8/3- Stem Cells and Hematopoiesis Flashcards Preview

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Flashcards in 8/3- Stem Cells and Hematopoiesis Deck (16):

What is hematopoiesis (def)? Characteristics?

Process of formation, development and differentiation of formed elements of blood

  • Very dynamic process
  • Highly regulated to maintain normal function
  • Hierarchal system


Three basic hematopoietic organs? Time frame?

Yolk sac: 16 days (blood islands)

Liver: 6 weeks (also placenta)

Bone marrow: 5 months


What organ(s) is/are responsible for postnatal hematopoiesis?

- Bone marrow

- Thymus


What organ is responsible for T-cell development?

At what age does this start?

Thymus: 7-8 weeks


When does aortogonadomesonephros form?

20-30 days


Developmental hematopoiesis process (figure)?


What is the basic hierarchy of hematopoietic stem cells (HSCs)?

Hematopoietic stem cell

- Lymphoid progenitors -> T cells, B cells, NK cells, dendritic cells

- Myeloid progenitors -> RBCs, Megakaryocytes/platelets, Monocytes/macrophages, Granulocytes 


Hematopoiesis chart (figure)


What are hematopoietic stem cells (HSCs) broadly? Cell markers?

Rare cells that are indistinguishable morphologically from lymphocytes

- Express certain cell markers, such as CD34 and have other characteristics that identify/separate them


Characteristics of HSCs?

- Multipotential; giving rise to all other hematopoietic cells

- Self-renewal: thereby able to maintain HSC numbers

- Quiescent: only dividing every few months (thought to be promoted by niche factors within bone marrow; protective against transformation and cancer development)


What are hematopoietic progenitor cells?

Especially in regard to HSCs?

More differentiated than HSCs

- Not multipotent

- No capacity for self-renewal

Have increased proliferative capacity

Have surface expression of specific receptors for hematopoietic growth factors

Divided into common myeloid progenitors and common lymphoid progenitors


What is myelopoiesis?

Refers to production of myeloid elements

Controlled by several growth factors, some of which affect multi-lineage, while others are restricted to one line:

- Erythropoeisis: Erythropoietin

- Platelet production: thrombopoietin

- Granulocyte production: granulocyte colony stimulating factor

Growth factors are used in many clinical settings


What is Lymphopoiesis: B cell differentiation (chart)?


What is Lymphopoiesis: T cell differentiation (chart)?

[typo in pic- should have opposite CD markers) 


Where does hematopoiesis occur?

Special micro-environment of the bone marrow stroma

- Matrix includes: endothelial cells, adipose cells, macrophages, fibroblasts, and ECM proteins


Where/how does stem cell trafficking occur?

Out of (mobilization) or into (homing) the matrix under influences of specific cytokines