1. Red bone marrow, erythropoiesis. Formation of leukocytes
Dr. Zita Puskár
EM I. (Gr 1-8) 21/11/2016

2. Formed elements of the blood
Red blood cells (erythrocyte)
White blood cells (leukocytes)
Agranulocytes
Lymphocytes
Monocytes
Granulocytes
Neutrophils
Eosinophils
Basophils
Platelets (thrombocytes)
Scanning electron microscop image from normal circulating human blood
Red blood cells (4-6 million/mm3)>Platelets ( /mm3)>white blood cells ( /mm3)

4. Name, (functions,) diameter, N or % and lifetime
Monocyte
D≈ µm, % = 4-6
T= months
Platelet
D≈ 2-3 µm, N= thousands
T=7-11 days
Small lymphocyte
D≈ 5-7 µm, % = 20-30
T= depending on the type 3 2 4 1
Red blood cell/erythrocyte
D≈ 7.5 µm, N=4-6 million
T= 120 days
Basophil granulocyte
D≈ µm, %=
T= 3-10 days
Eosinophil granulocyte
D≈ µm, %= 2-4
T= 6 days
Neutrophil granulocyte
D≈ µm, %=60-70
T= 3 days 5 6 7

5. Hemopoiesis/Hematopoiesis
Hemopoiesis: the process by which blood cells are formed.
Adult myelopoiesis – bone marrow
Erythropoiesis: formation of erythrocytes
Granulo(cyto)poiesis: formation of granulocytes
Monocytopoiesis: formation of monocytes
Thrombocytopoiesis: formation of thrombocytes (platelets)
Adult lymphopoiesis - bone marrow and lymphatic tissues
Lymphopoiesis: formation of lymphocytes

6. What we need for this?
A STEM CELL
What is a Stem Cell?

7. Hierarchy of Stem Cells
Totipotens stem cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg are also totipotent. These cells can differentiate into embryonic and extraembryonic cell types. „They have potential to create an entire organism.”
Pluripotent stem cells are the descendants of totipotent cells and can differentiate into cells derived from any of the three germ layers. „They can give rise to any cell, without the potential to create an entire organism.”
Multipotent stem cells can produce only cells of a closely related family of cells (e.g. stem cells differentiate into red blood cells, white blood cells, platelets, etc.). „They give rise to cells with a specific purpose and function.”
Unipotent cells can produce only one cell type, but have the property of self-renewal which distinguishes them from non-stem cells.
Multipotent

8. Hematopoietic Stem Cell (HSC)
HSC possess the ability of :
multi-potency (is the ability to differentiate into all functional blood cell) and
self-renewal (is the ability to give rise to HSC itself without differentiation).
Niche

9. Hematopoietic Stem Cell (HSC)

10. Formation of blood cells
Hematopoietic Stem Cell (HSC)
Pluripotential (true) stem cells: self-renewal, enormous proliferation, differentiation into multiple cell lineage
Myeloid SC Lymphoid SC
multipotential stem cells
CFU-Gemm
CFUs progenitor cells B T
Colony Forming Unit Cells: proliferate and differentiate into precursor cells in the presence of appropriate growth factors, cytokines,
morphologically indistinguishable from stem cells
BLASTs precursor cells proB T NK
Specific Colony Forming Cells
display different morphological characteristics

11. Synthesis and accumulation of hemoglobin Basophilia → Eosinophilia
Erythropoiesis
Synthesis and accumulation of hemoglobin ↓
Basophilia → Eosinophilia
Extrusion of the nucleus → Reticulocyte

12. Erythroid island

13. Regulating factors
Decrease of O2 → Erythropoietin (EPO, Kidney, Liver),
Growth/Differentation
IL-1, IL-3, IL-6
CSF-E (Colony Stimulating Factor- Erythro)
Maturation
Vitamin B12
Folic acid
Hemoglobin synthesis
Fe, Cu, Zn, Co
Vitamin C
Hormones

14. Megakaryopoesis - thrombopoesis
nuclear endomitosis → 64N DNA
Megakaryoblast ↓
Promegakaryocyte
Megakaryocyte
Thrombocytes
(platelets)
diploid 2n
poliploid 4n, 8n, 16n, 32n, 64n
Platelet: irregularly shaped fragments of megakaryocytes
Regulating factor : Thrombopoietin (Liver)

16. Megakaryopoesis - thrombopoesis
Megakaryoblast ↓
Promegakaryocyte
Megakaryocyte
Thrombocytes

17. Granulopoiesis Myeloblast ↓ Promyelocyte (azurophilic granules)
(specific granules→neurophil, basophil, eosinophil)
Metamyelocyte
(beggining the formation of lobulated nucleus, increased number of specific granules)
mature immature mature
basophil neutrophil eosinophil
„band”
(segmentation of the nucleus)
mature neutrophil

18. Granulopoiesis Myeloblast ↓ Promyelocyte (azurophilic granules)
(specific granules→neurophil, basophil, eosinophil)
Metamyelocyte
(beggining the formation of lobulated nucleus, increased number of specific granules)
mature immature mature
basophil neutrophil eosinophil
„band”
(segmentation of the nucleus)
mature neutrophil

19. Monopoesis

20. Lymphopoiesis

21. Embryonic hemopoiesis
Intrauterine – fetal hemopoiesis
First or prehepatic phase – blood islands in the wall of yolk sac
Second or hepatosplenothymic phase – liver and lymphatic tissues
Third or medullolymphatic phase – bone marrow and lymphatic tissues
Blood development:
Pimitive wave (1) →
Definitive wave (2-3)

22. Primitive wave in extra embryonic yolc sac
erythrocyte
tissue oxygenazition
Erythroid progenitor
not pluripotent
do not have renewal capability
macrophage

23. Definitive wave in embryo proper
19-day: the splanchnopleura is hemogenic
27-40-day: the aorta-gonad-mesonephros (AGM) region

24. Multipotent lymphomyeloid stem cells in the ventral site of the aorta
Tavian et al: Int J Dev Biol. 2010; 54(6-7):  
Fig. 1. Hematopoietic stem cell clusters inside human embryonic arteries. (A) Cross sections of a 34-day human aorta (Ao) stained with the anti-CD34 (green) and anti-CD45 (red) antibodies. Arrows indicate the clusters of hematopoietic stem cells adhering to the ventral aspect of the aortic endothelium (white arrowhead). (B) Confocal images at higher magnificationof the region included in the dotted white line in panel A show the changed morphology of endothelial cells underlying hematopoietic clustered progenitors (arrow).
Fig. 2. Expression of BB9/angiotensin-converting-enzyme (BB9/ACE) in the human embryo. Cross sections through the dorsal aorta (Ao) in a 34-day embryo. BB9/ACE is expressed by hematopoetic CD34+CD45+ cell clusters associated with the endothelium on the ventral site of the aorta (arrowheads), as well as by underlying endothelial CD34+ cells (white arrowheads).

25. Migration to the fetal liver and the spleen

26. …finally to the red bone marrow

27. 1. articular cartilage 2. spongy bone 3. compact bone 4
1. articular cartilage 2. spongy bone 3. compact bone 4. medullary/marrow canal 5. yellow bone marrow 6. periosteum 7. proximal epiphysis 8. diaphysis 9. distal epiphysis

28. Bone marrow aspirate

29. Red bone marrow A M S

30. Composition of red bone marrow
Specialized blood vessels sinuses (diameter: 50 –70 μm)
which are interposed between arteries and veins
Reticular fibers
Sponge like network of hemopoetic, reticular
and other cells
Sinuses: endothelial lining
basal lamina (barely)
outer (adventitial) reticular cell layer support for the developing blood cells
reticular fiber production
stimulating the differentiation of stem cells into blood cells
Cell types: developing blood cells, megakaryocytes, macrophages, mast cells, plasma cells, fat cells
Transitory opening of the sinusoids – aperture – basal lamina and the adventitial cells become displaced

33. Hematopoietic Stem Cell Transplantation
For patients with life threatening diseases (eg. multiple myeloma, leukemia)
HSC can be derived from:
bone marrow
peripheral blood
umbilical cord blood
Autologus - the patient’s own HSCs
Allogenic - the HSCs from a donor