Lecture 1: The blood and bone marrow Flashcards
What is cytopeania?
Abnormal blood cells, no specified
What is pancytopaenia?
All platelets, WBC, RBC
What are the 8 main lineages of cells in blood?
Erythroid - RBC
Granulocytes:
- Neutrophils
- Eosinophils
- Basophils
Megakaroyocytes - Monocytes
Lymhpoid cells - NK cells, B cells, T cells
platelets
All short lived…
What are the heamopoetic tissues of the body?
Bone marrow - Sternum, ribs, sacrum, vertebrae, long bones
Spleen (remaining 5%)
What is heamatopoesis?
Process by which mature blood cells are generated from stem cells in the bone marrow
When is heamatopoesis required?
Constantly, RBC have relatively short lives.
During stress i.e RBC loss, infection, additional cell growth required too.
Describe the heamopoetic stem cell heirarchy:
HSC (heamopoetic stem cells) -> CFU-s -> MPP -> CLP or CMP and this determines if it forms lymphocytes or everything else.
What is the origin of heamopoetic tissues in the fetus?
Liver.
Has shifted from the aorta-gonad-mesonephros area + Yolk sac (blood islands) + Placenta
Then from liver to bone
Whats the importance of placental contribution to heamopoetic stem cells?
Placental heamopeotic stem cells / primitive cells can be collected and used to build blood banks
How does heamopoesis change from infant to adult?
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
In disease states what can happen to heamopoetic tissues?
Heamopoesis can expand into the long bones, the liver and spleen can revert back to heamopoetic roles (extramedullary heamopatoesis) i.e splenomegaly
Whats a routine diagnosis to assess heamatopoeisis?
Iliac crest bone marrow collection
Describe the appearance of adult bone marrow:
- Heamopoetic marrow can be present in trabecular bone
- Decreases with age
- Heamopoetic cells and bone marrow stromal cells (microenvironment)
What cells create the heamopoetic bone marrow microenvironment?
- Fibroblasts, Macrophages, fat cells and endothelial cells
Physical support and a microenvironment
What is the life span of RBC, platelets and neutrophils?
RBC - 120 days
Platelet - 5-6 days
Neutrophil - 5-6hrs
Where does the maturation of heamopoetic cells occur?
Bone marrow
What proportion of the bone marrow population are heamopoetic stem cells?
Very small fraction, cant be identified under the microscope
Human stem cells express CD34 and this is used to measure stem cells
What are the sources of heamopoetic stem cells?
Bone marrow
Peripheral blood (can also be stimulated to circulate in higher numbers to avoid bone marrow biopsy)
Umbilical cord
Whats the benefits of collecting umbilical cord stem cells?
Can be stored and transplanted, more niave so they dont have to be closely monitored
How is heamatopoesis regulated?
Microenvironment
Key regulators i.e transcription factors -> EKLF or NF-E2
What are some growth factors of heamatopoesis?
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
What is a full blood count?
Peripheral blood cells, i.e complete blood count.
Looking at morphology under microscope etc.
What is assessed in a bone marrow aspirate?
- Cytological examination of haematopoietic cells
- Bone marrow trephine produces a core biopsy which is good for histological examination of marrow architecture and cellularity.
