Stem cells

Question 1

Give the definition of a stem cell.

Answer 1

Primitive cells that are capable of self renewal, making a range of cell types (pulripotent/ multipotent), and conversion into different cell types.

Question 2

What are the stem cells which can be derived both pre and post implanation?

Answer 2

hESCs- Human Embryonic Stem Cells

EpiSC- Epiblast Stem Cells

Question 3

Give an example of a stem cell source which can only be derived pre-implantation?

Answer 3

XEN- Extraembryonic endoderm stem cells (from yolk sack)

TS- Trophoblast stem cells

Question 4

Give and example of a stem cell source which can only be derived post-implantation?

Answer 4

Foetal

Adult/tissue specific

Question 5

Describe the process which allows stem cells to be derived from the blastocyst.

Answer 5

Derived from blastocyst in vitro
“immunosurgery” to remove trophoectoderm using “anti-trophoectoderm” antibodies which induce complement mediated killing.
leaving just inner cell mass🡪 isolated and cultured

Question 6

Describe some of the risks associated with using stem cells in the treatment of disease. (4 marks)

Answer 6

Lack of efficacy
Side effects
Cancer
Immuno-rejection

Question 7

How would you confirm the presence pluripotent stem cells?

Answer 7

Gene expression testing e.g. qPCR/ microarrays to look for the presence of several gene markers known to be present.
Functional testing- implanting into immune compromised mouse and growing a tetroma. Should be able to differentiate the 3 different cell layer types.

Question 8

Why is gene expression testing an imperfect method for identifying pluripotent stem cell material?

Answer 8

None of the gene markers that we are looking for are 100% tissue specific. We therefore need to look at several different markers together to make sure.

Question 9

How could you make an induced pluripotent stem cell?

Answer 9

Start out as somatic differentiated stem cells, remove the methylation and genetic marks on the DNA through viruses.

Question 10

What use would there be to create an induced pluripotent stem cell?

Answer 10

Can capture specific genome from a population/disease

Drug testing on normal and effected phenotypes

Question 11

How is invitro stem cell differentiation directed?

Answer 11

Exogenous signalling ligand.