Haematopoiesis

Question 1

Define stem cells, transient amplifying cells and mature cells.

Answer 1

Stem cells: Cells that have both the capacity to self-renew as well as to differentiate into mature, specialized cells at the clonal level

Transient Amplifying Cells: Cells that are immature but have lost the capacity to self renew. Highly proliferative and amplify the output of rare stem cells.

Mature cells: Cells that carry out specialized tissue functions. May or may not have lost most proliferative capacity.

Question 2

How do you show clonality?

Answer 2

Single Cell Assays
Retroviral Tagging and Southern Blot
Chromosome tagging/Translocations

Question 3

How can we identify hematopoietic stem cells?

Answer 3

1. Isolate single “HSC” or clonally marked groups of “HSCs”
2. Inject into lethally irradiated recipients that permit identification of injected cells
3. Wait 16-20 weeks
4. Show that at the clonal level, all blood cells came from a single donor
5. Repeat

Question 4

Where do the first hematopoietic cells come from in embryogenesis? Where do they go from there?

Answer 4

1st site - Blood Islands of the Yolk Sac
2nd site - Aorta Gonad Mesonephros
3rd site - Fetal liver - E10 to birth
Last - Bone marrow

Question 5

What is the difference ebtween embryonic and adult hematopoiesis?

Answer 5

Time
EH - Short (1-2 days to make a yolk sac red cell)
AH - Long (1w)

RBC
EH - nucleated
AH - non-nucleated

Globin
EH - embryonic globins
AH - adult globins

Location
EH - >1 location
yolk sac, AGM, fetal liver, spleen, bm
AH - only 1 location

Question 6

Do Yolk Sac and AGM stem cells develop independently or does one seed the other? How would you tell?

Answer 6

Tissue chimeras
- Chimera, in genetics, is an organism/tissue that contains at least 2 different sets of DNA, most often originating from the fusion of as many different zygotes (fertilized eggs)
- Put a quail embryo body in a chick blastoderm

Question 7

How do cells home and traffic?

Answer 7

1. Naive homing to Lymph Nodes
2. Inflammatory homing

Question 8

What is the HPC Trafficking Process?

Answer 8

1. Rolling adhesion
2. Tight binding
3. Diapedesis
4. Migration

Question 9

What are the three classes of proteins involved in the HPC trafficking process

Answer 9

Selectins and selectin ligands
Integrins and their ligands
Chemokines and chemokine receptors