Stem cells overview

Question 1

What are the 4 kinds of stem cells?

Answer 1

1)embryonic (pluripotent) 2)cord blood (multipotent) 3)adult blood-derived (multipotent) 4)adult (multi/oligo/uni)

Question 2

What is a paradigm?

Answer 2

One that serves as a pattern or model

Question 3

Where does self-renewal of hESC occur?

Answer 3

In vitro, not vivo

Question 4

What are problems/limitations with stem cells?

Answer 4

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

Question 5

What does the mesoderm give rise to?

Answer 5

muscles, blood, bv’s, connective tissues and the heart

Question 6

What does the ectoderm give rise to?

Answer 6

brain, spinal cord, nerve cells, hair skin teeth

Question 7

what does the endoderm give rise to?

Answer 7

the gut (pancreas, stomach, liver etc) lungs, bladder and germ cells

Question 8

What 4 things define an embryonic stem cell?

Answer 8

1) self renewal 2)pluripotent differentiation potential 3)immortal 4)surface antigens and transcription markers

Question 9

Self renewal?

Answer 9

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

Question 10

Pluripotent differentiation potential?

Answer 10

capable of forming all 3 germ layers of developing embryo.

Question 11

immortal?

Answer 11

endogenous telomerase activity protects telomere ends and confers protection from mortality

Question 12

surface antigens and transcription markers?

Answer 12

oct4, nanog. and sugar molecules found on cell surfaces.

Question 13

What are the 7 stages of current isolation protocols? XENO-FREE

Answer 13

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

Question 14

What can human fibroblasts be ustilised as?

Answer 14

basement membrane

Question 15

What does Xeno-free protocol remove?

Answer 15

contamination potential

Question 16

What did the isolation protocols used to do differently?

Answer 16

plate on irradiated mouse embryonic fibroblasts. very laborious

Question 17

What are 2 controls of self renewal?

Answer 17

Transcription factors (genes controlling expression of genes required for self renewal and repress expression of genes requires for differentiation) and soluble factors.

Question 18

What are the 4 stages of initial isolation?

Answer 18

Fertilisation, cleavage, early blastocyst and implantation.

Question 19

What is the fertilisation stage?

Answer 19

Oocyte + sperm = zygote

Question 20

What is the cleavage stage?

Answer 20

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

Question 21

What is the zona pellicula?

Answer 21

The protective outer membrane

Question 22

What is the early blastocyst stage?

Answer 22

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)

Question 23

Where are embryonic stem cells derived from?

Answer 23

the preimplantation blastocyst inner cell mass

Question 24

What are solutions to the problems/limitations associated with stem cells?

Answer 24

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

Question 25

What is the STILL THERE problem with tumoriegenicity?

Answer 25

Even after cells are no longer hESC there is persistant undifferentiated expansion - progenitor cells also carry a safety hazard

Question 26

What is UCB?

Answer 26

Umbilical cord blood stem cells which are no longer a waste product

Question 27

What are UCB an alternative to?

Answer 27

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