Lecture 16 Hematopoiesis

Question 1

List the characteristics of Stem Cells

Answer 1

May proliferate extremely well
Self-renewing
May differentiate into several (at least 2) different cell-types
May reconstitute tissues after injury

Question 2

Define Totipotent Cells

Answer 2

Give rise to all cells of an organism, including embryonic and extraembryonic tissues (cells which support embryonic development)

Question 3

Define Pluripotent Cells

Answer 3

Give rise to all cells of the embryo and subsequently adult tissues (embryonic stem cells

Question 4

Define Multipotent Cells

Answer 4

Give rise to different cell types of a given lineage (adult stem cells)

Question 5

Where are embryonic stem cells derived from?

Answer 5

Inner-cell mass of blastocyst

Question 6

What is the developmental capacity of an embryonic stem cell?

Answer 6

Pluripotent, differentiate to all cell lineages

Question 7

Where do adult stem cells come from?

Answer 7

Harvested from mature organs/tissues (bone marrow)

Question 8

What is the developmental capacity of an embryonic stem cell?

Answer 8

Multipotent

Question 9

Describe the hematopoietic sites during weeks 2-8 of gestation

Answer 9

Islands of hematopoiesis (blood islands) found in yolk sac wall
Give rise to nucleated erythrocytes
No leukocytes form during this phase

Question 10

Describe the hematopoietic sites during week 8-28 of gestation

Answer 10

Hematopoiesis first occurs in liver and then spleen

Normally ceases around time of birth

Question 11

Describe hematopoietic sites during six weeks gestation to birth and beyond

Answer 11

Hematopoiesis occurs in red bone marrow

Question 12

_______ is the source of all blood cells

Answer 12

Red marrow

Question 13

Prior to puberty, where does red marrow exist?

Answer 13

Skull, ribs, sternum, vertebrae, clavicles, pelvis, long bones

Question 14

After puberty, where does red marrow exist?

Answer 14

Same as before, except long bones

Question 15

Describe Extramedullary Hematopoiesis

Answer 15

In certain disease states, blood cell formation may occur in liver and spleen

Question 16

In time, most marrow is converted to yellow marrow, and red marrow is usually restricted to where?

Answer 16

Sternum and iliac crests

Question 17

Describe the stroma of bone marrow

Answer 17

Contains fibroblasts, reticular cells, adipose cells, & endothelial cells
Synthesizes & secretes hematopoietic growth factors

Question 18

Describe the parenchyma of bone marrow

Answer 18

Consists of various lineages of hematopoietic cells in different stages of differentiation

Question 19

Describe the sinusoids of bone marrow

Answer 19

Endothelial-lined spaces that connect arterial & venous vessels
Provides access for mature blood cells to move into the circulation

Question 20

Describe the hematopoietic cords of the bone marrow

Answer 20

Bands of parenchyma and stroma lying between the sinusoids

Where the actual blood cell formation is occurring

Question 21

What is the distribution of hematopoietic cells?

Answer 21

60% in granulocytopoiesis
30% in erythrocytopoiesis
10% in thrombocytopoiesis, monocytopoiesis, and lymphocytopoiesis

Question 22

Myeloid/erythroid ratio

Answer 22

Total volume of cells in granulocytopoiesis/total volume of cells in erythrocytopoiesis

Question 23

Name the characteristics of hematopoietic stem cells

Answer 23

Pluripotent
Can self-renew
Produce two kinds of multipotent precursor cells
Cannot be identified by morphology but can be recognized by cell surface markers

Question 24

What are the two multipotential precursor cells produced by hematopoietic stem cells?

Answer 24

Myeloid stem cells

Lymphoid stem cells

Question 25

What do myeloid stem cells give rise to?

Answer 25

All blood cell lines except lymphocytes

Question 26

What do lymphoid stem cells give rise to?

Answer 26

Lymphocytes

Question 27

What are the five kinds of colony-forming units that myeloid stem cells give rise to?

Answer 27

``` Erythroid CFU (from myeloid, but prod. RBCs) Megakaryocyte CFU (from myeloid, prod. RBCs) Basophil CFU (white blood cells) Eosinophil CFU (white blood cells) Granulocyte-Macrophage CFU (white BCs) ```

Question 28

Lymphoid Stem Cells give rise to what two kinds of cell lines?

Answer 28

T-cell progenitor | B-cel progenitor

Question 29

Where do T-cell progenitor cells mature?

Answer 29

In the Thymus

Question 30

Where do B-cell progenitor cells mature?

Answer 30

In the Bone Marrow

Question 31

List the series for Granulocyte-Macrophage CFU (macrophage series)

Answer 31

Monoblast - can divide Promonocyte Monocyte - normally found in circulation Macrophage

Question 32

List the series for Granulocyte-Macrophage CFU (neutrophil series)

Answer 32

``` Myeloblast - can divide Promyelocyte - can divide Myelocyte - can divide Metamyelocyte Band Cell - found in circulation Neutrophil - found in circulation ```

Question 33

List the series for Eosinophil and Basophil CFU

Answer 33

``` Myeloblast - can divide Promyelocyte - can divide Myelocyte - can divide Metamyelocyte Band cell - found in circulation Eosinophil or Basophil (becomes mast cell) - found in circulation ```

Question 34

List the series for the Megakaryocyte CFU

Answer 34

Megakaryoblast Megakaryocyte Platelets - found in circulation

Question 35

List the series for Erythroid CFU

Answer 35

``` Proerythroblast - can divide Basophilic erythroblast - can divide Polychromatophilic erythroblast - can divide Orthochromatic erythroblast Reticulocyte - found in circulation Erythrocyte - found in circulation ```

Question 36

What produce hematopoietic growth factors and cytokines?

Answer 36

Endothelial cells in the marrow, fibroblasts, and stromal cells

Question 37

What are the three major groups of hematopoietic growth factors?

Answer 37

Colony - stimulating factors Erythropoietin and thrombopoietin Cytokines (primarily interleukins)

Question 38

What produces granulocyte/monocyte colony-stimulating factor (GM-CSF)?

Answer 38

Endothelial cells, T cells, fibroblasts, and monocytes

Question 39

What do GM-CSFs stimulate?

Answer 39

Granulocytopoiesis and Monocytopoiesis

Question 40

Granulocyte colony stimulating factor directs:

Answer 40

CFU-G to proliferate and differentiate into myeloblasts

Question 41

What can be used following chemotherapy or radiation therapy to treat neutropenia?

Answer 41

Granulocyte colony stimulating factor (G-CSF)

Question 42

Monocyte colony stimulating factor commits:

Answer 42

CFU-GM to monocytic pathway

Question 43

Erythropoietin directs:

Answer 43

CFU-E to proliferate and differentiate into proerythroblasts

Question 44

Where is erythropoietin produced and in response to what?

Answer 44

Produced in the kidney in response to decrease in oxygen stimulation

Question 45

What is secondary polycythemia?

Answer 45

Any abnormal increase in total RBC mass resulting from hypoxia and stimulating release of erythropoietin

Question 46

What are the possible causes of secondary polycythemia?

Answer 46

Tetralogy of fallot and cigarette smoke

Question 47

Thrombopoietin directs formation of:

Answer 47

Megakaryoblasts

Question 48

Where is thrombopoietin produced?

Answer 48

In proximal convoluted tubules of kidney | In parenchymal cells & sinusoidal endothelial cells of the liver

Question 49

What do cytokines do?

Answer 49

Mediate positive and negative affects on cellular quiescence, apoptosis, proliferation, and differentiation

Question 50

Examples of Cytokines

Answer 50

Interleukin-3 GM-CSF Fit-3 ligand Kit ligand

Question 51

Name other ECM components that also play a role in hematopoietic growth regulation

Answer 51

Heparin Sulfates Collagens Laminin Fibronectin

Question 52

What do chemokines do?

Answer 52

Regulate blood cell trafficking and homing to sites of need | May serve as positive and negative growth regulators

Question 53

What do chemokines bind to?

Answer 53

Guanine protein-coupled transmembrane receptors

Question 54

Give an example of a chemokine

Answer 54

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