Transcript Stem Cells from Skin Cells?!?

All cells in a person have the same DNA
Yet eye cells differ from nose cells
Central dogma of biology
Genetic
engineeri
ng
DN
RNA
A
Niche
factors
Tissue
therapy
Protein
Cell
type
Matrix Molecules
Self-Renewal
Soluble Factors
Other Cells
Differentiation
Little, et al. Chemical Reviews (2008).
Low stress levels
 Regular exercise
 Enriching experiences
 Learning new information
 Healthy diets: rich in antioxidants
 Avoid excessive drinking

Skin cells
iPS cells
Are fully differentiated cells
 Can not become any other cell type
 Can only divide to make more
fibroblasts
 Contact inhibition

Randomly inserts DNA into genome of
cells
 Can make special retroviruses with
whatever gene you want
 Can’t really control how
many copies of genes

Only turn on a drug resistance gene
when stem cell state
 Do this by using a gene that is only
expressed in stem cells
 Add drug resistance to promoter region
of that gene
 Takes around 16 days for resistance gene
to be expressed- some secondary
change

Sox2- Self Renewal
 Oct4- Differentiation switch
 Klf4- p53 pathway, Oncogene
 c-Myc- Global Histone Acetylation,
Oncogene

Without Oct 3/4 or Klf: no colonies
 Without Sox2: rough morphology
 Without c-Myc: flatter cells, now know
actually can do without c-myc-just very
low efficiency

Tried to inject into blastocyst to make
baby mice but failed
 Final and best test of pluripotency

Still working with mouse model
 Used different drug selection marker
 Same 4 genes
 Much more closely resemble ES cells

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Treatment of DNA with bisulfite converts cytosine residues to uracil,
but leaves 5-methylcytosine residues unaffected
Introduces specific changes in the DNA sequence that depend on the
methylation status of individual cytosine residues
Used Oct3/4, Sox2, Nanog and Lin28
Used the animal’s own cells- no immune
rejection!
 Transfected with all four genes, but cmyc taken out after time- prevent
tumors!
 Sickle Cell Anemia has known genetic
basis-so target that gene and change it
back to normal!
 Inject it back into the animal after
radiation to reconstitute the whole blood
system!

Any disease with a single genetic
mutation could be easily cured!
 Tissue regeneration after accidents or
diseases
 “Nanobots”
 Companies have already started testing
iPS for therapy

No way FDA will approve a therapy with
an oncogene
 Use of retroviruses can lead to mutations
and cancers
 So many changes in the DNA can be
harmful
 Probably hard to target to some areas
