The document discusses the origin and development of blood cells through the process of hematopoiesis. It describes how hematopoietic stem cells in the bone marrow differentiate into the various blood cell lineages through regulated stages of proliferation and maturation. Key points covered include the major sites of hematopoiesis, growth factors involved in lineage commitment and differentiation, and the morphological changes that occur as progenitors mature into red blood cells, white blood cells, platelets or megakaryocytes. The process of hematopoiesis is tightly controlled to maintain blood cell homeostasis.
2. Defination : “The processes involved in the production of all of the various cells of the blood
from the HSCs are collectively called hematopoiesis”
Highly regulated process -- to maintain circulating cell numbers within relatively constant
levels and to respond rapidly to conditions requiring extra cells .
Maintains balance between self-renewal, terminal differentiation, migration, and cell
death.
3. 3 wk : formation of blood islands from yolk
sac
Primitive hematopoiesis
Definitive hematopoietic tissue
LTR-HSC (produce all lineages)
6 wk : liver becomes hematopoietic organ
6-8 wk : spleen (until 8th month)
12-14wk : bone marrow (life-long)
4.
5. Bone marrow/Medullary Hematopoiesis
In children :
Axial skeleton:
Cranium
Ribs.
Sternum
Vertebrae
Pelvis
Appendicular skeleton:
Bones of the Upper & Lower limbs
In Adults in:
• The axial skeleton
• The proximal ends of the appendicular skeleton.
8. -0.5% of total hematopoietic precursor cells
Multilineage differentiation potential
Population maintained by self renewal
Quiescent cell population
Stable population size
Not morphologically recognizable
9. 3% of total HPC
Restricted developmental potential
Multipotential – unipotential
Transit population with restricted self renewal
Population amplified by proliferation.
Not morphologically recognizable
10. >95%
Transit population, numerically amplified by proliferation
Proliferative sequence completes before full maturation
Morphologically recognizable
11.
12. Pluripotent Stem cells:
Has a diameter of 18 – 23 μ.
Giving rise to: both Myeloid and Lymphoid series of cells
Capable of extensive self-renewal.
Myeloid Stem cells:
Generate myeloid cells:
Erythrocytes
Granulocytes: PMNs, Eosinophils & Basophils.
Megakaryocytes
Lymphoid Stem cells:
Lymphocytes - B, T cells, Plasma cells, NK cells
13.
14. Cellular Extra cellular
•Adipocytes
•Endothelial cells
•Fibroblasts
•T- cells
•Macrophages
•Soluble factors – cytokines, GF
•ECM – collagen, GAGs,
cytoadhesion molecules
•Expression of homing
receptors.
•GFs
•Membrane proteins
•ECM components
•Regulation of HSC, PGC
differentiation
•Structural support
•Cell – cell interactions
•Adhesion of precursors to ECM
proteins
15.
16. Glycoprotein hormones
Regulate
proliferation , differentiation and survival of haemopoietic precursor cells
the function of mature blood cells.
Source : T lymphocytes, monocytes, marcrophages and stromal cells.
except for :
erythropoietin, (90% synthesized in kidney)
thrombopoietin, (liver)
17. Multiple biological activities (Pleiotrophy)
Similar or identical activities ( redundancy )
Individually – poor, function – interplay of several GFs together
Interact with membrane receptors - lineage specific
Requirements change during differentiating process
Affect hematopoiesis directly or indirectly
Act synergistically with other cytokines
19. GM-CSF
Granulocyte-Macrophage colony stimulating factor
M-CSF
Macrophage colony stimulating factor
Erythropoietin
Erythropoiesis stimulating hormone
(These factors have the capacity to stimulate the proliferation of
their target progenitor cells when used as a sole source of
stimulation)
Thrombopoietin
Stimulates megakaryopoiesis
20. Quiescent state of stem cells
Oppose the actions of positive regulators
Includes –
Interferons
TGF-β – Induces apoptosis
TNF – inhibits all CFUs
PGEs – inhibit granulopoiesis and monopoiesis
Acidic isoferritins
Lactoferrin - from mature neutrophils – feedback inhibition
Di OH vitamin D3
T and NK cells
SCI/MIP 1α - inhibit stem cells
22. Local environmental control
Stromal cell mediated Haemopoiesis
Haemopoietic
growth factors (Humoral regulation)Apoptosis
There should be a balance between cell production and cell death except at the times of requirement
23.
24.
25. BFU-E: Burst Forming Unit – Erythrocyte:
Give rise each to thousands of nucleated erythroid precursor
cells, in vitro.
Undergo some changes to become the Colony Forming Units-
Erythrocyte (CFU-E)
Regulator: Burst Promoting Activity (BPA)
28. Orthochromatic normoblast •10-15 microns
•Small and pyknotic nucleus
•Pink- salmon cytoplasm
•Mitoses absent
Reticulocyte •Reticular nuclear fragments
•Nucleus extruded
•Slightly larger than RBCs
Erythrocyte •7.5m in diameter
•Anucleate
•Salmon color
29. ERYTHROPOIESIS
15-20µm- basophilic cytoplasm, nucleus with
nucleoli.
14-17µm-mitosis, basophilic cytoplasm, nucleoli
disappears.
10-15µm-’POLYCHROMASIA’
Hb appears, nucleus condenses.
7-10µm- PYKNOTIC Nucleus.
Extrusion, Hb is maximum.
7.3µm- Reticulum of basophilic material in the
cytoplasm.
7.2µm- Mature red cell with Hb.
30. MOST IMPORTANT REGULATOR :
“TISSUE OXYGENATION”
ERYTHROPOIETIN
IRON
VITAMINS:
Vitamin B12
Folic Acid
MISCELLANEOUS
35. Granulocyte Maturation
• Includes neutrophils, eosinophils, basophils
• Regulated by IL-3,GM-CSF, G-CSF
• Bone Marrow: Four stages,
– Most granulocytes are neutrophils;
• Marrow & Blood: Immature band form
– Normal to low % of band neutrophils in the blood
– An increased %of immature neutrophils in the blood(e.g, bands, metas) is called a
‘left shift’
• Blood: Mature segmented form
• Short lifespan, 1-2 days after marrow release
36. Size (µm) Nucleus Cytoplasm N:C ratio Granules CD
markers
Matura
tion
transit
time
Myeloblast
(0.2-1.5)
14-20 Round-oval ,
delicate lacy
chromatin,
nucleoli
Deep blue High Absent CD13,33,
34,38
1 day
Promyelocyte
(2-4)
15-21 Round- oval,
more
condensed
than blast,
nucleoli
Deep blue High Large, reddish purple,
primary (azurophilic)
CD33,38 1-3
days
Myelocyte (8-
16)
12-18 Round-oval,
chromatin
more
condensed
Light pink, blue
patches
Decreased Small pink red, (specific
granules)
Azurophilic granules,(dec)
secretory vesicles.
1-5
days
Metamyelocyt
e (9-25)
10-18 Kidney bean
shape,
condensed
chromatin
pink decreased Small pink red specific
granules, few azurophilic,
secretary vesicles
0.5-4
days
Band (9-15) 9-15 Horse shoe
shaped
Pink Decreased Abundant small pink red
specific granules, few
azurophilic, secretory
vesicles, tertiary granules
0.5-4
days
Polymorphon
uclear ( 6-12)
9-15 Segmented, 2-
4 lobes
pink Decreased As in band CD 15,
16,11b,18
1-5 days
44. Monocytopoiesis
MONOBLAST •Large cell (15-25 )
•Nucleus oval
•Cytoplasm without granule or few azurophlic
granule
•Differentiate to the Promonocyte
PROMONOCYTE Divide twice in the course of their
development into monocytes
MONOCYTE •Mature monocytes enter the
bloodstream, circulate.
then enter the connective tissues,
where they mature into macrophages.
•CD 11b,13,14,15
Macrophage •CD 68
56. • Devoid of cytoplasm
• Ingested by macrophages
57. PPSC CFU- GEMM
IL 3 & 6 , 11
IL-3 & GM-CSF
CFU- MEGA
IL-3 , TPO
TPO
MEGAK’BLAST
MATURE
FUNCTIONING
MEGA
IL-6 and IL-11 act in syn
IL-3
Maturation of
megakaryocytes
Increases platelet
production
No effect on
ENDOMITOSIS
TPO is primary regulater of
thrombopoiesis
Also k/a mpl ligand or
(MGDF)
MAJOR physiologic regulator
of megakaryocyte proliferation
and platelet production
Influences all stages
Tpo levels are inversely prop
to platelets counts
7days