell (MES) colony
The product – skin cells transformed into cells which are just like ES cells
But will they act like ES cells – will they have pluripotency?
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• Question…Question…• What’s the best container for What’s the best container for
growing mouse cells?growing mouse cells?• Answer…Answer…
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SCID mice with teratomas from injected transformed cells
So it looks like these cells are pluripotent
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• These newly transformed pluripotent cells are called – Induced pluripotent stem cells– (or iPS cells for short)
• And we know we can get whole organisms from these iPS cells because…
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Generation of ES cells
zona
Trophoectoderm Inner cell mass
ES cells are pluripotentialES cells provide the system where we are able to modify the genome
MAC3 ES cells
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What if we stick cells back into an embryo?
ChimaerasiPS cells from black mouse
ES cells from white mouse
Return to pseudopregnant fosters
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This mouse works! But can we get a whole mouse from iPS cells?
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Great – can we do it with humans?Great – can we do it with humans?
• Yes! Here it is!
Human dermofibroblasts
(HDF’s)
Transformed HDF’s making colony just like
an ES cell colony
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• We can now turn ordinary skin cells into…– Cardiac tissue– Liver cells– Muscle cells– Neural cells– Blood cells– Back into skin cells– http://www.youtube.com/watch?v=IjU81a5TjZs&f
eature=fvw
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But there are some big problemsBut there are some big problems
• The pluripotency genes are turned off during development for a reason
• Mice produced from iPS cells very often died of cancer
• If you can find a safe way of using iPS cells therapeutically, you will win a Nobel prize