Lecture 1: The blood and bone marrow

Question 1

What is cytopeania?

Answer 1

Abnormal blood cells, no specified

Question 2

What is pancytopaenia?

Answer 2

All platelets, WBC, RBC

Question 3

What are the 8 main lineages of cells in blood?

Answer 3

Erythroid - RBC

Granulocytes:

• Neutrophils
• Eosinophils
• Basophils

Megakaroyocytes - Monocytes

Lymhpoid cells - NK cells, B cells, T cells

platelets

All short lived…

Question 4

What are the heamopoetic tissues of the body?

Answer 4

Bone marrow - Sternum, ribs, sacrum, vertebrae, long bones

Spleen (remaining 5%)

Question 5

What is heamatopoesis?

Answer 5

Process by which mature blood cells are generated from stem cells in the bone marrow

Question 6

When is heamatopoesis required?

Answer 6

Constantly, RBC have relatively short lives.

During stress i.e RBC loss, infection, additional cell growth required too.

Question 7

Describe the heamopoetic stem cell heirarchy:

Answer 7

HSC (heamopoetic stem cells) -> CFU-s -> MPP -> CLP or CMP and this determines if it forms lymphocytes or everything else.

Question 8

What is the origin of heamopoetic tissues in the fetus?

Answer 8

Liver.

Has shifted from the aorta-gonad-mesonephros area + Yolk sac (blood islands) + Placenta

Then from liver to bone

Question 9

Whats the importance of placental contribution to heamopoetic stem cells?

Answer 9

Placental heamopeotic stem cells / primitive cells can be collected and used to build blood banks

Question 10

How does heamopoesis change from infant to adult?

Answer 10

Infancy
- Heamatopoiesis present in all bones
Adult
- Proximal axial skeleton
- Marrow space increasingly replaced with fat
- BUT can revert to fetal patterns in disease state

Question 11

In disease states what can happen to heamopoetic tissues?

Answer 11

Heamopoesis can expand into the long bones, the liver and spleen can revert back to heamopoetic roles (extramedullary heamopatoesis) i.e splenomegaly

Question 12

Whats a routine diagnosis to assess heamatopoeisis?

Answer 12

Iliac crest bone marrow collection

Question 13

Describe the appearance of adult bone marrow:

Answer 13

• Heamopoetic marrow can be present in trabecular bone
• Decreases with age
• Heamopoetic cells and bone marrow stromal cells (microenvironment)

Question 14

What cells create the heamopoetic bone marrow microenvironment?

Answer 14

• Fibroblasts, Macrophages, fat cells and endothelial cells

Physical support and a microenvironment

Question 15

What is the life span of RBC, platelets and neutrophils?

Answer 15

RBC - 120 days
Platelet - 5-6 days
Neutrophil - 5-6hrs

Question 16

Where does the maturation of heamopoetic cells occur?

Answer 16

Bone marrow

Question 17

What proportion of the bone marrow population are heamopoetic stem cells?

Answer 17

Very small fraction, cant be identified under the microscope

Human stem cells express CD34 and this is used to measure stem cells

Question 18

What are the sources of heamopoetic stem cells?

Answer 18

Bone marrow
Peripheral blood (can also be stimulated to circulate in higher numbers to avoid bone marrow biopsy)
Umbilical cord

Question 19

Whats the benefits of collecting umbilical cord stem cells?

Answer 19

Can be stored and transplanted, more niave so they dont have to be closely monitored

Question 20

How is heamatopoesis regulated?

Answer 20

Microenvironment

Key regulators i.e transcription factors -> EKLF or NF-E2

Question 21

What are some growth factors of heamatopoesis?

Answer 21

Growth factors determine the final product of HSC…

i.e EPO for RBC development, TPO (Thrombopoietin) for platelets, G-CSF (granulocyte colony stimulating factor) for neutrophils, M-CSF for monocytes

Question 22

What is a full blood count?

Answer 22

Peripheral blood cells, i.e complete blood count.

Looking at morphology under microscope etc.

Question 23

What is assessed in a bone marrow aspirate?

Answer 23

• Cytological examination of haematopoietic cells
• Bone marrow trephine produces a core biopsy which is good for histological examination of marrow architecture and cellularity.