Stem cells Flashcards
Progenitors
Cells that proliferate for a limited number of cycles before differentiation
Cell lineage
developmental history of a differentiated cell as traced back to the cell form which it arises
Blastomere
the cell type of the early embryo that is generated by cleavage of the zygote
Blastocyst
the spherical embryo at the time of implantation, consisting of the primary tissue types
What are the three primary tissue types?
trophectoderm
epiblast
primitive endoderm
Trophectoderm
precursor of the placenta
Epiblast
the founding tissue of the embryo proper that gives rise to all fetal tissues
Primitive endoderm
extraembyronic tissue that initially covers the epiblast surface and later gives rise to the yolk sac tissue
Potency
ability of a cell to differentiate into one or more cell types
Totipotency
ability of a cell to give rise to a fully functional organism, both embryonic and extraembryonic tissues
Pluripotency
ability of a cell to develop into all embryonic but not extraembryonic cell types, including the germ cells
What are the hallmarks of pluripotency?
expression of pluripotency TFs
teratocarcinoma formation
Germ layers
the first specialised precursors of different embryonic cell types
Ectoderm
Surface, neural and neural crest
makes skin, PNS and CNS
Mesoderm
axial, paraxial, intermediated and lateral
makes blood, heart, muscle and kidneys
Endoderm
gut and internal organs
makes liver, pancreas, intestines
How is cell lineage decided during gastrulation?
in a regionalised manner- so the location of a cell predicts its identity in response to distinct signals that activate lineage specific TFs
Epithelium
cells that line the surface of a structure, characterised by tight junctions and polarised morphology
Epithelial to mesenchymal transition
a process during which cells lose their epithelila characteristics, gain a less regular appearance and become migratory
breakdown of basement membrane and loosening of cell cell contacts
Neuromesodermal progenitors
bipotent- paraxial mesoderm
future skeletal muscle, bone, cartilage and vertebrae
OR spinal cord
What do defects in neuromesodermal progenitors lead to?
spina bifida
currarino syndrome
sacral agenesis
sponylocostal dysotosis
What do haematopoietic stem cells give rise to?
all blood cell types
Aorta-gonad-mesonephros region
embryonic tissue originating from the para-aortic sphlanchopleura and consisting of the dorsal aorta and urogenital ridges
involved in generating HSCs prior to onset of haematopoisis in fetal liver
Why are embyros and stem cells difficult to study?
they have small cell numbers and have difficulties with in utero development and ethics
How do you capture pluripotent embryonic stem cells?
plate on layer of feeder cells (irradiated stromal cells from later embryos)
once they have divided a few times disaggregate and replate
What are the critical signals to maintain cells in a self-renewing undifferentiated state?
mice- leukaemia inhibitory factor
humans- FGF2 and TGF beta
What are the main pluripotency factors expressed by ESCs?
Oct4
Nanog
Sox2
3D
remove signals that keep cells in an undifferentiated state such as BMP and LIF (mice) and FGF2 (humans)
grow in aggregates in the presence or absence of signals
Advantages of 3D approach
recapitulates more accurately ambryonic development