3. 6 Stem cells Flashcards
scar
occurs in heart and brain. Occurs when we damage the substratum bc we grow back a different type of substratem and collagen may not return to normal
regeneration
if you don’t dammage the substratum. In the liver with minor injury regeneration occurs around the sinusoids. But even in major injury the liver tries to repair so you still get nodules.
continuously dividing/labile cells
epithelium,
bone marrow
quiescent (stable) cells
liver (but if you cut some out it will undergo extensive replication so has the capacity for division)
non-dividing (permanent) cells
neurons, skeletal muscle (lost capacity to divide)
Stem cells
pluripotent cells with prolonged capacity for asymmetrical or stoiciastic division - on cell differentiates other cell remains a stem cell
Embryonic Stem cells
in blastocyst (32cell) that can grow and differentiate into all of the cell types in the body
cell lines of ES can
be made that divide in an undifferentiated state or can be induced to differentiate in several directions
ES are used to make
knock out mice
ES have the potential for
replacement organs and tissues - therapeutic cloning
Engineered stem cells (close to ES cells)
transfer nucleus of adult differentiated cell to an ovum in which the nucleus has been removed. Transfer an ovum to surrogate mother to develop into embryo (embryonic stem cells)
Ethical and biological accuracy problems because of
adult pattern of histone methylation and aberant gene expression
another engineering method
transfect differentiated adult cells with combinations of genes from ES cells
(Oct3/4, Sox2, c-myc, Kfl4, Nanog, Lin28) and
culture in vitro.
These are known as
induced pluripotent stem cells (iPS)
and have been used in mice to reverse
sickle cell disease
Adult stem cells
cell in certain areas of various organs (niches) of mature individuals that have limited capacities for division/differentiation (like basal cells that turn into karytinocytes)
Adult stem cells are found in
the bone marrow -
hematopoetic (HSCs) and
stromal (SCx)
HSCs can make
all blood cells but also may be able to form other types such as neurons
Stromal cells can make
cartilage,
bone ,
muscle ,
fat cells
Multipotent Adult Progenitor Cells are found in
the bone marrow
MAPCs can divide
in culture without snescence
MAPCs can be induced to form
meso,
endo, and
neuroectodermal cells
MAPCs from all sites have similar
gene expression profiles suggesting similar origin
tissue stem cells
committed to cell type of tissue origin
Tissue stem cells in the liver
most regeneration hepatocytes but stem cells that form oval cells also contribute
Tissue stem cells in the brain
prototype of nonproliferative tissue, but division of neurons occurs in hippocampus and periventricular areas
tissue stem cells in skeletal muscles
satellite cells
pluriSC to endothelial cells
VEGF
FGF2
pluriSC to chondroblasts
sox9
pluriSC to osteoblasts
CBFA1
pluriSC to fat cell
PPARgamma
pluriSC to myotube
myoD,
myogenin,
other
stemcells in homeostasis and repair
in most tissues either parenchyma or intermediate stem cells (basal/crypt) contribut to renewal and repair.
They can divide but are commited and are at leveles of differentiation beyond a true tissue stem cell.
The stemcells replenish the pool of replicating comited stem cells. during injury, stemcells kick in if commited or parenchymal cells cant handle the job.
