Stem cells overview Flashcards
What are the 4 kinds of stem cells?
1)embryonic (pluripotent) 2)cord blood (multipotent) 3)adult blood-derived (multipotent) 4)adult (multi/oligo/uni)
What is a paradigm?
One that serves as a pattern or model
Where does self-renewal of hESC occur?
In vitro, not vivo
What are problems/limitations with stem cells?
differentiation in vit is not the same thing as in viv, PLUS a defining characteristic of embryonic stem cells is their capacity to form teratomas invivo, in other words, undifferentiated cells are tumourigenic
What does the mesoderm give rise to?
muscles, blood, bv’s, connective tissues and the heart
What does the ectoderm give rise to?
brain, spinal cord, nerve cells, hair skin teeth
what does the endoderm give rise to?
the gut (pancreas, stomach, liver etc) lungs, bladder and germ cells
What 4 things define an embryonic stem cell?
1) self renewal 2)pluripotent differentiation potential 3)immortal 4)surface antigens and transcription markers
Self renewal?
cycles of division that repeatedly generate at least one daughter equivalent to the mother cell with latent capacity for differentiation. the DEFINING property of stem cells
Pluripotent differentiation potential?
capable of forming all 3 germ layers of developing embryo.
immortal?
endogenous telomerase activity protects telomere ends and confers protection from mortality
surface antigens and transcription markers?
oct4, nanog. and sugar molecules found on cell surfaces.
What are the 7 stages of current isolation protocols? XENO-FREE
1) fresh/frozen IVF cleavage stage embryos obtained 2)cultured to blastocyst stage 3)pronase to remove zona pellicula 4)immunosurgery to remove trophoblast 5)plated on specialised media 7)mechanical dissociation initially then dispase to dissociate
What can human fibroblasts be ustilised as?
basement membrane
What does Xeno-free protocol remove?
contamination potential
What did the isolation protocols used to do differently?
plate on irradiated mouse embryonic fibroblasts. very laborious
What are 2 controls of self renewal?
Transcription factors (genes controlling expression of genes required for self renewal and repress expression of genes requires for differentiation) and soluble factors.
What are the 4 stages of initial isolation?
Fertilisation, cleavage, early blastocyst and implantation.
What is the fertilisation stage?
Oocyte + sperm = zygote
What is the cleavage stage?
1)zygote cleaves into paired blastomeres 2) blastomeres are contained within zona pellicula (protective outer membrane) 3) Continuted cleavage into 16 cells, now called Morula 4) leaves fallopian tube and enters uterine cavity
What is the zona pellicula?
The protective outer membrane
What is the early blastocyst stage?
1)cell division continues 2)blastocele cavity forms 3)cells flatten and compact on the inside of the cavity, zp remains same size, now called a blastocyst (two cell types, embryoblast which is inner cell mass and trophoblast)
Where are embryonic stem cells derived from?
the preimplantation blastocyst inner cell mass
What are solutions to the problems/limitations associated with stem cells?
1) application of hESC to bioreactor technology with approximation to tissue architecture and biochemical/physical signalling solves the in vitro/vivo shiz 2)removal of undifferentiatied hESC through genetic modification or cell sorting solved tumorigenicity
What is the STILL THERE problem with tumoriegenicity?
Even after cells are no longer hESC there is persistant undifferentiated expansion - progenitor cells also carry a safety hazard
What is UCB?
Umbilical cord blood stem cells which are no longer a waste product
What are UCB an alternative to?
BM transplantation, as it is a richer source of haematopoietic stem cells (HSC)/per volume than BM or peripheral blood AND less graft vs host disease
